JPH0726605B2 - Capacitor discharge type internal combustion engine ignition device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a capacitor discharge type ignition device for an internal combustion engine.

[Prior Art] As a capacitor discharge type internal combustion engine ignition device,
As known from 57-120763, there is known a so-called pulsarless ignition device that uses a negative half-cycle voltage of a capacitor charging exciter coil as a signal for determining ignition timing without using a pulsar coil. Has been.

FIG. 5 shows a circuit configuration of a conventional pulsarless type capacitor discharge type internal combustion engine ignition device. In FIG. 5, 1 is an exciter coil arranged in a magneto generator driven by the internal combustion engine, and 2 is 1 Ignition coil having secondary coil 2a and secondary coil 2b, 3 is an ignition energy storage capacitor connected to the primary coil of the ignition coil, and 4 and 5 are charged in the capacitor 3 by the positive half cycle output of the exciter coil 1. A diode provided for flowing a current, 6 is a discharge control thyristor for discharging the electric charge of the capacitor 3 to the primary coil 2a, and 7 and 8 are negative half cycle outputs of the exciter coil 1 and send a trigger signal to the thyristor 6. A diode provided for giving, 9 is a resistor connected between the gate and cathode of the thyristor 6, and 10 is attached to a cylinder of an engine (not shown). The is a spark plug.

In this ignition device, the diode 4 and the primary coil 2a are driven by the positive half cycle output voltage of the exciter coil 1.
And the capacitor 3 is charged to the polarity shown through the diode 5. Then, a trigger signal is applied to the exciter coil 1 by the negative half cycle output voltage of the exciter coil 1, and the thyristor 6 becomes conductive. As a result, the electric charge of the capacitor 3 is discharged through the thyristor 6 and the primary coil 2a of the ignition coil, and a large magnetic flux change occurs in the magnetic flux interlinking with the secondary coil 2b. Therefore, a high voltage is induced in the secondary coil 2b, and a spark is generated in the spark plug 10.

In this way, if the thyristor 6 is triggered by the output of the negative half cycle of the exciter coil, the pulsar coil is not required, so that the structure of the generator can be simplified.

[Problems to be Solved by the Invention] When the above conventional ignition device is used, the characteristic of the ignition timing θ with respect to the rotation speed N [rpm] is a curve a shown by a broken line in FIG.
The ignition timing is advanced even in the starting rotation region. When the ignition timing is advanced in the starting rotation range as described above, there is a case where the engine fails to start due to a ketchin (a phenomenon in which the piston is pushed back because the ignition is too early) at the time of starting. Particularly in the case of a kick-start type engine, if the kicking occurs, the kick petal may cause a strong reaction and the driver may be injured.

Therefore, as shown in JP-A-61-178560, when the engine is running at low speed, the ignition operation is performed at the peak position of the output voltage of the negative half cycle of the exciter coil, and the engine speed becomes equal to or higher than the set value. A pulsarless-type capacitor discharge ignition device was proposed in which the ignition operation is performed near the rise of the voltage in the negative half cycle at that time. According to this ignition device, since the ignition timing in the engine starting rotation region can be fixed at the peak position of the negative half cycle of the exciter coil, it is possible to prevent the occurrence of ketching.

However, in this conventional ignition device, when the engine speed reaches the set value, the ignition timing advances stepwise until the output voltage rises in the negative half cycle of the exciter coil, so in the medium-high speed region of the engine. When the characteristic of gradually advancing the ignition timing is required, there is a problem that the requirement cannot be met.

An object of the present invention is to prevent the ignition timing from advancing in the starting rotation region, and to gradually advance the ignition timing in a region above the set rotational speed. It is to provide an engine ignition device.

