JPH045735Y2 - - 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 provided to discharge the charge of the ignition energy storage capacitor through the primary coil of the ignition coil when conductive, and an output voltage of the other half cycle of the exciter coil or a voltage corresponding to the output voltage. and a discharge control thyristor trigger circuit that has a pair of signal input terminals to which is applied as a signal voltage, and provides an ignition signal to the thyristor when the voltage between the signal input terminals reaches a predetermined level. A discharge type ignition system is used.

In this ignition system, an ignition energy storage capacitor is charged by the output of one half cycle of the exciter coil, and a trigger signal is supplied to the discharge control thyristor by the output of the other half cycle of the exciter coil at the engine ignition timing. Ru. This causes the discharge control thyristor to conduct, discharging the charge in the ignition energy storage capacitor to the primary coil of the ignition coil, and this discharge causes a large magnetic flux change in the iron core of the ignition coil, causing the secondary Next, a high voltage for ignition is induced in the 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.

[Problem to be solved by the invention] In the conventional capacitor discharge type internal combustion engine ignition system as described above, the output voltage of the other half cycle of the exciter coil or a voltage corresponding to this voltage reaches a predetermined trigger level. When the trigger signal is supplied to the discharge control thyristor, the ignition timing α (the angle measured from the top dead center of the engine toward the advance side) relative to the rotational speed N (rpm) of the internal combustion engine
The characteristic is as shown by the symbol a in FIG. 2, and is a characteristic in which the ignition timing is gradually delayed when the engine is running at high speed. With such characteristics, the rotational speed of the engine increases too much in the high-speed range of the engine, resulting in problems such as engine seizure. To prevent this, the second
As indicated by the symbol b in the figure, it is necessary to rapidly retard the ignition timing or cause a misfire at the set rotational speed Ns in the high speed region of the engine.

Furthermore, as seen in Japanese Patent Application Laid-Open No. 57-181971, there is a circuit that uses the output of the negative half cycle of the exciter coil to give a trigger signal to the thyristor for controlling discharge, and a circuit that uses the output of the positive half cycle of the exciter coil to charge up to a constant voltage. A circuit that transfers the charge of the capacitor to the auxiliary capacitor when the output of the negative half cycle of the capacitor and exciter coil reaches a set level, and a circuit that transfers the charge of the capacitor to the auxiliary capacitor when the engine rotation speed reaches the set value and the terminal voltage of the auxiliary capacitor increases. An ignition device has been proposed that includes a circuit that becomes conductive when a set value is reached and bypasses a portion of the trigger signal of the discharge control thyristor through the resistor.

According to this ignition device, a part of the trigger signal given to the discharge control thyristor by the output of the negative half cycle of the exciter coil is bypassed from the thyristor when the engine rotational speed reaches the set value. The phase in which the thyristor is triggered is delayed, and the ignition timing is delayed.

However, in this conventional ignition system, in order to trigger a circuit that transfers the charge of the capacitor charged to a constant voltage by the output of the positive half cycle of the exciter coil to the auxiliary capacitor,
Since a part of the output of the negative half cycle of the exciter coil used to trigger the discharge control thyristor is used, there is no need to delay the ignition timing, and there is a risk that the ignition timing will be delayed in the region lower than the set rotation speed. It was hot.

Additionally, in order to reliably prevent engine seizure due to overspeeding, it is sometimes desirable to cause the engine to misfire when the rotational speed exceeds a set value, but conventional devices Although it was possible to retard the ignition timing, it was not possible to cause a misfire.

Furthermore, in the above-mentioned conventional ignition system, in order to set the rotation speed at which the retardation starts, the timing of transferring the electric charge of the capacitor charged by the output of the positive half cycle of the exciter coil to the auxiliary capacitor, and the timing of transferring the electric charge of the capacitor to the auxiliary capacitor are determined. The problem is that the circuit design becomes complicated because three conditions need to be set appropriately: the discharge time constant of the discharge control thyristor, and the timing of triggering the circuit that bypasses a part of the trigger signal to the discharge control thyristor. It was hot.

The purpose of this invention is to provide an ignition system for an internal combustion engine that is capable of rapidly retarding the ignition timing when the engine speed exceeds a set value, and then causing the engine to misfire if the engine speed increases further. Our goal is to provide the following.

[Means for Solving the Problems] The present invention, as shown in FIG.
The ignition energy storage capacitor C is charged to one polarity by the output Ve1 of one half cycle of Le.
1, when electrical conduction occurs, the charge of the ignition energy storage capacitor C1 is transferred to the primary coil W of the ignition coil IG.
1, and a pair of signal input terminals t1 to which the output voltage Ve2 of the other half cycle of the exciter coil Le or a voltage corresponding to the output voltage is applied as a signal voltage. t2 and a thyristor trigger circuit ST for controlling a discharge that provides an ignition signal to the thyristor S1 when the voltage Vs between the signal input terminals reaches a predetermined trigger level. This allows the ignition timing to be rapidly delayed or misfire to occur at high speeds.

Therefore, in the present invention, there is provided a semiconductor switch 1 for controlling ignition timing which is connected in parallel between the signal input terminals t1 and t2 and which substantially short-circuits the signal input terminals when conductive, and an exciter coil Le.
The ignition timing control capacitor C3 is charged to a fixed voltage by the output of one half cycle of and a semiconductor switch trigger circuit 2 which continues to supply the discharge current of the ignition timing control capacitor to the ignition timing control semiconductor switch as a trigger signal current for a fixed trigger period. There is.

The discharge time constant of the ignition timing control capacitor C3 is set such that the trigger period ends after the time when the output of the other half cycle of the exciter coil Le rises when the rotational speed of the internal combustion engine reaches the set value. is set to

[Operation] In the above ignition system, when the engine speed is less than the set value Ns, the semiconductor switch for controlling the ignition timing is cut off before the output of the other half cycle of the exciter coil Le rises. , the semiconductor switch does not affect the conduction timing (ignition timing) of the discharge control semiconductor switch. In contrast, the engine rotational speed is the set value Ns
In this case, when the output of the other half cycle of the exciter coil Le rises, the trigger signal is still being applied to the ignition timing control semiconductor switch, so the output of the other half cycle of the exciter coil Le rises. At the same time, the semiconductor switch becomes conductive and substantially shorts the signal input terminals. If the signal terminals are short-circuited, the timing at which the discharge control thyristor is triggered is delayed. If the rotational speed further increases and the ignition timing control semiconductor switch remains conductive throughout the period in which the voltage between the signal input terminals exceeds the trigger level, the engine will misfire.

If a switch element with a self-holding function such as a thyristor is used as a semiconductor switch for ignition timing control, when the output of the other half cycle of the exciter coil Le rises when the rotational speed reaches the set value, approximately At the same time, the semiconductor switch becomes conductive and continues to substantially short circuit the signal input terminals for the entirety of the other half cycle of the exciter coil, causing the engine to misfire.

As described above, according to the present invention, when the engine rotation speed exceeds a set value, the ignition timing of the engine is suddenly delayed or the engine misfires, thereby preventing the engine rotation speed from increasing excessively. It is possible,
It is possible to prevent engine seizure.

In addition, with the above configuration, the set value of the rotational speed at which sudden retardation or misfire starts can be adjusted simply by adjusting the discharge time constant of the ignition timing control capacitor, which eliminates the need to adjust many conditions. The circuit design can be made easier compared to conventional ignition devices.

Furthermore, in the above configuration, the output of the other half cycle of the exciter coil (the output used to trigger the discharge control thyristor) is not used at all in the trigger circuit of the semiconductor switch for ignition timing control.
The trigger circuit does not affect the triggering of the discharge control thyristor in a region below the set rotational speed.

[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. Therefore the exciter coil Le
is one half cycle voltage (hereinafter referred to as positive direction voltage) Ve1, and the capacitor C1 is charged to the polarity shown in the figure through the diode D1.

