JPH01117984A - Ignitor for condenser discharge type internal combustion engine - Google Patents

Abstract

PURPOSE:To protect a converter circuit by generating a stop instruction for the converter circuit when the between gate-cathode voltage of a thyristor becomes over a standard voltage which is set lower than the trigger level of the thyristor. CONSTITUTION:An ignitor is equipped with a main converter circuit 10 equipped with a switching element 14, condenser 4 which is installed onto the primary side 1a of an ignition coil 1 and charged by the main converter circuit 10, thyristor 5 which electric-discharges the electric charge of the condenser 4 into the primary coil 1a, and a thyristor trigger circuit 29. In this case, a condenser 32 and a resistor 33 are connected in parallel between the gate and cathode of the thyristor 5. Further, a comparison circuit 34 which compares the voltage between the gate and cathode and a standard voltage and outputs each instruction for operation or stop is installed. For example, a control circuit 45 which supplies the driving pulses into the switching element 14, when an operation instruction is generated is installed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a capacitor-discharge type internal combustion engine combustion engine.

[Prior Art] As is well known, the capacitor discharge type internal combustion eII! The Q ignition device is provided with an ignition energy storage capacitor provided on the primary side of the ignition coil, and is arranged to discharge the charge of the ignition energy storage capacitor to the primary coil of the ignition coil when electrical conduction occurs. It consists of a thyristor and an iris trigger circuit that provides a trigger signal to the internal combustion engine's ignition timing.

When this type of ignition device is driven using a battery as a power source, the primary current of the transformer is interrupted by a switching element that is turned off by J million in response to the drive pulse obtained from the oscillator, thereby reducing the back pressure of the battery voltage. A DC converter is provided, and the capacitor is charged by the output of the converter.

In this way, in an ignition system using a DC-DC converter, in order to protect the converter, it is necessary to stop the operation of the converter when the thyristor is conducting to prevent a large short-circuit current from flowing from the converter through the thyristor. Furthermore, in order to prevent commutation failure of the thyristor, it is necessary to stop the operation of the converter when the thyristor is conductive.

As a conventional 6-ignition device of this type, Japanese Patent Application Laid-open No. 132-1988
No. 084, this conventional ignition device uses both an output voltage detection circuit that detects the output voltage of the converter and a series circuit of multiple diodes inserted in the middle of the capacitor discharge circuit. A current detection circuit is installed to detect the discharge current from the seven voltages. When 11) is established, the oscillation of the oscillator that generates the pulse that drives the switching element of the converter is stopped.

[Problems to be solved by the invention] In the conventional ignition system described above, the converter operation cannot be stopped until after the thyristor actually conducts and current flows. The output of the inverter was short-circuited by the thyristor, and the old flame could not be prevented from growing larger.

In addition, in the conventional device described above, a series circuit of diodes was inserted in the middle of the discharge circuit and the discharge current was detected by the voltage across the circuit, so a loss also occurred in this series circuit of diodes, resulting in a total loss of 1Ω. There was a problem in that the amount of energy became considerably large, resulting in a decrease in efficiency.

An object of the present invention is to protect a converter circuit and prevent commutation failure of a thyristor without increasing losses, thereby enabling efficient but reliable operation of a capacitor discharge type ignition device for an internal combustion engine. Our goal is to provide the following.

[Means for solving the problems] As seen in FIG. 1 showing an embodiment of the present invention,
The DC voltage R voltage converter circuit 12 having a switching element 14 that is turned on and off by the drive pulse Vp is electrically connected to the ignition energy storage capacitor 4 installed on the primary side of the ignition coil 1 and charged by the output of the converter circuit 12. When the ignition energy storage capacitor 4
A capacitor discharging type comprising a thyristor 5 installed to discharge the electric charge to the primary coil 1a of the ignition coil 1, and a trigger circuit 29 for applying a trigger signal between the gate and cathode of the thyristor 5. In the ignition system for internal combustion engines, the game of thyristor 5! - Compare the resistor 33 and capacitor 32 connected in parallel between the cathodes and the gate-cathode voltage V (lk) of the thyristor 5 with a reference voltage Vrl set lower than the trigger level of the thyristor to determine the gate-cathode voltage Vok. A comparator circuit 34 outputs a moving n command signal to the voltage lower than /fi base t\ voltage Vr1 and outputs a stop F command signal 1' when the gate-cathode lightning voltage VOk becomes equal to or higher than the L4 quasi-voltage Vr1; The present invention is characterized in that a drive pulse supply control circuit/15 is provided which supplies the drive pulse Vp to the switching element 14 when a signal is generated and stops the supply of the drive pulse at 11) when a stop command is generated. .