[Means for Solving the Problems] The present invention provides an exciter coil arranged in a generator driven by an internal combustion engine, an ignition coil, and an exciter coil provided on the primary side of the ignition coil and output by the exciter coil. An ignition energy storage capacitor charged by a voltage of a positive half cycle, a discharge control thyristor provided to discharge the charge of the ignition energy storage capacitor to the primary coil of the ignition coil when conducting, and an exciter. In a capacitor discharge type internal combustion engine ignition device provided with a trigger circuit that triggers the thyristor by a negative half cycle voltage output from a coil, ignition timing is prevented from advancing in a starting rotation region.

Therefore, in the present invention, the trigger circuit is composed of a trigger signal supply circuit that gives a trigger signal to the thyristor by the negative half cycle voltage of the exciter coil, a peak trigger circuit, and a waveform advance switching control circuit.

The peak trigger circuit conducts the peak trigger transistor switch which is provided so as to bypass the trigger signal from the thyristor when conducting, and the transistor switch which conducts when the negative half cycle voltage of the exciter coil rises. A transistor control circuit that shuts off the transistor switch when the negative half-cycle voltage of the exciter coil reaches a peak, and a trigger signal supply circuit until the output voltage of the negative half-cycle of the exciter coil reaches the peak. It serves to prevent the trigger signal from being supplied from the thyristor.

The waveform advance switching control circuit is charged by the advance switching control transistor switch, which is provided so as to turn off the peak trigger transistor switch when the waveform is advanced, and the negative half cycle output voltage of the exciter coil. A speed detection capacitor, a discharge resistance for discharging the electric charge of the speed detection capacitor with a constant time constant, and the advance angle switching control transistor switch when the terminal voltage of the speed detection capacitor exceeds a set value. A peak trigger circuit before the output voltage of the negative half cycle of the exciter coil reaches a peak due to conduction of the transistor for controlling the advance angle switching when the engine speed exceeds the set value. Of the transistor switch is forcibly cut off, and the trigger signal supply circuit switches to the thyristor. Moth signal allows the supplied.

[Operation] With the above-described configuration, the peak trigger circuit operates when the engine speed is less than the set value, so that the trigger signal supply circuit starts the operation only when the negative half cycle output voltage of the exciter coil reaches the peak. A trigger signal is supplied to the discharge control thyristor, and an ignition operation is performed near the peak of the output voltage of the negative half cycle of the exciter coil. Therefore, the ignition timing in the starting rotation region can be fixed near the peak position of the output voltage of the negative half cycle of the exciter coil by appropriately selecting the set value of the engine rotation speed, and the ignition timing in the starting rotation region can be fixed. Can be prevented from advancing.

When the engine speed exceeds the set value, the advance angle switching control transistor switch becomes conductive at the position where the phase advances from the peak position of the negative half cycle output voltage of the exciter coil, forcing the peak trigger transistor switch. In order to allow the trigger signal to be supplied from the trigger signal supply circuit to the thyristor, the ignition timing is advanced from the peak position of the negative half cycle output voltage of the exciter coil. The peak value of the output voltage in the negative half cycle of the exciter coil rises as the engine speed increases, and the phase at which the terminal voltage of the speed detection capacitor reaches the set value advances. The position where the transistor switch becomes conductive gradually advances as the engine speed increases. Therefore, in the region above the set engine speed, the ignition timing of the engine gradually advances as the engine speed increases. When the engine speed increases to some extent and the output voltage of the exciter coil becomes saturated, the advance of the ignition timing stops.

Therefore, according to the present invention, for example, as shown by the curve b in FIG. 4, it is possible to obtain the characteristic that the ignition timing is constant in the starting rotation region and the ignition timing is gradually advanced in the medium and high speed regions. It is possible to prevent the occurrence of ketchin.

Embodiments Embodiments 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 Ex is an exciter coil, IG is an ignition coil having a primary coil w1 and a secondary coil w2, C1 is an ignition energy storage capacitor, and S1 is A discharge control thyristor and P are spark plugs. Further, R1 to R5 are resistors, D1 to D5 are diodes, C2 is a peak trigger control capacitor, C3 is a speed detection capacitor, T1 and T2 are transistors, and Z1 is a zener diode.

