JPH0363674B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an ignition device for an internal combustion engine using an ignition spark method. This device is mainly used for ignition of internal combustion engines for automobiles.

[Prior art]

Conventional ignition devices used in internal combustion engines reduce ignition energy at high speeds and only generate one spark, making them vulnerable to blowouts. In particular, the CDI method has the problem that it is prone to misfires because the flame does not grow during startup or at low speeds.

[Purpose of the invention]

The purpose of the present invention is to ensure that ignition energy is not insufficient at high speeds, and that flame failure or misfire does not occur at low speeds, based on the concept of continuously generating multiple sparks for an appropriate period at extremely short cycles. The object of the present invention is to secure a flame duration as long as possible, thereby improving ignition performance, and to prevent malfunction and destruction of switching elements so that these elements can operate safely and reliably.

(Structure of the Invention) The present invention includes a DC power source that generates a DC voltage, two primary coils, a first and second coil, and one secondary coil, and an ignition coil having a primary coil midpoint connected to one end of each; a spark plug connected to the secondary coil;
A capacitor connected to the center tap of the primary coil, a first switching element forming a closed circuit together with the first portion of the primary coil, the capacitor, and the DC power supply; Second
and a second switching element forming a closed circuit together with the capacitor, the first switching element and the second switching element operating in accordance with the ignition instruction signal and alternately conducting at a predetermined timing. and a signal generation circuit that generates an energization signal as shown in FIG.
An ignition device for an internal combustion engine is provided in which a secondary coil and a secondary coil are wound around the same core with only a portion of the secondary coil overlapping each other.

(Embodiment) An ignition system for an internal combustion engine as an embodiment of the present invention is shown in FIG.

The DC power supply 1 is a power supply using a battery, for example, and supplies DC voltage to the DC-DC converter 3 via the engine key switch 2. The engine key switch 2 is a switch that is closed when the engine is running and opened and closed when the engine is stopped. In addition, the DC-DC converter 3 converts the DC voltage of the DC power supply 1, for example, 12V, to approximately 20V.
It is a converter that converts the voltage into DC voltage, and after self-oscillating the transistor and boosting the voltage with the transformer,
It rectifies and supplies high voltage DC. The capacitor 4 is for smoothing and storing the output voltage of the DC-DC converter 3 and for supplying a transient large current, which will be described later.

The ignition magnetic detection device 5 includes a signal rotor 51 and a pickup 53. The signal rotor 51 is made of magnetic material and is used for detecting ignition timing.
It has a number of protrusions 52 corresponding to the number of cylinders, and is attached to a distributor shaft (not shown) that rotates synchronously at half the engine speed. The pick-up 53 is for detecting ignition timing, and is composed of a coil 533 and a permanent magnet 532 wound around a magnetic core 531 made of a magnetic material.
is arranged so that a closed magnetic path is formed when the magnetic core 531 of the pickup 53 faces the magnetic core 531 of the pickup 53.

Although not shown, the phase relationship between the signal rotor 51 and the pickup 53 changes appropriately depending on the engine speed and load, so that optimal ignition timing can be obtained.

The shaping circuit 6 is a circuit that shapes the waveform of the output signal of the pickup 53 and outputs a signal of "1" level (hereinafter simply referred to as "1") corresponding to the ignition timing. Details of the shaping circuit 6 in the device of FIG. 1 are shown in FIG. In this figure 2, the resistor 61
1,612, and a bias voltage Vb set by a capacitor 613 is applied to one end of the coil 533 of the pickup 53 via the terminal 601. This bias voltage Vb is further applied to the inverting input terminal of comparator 614 as a reference voltage. The non-inverting input terminal of the comparator 614 is connected to the other end of the coil 533 via the terminal 602, and the comparator 6
At the output of 14, a signal of "1" or "0" level (hereinafter simply referred to as "0") is generated.

Positive feedback is applied from the output of the comparator 614 to the non-inverting input terminal via a resistor 615.
Since this positive feedback circuit has a Schmitt trigger function with hysteresis, it is effective in preventing malfunctions due to noise. The output of comparator 614 is inverted by inverter 616 and output as an ignition timing signal via terminal 603.