[Operation of the invention] As shown in L, a resistor and a resistor are connected in parallel between the thyristor's gate and cathode, and the voltage between the gate and cathode of the thyristor is compared with 1.4r\voltage. If you avoid generating a stop command signal for the convert circuit when the voltage between the gate and cathode exceeds the IJ quasi-voltage set lower than the thyristor trigger level, the stop command signal will not be generated before the thyristor is triggered. Since the operation of the converter circuit can be stopped, no short-circuit current will flow from the converter circuit side through the thyristor when the thyristor becomes conductive. Therefore, the converter circuit can be protected and loss can be reduced.

Furthermore, when a thyristor is conductive, a voltage drop occurs between the gate and cathode due to the current flowing between the anode and cathode of the thyristor, and this voltage drop charges the capacitor connected between the gate I and the cathode of the thyristor. The voltage between the goo 1 and the catho 1 of the thyristor is maintained above the reference voltage.

Therefore, the comparator circuit continuously generates an open/stop command signal in which the thyristor is in a conductive state, and the converter stops its output during this time, so that commutation of the thyristor is reliably performed.

With the above configuration, there is no need to insert a current detection diode into the discharge circuit of the ignition energy storage capacitor, so no extra loss is caused.
The operation of the converter circuit can be stopped by detecting the operation of the iris, and commutation can be performed reliably by the iris.

According to the present invention, it is possible to reduce loss compared to the conventional method, prevent commutation failure of the τ thyristor, and protect the converter circuit, and improve the efficiency of the charger. .

[Example] The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the present invention. In the same figure, J3 is 1t, L is a primary coil 1a whose one end is grounded, and a secondary coil 1b is on the right, and 2 is an ignition coil shown in the figure. - This is a spark plug inserted into a cylinder of an engine, and the output voltage of the secondary coil 1b of the ignition coil is applied to this spark plug 2. A diode 3 with its cathode facing GJ is connected in parallel to both ends of the primary coil 1a, and one end of an ignition energy storage capacitor 4 is connected to the non-grounded terminal of the primary coil 1a. A thyristor 5 is connected between the other end of the capacitor 4 and the ground with its cathode facing the ground, and a series circuit of a protective capacitor 6 and a resistor 7 is connected in parallel between the anode and cathode of the thyristor 5. There is.

In order to charge the ignition energy storage capacitor 4, a converter circuit 12 consisting of a converter main circuit 10 and an oscillation circuit 11 is provided.

Converter main circuit 10 includes transformer 13 and electric field effect!・
It consists of a run risk 14, a resistor 15, and a diode 16. One end of the primary coil of the transformer 13 is connected via a power switch 18 to the positive electrode of a battery 17 whose zero pole is grounded, and the other end is connected to the drain of a field effect transistor 14 . The source of the field effect transistor 14 is grounded, and a resistor 15 is connected between the gate and source of the field effect transistor. One end of the secondary coil of the transformer 13 is grounded, and seven nodes of the diode 16 are connected to the other end of the secondary coil.

In this example, the field effect transistor 14 constitutes the switching element of the converter circuit.

The oscillation circuit 11 generates pulses for turning on and off the field effect transistor 14, and in this example, it is composed of a known unstable multivibrator constituted by an amplifier 19, resistors 20 to 24, and a capacitor 15. ing. The output pulse Vp' of this oscillation circuit (Fig. 3G
) is supplied to the gate of the field effect transistor 14 through an AND circuit 26 as a drive pulse Vp.

The field effect 1-run risk 14 is turned on and off by this driving pulse, and the primary current of the redorance 13 is intermittent when the field effect 1 to transistor is turned on and off. When the primary current of the transformer 13 is interrupted, a high voltage is induced in its secondary coil, and this voltage is rectified by the diode 16 and applied to the ignition energy storage capacitor 1. As a result, the battery 4 is charged to the polarity shown.