In this embodiment, the exciter coil → diode D1 → capacitor C1 → primary coil w1 → resistor R1 having a sufficiently small resistance value
→ Exciter coil Ex circuit and exciter coil Ex
→ Diode D1 → Capacitor C1 → Primary coil w1 → Diode D4 → Resistance R3 → Capacitor C2 → Exciter coil A circuit that charges the ignition energy storage capacitor C1 with the positive half cycle output voltage Ve of the exciter coil by the circuit of Ex A charging circuit is configured, and the ignition energy storage capacitor C1 is charged to the polarity shown by these capacitor charging circuits.

Further, the exciter coil Ex → resistor R2 → diode D3 → gate-cathode circuit of thyristor S1 → diode D2 → exciter coil Ex circuit constitutes a trigger signal supply circuit, and exciter coil Ex has negative half cycle output voltage Ve ′. Thyristor through this circuit when generating
The trigger signal is supplied to S1.

A peak trigger circuit A and an advance angle switching control circuit B are provided to control the time when the trigger signal is applied to the thyristor S1 through the trigger signal supply circuit. The peak trigger circuit A is composed of a transistor T1, a resistor R3, a diode D4 and a capacitor C2 which form a transistor switch for peak trigger, and the transistor T1 has a collector-emitter circuit through a diode D3 and a thyristor.
It is connected in parallel to the gate-cathode circuit of S1. The transistor T1 becomes conductive by being supplied with the base current through the capacitor C2 and the resistor R3 when the exciter coil Ex generates the negative half cycle output voltage Ve '. When the transistor T1 is conducting, almost all the trigger signal given to the thyristor S1 from the exciter coil Ex through the resistor R2 and the diode D3 flows to the transistor T1 side, so that the trigger signal is not supplied to the thyristor S1 and the thyristor S1 is not supplied. Are kept in the shut-off state. When the output voltage of the negative half cycle of the exciter coil reaches the peak and the charging of the capacitor C2 is stopped, the base current of the transistor T1 becomes zero, so that the transistor T1 is cut off and the exciter coil passes through the resistor R2 and the diode D3. Allow the trigger signal to be supplied to thyristor S1 (through the trigger signal supply circuit). In this example, the capacitor C2, the resistor R3, and the diode D4 form a transistor control circuit that controls the peak trigger transistor T1.

The advance angle switching control circuit B is composed of a transistor T2 forming a transistor switch for advancing angle switching control, a speed detecting capacitor C3, resistors R4 and R5, a diode D5 and a zener diode Z1.

The speed detection capacitor C3 is charged in the path of the exciter coil Ex → diode D5 → resistor R4 → capacitor C3 → diode D2 → exciter coil Ex when the exciter coil Ex generates a negative half cycle voltage. The electric charge of the speed detecting capacitor C3 is discharged with a constant time constant through the discharging resistor R5. The terminal voltage of the speed detection capacitor C3 rises with the increase of the output voltage of the exciter coil with the increase of the rotation speed of the internal combustion engine, the rotation speed of the internal combustion engine reaches the set value, and the terminal voltage of the capacitor C3 changes. The Zener diode Z1 which reaches the set value is turned on to give a base current to the transistor T2, thereby turning on the transistor T2. When transistor T2 conducts, the base current provided to transistor T1 through capacitor C2 is shunted through transistor T2, thereby turning off transistor T1.
In this example, the Zener diode Z1 constitutes a transistor trigger circuit that triggers the transistor T2 when the terminal voltage of the speed detecting capacitor C3 reaches a set value.

Next, the overall operation of the above embodiment will be described with reference to FIG. FIG. 2A shows the output voltage of the exciter coil, and FIG. 2B shows the terminal voltage Vc of the speed detecting capacitor C3.
The waveform of 3 is shown. 2 (C) and (D) show the on / off operation of the transistors T2 and T1, respectively.
(E) in the figure shows the gate-cathode voltage Vgk of the thyristor S1.
Is shown.

