JPS6338546B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ignition device for an internal combustion engine, and particularly to a capacitor discharge type ignition device for an internal combustion engine.

[Prior art] A capacitor discharge type ignition system for an internal combustion engine charges an ignition energy storage capacitor with the output of one half cycle of an exciter coil, and ignites the charge in this capacitor through a discharge control thyristor at the engine ignition position. A high voltage for ignition is induced in the secondary coil of the ignition coil by discharging the primary coil of the coil. In conventional ignition devices of this type, a signal coil that generates a signal that determines the ignition position was provided separately from the exciter coil, and the output of this signal coil gave an ignition signal to the thyristor.However, recently, the exciter coil A device that uses the output of the thyristor to provide an ignition signal to a thyristor has come into use. 1st
The figure shows the circuit of a conventional ignition system that uses the output of an exciter coil to give an ignition signal to a discharge control thyristor. It is an exciter coil. One end of the exciter coil 1 is grounded, and the other end is connected through a diode 2 to one end of an ignition energy storage capacitor 3. The other end of the capacitor 3 is connected to one end of a primary coil 4a of an ignition coil 4, and the other end of the ignition coil 4a is connected to an anode of a diode 5 whose cathode is grounded. A diode 6 with an anode facing the capacitor 3 is connected in parallel to both ends of the primary coil 4a, and a spark plug 7 attached to a cylinder of the engine is connected to both ends of the secondary coil 4b. An anode of a discharge control thyristor 8 is connected to one end of the capacitor 3, and a cathode of the thyristor 8 is connected to an anode of the diode 5. One end of a resistor 9 and the anode of a Zener diode 10 are connected to the gate of the thyristor 8.
The other end of the resistor 9 is connected to the cathode of the thyristor 8. A resistor 11 is connected between the cathode of the Zener diode 10 and the cathode of the thyristor 8, and the cathode of a diode 12 whose anode is grounded is connected to the connection point between the resistor 11 and the cathode of the Zener diode 10, and the cathode is connected to the anode of the thyristor 8. The anode of the connected diode 13 is connected. Further, the cathode of a diode 14 is connected to one end of the non-grounded side of the exciter coil 1, and the anode of the diode 14 is connected to the thyristor 8.
connected to the cathode of In this circuit, a Zener diode 10, a resistor 11, and diodes 12 to 14 constitute a signal circuit 20 that provides an ignition signal to the thyristor 8.

In the ignition system shown in Fig. 1 above, the waveform of the no-load voltage Ve of the exciter coil 1 is as shown by the wire in Fig. 2A, and the output of one half cycle of this voltage (hereinafter referred to as positive direction output) causes the capacitor to 3 is charged to the polarity shown. Next, due to the output of the other half cycle of the exciter coil (hereinafter referred to as negative direction output), a current flows through the path of exciter coil 1 → diode 12 → resistor 11 → diode 14 → exciter coil 1, and a voltage drop occurs across resistor 11. occurs. The voltage V across this resistor 11
11 is above the Zener voltage of the Zener diode 10, a firing signal is given to the thyristor 8. As a result, the thyristor 8 becomes conductive, and the charge in the capacitor 3 passes through the thyristor 8 to the primary coil 4.
discharge to a. This discharge current causes the ignition coil 4 to
A large magnetic flux change occurs in the iron core of the secondary coil 4b.
High voltage induces This high voltage generates a spark in the spark plug 7, and the engine is ignited. In this ignition system, the waveform of the terminal voltage Vc of the capacitor 3 with respect to the engine rotation angle θ is as shown in Figure 2A, and the waveform of the charging current Ic of the capacitor 3 is as shown in Figure 2B. be. The waveform of the voltage V11 across the resistor 11 is as shown in FIG. 2C, and ignition occurs when this voltage V11 reaches the Zener voltage of the Zener diode 10, as described above. Note that the voltage across the resistor 11 is actually short-circuited due to the conduction of the thyristor 8. The waveforms indicated with symbols N ₁ to _{N 7} in FIGS. 3A to C are the engine rotational speeds (rpm) of N ₁ ,
The waveform when N ₂ ...N ₇ (N ₁ <N ₂ <N ₇ ) is shown.