In order to obtain rotation angle information and speed information of the internal combustion engine, a reluctor 27 that rotates in synchronization with the rotation of the engine and a signal coil 28 that induces a voltage due to changes in magnetic flux caused by the rotation of the reluctor are provided. A signal generator is provided, and the output of the signal coil 28 is input to an iris trigger circuit 29 whose power source is a stabilized power supply circuit 31 which receives the output voltage of the battery 17 and outputs a constant voltage.

The thyristor trigger circuit 29 obtains rotation angle information and speed information from the signal coil 28, determines the ignition timing Ill at each rotation speed, and supplies the thyristor 5 with a trigger signal {circle around (2)} at the determined ignition timing. In this example, as shown in FIG. 3(A), the signal coil 28 rises above the threshold level at time t1 corresponding to the maximum advance position of the internal combustion engine and at time t2 corresponding to the minimum advance position. signal V
SI and Vs2, and the thyristor trigger circuit 29 outputs a trigger signal Vt whose generation position changes between the maximum advance angle position and the minimum advance angle position. FIG. 3(B) shows an example of this trigger signal, and the trigger signal Vt in this example rises at 6q tl when the ignition timing is slightly advanced, and falls at time t2 corresponding to the minimum advance position. This is a rectangular wave signal. The rising position of the signal V changes depending on the rotational speed of the engine. When the ignition timing is delayed to the I4 small advance position, the rising position and falling position of the trigger signal Vt match, and the trigger signal becomes 1! In this example, a signal Vs2 which is equal to or higher than the threshold cold level at the minimum advance position is supplied from the signal coil 28 through the diode 30 between the gate and cathode of the thyristor 5, and at the minimum advance position n, this signal I am trying to give trigger confidence to Lily Lister 5 in VS2.

The thyristor 1-98 circuit 29 takes various configurations depending on the engine ignition time ↑1, but the configuration of this thyristor trigger circuit J3 in the present invention is arbitrary. Engine rotation speed N
FIG. 2 shows an example of the characteristics of the ignition timing θi with respect to the ignition timing θi.

A capacitor 3 is connected between the goo 1 and the cathode of the thyristor 5.
2 and resistor 33 are connected in a 11tL column, and thyristor 5
The gate-cathode voltage V (Ik) is input to the negative phase input terminal of the comparison circuit 34.The output If of the stabilized power supply circuit 31 is connected to the positive phase input terminal of the comparison circuit 34 through the resistor 35.
A reference voltage Vr1 obtained by dividing the voltage by a voltage dividing circuit including a variable resistor 36 and a variable resistor 36 is input. The comparison circuit 34U compares the gate-cathode voltage Vak of the thyristor with the reference voltage Vrl, and outputs No. 18 of high level (logic state is "1") when vrl>V(lk), and Vrl≦Va
When k, a low level signal (logic state is "0") is output. In this example, the high level signal obtained from the comparison circuit 34 is used as the vJ operation command signal, and the low level signal obtained from the comparison circuit 34 is used as the stop command signal. The reference voltage v"1 is set lower than the 1-trigger level of the thyristor 5, so that the output of the comparison circuit 34 becomes a low level before the gate-cathode voltage gk of the thyristor 5 reaches the trigger level of the thyristor 5. The output v1 of the comparison circuit 34 is input to the AND circuit 26.

Further, the anode of a diode 37 is connected to the non-grounded terminal of the secondary coil of the transformer 13 of the converter circuit, and a series circuit of a resistor 38 and a variable resistor 39 is connected between the cathode of the diode 37 and the ground. . A capacitor 40 is connected to both ends of the series circuit of the resistor 38 and the variable resistor 39.
are connected in parallel, and a diode 37, a 1W resistor 38, a variable resistor 39, and a capacitor 40 constitute an output voltage detection circuit 41 that detects the output voltage of the converter circuit. This output voltage detection circuit 41 is connected to a variable resistor 39
A detection voltage ``0'' is generated across both ends of , and this detection voltage is input to the negative phase input terminal of the comparator circuit 42 . Comparison circuit 42
The output voltage of the stabilized power supply circuit 31 is divided by a voltage dividing circuit consisting of a series circuit of resistors 2A43 and 44, and a set voltage Vr2 is inputted to the positive phase input terminal of. The comparison circuit 42 compares the detection voltage vO and the set voltage Vr2, and when VF6>VO, the comparison circuit 42 determines the n level (the logic state is "1").
), and when vr2≦VO, outputs (L;Q) of low level (logic state is "0"). In this example, the n-level signal obtained from the comparator circuit 42 is the fJJ operation command signal. The low level signal obtained from the comparator circuit 34 is used as a stop command signal.The output V2 of the comparator circuit 42 is input to the AND circuit 26.

