JPH045736Y2 - - 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 internal combustion engine, the ignition timing of the internal combustion engine becomes almost constant, and the ignition timing (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, resulting in problems such as engine seizure.

As seen in Japanese Patent Application Laid-Open No. 59-7774, an integral capacitor is provided which is charged at a predetermined time constant during one revolution of the engine, and the voltage across the integral capacitor is compared with a reference voltage. An ignition system has been proposed in which the position where the voltages match is set as the ignition position, and the ignition timing is gradually delayed as the engine rotation speed increases in a region where the engine rotation speed exceeds a set value.

In this way, if the ignition timing is gradually delayed in the range above the set rotation speed, the increase in rotation speed will eventually be suppressed, but in this case, the effect of limiting the engine rotation speed will not be immediately realized. First, even if the engine rotational speed exceeds the set value, the rotational speed will increase for a while. Therefore, the characteristic of gradually retarding the ignition timing as the engine rotational speed increases is not suitable for the purpose of preventing the engine rotational speed from exceeding a permissible value and preventing engine seizure.

In order to prevent the engine rotation speed from exceeding the allowable value and reliably prevent engine seizure, it is necessary to rapidly retard the ignition timing when the engine rotation speed exceeds the set rotation speed (allowable rotation speed). .

SUMMARY OF THE INVENTION An object of the present invention is to provide an ignition system for an internal combustion engine that can suppress an increase in engine rotational speed by rapidly retarding ignition timing in a high-speed region of the 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
The first ignition timing control capacitor C2 is charged to one polarity by the output of one half cycle of the exciter coil Le, and the terminal voltage of the first ignition timing control capacitor C2 is constant through the current limiting means R4. The second battery is charged to one polarity with a time constant of
A reset switch Swr is connected in parallel to the ignition timing control capacitor C3 and the second ignition timing control capacitor C3, and conducts when triggered by a half-cycle output voltage generated after the signal coil Ls. , a charging voltage limiting Zener diode Z2 connected in parallel to both ends of the first ignition timing controlling capacitor C2 to limit the charging voltage of the first ignition timing controlling capacitor to a constant value, and a second ignition timing controlling capacitor C2. An ignition signal supply control switch that conducts when the terminal voltage of the timing control capacitor C3 reaches a set value and provides an ignition signal to the discharge control thyristor S1 with a half-cycle output voltage generated at the tip of the signal coil Ls. Swg and a retard signal supply circuit that supplies a firing signal to the discharge control thyristor S1 with a half-cycle output generated after the signal coil Ls, and are connected so that current flows through the signal coil Ls when conductive. and a signal voltage limiting Zener diode Z1 that becomes conductive to limit the terminal voltage of the signal coil when the output generated at the tip of the signal coil exceeds a certain level.

[Operation of the invention] In the above ignition device, the ignition timing control capacitor C2 is charged to one polarity with a constant voltage by the output of one half cycle of the exciter coil Le.
The voltage of the capacitor C2 charges the second ignition timing control capacitor C3 at a constant time constant. When the terminal voltage of this capacitor C3 exceeds a set value, the ignition signal supply control switch Swg becomes conductive and supplies an ignition signal to the thyristor S1 with a half-cycle output voltage Vs1 generated at the tip of the signal coil Ls. The charge in the second ignition timing control capacitor is discharged when the half-cycle output voltage Vs2 generated after the signal coil Ls rises and the reset switch is turned on.

If the engine speed is less than the set value, the terminal voltage of the second ignition timing control capacitor has already exceeded the set value when the output voltage Vs1 of the previous half cycle of the signal coil Ls is generated. , the ignition signal supply control switch Swg becomes conductive and provides an ignition signal to the thyristor S1. Therefore, when the engine speed is less than the set value, the output voltage Vs1 of the previous half cycle of the signal coil Ls is the output voltage of the thyristor S1.
The ignition operation is performed at the position of the angle θ1 where the trigger level is reached.

Thereafter, when the half-cycle voltage Vs2 generated after the signal coil Ls rises, an ignition signal is supplied to the thyristor S1 through the retard signal supply circuit, but at this time the ignition energy storage capacitor has already been discharged. has been completed, so there is no effect on ignition operation.

As the engine rotation speed increases, the charging period of the second ignition timing control capacitor becomes shorter, and when the engine rotation speed reaches the set value Ns, the voltage of the previous half cycle of the signal coil Ls decreases. When this happens, the terminal voltage of the second ignition timing control capacitor is still lower than the set value. Therefore, the switch for controlling the ignition signal supply cannot conduct at this time, and depending on the output voltage of the previous half cycle of the signal coil Ls, no ignition signal is supplied to the thyristor S1. In this state, the ignition signal is supplied from the retard signal supply circuit to the thyristor S1 by the output of the signal coil Ls in the next half cycle. Therefore, when the rotational speed of the engine exceeds the set value, the ignition operation is performed at the angle θ2 where the output voltage of the signal coil in the next half cycle reaches the trigger level.