The exciter coil Ex induces an AC voltage as shown in FIG. 2 (A) in synchronization with the rotation of the internal combustion engine. When the exciter coil Ex outputs a positive half cycle voltage Ve, the ignition energy storage capacitor C1 is charged to the polarity shown.

When the exciter coil Ex outputs a negative half cycle voltage Ve ', the speed detecting capacitor C3 is charged. When the negative half-cycle voltage of the exciter coil has peaked, the charge on capacitor C3 is discharged through resistor R5 with a constant time constant. The waveform of the terminal voltage Vc3 of the capacitor C3 is the second
As shown in FIG. In FIG. 2 (B), polygonal lines N1, N2 and N3 show waveforms when the rotation speed N is N1, N2 and N3, respectively. When the engine speed N is less than the set value N1, the terminal voltage Vc3 of the capacitor C3 does not reach the Zener voltage Vz1 of the Zener diode Z1, so that the Zener diode does not conduct and the transistor T2 does not conduct.

In this state, the exciter coil Ex outputs a negative half-cycle voltage Ve ′ and, at the same time, a base current flows through the transistor T1 through the capacitor C2 and the resistor R3, so that the transistor T1 becomes conductive and a trigger signal is supplied to the thyristor S1. Prevent it.

When the negative half cycle output voltage of the exciter coil Ex reaches its peak, the charging of the capacitor C2 is stopped, and the transistor T1 is turned off. When the transistor T1 is cut off, a trigger signal is supplied from the exciter coil to the thyristor S1 through the resistor R2 and the diode D3, and the thyristor S1 becomes conductive. Due to the conduction of the thyristor S1, the charge of the capacitor C1 is transferred to the thyristor S1 and the primary coil w1.
To discharge through. This causes a large change in the magnetic flux interlinking with the secondary coil of the ignition coil.
High voltage is induced in w2. Since the high voltage is applied to the spark plug P, sparks are generated in the spark plug and the engine is ignited. As described above, in the starting rotation region where the engine speed is less than the set value N1, the ignition operation is performed at the position θ1 at which the output voltage of the negative half cycle of the exciter coil Ex reaches the peak.

When the rotation speed exceeds the set value N1 and becomes N2, for example, the terminal voltage Vc3 of the speed detection capacitor C3 changes to the zener diode Z1.
Therefore, the transistor T2 becomes conductive at the position value θ2 before the output voltage of the negative half cycle of the exciter coil Ex reaches the peak, and the transistor T1 is cut off. Since the transistor T2 is cut off at the position of θ2 and the trigger signal is given to the thyristor S1 at the same time, the ignition timing becomes θ2 and the ignition timing becomes the peak position θ.
It goes beyond 1.

When the rotation speed further rises to N3, the terminal voltage Vc3 of the speed detecting capacitor C3 always exceeds the Zener voltage Vz1. In this state, the transistor T1 is held in the cut-off state for the entire negative half cycle of the exciter coil, so that the voltage of the negative half cycle of the exciter coil rises, and at the same time, the resistor R2 and the diode D3 are released from the exciter coil.
A signal is given to the thyristor S1 through and, and when the signal reaches the trigger level of the thyristor S1, the thyristor S1 becomes conductive and the ignition operation is performed. Since the phase at which the signal given to the thyristor S1 from the exciter coil Ex through the resistor R2 and the diode D3 reaches the trigger level of the thyristor S1 advances as the peak value of the negative half cycle output voltage of the exciter coil increases, The ignition timing advances while the peak value of the output voltage of the negative half cycle of the exciter coil increases with the increase of the rotation speed. When the rotational speed of the engine rises to some extent, the output voltage of the exciter coil saturates and the ignition timing advances. When the rotation speed further increases, the output voltage of the exciter coil tends to decrease, so the ignition timing is gradually delayed. Therefore, the characteristic of the ignition timing with respect to the rotation speed N obtained by the above embodiment is as shown by the curve b in FIG. 4, and the characteristic that the ignition timing is constant in the starting rotation region is obtained.