In this example, the AND circuit 26 is a drive pulse supply control circuit that supplies a drive pulse to the switching element (field effect transistor 14) when an operation command signal is generated and stops supplying the drive pulse when a stop command is issued. 4
5 are configured.

Next, the operation of the above embodiment will be explained.

When the iris signal Vt is not applied to the iris register 5, the output V1 of the comparator circuit 34 (see FIG. 3F)
The logical state of is "1". In addition, when the output voltage of the converter circuit is below the set value and the detection voltage 0 is lower than the set voltage Vr2 (when the capacitor 4 is not sufficiently charged), the output V2 of the comparator circuit 42 (Fig. (see E) has a logic state of "1". Since the AND condition of the AND circuit 2G is satisfied every time the 1,1 generating circuit 11 generates a pulse, the driving pulse Vp is applied to the gate of the field effect transistor 14 through the AND circuit 26, and the field effect transistor A high voltage is induced in the secondary coil of the transformer 13 by repeating on and off operations. This voltage is applied to the capacitor 4 through the diode 16, so that the capacitor 4 is charged to the polarity shown and the =1
The terminal voltage Vc of the terminal V increases as shown in FIG. 3(D).

Charging of the capacitor 4 is completed, the output voltage of the converter circuit becomes higher than the set value, and the detection voltage VO becomes the set voltage Vr2.
When this happens, the logic state of the output of the comparator circuit 42 becomes rOJ, and the output signal of the AND circuit 26 becomes "0". Therefore, the field effect transistor 14 is maintained in a disconnected state, the operation of the converter circuit is stopped, and the charging of the capacitor 4 is stopped.

In this way, in this embodiment, the operation of the T1 inverter circuit is stopped when the output voltage of the inverter circuit exceeds the set value, so it is possible to prevent excessive voltage from being applied to the capacitor 4, and As the capacitor 4, a capacitor having the minimum necessary withstand voltage can be used.

When the trigger signal Vt is applied from the thyristor trigger circuit 29 to the gate cathode of the thyristor 5, the capacitor 32 is charged by the signal, and the voltage Vok between the gate and cathode of the thyristor 5 increases as shown in FIG. 3(C). It increases as the capacitor 32 is charged. The gate-cathode voltage Vgk of the thyristor 5 is the reference voltage Vrl
When you reach .

Since the output of the comparison circuit 34 becomes a low level, the output J of the AND circuit 26 becomes rOJ, the supply of the drive 01 pulse to the field effect 1-run risk 14 is stopped, and the operation of the converter circuit is stopped. Next, the voltage Vok between the cathode and gate of the thyristor 5 is set to the trigger level of the thyristor 5.
(When the voltage reaches +, the thyristor 5 becomes conductive and the capacitor 4
is discharged to the primary coil 1a of the ignition coil. At this time, the anode current 1a flowing through the thyristor 5 is shown in Fig. 3 (
1) is shown. This discharge of the capacitor causes a large change in magnetic flux in the iron core of the ignition coil, inducing a convex voltage in the secondary coil. Since this zero voltage is applied to the spark plug 2, a spark is generated in the spark plug and the engine is ignited.