[Problems to be Solved by the Invention] As is clear from the waveforms in FIGS. 3A to 3C, the angle at which charging of the capacitor 3 ends (θ ₁ , θ ₂ ...θ ₇ )
is delayed as the rotation speed increases, and the rise of the negative voltage of the exciter coil is also delayed, so the rise of the voltage V11 across the resistor 11 is also delayed as the rotation speed increases. .
Assuming that the Zener diode 10 has a Zener voltage of Vz1 shown in FIG. The amount of retardation increases in the high speed range. In this way, if the ignition position is significantly retarded in the high speed range, the performance of the engine in the high speed range deteriorates, which is undesirable.

On the other hand, if a Zener diode 10 with a Zener voltage of Vz1'(>Vz1) shown in FIG. The amount of retardation in the region can be significantly reduced. However, in this case, the rotational speed No' at which the ignition operation starts is the same as the rotational speed No' at which the ignition operation starts when a Zener diode with a Zener voltage of Vz1 is used.
This results in a problem that the starting speed of the engine becomes high. Further, in both curves a and b, there is a problem in that the ignition position is advanced when the engine is running at low speeds, resulting in unstable operation. In this way, with the conventional ignition system shown in Figure 1, the amount of retardation of the ignition position increases at high speeds, the operating rotational speed increases, or the ignition position advances at low speeds. The disadvantages are that the starting rotational speed is low, the ignition position hardly advances at low speeds, and it is not possible to obtain an ignition system in which the ignition position is hardly retarded at high speeds.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ignition system for an internal combustion engine that has a low starting rotational speed, has almost no advance in the ignition position at low speeds, and has a small amount of retardation at high speeds.

[Means for Solving the Problems] The present invention includes an exciter coil 1 that induces an alternating current voltage in synchronization with the rotation of an internal combustion engine, and an ignition coil 4.
and an ignition energy storage capacitor 3 which is provided on the primary side of the ignition coil 4 and is charged by the output of one half cycle of the exciter coil 1. An ignition device for an internal combustion engine comprising a discharge control thyristor 8 that causes discharge through the primary coil 4a of the ignition coil 4, and a signal circuit 20 that provides an ignition signal to the discharge control thyristor 8 at the ignition position of the engine. Solve the problem.

The signal circuit 20 of the present invention includes an exciter coil 1
The output voltage of the other half cycle of is equal to the predetermined threshold Vz
3 or more, the first signal supply circuit 11, 26 gives an ignition signal to the discharge control thyristor 8.
30 and the other half cycle output voltage of the exciter coil 1 reaches a set level Vz1 or higher, which is higher than the threshold Vz3 of the first signal supply circuit, a second signal that provides an ignition signal to the discharge control thyristor 8. When conduction occurs between the supply circuits 11, 10, the ignition position control capacitor 23, and the capacitor charging circuit 11, 21, which discharges the ignition position control capacitor 23 to a constant voltage by the output voltage of the other half cycle of the exciter coil 1. An ignition position control semiconductor switch is provided to prevent an ignition signal from being applied to the discharge control thyristor 8 through the first signal supply circuit, and conducts the charging current flowing through the ignition position control capacitor 23 as a conduction signal. It was composed of 24.

Further, an exciter shorting thyristor 15a is connected in parallel to the exciter coil 1 in such a direction that the output voltage of one half cycle of the exciter coil 1 is applied between the anode and the cathode in the forward direction.
A retard prevention circuit 15 is provided, which includes trigger circuits 15b to 15e that trigger the exciter short circuit thyristor 15a when the output voltage of one half cycle of the exciter coil 1 reaches the set value Vz2.

[Embodiments] Hereinafter, embodiments of the ignition device of the present invention will be described in detail with reference to FIGS. 3 to 6.

Embodiment 1 FIG. 3 shows the first embodiment of the present invention, in which each part designated with reference numerals 1 to 14 is the same as each part designated with the same reference numeral in FIG. It is equivalent. This embodiment differs from the circuit shown in FIG. 1 in that a delay prevention circuit 15 is added and in the configuration of a signal circuit 20. Retard prevention circuit 15
includes an exciter shorting thyristor 15a whose anode is connected to one end of the non-grounded side of the exciter coil 1 and whose cathode is grounded through a diode 5, and a resistor 15b is connected in parallel between the gate and cathode of this thyristor 15a. One end of the non-grounded side of the exciter coil 1 is also connected to one end of a resistive voltage divider circuit consisting of a series circuit of resistors 15c and 15d, and the other end of this voltage divider circuit is connected to a diode 5.
is grounded through. Further, a cathode of a Zener diode 15e is connected to a voltage dividing point of the voltage dividing circuit, and an anode of the Zener diode 15e is connected to a gate of a thyristor 15a. The resistors 15c, 15d and the Zener diode 15e constitute a trigger circuit that triggers the thyristor 15a when the positive output voltage of the exciter coil 1 reaches a set value, and this trigger circuit and the thyristor 15a form a delay prevention circuit 15. is configured. Further, in the signal circuit 20, the anode of a thyristor 26 as a signal supply semiconductor switch is connected to the connection point between the resistor 11 and the Zener diode 10, and the cathode of the thyristor 26 is connected to the gate of the thyristor 8 through a diode 27. Resistors 28 and 2 are connected between the anode gate and the gate cathode of the thyristor 26, respectively.
9 are connected in parallel, and a voltage V11 is applied across the resistor 11.
When this appears, an ignition signal is given to the thyristor 26 through the resistor 28. The collector of a transistor 24 as a semiconductor switch for controlling the ignition position is connected to the gate of the thyristor 26, and the emitter of the transistor 24 is connected to the cathode of the thyristor 26. A diode 25 is connected between the base and emitter of the transistor 24 with its anode facing toward the emitter of this transistor.
are connected in parallel, and one end of an ignition position control capacitor 23 is connected to the base of the transistor 24. The other end of the capacitor 23 is connected to the cathode of a Zener diode 22 whose anode is connected to the emitter of a transistor 24 and one end of the resistor 21, and the other end of the resistor 21 is a connection point between the resistor 11 and the cathode of the Zener diode 10. It is connected to the.

In the embodiment shown in FIG. 3, a thyristor 26, a diode 27, and resistors 28, 29 provide an ignition signal to the thyristor 8 when the negative voltage of the exciter coil 1 exceeds a predetermined threshold. When the first signal supply circuit is configured and the negative direction voltage of the exciter coil 1 becomes equal to or higher than the set level (Zener voltage of the Zener diode 10) which is higher than the threshold of the first signal supply circuit due to the Zener diode 10, A second signal supply circuit is configured to supply an ignition signal to the thyristor 8. Also, diode 12, resistor 11, resistor 2
1, Zener diode 22, capacitor 23,
The base-emitter circuit of the transistor 24 and the diode 5 constitute a capacitor charging circuit that charges the capacitor 23 to a constant voltage (Zener voltage of the Zener diode 22) using the negative voltage of the exciter coil 1. The transistor 24, which serves as a semiconductor switch for controlling the ignition position, is supplied with a base current (conducting signal) only during the period when the capacitor 23 is charged, and becomes conductive, so that the ignition signal supplied to the thyristor 26 is transferred from the thyristor 26 to the transistor 24. This prevents the ignition signal from being applied to the discharge control thyristor 8 through the thyristor 26.

Operation of Embodiment 1 First, the operation in the high speed region will be explained. Third
In the circuit shown in the figure, the positive output voltage of exciter coil 1 (approximately equal to the charging voltage of capacitor 3).
When Nz2 reaches the set value and the voltage across the resistor 15d reaches the Zener level of the Zener diode 15e, an ignition signal is input to the thyristor 15a. Thyristor 15a then becomes conductive and short-circuits exciter coil 1. As shown in FIG. 4A, the charging voltage Vc of the capacitor 3 is determined when the rotational speed is N ₁ , N ₂ ,
As the voltage rises as N ₃ , . . . , the rise becomes gradual, so that the phase in which the voltage across the resistor 15d reaches the Zener level of the Zener diode 15e is delayed. Therefore, the angular width at which the exciter coil 1 is short-circuited becomes narrower as the rotational speed increases. Figure 4B shows the charging current Ic of the capacitor 3 at the rotational speed _N1 to _N7 , and Figure C shows the charging current Ic at the rotational speed N1 to N7.
The anode current Ia of the thyristor 15a at _N1 to _N7 is shown. As is clear from these figures, the angular width at which the exciter coil 1 is short-circuited becomes narrower as the rotation speed increases, so the angle at which the anode current of the thyristor 15a ends is almost constant with respect to the rotation speed. It stops changing. Therefore, the rising angle of the negative direction voltage of the exciter coil 1 hardly changes with the rotation speed, and as shown in FIG. 4D, the voltage V11 across the resistor 11 does not change much even if the rotation speed changes. I won't. Therefore resistance 1
The rising position of the voltage V11 at both ends of the voltage V1 gradually stops changing as the rotation speed increases, and this voltage V1
1 is the Zener level of Zener diode 10
The position (igniter) that reaches Vz1 does not change much. Therefore, the ignition position α for the rotational speed N
The characteristics are as shown in FIG. 5B, and there is no delay in the ignition position in the high speed range. In addition, in Fig. 5B, TDC indicates the top dead center of the engine.

Next, the operation in the low speed region will be explained. resistance 1
1, the capacitor 23 is charged at a predetermined time constant through the resistor 21 and the base-emitter of the transistor 24, and the transistor 24 is conductive while the charging current of the capacitor 23 is flowing. This transistor 24
During the period in which the thyristor 26 is conducting, no firing signal is applied to the thyristor 26, so the thyristor 26 is in an off state. When the terminal voltage Vc2 of the capacitor 23 reaches the Zener level Vz3 of the Zener diode 22, the charging of the capacitor 23 ends, so the transistor 24 is turned off, and the voltage V11 across the resistor 11 gives an ignition signal to the thyristor 26. It will be done. Therefore, the thyristor 26 becomes conductive,
An ignition signal is given to the discharge control thyristor 8. When the engine speed N is in a low speed region lower than the set value _N2 , for example, when N= _N1 (< _N2 ),
The voltage V11 across the resistor 11 is set so as not to reach the Zener level Vz1 of the Zener diode 10. Therefore, in the low speed region, an ignition signal is applied to the thyristor 8 through the thyristor 26 at the angle θ ₁ where the terminal voltage Vc2 of the capacitor 23 reaches the Zener level Vz3 of the Zener diode 22, and ignition is performed. Next, when the engine speed N reaches the set value _N2 , the terminal voltage Vc2 of the capacitor 23 reaches the Zener level Vz3, and the voltage V11 reaches the Zener diode 1.
When the rotation speed exceeds the set rotation speed N ₂ and reaches, for example, N ₃ (>N ₂ ), the capacitor 23
The voltage V11 across the resistor 11 reaches the Zener level Vz1 of the Zener diode 10 before the terminal voltage Vc2 of the Zener diode 10 reaches the Zener level Vz3. Therefore, in the rotation range of the set rotation speed _N2 or higher, an ignition signal is applied to the thyristor 8 through the Zener diode 10 by the voltage V11, and an ignition operation is performed. Referring to Figure 5A, the voltage V when the rotational speed is N ₁ , N ₂ and N ₃
11 and capacitor 23 with respect to the rotation angle θ. As is clear from the figure, the charging voltage of the capacitor 23 (voltage V1
The slope of the rise in step 1) becomes steeper as the rotation speed increases, but the charging start position delays as the rotation speed increases, so the position where the terminal voltage Vc2 of the capacitor 23 reaches the Zener level Vz3 is ultimately It becomes approximately constant (=θ ₁ ), and in the low speed region of the engine (N<
The ignition position at N ₂ ) becomes approximately constant. Area exceeding the set rotation speed N ₂ (Zener diode 10
The operation in the region where the ignition signal is applied to the thyristor 8 through the thyristor 8 is as described above, and the delay prevention circuit 15 prevents the ignition position from being delayed in the high speed region. Therefore, the characteristics of the ignition position α with respect to the rotational speed N in the embodiment shown in FIG. 3 are as shown in FIG. By doing so, it is possible to obtain characteristics that become constant again in the high-speed region.

Embodiment 2 FIG. 6 shows a second embodiment of the present invention, in which the thyristor 26 in the embodiment of FIG. 3 is replaced with a resistor 30. In this embodiment, the terminal voltage Vc2 of the capacitor 23 is the Zener level Vz3 of the Zener diode 22.
When the transistor 24 is cut off, the thyristor 8 is connected through the resistor 30 and the diode 27.
The operation is similar to that of the embodiment shown in FIG. 3, except that the ignition signal is applied to the ignition signal.

Note that when the firing signal is given to the thyristor 8 through the resistor 30 at low speeds as in the embodiment shown in FIG. 3, when the firing signal is given to the thyristor 8 through the thyristor 26 as shown in FIG. It is inevitable that the rotational speed at which the ignition operation starts will be somewhat higher than that of the engine. Therefore, the embodiment of FIG. 3 is advantageous when it is necessary to have a particularly low engine starting speed.

[Effects of the Invention] As described above, according to the present invention, the exciter short-circuiting thyristor is provided in parallel with the exciter coil, and the half-cycle output voltage of the exciter coil that provides the firing signal to the discharge control thyristor is set. By making the exciter short circuit thyristor conductive when the value is reached, the position where the ignition signal is applied to the discharge control thyristor hardly changes in the high speed range of the engine, so the ignition position can be changed in the high speed range. This can prevent delays.

Further, since the first and second signal supply circuits that supply the ignition signal to the discharge control thyristor are provided and the threshold values of the two signal supply circuits are made different, the ignition operation starting rotation speed can be lowered.

Furthermore, the capacitor for ignition position control is charged to a constant voltage by the output of the other cycle of the exciter coil, and the capacitor is electrically connected only during the period when the charging current is flowing through the capacitor, and is discharged through the first signal supply circuit having a low threshold. By providing a semiconductor switch for controlling the ignition position that prevents the ignition signal from being applied to the control thyristor, the position at which the ignition signal is applied through the first signal supply circuit is kept approximately constant, thereby preventing ignition at low speeds. This has the advantage that the position can be kept approximately constant, and that the engine operation can be prevented from becoming unstable due to advancement of the ignition position at low speeds.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing a conventional example, Figure 2 A to C
1 is a voltage or current waveform diagram for explaining the operation of FIG. 1, FIG. 2D is a diagram showing the ignition characteristics of the ignition device of FIG. 1, and FIG. Circuit diagrams, FIGS. 4A to D are voltage or current waveform diagrams explaining the operation of the embodiment of FIG. 3, and FIGS. 5A and B.
are a voltage waveform diagram for explaining the operation of the embodiment shown in FIG. 3 and a line diagram showing the ignition characteristics obtained by the embodiment, respectively, and FIG. 6 is a circuit diagram showing the second embodiment of the present invention. be. 1...exciter coil, 2...diode, 3...
Ignition energy storage capacitor, 4... Ignition coil, 5... Diode, 7... Spark plug, 8... Thyristor for discharge control, 10... Zener diode,
11... Resistor, 12-14... Diode, 20... Signal circuit, 15... Retard angle prevention circuit, 15a... Thyristor for exciter short circuit, 15c, 15d... Resistor, 1
5e... Zener diode, 21... Resistor, 22...
Zener diode, 23...capacitor, 24...
Transistor, 25...Diode, 26...Signal supply thyristor, 27...Diode, 28-30
…resistance.

Claims (1)

[Claims] 1. An exciter coil that induces an alternating current voltage in synchronization with the rotation of an internal combustion engine, an ignition coil, and an exciter coil that is provided on the primary side of the ignition coil and has an output of one half cycle of the exciter coil. an ignition energy storage capacitor to be charged; a discharge control thyristor that discharges the charge of the ignition energy storage capacitor through a primary coil of the ignition coil when electrically connected; and a discharge control thyristor at the ignition position of the engine. and a signal circuit that provides an ignition signal to an ignition thyristor, wherein the signal circuit controls the discharge control when the output voltage of the other half cycle of the exciter coil exceeds a predetermined threshold. a first signal supply circuit that provides an ignition signal to the thyristor; and the discharge control when the output voltage of the other half cycle of the exciter coil exceeds a set level higher than the threshold of the first signal supply circuit. a second signal supply circuit that supplies an ignition signal to the thyristor; a capacitor charging circuit that charges the ignition position control capacitor to a constant voltage using the output voltage of the other half cycle of the exciter coil; and is provided so as to prevent an ignition signal from being applied to the discharge control thyristor through the first signal supply circuit when conductive, and conducts the charging current flowing through the ignition position control capacitor as a conduction signal. and a semiconductor switch for controlling the ignition position, and an exciter short circuit connected in parallel to the exciter coil in such a direction that the output voltage of the one half cycle of the exciter coil is applied in the forward direction between the anode and the cathode. and a trigger circuit that triggers the exciter short circuit thyristor when the output voltage of the one half cycle of the exciter coil reaches a set value. Engine ignition system.