FIG. 3 shows a modification of the advance angle switching control circuit B.
In this embodiment, a resistor R6 is inserted between the resistor R4 and the diode D5 of the advance angle switching control circuit B of the embodiment shown in FIG.
Zener diode Z2 was inserted between the connection point of R6 and R6 and ground.

In this way, connect the Zener diode Z2 and
If the terminal voltage of C3 is made constant, if the output voltage of the exciter coil Ex changes due to the fluctuation of the gap between the rotor and the stator of the magnet generator, the advance angle start rotation speed and advance angle end It is possible to prevent the rotation speed from changing.

[Advantages of the Invention] As described above, according to the present invention, the peak that fixes the position where the trigger signal is applied to the thyristor when the engine speed is less than the set value to the peak position of the output of the negative half cycle of the exciter coil. With the provision of a trigger circuit, an advance angle switching control circuit that releases the function of the peak trigger circuit and switches to advance angle control when the engine speed exceeds a set value is provided. It is possible to obtain a characteristic in which the ignition timing is gradually advanced in the middle and high speed regions while keeping it constant. Therefore, it is possible not only to prevent the occurrence of ketching at the time of starting the engine, but when the characteristic of gradually advancing the ignition timing in the medium to high speed region of the engine is required,
We can meet that demand.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a signal waveform diagram of each portion of FIG. 1, and FIG. 3 is a main portion of another embodiment of the present invention. FIG. 4 is a circuit diagram showing the ignition characteristics obtained by the ignition device of the present invention and ignition characteristics obtained by the conventional ignition device, and FIG. 5 is a diagram for a conventional capacitor discharge internal combustion engine. It is a circuit diagram showing a circuit configuration of an ignition device. IG ... Ignition coil, C1 ... Ignition energy storage capacitor, S1 ... Discharge control thyristor, A ... Peak trigger circuit, B ... Advance angle switching control circuit, T1 ... Configure peak trigger transistor switch Transistor, T2 ...
... Advance angle switching control transistor Switch transistor, C2 ... Capacitor, C3 ... Speed detection capacitor, R5 ... Discharge resistor, Z1 ... Zener diode.

Front Page Continuation (72) Inventor Etsuro Kubota 3744 Ooka, Numazu City, Shizuoka Prefecture Domestic Electric Machinery Co., Ltd.

Claims (1)

[Claims] 1. An exciter coil disposed in a generator driven by an internal combustion engine, an ignition coil, and a primary side of the ignition coil, which is charged by an output voltage of a positive half cycle of the exciter coil. An ignition energy storage capacitor, a discharge control thyristor provided to discharge the charge of the ignition energy storage capacitor to the primary coil of the ignition coil when conducting, and a negative half cycle of the exciter coil. And a trigger circuit for triggering the thyristor by the output voltage of the capacitor discharge type internal combustion engine ignition device, the trigger circuit, a trigger for giving a trigger signal to the thyristor by the output voltage of the negative half cycle of the exciter coil When the signal supply circuit and the signal supply circuit are conducted, the trigger signal is sent to the thyristor. A peak-triggering transistor switch provided so as to bypass, and when the negative half-cycle voltage of the exciter coil rises, the transistor switch is turned on and the negative half-cycle voltage of the exciter coil peaks. A peak trigger circuit provided with a transistor control circuit for shutting off the transistor switch when reached, and a transistor switch for advancing switching control provided so as to turn off the peak trigger transistor switch when turned on. The speed detecting capacitor charged by the output voltage of the negative half cycle of the exciter coil, the discharging resistor for discharging the electric charge of the speed detecting capacitor with a constant time constant, and the terminal voltage of the speed detecting capacitor are When it exceeds the set value, the transistor switch for advance angle switching control Capacitor discharge type ignition device for an internal combustion engine, characterized by comprising the advance Tsunokiri over control circuit that includes a transistor triggering circuit which conducts.