When the thyristor 5 is conductive, a voltage drop occurs between the gate and cathode of the thyristor, and the capacitor 32 is charged by this voltage drop.
- cathode voltage vllIk is maintained at or above the reference voltage Vr1. As the anode current of the thyristor is exhausted, the charge in the b capacitor 32 is not discharged immediately, but the b current is supplied through the resistor 33 at a constant time constant, and the voltage at the terminal of the capacitor 4J 32 falls below the reference voltage Vrl. Therefore, the comparator circuit 34 maintains a constant 11 while the anode current is flowing through the thyristor 5, and even after the anode current of the thyristor 5 becomes zero.
A stop command signal with a logic state of "0" is output continuously for 4 hours, and during this period, the AND/D circuit 26 turns off the field effect transistor 14.
The operation of the converter is stopped by stopping the supply of drive pulses to the converter. Therefore, the commutation of the thyristor 5 can be ensured.

In the waveform of the voltage Vgk between the gate and cathode of the thyristor shown in FIG. mountain vb that appears in
is given from the signal coil 28 through the diode 30 (i''+N V s2).

In the above embodiment, an output voltage detection circuit 41 that detects the output voltage of the converter circuit and a comparison circuit 42 that compares the output of this detection circuit with the set voltage are provided (), so that the output voltage of the converter circuit is set to the set value. Although the operation of the converter circuit is stopped when the above occurs, if the withstand voltage of the ignition energy storage syndenser 4 is not a problem, these circuits can be omitted, and in that case, the AND circuit 26 A two-person circuit is used.

[Effects of the Invention] As described above, according to the present invention, a resistor and a resistor are connected in parallel between the gate cathode of a thyristor, and the voltage between the gate cathode and the gate cathode of the thyristor is compared with a reference voltage. Since the converter circuit stop command signal is generated when the voltage exceeds the reference voltage set lower than the thyristor trigger level, the converter circuit stop command signal is generated before the thyristor is triggered. Operation can be stopped. Accordingly,
When the thyristor becomes conductive, the converter circuit can be protected by preventing a short $8ffl current from flowing through the nyristor from the converter circuit side, and there is an advantage that loss can be reduced.

Historically, in the present invention, when the thyristor is conductive, the voltage drop between the gate 1 and the power sword of the thyristor is charged by the voltage drop between the gate 1 and the power sword of the thyristor. ! Since the voltage is maintained at or above the standard voltage and the stop command signal is continuously generated from the comparator circuit, the output of the converter can be stopped while the thyristor is conducting, resulting in a +1 irrisk transfer. This has the advantage of ensuring that the flow is carried out reliably.

According to the present invention, there is no need to insert a current detection diode into the discharge circuit of the ignition energy storage capacitor. It is highly efficient and operates reliably: Electric internal combustion engine No. 1 No. 11i! It can be used as an ignition device.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing an example of ignition characteristics obtained by the embodiment of Fig. 1, and Fig. 3 shows signal waveforms at various parts of Fig. 1. FIG. DESCRIPTION OF SYMBOLS 1... Ignition coil, 2... Spark plug, 4... Capacitor for ignition energy Mv4, 5... Thyristor, 10... Converter main circuit, 11... Generation circuit,
12... converter circuit, 13... transformer, 14
...Field effect transistor (switching element) 1
7... Battery, 26... AND circuit, 28...
Signal coil, 29... Thyristor trigger circuit, 32.
... Capacitor, 33... Resistor, 34... Comparison circuit, 45... Drive pulse supply f1. control circuit. , t'-1

Claims (1)

[Claims] A DC voltage step-up converter circuit having a switching cable that is turned on and off by a drive pulse, and one of the ignition coils.
an ignition energy storage capacitor provided on the next side and charged by the output of the converter circuit; and a thyristor provided so as to discharge the charge of the ignition energy storage capacitor to the primary coil of the ignition coil when electrically connected. and a thyristor trigger circuit that provides a trigger signal between the gate cathode of the thyristor, a resistor and a capacitor connected in parallel between the gate cathode of the thyristor, and the gate of the thyristor. The voltage between the cathodes is compared with a reference voltage set lower than the trigger level of the thyristor, and when the voltage between the gate and cathodes is less than the reference voltage, an operation command signal is output, and the voltage between the gate and cathodes becomes equal to or higher than the reference voltage. a comparison circuit that outputs a stop command signal when the operation command signal is generated; and a drive pulse supply control circuit that supplies a drive pulse to the switching element when the operation command signal is generated and stops supplying the drive pulse when the stop command is generated. An ignition device for a capacitor discharge type internal combustion engine, characterized by comprising: