JP2806102B2 - Ignition device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor discharge type ignition device for an internal combustion engine which stops the ignition operation when the rotation speed of the internal combustion engine exceeds a set value and controls the rotation speed of the engine. It is.

[0002]

2. Description of the Related Art In a vehicle driven by an internal combustion engine, it is necessary to prevent excessive speed from occurring for safety reasons. For this reason, an ignition device having a function of stopping the ignition operation of the engine when the vehicle speed or the rotation speed of the engine exceeds a predetermined speed to prevent the internal combustion engine from over-rotating is used.
Japanese Patent Application Laid-Open No. 59-16 / 1984 discloses this type of internal combustion engine ignition device.
The device shown in US Pat. No. 8,273 is known. In this ignition device, the output of the vehicle speed detection means is converted into a vehicle speed detection voltage proportional to the vehicle speed, and this vehicle speed detection voltage is compared with a predetermined reference voltage. When the vehicle speed detection voltage exceeds the reference voltage, the ignition power supply The output of the power generation coil is bypassed from the ignition circuit to stop the ignition operation of the engine. As a result, the ignition operation is restarted when the vehicle speed decreases and the output voltage falls below the reference voltage.

[0003]

In the above conventional ignition device, the ignition operation is completely stopped when the rotation speed of the engine exceeds the set value. Therefore, when the rotation speed exceeds the set value. When the output of the engine is lost and the rotation speed of the engine drops below the set value and the ignition operation is restarted, the entire output of the engine is rapidly generated. For this reason, there has been a problem that the output fluctuation of the engine near the set rotation speed becomes remarkably large, giving a driver discomfort. In order to alleviate this to some extent, in the past, the limit speed was set in the speed range where the output drops past the speed at which the engine generates the maximum output. In order to use the engine effectively, it is required to design the engine such that the output of the engine becomes maximum near the limit rotational speed. Therefore, in the ignition device having the overspeed prevention function as described above, the impact due to the fluctuation of the engine output occurring near the predetermined limit rotation speed is large, and particularly the rotation speed at which the ignition operation is stopped and the rotation speed at which the ignition operation is restarted. In the case where there is hysteresis between them, there is a problem that this impact becomes extremely large.

[0004] It is an object of the present invention to discharge control in which an ignition energy storage capacitor is charged with the output of an exciter coil provided in an AC generator driven by an internal combustion engine, and the charge of this capacitor is conducted to the ignition timing of the engine. Discharge of the primary coil of the ignition coil through the power soyrister to generate an ignition voltage in the secondary coil of the ignition coil when the engine rotation speed exceeds a set value An internal combustion engine capable of limiting the rotational speed of the engine to a value close to a set value by reducing the ignition voltage, and preventing a sudden impact on the vehicle due to a sudden change in the output of the engine. It is an object of the present invention to provide an ignition device for a vehicle.

[0005]

In order to achieve the above object, according to the present invention, a capacitor discharge type ignition circuit is further charged with an ignition energy storage capacitor when the rotational speed of the internal combustion engine exceeds a set value. A misfire control circuit for stopping the ignition operation by preventing the ignition operation, and a thinning control circuit for periodically stopping the operation of the misfire control circuit and restoring the ignition operation.

The misfire control circuit includes a misfire control thyristor provided so as to bypass the charging current of the ignition energy storage capacitor when the capacitor is turned on from the capacitor, and a misfire control circuit using the output of one half cycle of the exciter coil. A thyristor firing circuit that supplies a firing signal to the thyristor, a speed detection capacitor that is charged with a constant time constant by the output of the other half cycle of the exciter coil, and a constant time constant that charges the speed detection capacitor Is connected to the discharge circuit of the speed detection capacitor and the ignition circuit of the misfire control thyristor, and is controlled by the speed detection voltage obtained at both ends of the speed detection capacitor. Prevents the ignition signal from being supplied to the control thyristor, and controls the misfire when the speed detection voltage exceeds the set value. Firing signal and a thyristor firing control switch to allow the given thyristor.

The thinning control circuit includes a small resistor connected in series to the misfire control thyristor, a thinning control capacitor charged with a constant time constant by a voltage across the small resistor, and a thinning control capacitor. It is connected to a thinning control capacitor discharge circuit that discharges electric charge with a constant time constant and a firing circuit of a misfire control thyristor, and conducts and conducts when the voltage across the thinning control capacitor reaches a set value. The firing signal is prevented from being applied to the misfire control thyristor for a period of time, and when the voltage between both ends of the thinning control capacitor is less than the set value, the state is cut off and the fire signal is supplied to the misfire control thyristor. And a thinning-out control switch for allowing

[0008] The above "small resistance" means a current limiting element having a sufficiently small resistance value. The resistance value of the small resistor can prevent the ignition energy storage capacitor from being charged by the voltage generated at both ends of the series circuit of the thyristor and the small resistor when the misfire control thyristor conducts, thereby preventing the ignition operation from being performed. Set small enough. A normal resistor can be used as the small resistor, but a diode or the like may be used.

[0009]

In the above arrangement, the ignition energy storage capacitor is charged by the output of one half cycle of the exciter coil. When the exciter coil generates the output of one half cycle, the output for the misfire control is generated by the output. When a firing signal is given to the thyristor, no ignition voltage is generated because the charging current of the ignition energy storage capacitor is bypassed through the misfire control thyristor.

After the speed detecting capacitor is charged by the output of the other half cycle of the exciter coil, it is discharged with a constant time constant through the speed detecting capacitor discharging circuit. If the speed detection voltage obtained at both ends of the speed detection capacitor is equal to or lower than a set value, the thyristor firing control switch acts to prevent the firing signal from being supplied to the misfire control thyristor. When the detection signal exceeds the set value, the thyristor ignition control switch acts to allow the ignition signal to be supplied to the misfire control thyristor. The period during which the speed detection voltage is higher than the set value increases as the engine speed increases,
When the engine speed exceeds the set rotation speed, the state where the speed detection voltage exceeds the set value continues until the firing signal of the misfire control thyristor is generated by the output of one half cycle of the exciter coil. In this state, a firing signal is given to the misfire control thyristor every time one half cycle output is generated in the exciter coil, and the charge current of the ignition energy storage capacitor is bypassed by the misfire control thyristor every time.

In the present invention, a thinning control circuit is further provided for periodically stopping the operation of the misfire control circuit. When the misfire control thyristor is turned on, an output of one half cycle of the exciter coil causes a current to flow through a small resistor connected in series to the misfire control thyristor, and the thinning control capacitor is fixed at a voltage generated across the small resistor. Is charged with the time constant of When the output of the exciter coil turns to the other half cycle, the thinning control capacitor is discharged with a constant time constant through the thinning control capacitor discharging circuit.

While the voltage at both ends of the thinning control capacitor is equal to or higher than the set value, the thinning control switch is turned on, so that no ignition signal is supplied to the misfire control thyristor. Therefore, the misfire control thyristor becomes non-conductive, a charging current is supplied to the ignition energy storage capacitor, and the ignition operation is performed. When the voltage at both ends of the thinning control capacitor drops below the set value, the thinning control switch is shut off, and when the output of one half cycle occurs again in the exciter coil, the ignition signal is again supplied to the misfire control thyristor. The misfire control thyristor is turned on again, and the above operation is repeated.

As described above, in the device of the present invention, when the rotational speed of the internal combustion engine exceeds the set value, the ignition stop operation is started by the misfire control circuit, but the operation of the misfire control circuit is periodically performed by the thinning control circuit. The engine is intermittently ignited because the engine is temporarily stopped and the ignition operation is restored. As a result, the output of the engine decreases and the rotation speed decreases. When the rotation speed falls below the set value, ignition is performed again at each ignition timing, and the rotation speed increases. These operations are repeated to limit the rotation speed of the engine to a set value or less.

In the ignition device of the present invention, the engine does not completely misfire when the rotation speed of the engine exceeds the set value. The output of the engine does not fluctuate greatly.
Therefore, it is possible to prevent a large impact from being generated on the vehicle during the overspeed prevention operation, and it is possible to improve driving feeling.