Therefore, in the device of the present invention, as indicated by the symbol b in FIG.
In the region of Ns or more, the angle θ lags behind the angle θ1
Ignition occurs in position 2. 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 A resistor R1 is connected in parallel between the gate and cathode of the thyristor S1.

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 Fig. 2A with respect to the rotational angle θ of the engine, and in one half cycle (positive half cycle in this example) of this AC voltage, it passes through the diode D1 to the capacitor. C1 is charged to the polarity shown.

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 negative direction signal voltage, and the signal voltage of the half cycle generated later.
Vs2 is called a positive direction signal voltage. One end of the signal coil Ls is a Zener diode Z with its anode grounded.
The other end is connected to the gate of the thyristor S1 via a diode D3 whose anode is directed toward the signal coil. A diode D4 with its anode facing the ground is connected between the other end of the signal coil Ls and the ground. In this example, the circuit from the signal coil Ls to the gate of the thyristor S1 via the diode D3 is used for retarding the ignition signal to be supplied to the thyristor S1 using a half-cycle positive signal voltage Vs2 generated later in the signal coil. A signal supply circuit is configured. In addition, a PNP transistor TR1 is connected to one end of the signal coil Ls.
The emitter of this transistor is connected, and the collector of this transistor is connected to the anode of a diode D5 whose cathode is connected to the gate of the thyristor S1. The base of transistor TR1 is connected to the collector of transistor TR2 whose emitter is grounded, and resistor R2 is connected to the collector of transistor TR2.
connected via.

The anode of a diode D6 is connected to the non-grounded terminal of the exciter coil Le, and the diode D
The cathode of No. 6 is connected to one end of the first ignition timing control capacitor C2 via a resistor R3.
The other end of the capacitor C2 is grounded, and the first ignition timing control capacitor C2 is charged with the output voltage of one half cycle of the exciter coil Le through the diode D6 and the resistor R3 to the polarity shown.

A charging voltage limiting Zener diode Z2 with an anode facing the ground side is connected in parallel to both ends of the first ignition timing control capacitor C2, and the capacitor C2 is charged at a constant voltage up to the Zener voltage of the Zener diode Z2.

The anode of a diode D7 is connected to the non-grounded terminal of the capacitor C2 via a resistor R4 as a current limit blocker, and a second ignition timing control capacitor C3 is connected between the cathode of the diode D7 and the ground.
is connected. The non-grounded terminal of capacitor C3 is an NPN transistor whose emitter is grounded.
The collector of TR3 is connected and the transistor TR
The base of 3 is connected to the cathode of a diode D8 whose anode is connected to one end of the signal coil Ls. The transistor TR3 constitutes a reset switch Swr, and the base current is supplied to the transistor TR3 through the diode D8 by the positive direction signal voltage Vs2 outputted from the signal coil Ls. This allows the transistor TR
3 becomes conductive, and the capacitor C3 is instantaneously discharged across the collector and emitter of the transistor TR3. The cathode of a Zener diode Z3 is connected to the collector of the transistor TR3, and the anode of this Zener diode is connected to the collector of the transistor TR3.
Connected to the base of TR2.

In this example, diodes D2 to D8
, Zener diodes Z1 to Z3, capacitors C1 and C2, resistors R1 to R4, and transistors TR1 to TR3, and a discharge control thyristor trigger circuit T that uses the output of the signal coil Ls as an input to trigger the discharge control thyristor S1. is configured, and transistors TR1 and TR
2, resistor R2, and Zener diode Z3 conduct when the terminal voltage of the second ignition timing control capacitor C3 reaches the set value, and the signal coil
A switch Swg for the ignition signal supply control circuit is configured to provide an ignition signal to the thyristor S1 using the half-cycle output voltage (negative direction signal voltage Vs1) in which Ls is generated first.

In the embodiment described above, the ignition coil energy storage capacitor C1 is charged with the output voltage of one half cycle of the exciter coil Le through the diode D1 to the polarity shown. When an ignition signal is supplied from the trigger circuit T to the thyristor S1 at the ignition timing of the engine, the thyristor S1
becomes conductive, and the charge of capacitor C1 is transferred to thyristor S
1 and the primary coil of the ignition coil. This 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.

Further, by the output of one half cycle of the exciter coil Le, the first ignition timing control capacitor C2 is charged with a constant voltage to the polarity shown in the figure through the diode D6 and the resistor R3. This capacitor C2
Due to the terminal voltage of resistor R4 and diode D7
The second ignition timing control capacitor C3 is charged at a constant time constant. This capacitor C3
When the terminal voltage of becomes higher than the set value, Zener diode Z3 becomes conductive and transistors TR1 and TR
2, the base current flows through both transistors TR1,
TR2 becomes conductive. When the transistor TR1 conducts (when the ignition signal supply control switch Swg conducts), the half-cycle output voltage Vs1 generated at the tip of the signal coil Ls is applied to the thyristor S1 through the emitter-collector of the transistor TR1 and the diode D5. An ignition signal is provided.