The cathode of a diode D2 is connected to the non-grounded terminal of the exciter coil Le, and one of the pair of signal input terminals t1 and t2 of the trigger circuit ST that triggers the thyristor S1 is connected to the diode D2.
2 anodes. The other signal input terminal t2 is grounded, and a resistor R1 is connected between the signal input terminals t1 and t2. Signal input terminal t1
A signal storage capacitor C2 is connected between the capacitor C2 and the gate of the thyristor S1, and the cathode of a signal supply thyristor S2 whose anode is grounded is connected to the connection point between the capacitor C2 and the input terminal t1. Between the anode and gate of thyristor S2 is a Zener diode Z1 with its cathode facing the ground side.
is connected, and a resistor R2 is connected between the gate and cathode of the thyristor S2. Further, a resistor R3 is connected between the gate and cathode of the thyristor S1, and the thyristor S2, resistors R1 to R3, capacitor C2, and Zener diode Z1 provide
It has a pair of signal input terminals t1 and t2 to which the output voltage (hereinafter referred to as negative direction voltage) Ve2 of the other half cycle of the exciter coil Le or a voltage corresponding to the output voltage Ve2 is applied as the signal voltage Vs. A discharge control thyristor trigger circuit ST is configured to provide a firing signal to the thyristor S1 when the voltage Vs between the signal input terminals reaches a predetermined trigger level. That is, when the exciter coil Le outputs a negative direction voltage Ve2, a current flows through the resistor R1 and the diode D2, and the voltage drop generated across the resistor R1 due to this current becomes the signal voltage Vs.
used as. Further, the capacitor C2 is charged to the polarity shown in the figure by the negative direction voltage Ve2 of the exciter coil Le through the resistor R3 and the diode D2. When the voltage Vs across the resistor R1 exceeds a predetermined trigger level (Zener level Vz1 of the Zener diode Z1), a firing signal is given to the thyristor S2, so the thyristor S2 becomes conductive, and the charge in the capacitor C2 is transferred to the thyristor S1. Discharge occurs between the gate and cathode and through the thyristor S2. This discharge current supplies a firing signal to the thyristor S1, causing the thyristor S1 to conduct.

The anode of a diode D3 is also connected to the non-grounded terminal of the exciter coil Le through a resistor R4, and an ignition timing control capacitor C3 is connected between the cathode of this diode and the ground.
A charging voltage control thyristor S3 with its cathode facing the ground is connected between the anode of the diode D3 and the ground, and the cathode and anode of a Zener diode Z2 are connected to the anode and gate of the thyristor S3, respectively. A resistor R5 is connected between the gate cathode of the thyristor S3, and a resistor R5 is connected between the thyristor S3, the Zener diode Z2, and the resistor R.
5 constitutes a charging control circuit that controls the charging voltage of the capacitor C3 to a constant voltage. That is, the capacitor C3 is charged to the illustrated polarity through the diode D3 by the output voltage Ve1 of one half cycle of the exciter coil Le. The terminal voltage of capacitor C3 is Zener diode Z2
When the zener level Vz2 is reached, the thyristor S
Since the firing signal is supplied to the thyristor S
3 conducts, bypassing the charging current to capacitor C3 from the capacitor C3. Therefore, capacitor C
3 is charged to the Zener diode voltage Vz2 of the Zener diode Z2.

The cathode of a Zener diode Z3 is connected to the non-grounded terminal of the capacitor C3 through a resistor R6, and the base of an NPN transistor TR1 constituting the semiconductor switch 1 for controlling ignition timing is connected to the anode of the Zener diode Z3. The emitter and collector of the transistor TR1 are connected to the signal input terminals t1 and t2, respectively, and the cathode of the Zener diode Z3 and the signal input terminal t
1 and a resistor R7 is connected between the two. Further, a diode D4 with its cathode facing the ground side is connected between the signal input terminal t1 and the ground.

In this embodiment, the ignition timing control capacitor C3 is charged to a constant voltage by the output of one half cycle of the exciter coil Le by the thyristor S3, the Zener diode Z2, the diode D3, the resistor R5, and the ignition timing control capacitor C3. A charging circuit is configured. Also, capacitor C
3. Resistor R6, Zener diode Z3, base-emitter circuit of transistor TR1, resistor R7
A discharging circuit is configured by the diode D4 to discharge the charge of the ignition timing control capacitor C3 at a constant time constant through the trigger signal current conduction circuit of the ignition timing control semiconductor switch 1 (in this example, the base-emitter circuit of the transistor TR1). These charging circuits and discharging circuits constitute a semiconductor switch trigger circuit 2.

Next, the operation of the above embodiment will be explained. When the exciter coil Le outputs a positive voltage Ve1, the capacitor C1 is charged to the polarity shown through the diode D1, and at the same time, the capacitor C3 is charged to the polarity shown through the resistor R4 and the diode D3. When the terminal voltage of the capacitor C3 reaches the Zener voltage Vz2 of the Zener diode Z2, the thyristor S3 becomes conductive, so that charging of the capacitor C3 is stopped. The positive direction voltage of the exciter coil Le is the Zener voltage of the Zener diode Z2.
When it becomes lower than Vz2, the charge of capacitor C3 is transferred to resistor R6, Zener diode Z3, and transistor.
Discharge occurs between the base and emitter of TR1 and through the diode D4, and the transistor TR1 becomes conductive. The conduction state of this transistor TR1 is the voltage across the capacitor C3 (trigger signal voltage) Vts
This period continues for T1 until the voltage obtained by subtracting the voltage drop by the resistor R6 becomes lower than the Zener voltage of the Zener diode Z3 (this period is referred to as a trigger period in the present invention). The waveform of the voltage Vts across this capacitor C3 is shown in FIG. 3B.

When the exciter coil Le outputs a negative voltage Ve2, the capacitor C2 is charged through the resistor R3 and the diode D2, and at the same time, current flows through the resistor R1 and the diode D2, and a voltage Vs is generated across the resistor R1. When this voltage Vs exceeds the Zener voltage Vz1 of the Zener diode Z1, the charge of the capacitor C2 is discharged through the thyristor S2, and a firing signal is given to the thyristor S1. This causes the thyristor S1 to conduct and the charge on the capacitor C1 is discharged through the thyristor S1 and the primary coil W1 of the ignition coil. This discharge causes a large magnetic flux change in the iron core of the ignition coil, and a high voltage is induced in the secondary coil W2. Since this high voltage is applied to the spark plug P, a spark is generated in the spark plug, and the engine is ignited.

In the above embodiment, the trigger period T1 during which the trigger signal is applied to the semiconductor switch 1 is constant. When the engine speed is less than the set value, the supply of the trigger signal to semiconductor switch 1 (trigger period T1) ends before the output of the negative half cycle of the exciter coil rises, so the exciter Even when the output of the negative half cycle of the coil rises, the semiconductor switch 1 does not conduct, and the semiconductor switch 1 has no effect on the triggering of the discharge control thyristor S1. Therefore, in the region below the set rotation speed, the negative half cycle output characteristics of the exciter coil and the discharge control thyristor trigger circuit ST
The ignition characteristics are determined by the characteristics of.

When the rotational speed of the engine exceeds the set value, since the trigger signal is still being applied to the semiconductor switch 1 when the output of the negative half cycle of the exciter coil rises, the semiconductor switch becomes conductive. The signal input terminals t1 and t2 of the discharge control thyristor trigger circuit ST are substantially short-circuited. Since capacitor C2 of the trigger circuit is not charged during the period when signal input terminals t1 and t2 are short-circuited,
The phase in which the terminal voltage of the capacitor C2 reaches a level that makes the Zener diode Z1 conductive (the phase in which the signal voltage Vs reaches the trigger level) is delayed, and the ignition timing is delayed. The period during which the trigger signal input terminals are short-circuited becomes longer as the engine speed increases, so the ignition timing becomes more and more delayed as the engine speed increases, as shown by the broken line in Figure 2. A retard characteristic in which the ignition timing is rapidly delayed is obtained.

When the rotational speed of the engine further increases and the semiconductor switch 1 becomes conductive for the entire period in which the signal voltage Vs is equal to or higher than the trigger level, the trigger signal is no longer given to the discharge control thyristor S1, so the ignition operation is stopped. The engine will misfire.

In this way, with the ignition system of this embodiment, when the engine rotational speed exceeds the set value, the ignition timing of the engine is first delayed, and when the rotational speed further increases, the engine misfires, resulting in an excessive engine rotational speed. can be reliably prevented.

In the above embodiment, the transistor TR1 constituting the semiconductor switch 1 can be replaced with a thyristor S4 as shown in FIG. In this case, when the rotational speed reaches the set value Ns, the period (trigger period) T1 for which the firing signal is continued to be applied to the thyristor S4 is the negative direction voltage Ve of the exciter coil Le.
If the length of the trigger period T1 is set so that the state ends after the time when 2 rises, when the negative direction voltage Ve2 of the exciter coil Le is generated when the engine rotation speed reaches the set value Ns, At the same time, thyristor S4 becomes conductive and short-circuits resistor R1, so that an ignition signal cannot be applied to thyristor S1, and the engine does not ignite. That is, in this case, when the engine rotational speed exceeds the set rotational speed, the engine misfires, and an increase in engine speed is suppressed.

[Effects of the invention] As described above, according to the invention, when the engine rotational speed exceeds a set value, the ignition timing of the engine is suddenly delayed or the engine misfires. This has the advantage of preventing the engine from rising excessively and reliably preventing engine seizure.

In addition, according to the present invention, the set value of the rotational speed at which sudden retardation or misfire occurs can be adjusted simply by adjusting the discharge time constant of the ignition timing control capacitor, so it was necessary to adjust many conditions. It has the advantage that circuit design can be made easier compared to conventional ignition devices.

Furthermore, according to the present invention, since the semiconductor switch trigger circuit does not use the output of the other half cycle of the exciter coil (the output used to trigger the discharge control thyristor), the semiconductor switch trigger circuit does not use the output of the other half cycle of the exciter coil (the output used to trigger the discharge control thyristor). There is an advantage that the circuit does not affect the triggering of the discharge control thyristor.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing an embodiment of the present invention, Figure 2 is a diagram comparing the ignition characteristics obtained by the present invention with the ignition characteristics of a conventional device, and Figure 3 is a summary of Figure 1. FIG. 4 is a circuit diagram showing another example of the ignition timing control semiconductor switch used in the present invention. IG...Ignition coil, Le...Exciter coil,
P...Spark plug, C1...Ignition energy storage capacitor, C2...Signal storage capacitor,
D1-D4...Diode, Z1-Z3...Zener diode, R1-R7...Resistor, TR1...
...Transistor, ST...Thyristor trigger circuit for discharge control, 1...Semiconductor switch for ignition timing control, 2...Semiconductor switch trigger circuit.

Claims (1)

[Claim for Utility Model Registration] An ignition coil IG and an ignition energy storage capacitor C1 charged to one polarity by the output of one half cycle of an exciter coil Le disposed in a generator driven by an internal combustion engine. , when conductive, the ignition energy storage capacitor C1
A discharge control thyristor S1 is provided to discharge the electric charge through the primary coil of the ignition coil IG, and an output voltage of the other half cycle of the exciter coil Le or a voltage corresponding to the output voltage is used as a signal voltage. and a discharge control thyristor trigger circuit ST having a pair of signal input terminals t1 and t2 to which a voltage is applied, and giving an ignition signal to the thyristor S1 when the voltage between the signal input terminals reaches a predetermined trigger level. The ignition device for an internal combustion engine includes: a semiconductor switch 1 for ignition timing control that is connected in parallel between the signal input terminals t1 and t2 and substantially shorts the signal input terminals when conductive; and the exciter coil Le. The ignition timing control capacitor C3 is charged to a constant voltage by the output of one half cycle of the ignition timing control capacitor C3, and the charge of the ignition timing control capacitor C3 is kept constant through the energization path of the trigger signal current of the ignition timing control semiconductor switch 1. and a semiconductor switch trigger circuit 2 which continues to supply the discharge current of the ignition timing control capacitor to the ignition timing control semiconductor switch as a trigger signal current for a certain trigger period. The ignition timing control capacitor C is configured such that the trigger period ends after the time when the output of the other half cycle of the exciter coil Le rises when the rotational speed of the internal combustion engine reaches a set value.
An ignition device for an internal combustion engine, characterized in that a discharge time constant of 3 is set.