[0015]

FIG. 1 schematically shows an embodiment of the present invention, in which 1 is a primary coil 1a having one end grounded.
An ignition coil 2 having a secondary coil 1b is an ignition plug attached to a cylinder of an engine (not shown), and the output of the secondary coil 1b is applied to the ignition plug. One end of an ignition energy storage capacitor C1 is connected to the non-ground side terminal of the primary coil 1a, and a discharge control thyristor S1 is connected between the other end of the capacitor C1 and ground with its cathode facing the ground side. Have been. Reference numeral 3 denotes an ignition timing determination circuit for giving a trigger signal to the gate of the discharge control thyristor S1 at the ignition timing of the internal combustion engine. A main ignition circuit 4 is constituted by the ignition energy storage capacitor C1, the discharge control thyristor S1, and the ignition timing determination circuit 3.

An exciter coil 5 is provided in an AC generator driven by an internal combustion engine (not shown) and generates an AC voltage Ve (see FIG. 4A) in synchronization with the rotation of the engine.
When an output of one half cycle in the direction indicated by the solid line arrow is generated in the exciter coil 5, a path of the exciter coil 5 → the diode D1 → the ignition energy storage capacitor C1 → the primary coil 1a of the ignition coil → the exciter coil 5 is formed. The capacitor C1 is charged to the polarity shown by the capacitor charging circuit.

As the ignition timing determination circuit 3, for example, as shown in FIG. 2, a thyristor S2, a diode D1, a Zener diode Z1, a capacitor C2, and resistors R1 to R4.
Can be used. In the ignition timing determination circuit shown in FIG. 2, the cathode of the diode D2 is connected to the non-ground side terminal of the exciter coil 5 and the capacitor C
The connection point between the resistor 2 and the resistor R2 is connected to the gate of the discharge control thyristor S1. When the output of the other half cycle in the direction of the dashed arrow shown in the drawing occurs in the exciter coil 5, the exciter coil 5 → the resistor R2 → the capacitor C2 → the resistor R
3 → Diode D2 → Capacitor C2 is charged to the polarity shown in the path of exciter coil 5, and when the voltage across Zener diode Z1 reaches the Zener voltage of the Zener diode, thyristor S2 conducts and capacitor C2 is turned on.
2 discharges through resistor R2, thyristor S2 and resistor R3. At this time, the voltage generated at both ends of the resistor R2 serves as a trigger signal to make the discharge control thyristor S1 conductive. As a result, the electric charge of the ignition energy storage capacitor C1 is discharged to the primary coil 1a of the ignition coil through the discharge control thyristor S1, and at this time, a spark is blown to the ignition plug 2 by the high voltage induced in the secondary coil 1b. When the thyristor S2 is turned on, the output of the exciter coil 5 in the direction of the dashed arrow is short-circuited through the thyristor S2 and the diode D2. In this embodiment, the ignition coil 1, the main ignition circuit 4, the diode D1 and the exciter coil 5 constitute a capacitor discharge ignition circuit.

Reference numeral 6 denotes a misfire control circuit provided to prevent charging of the ignition energy storage capacitor C1 to stop the ignition operation when the rotational speed of the internal combustion engine exceeds a set value. This is a thinning-out control circuit provided to periodically stop the operation of the control circuit 6 and return the ignition operation.