The electric charge of the second ignition timing control capacitor C3 is increased by the rise of the half-cycle output voltage Vs2 generated after the signal coil Ls, which causes the charge of the transistor TR3 to rise.
When the reset switch Swg becomes conductive, a discharge occurs between the collector and emitter of the transistor TR3.

If the engine speed is less than the set value, the second
As shown in Figure B, when the output voltage Vs1 of the previous half cycle of the signal coil Ls is generated, the terminal voltage Vc3 of the second ignition timing control capacitor C3 has already been generated.
becomes higher than the set value Vt, the Zener diode Z3 becomes conductive, and as shown in FIG. 2D, the transistors TR2 and TR1 (ignition signal supply control switch Swg) become conductive. Therefore the signal coil Ls
Due to the negative direction signal voltage Vs1, the transistor TR1
A firing signal is applied to thyristor S1 through. In this way, when the rotational speed of the engine is less than the set value, the output voltage (negative direction signal voltage) Vs1 of the previous half cycle of the signal coil Ls is
The ignition operation is performed at the position of the angle θ1 where the trigger level of 1 is reached.

Thereafter, when the half-cycle voltage Vs2 generated after the signal coil Ls rises, an ignition signal is supplied to the thyristor S1 through the retard signal supply circuit, but at this time the ignition energy storage capacitor has already been discharged. has been completed, so there is no effect on the ignition operation.

As the rotational speed of the engine increases, the charging period of the second ignition timing control capacitor C3 becomes shorter. Since the charging voltage of the capacitor C3 is constant, when the engine speed reaches the set value Ns, as shown by the broken line in Fig. 2C, the voltage of the previous half cycle of the signal coil Ls is generated. The terminal voltage Vc3 of the ignition timing control capacitor C3 of No. 2 is still lower than the set value Vt. Therefore, at this point, the transistor of the switch Swg for controlling the firing signal supply
TR1 and TR2 cannot conduct, and depending on the output voltage of the previous half cycle of the signal coil Ls, no firing signal is provided to the thyristor S1.
In this state, the thyristor S1 is output from the retard signal supply circuit in the next half cycle of the signal coil Ls.
An ignition signal is supplied to the thyristor S1, and when the ignition signal becomes equal to or higher than the trigger level Vg at the angle θ2, the thyristor S1 becomes conductive. Therefore, when the engine rotational speed exceeds the set value, the angle θ at which the output voltage of the next half cycle of the signal coil reaches the trigger level
Ignition operation is performed at position 2.

As mentioned above, when the engine speed exceeds the set value, transistors TR1 and TR2 of the ignition signal supply control switch Swg are no longer conductive, and current no longer flows from the signal coil Ls through the switch Swg. The generated negative direction signal voltage Vs1 increases, but when the negative direction signal voltage Vs1 exceeds a certain value, the signal voltage limiting Zener diode Z1 becomes conductive and the signal coil Ls
Since current flows through the signal coil Ls, it is possible to prevent the no-load voltage of the signal coil Ls from increasing.

Therefore, in the device of the above embodiment, as indicated by the reference numeral b in FIG. 3, ignition is performed at the angle θ1 in the range below the set rotational speed Ns, and at the angle θ1 in the range above the set rotational speed Ns. Ignition occurs at a position at an angle θ2 that is delayed from 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.

[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, since a signal voltage limiting Zener diode is provided to prevent the half-cycle output generated after the signal coil from becoming excessive, there is an advantage that the withstand voltage of the elements connected to the signal coil can be lowered.

[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... First ignition timing control capacitor, C3... Second ignition timing control capacitor, D1 to D8... Diode, Z1 to Z3... Zener diode, R1 to R4... ...Resistance, 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. an ignition device for an internal combustion engine, comprising: a discharge control thyristor trigger circuit that receives the output of the exciter coil as an input and triggers the thyristor at the ignition timing of the internal combustion engine; a first ignition timing control capacitor that is charged to one polarity, and a second ignition timing capacitor that is charged to one polarity at a constant time constant through a current limiting means using the terminal voltage of the first ignition timing control capacitor. a control capacitor; a reset switch connected in parallel to the second ignition timing control capacitor and conductive when triggered by a half-cycle output voltage generated after the signal coil; a charging voltage limiting Zener diode connected in parallel to both ends of the ignition timing control capacitor to limit the charging voltage of the first ignition timing control capacitor to a constant value; an ignition signal supply control switch that conducts when the terminal voltage reaches a set value and supplies an ignition signal to the discharge control thyristor with a half-cycle output voltage generated at the tip of the signal coil; a retard signal supply circuit that supplies an ignition signal to the discharge control thyristor with a half-cycle output generated later; 1. An ignition device for an internal combustion engine, comprising a signal voltage limiting Zener diode that becomes conductive to limit the terminal voltage of the signal coil when a half-cycle output exceeds a certain level.