The misfire control circuit 6 is configured, for example, as shown in FIG. In this example, a misfire control thyristor S3 in which an anode is connected through a resistor R5 to a cathode of a diode D1 of a charging circuit of an ignition energy storage capacitor.
A thyristor firing circuit 8 comprising a diode D3, resistors R6 and R7, and a Zener diode Z2 for providing a firing signal to the misfire control thyristor S3 by the output of one half cycle of the exciter coil 5 in the direction indicated by the solid line arrow. An emitter-collector circuit is connected between the connection point between the resistor R6 of the thyristor firing circuit 8 and the Zener diode Z2 and the ground so that, when the thyristor is turned on, the ignition signal to the misfire control thyristor S3 is bypassed. A thyristor firing control switch 9 comprising a transistor T1 and a field effect transistor F1 connected in parallel between the transistor T1 and the base collector of the transistor T1 for controlling the conduction of the transistor T1, and a gate and source of the field effect transistor F1. Connected, the output of the other half cycle of the exciter coil 5 in the direction indicated by the broken line in the figure. More Zener diode Z
3, a speed detecting capacitor C3 charged through a series circuit of a resistor R8 and a diode D4, and a speed detecting capacitor discharging circuit comprising a series circuit of a resistor R9 and an adjusting resistor Rf connected in parallel to the speed detecting capacitor C3. 10 is provided. A resistor R11 to R12 and a thermistor R for temperature compensation are provided between the emitter and the base of the transistor T1.
f, and a Zener diode Z4 for limiting the maximum charging voltage of the speed detecting capacitor C3 is connected between both ends of the speed detecting capacitor C3.

Further, the thinning control circuit 7 of this embodiment uses a small resistor R13 connected in series between the cathode of the misfire control thyristor S3 of the misfire control circuit 6 and the ground, and a voltage between both ends of the small resistor R13. A thinning control capacitor C4 charged with a constant time constant through a series circuit of a diode D5 and a resistor R14, and a resistor R15 connected in parallel with the capacitor C4 discharges the charge of the capacitor C4 with a constant time constant. Thinning control capacitor discharge circuit 11
And a thinning control switch 12 composed of a transistor T2 connected in parallel between the emitter and collector of the transistor T1 of the misfire control circuit 6. The base of the transistor T2 is connected to the non-ground terminal of the thinning control capacitor C4 through the resistor R16. The transistor T2 conducts when the voltage across the thinning control capacitor C4 is equal to or higher than a set value Vtr determined by the ON level of the transistor T2, and is turned off when the voltage across the capacitor C4 is lower than the set value Vtr.

Next, the operation of the above embodiment will be described. First, the operation of the misfire control circuit 6 will be described with reference to FIG. Assuming now that the output voltage Ve (see FIG. 4A) of the exciter coil 5 has shifted to the other half cycle (the lower half in FIG. 4A) at the angular position θ0, the output of the other half cycle causes the speed detecting capacitor C3 to become active. Exciter coil 5 → capacitor C3 → Zener diode Z3 → resistor R8 → diode D4 → charged to the polarity shown in the path of exciter coil 5 and voltage Vc3 across capacitor C3 (see FIG. 4B).
Rises from the angular position θ0. The maximum value of the voltage Vc3 is limited by the Zener voltage Vz4 of the Zener diode Z4. When the thyristor S2 of the ignition timing determination circuit 3 (FIG. 2) becomes conductive at the ignition angle position .theta.i of the engine and the output of the exciter coil 5 is short-circuited, the speed detecting capacitor C
The charge 3 is discharged with a constant time constant through the speed detecting capacitor discharging circuit 10, and the voltage Vc3 of the capacitor C3 decreases. The voltage Vc3 across the capacitor C3 is applied between the gate and source of the field effect transistor F1 as a speed detection voltage. When the speed detection voltage Vc3 is equal to or lower than the set value Vfr set by the cut-off level of the field effect transistor F1, the field effect transistor F1 conducts and the transistor T1 conducts (ON). The supply of the ignition signal to the thyristor S3 is blocked. When the speed detection voltage Vc3 exceeds the set value Vfr, the field effect transistor E1 becomes non-conductive and the transistor T1 also becomes non-conductive (OFF), so that the supply of the ignition signal to the misfire control thyristor S3 is permitted. .
FIG. 4B illustrates a change in the speed detection voltage Vc3 by comparing the case where the engine speed is lower than the set value (broken line) and the case where the engine speed is higher than the set value (solid line). C) shows the ON / OFF state of the corresponding transistor T1.

When the engine is running at a low speed, the speed detection voltage Vc3 decreases from the angular position θi and reaches the set value Vfr at the angular position θt '. The angular position at which the speed detection voltage Vc3 reaches the set value Vfr is delayed as the rotational speed of the engine increases, and at high speed, the speed detection voltage Vc3 reaches the set value Vfr at the illustrated angle position θt. In this embodiment, when the rotation speed reaches a set value at a high speed of the engine, the angular position θt is determined by the angular position θ at which the output of one half cycle of the exciter coil 5 (the upper half in FIG.
The resistance value of the speed detecting capacitor discharging circuit 10 is selected so as to coincide with 1.

Therefore, when the rotational speed of the engine exceeds the set value, the non-conductive (OFF) state of the transistor T1 continues until the output of the exciter coil 5 for one half cycle occurs. Thyristor S3 for misfire control every time a half cycle output of
Is supplied with a firing signal Vt (see FIG. 4D).

Next, the operation of the thinning control circuit 7 will be described with reference to FIG. When the rotational speed of the engine is equal to or lower than the set value, the transistor T1 of the misfire control circuit 6 is conducting when the output of the exciter coil 5 in one half cycle in the direction of the solid line arrow is generated, and the misfire control thyristor S3 Does not conduct, the ignition operation is performed at each ignition timing.

When the rotational speed of the engine exceeds the set value, when the output Ve of the exciter coil 5 turns to one half cycle (upper half of FIG. 5A), the transistor T1 is turned off (OFF). (See FIGS. 4C and 5D). If the transistor T2 (thinning control switch) of the thinning control circuit 7 connected in parallel with the transistor T1 is in the conducting (ON) state while the transistor T1 is in the cut-off state, the misfire control is performed. The supply of the ignition signal to thyristor S3 is blocked, and the ignition operation is performed. When the transistor T1 is in the cut-off state and the transistor T2 is also in the cut-off (OFF) state, an ignition signal is given to the misfire control thyristor S3, and the misfire control thyristor S3 conducts. The operation is stopped.

Assuming that the ignition signal Vt (see FIG. 5E) is given to the misfire control thyristor S3 at the rotation angle position θ1 and the thyristor S3 becomes conductive, the exciter coil 5
A current flows through the small resistor R13 through the misfire control thyristor S3 due to the output of one half cycle of the above, and at this time, the thinning control capacitor C4 is charged to the polarity shown in FIG. Is done. The voltage Vc4 (see FIG. 5B) across the capacitor C4 rises from the angular position θ1. When the output voltage Ve of the exciter coil 5 shifts to the other half cycle at the angular position .theta.2, the charge of the capacitor C4 is discharged at a constant time constant through the resistor R15 constituting the thinning control capacitor discharge circuit 11, and both ends of the capacitor C4 are discharged. Voltage Vc4 decreases. The transistor T2 is on during the period of θs1 to θs2 when the voltage Vc4 across the capacitor C4 is equal to or higher than the set value Vtr (the ON state in FIG. 5C). During this period, the broken line is shown in FIG. The ignition signal Vt 'is prevented from being applied to the misfire control thyristor S3. After the angular position θs2, the ignition signal Vt is again output at the angular position θ7 at the misfire control thyristor S3.
, The same operation as described above is repeated. The time corresponding to the period .theta.s1 to .theta.s2 during which the transistor T2 is conducting can be adjusted by the resistance values of the charging resistor R14 and the discharging resistor R15 of the thinning control capacitor C4. In the example shown in FIG. 5, the charging current of the ignition energy storage capacitor C1 due to the half-cycle output shown by hatching in FIG. Thyristor S3 for misfire control
As a result, the charging voltage Vc1 of the ignition energy storage capacitor C1 becomes as shown in FIG. 5 (F).
Therefore, in this case, one of the three sparks generated in the spark plug 2 is periodically thinned out, causing a misfire, and the discharge current i2 of the spark plug 2 becomes as shown in FIG. 5 (G). Also in this example, the normal ignition of the internal combustion engine is
Is performed once per cycle of the AC output of
The same mode is used in the case where the engine is misfired once after being ignited twice at the regular ignition timing of the engine and once for every two cycles of the AC output of the exciter coil 5. Periodic ignition is performed.

[0027]

As described above, according to the present invention, when the rotational speed of the internal combustion engine exceeds a set value, the ignition energy storage capacitor is prevented from being charged and the ignition operation is stopped, and the misfire control circuit. A thinning control circuit that periodically stops the operation of the misfire control circuit and returns the ignition operation,
Since the ignition of the engine is periodically reduced when the engine speed exceeds the set value, it is possible not only to limit the engine speed to around the set value, but also to set the There is an advantage that it is possible to prevent the output of the engine from fluctuating abruptly in the vertical direction from applying a large impact to a vehicle equipped with the engine.

[Brief description of the drawings]

FIG. 1 is a circuit diagram schematically showing a configuration of an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a specific example of an ignition timing determination circuit used in the embodiment of FIG.

FIG. 3 is a circuit diagram showing a specific example of a misfire control circuit and a thinning control circuit used in the embodiment of FIG.

4 is a waveform diagram showing voltage waveforms of various parts of a misfire control circuit portion of FIG . 3 and ON / OFF states of switches.

FIG. 5 is a waveform diagram showing a voltage or current waveform of each part in FIGS . 1 and 3 and an on / off state of a switch.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ignition coil, 2 ... Spark plug, 3 ... Ignition timing decision circuit, 4 ... Main ignition circuit, 5 ... Exciter coil, 6 ... Misfire control circuit, 7 ... Thinning control circuit, 8 ... Thyristor ignition circuit, 9 ... Thyristor Firing control switch, 10: speed detection capacitor discharge circuit, 11: thinning control capacitor discharge circuit, 12: thinning control switch, C1: ignition energy storage capacitor, C3: speed detection capacitor, C4 thinning control Capacitor, S1: Discharge control thyristor, S3: Misfire control thyristor, R13: Small resistance.

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Claims (1)

(57) [Claims] An ignition coil, an exciter coil provided in an AC generator driven by an internal combustion engine, an ignition energy storage capacitor provided on the primary side of the ignition coil, A main ignition circuit comprising: a discharge control thyristor provided to discharge electric charge to a primary coil of an ignition coil; and an ignition timing determination circuit for providing a trigger signal to the thyristor at an ignition timing of an internal combustion engine; A capacitor charging circuit for charging the ignition energy storage capacitor with the output of one half cycle; and stopping the ignition energy storage by stopping charging of the ignition energy storage capacitor when the rotation speed of the internal combustion engine exceeds a set value. A misfire control circuit; and a thinning-out control for periodically stopping the operation of the misfire control circuit to return the ignition operation. A misfire control circuit, comprising: a misfire control circuit, the misfire control circuit comprising: a misfire control thyristor provided to bypass a charging current of the ignition energy storage capacitor from the capacitor when the conduction occurs. A thyristor ignition circuit for providing an ignition signal to the misfire control thyristor at the output of one half cycle of the exciter coil; and a speed detection capacitor charged with a constant time constant by the output of the other half cycle of the exciter coil. A speed detection capacitor discharge circuit for discharging the charge of the speed detection capacitor with a constant time constant; and a speed detection circuit connected to a firing circuit of the misfire control thyristor, and obtained at both ends of the speed detection capacitor. The ignition signal is sent to the misfire control thyristor when the speed detection voltage is equal to or less than a set value. And a thyristor ignition control switch that allows the ignition signal to be supplied to the misfire control thyristor when the speed detection voltage exceeds a set value. A small resistor connected in series to the misfire control thyristor; a thinning control capacitor charged by a voltage at both ends of the small resistor with a constant time constant; and a charge of the thinning control capacitor having a constant time constant. A discharge circuit for discharging the thinning-out control, and a firing circuit of the thyristor for controlling the misfiring, which conducts when the voltage between both ends of the capacitor for controlling the thinning-out reaches a set value and conducts during the misfire. The firing signal is prevented from being supplied to the control thyristor. It ignition device for an internal combustion engine and said that a thinning control switch to allow the firing signal is applied to the misfire control thyristors.