In FIG. 1, the trigger signal generation circuit 7 generates two trigger signals S(A) to S(B) having a phase difference of 180° from each other, repeating in short cycles for a predetermined period, from the ignition timing signal from the shaping circuit 6. make. Details of the trigger signal generation circuit 7 in the apparatus shown in FIG. 1 are shown in FIG. In FIG. 3, the ignition timing signal from the shaping circuit 6 is led to the one-shot multi 711 via the terminal 701. One shot multi 71
1 is triggered by the rise of this ignition timing signal, and a signal of "1" is generated at the output terminal Q for a certain period of time (for example, 2 msec) determined by a capacitor 712 and a resistor 713.

Noah gates 714 and 715 are reset,
They are connected together to form a flip-flop, and the output of the one-shot multi 711 is "1".
Then, the output of the NOR gate 714 becomes "0" and the output of the NOR gate 715 becomes "1". The binary presettable up-down counter 717 is 4.
It is a bit counter circuit, and the output of a NOR gate 714 is led to its reset terminal. When the output of the NOR gate 714 becomes "0", it starts counting, and when it becomes "1", it is reset. In addition,
This counter 717 is set to down count mode and does not use the preset function.

Clock generating circuit 716 is a circuit that continuously generates a clock signal having a frequency of, for example, about 80 KHz, and the clock signal is introduced to a clock input terminal of counter 717. One input terminal of the NOR gate 718 is connected to the output terminal of the one-shot multi 711, and the other input terminal is connected to the output terminal of the counter 717.
Connected to the Q _D output terminal, which is a 1/16 frequency division output. When the levels of both output terminals become "0", the output of the NOR gate 718 becomes "1".
This output is led to NOR gate 715, which inverts a flip-flop composed of NOR gates 714 and 715.

The _QD output of counter 717 is further guided to one-shot multis 721 and 728 via inverter buffers 719 and 720, respectively. One shot multi 721 is inverter buffer 71
It is triggered by the fall of the output of 9, and is held for a certain period of time determined by the capacitor 722 and resistor 723 (for example,
A “0” signal is generated at the output terminal for 5μsec). This signal is conducted to the base of transistor 726 via resistors 724 and 725. When the terminal of the one-shot multi 721 is "0", the transistor 726 is turned on and generates a "1" trigger signal S(A) at its collector, that is, the terminal 702.

The one-shot multi 728 is triggered by the rising edge of the output of the inverter buffer 720, and generates a "0" signal at the output terminal for a certain period of time (for example, 5 μsec) determined by the capacitor 729 and resistor 730. This signal is guided to the base of transistor 733 via resistors 731 and 732. When the terminal of the one-shot multi 728 is "0", the transistor 733 is turned on, and the trigger signal S of "1" is applied to its collector, that is, the terminal 703.
Output (B).

Next, the power circuit 18 shown in FIG. 1 will be explained.

The thyristor 13 has an anode connected to the capacitor 4.
, and its cathode is connected to one end of the first primary coil 161 of the ignition coil 16 . A trigger signal S(A) is applied to the gate of the thyristor 13 from the trigger signal generation circuit 7 via an insulating pulse transformer 14, and further to the diode 13.
1, resistor 132, capacitor 133, resistor 134
It is supplied through a noise prevention circuit consisting of. The resonance capacitor 15 is connected to the primary coil midpoint 160 of the ignition coil 16 . This thyristor 13 forms one closed circuit consisting of the capacitor 4, the thyristor 13, the primary coil 161, and the resonance capacitor 15.

The thyristor 20 has an anode connected to the primary coil 1.
62, and its cathode is connected to one end (GND) of the resonance capacitor 15. A trigger signal generation circuit 7 is connected to the gate of the thyristor 20.
Trigger signal S(B) is passed through a pulse transformer 21, and then a diode 201, resistors 202, 20
4. The signal is supplied through a noise prevention circuit consisting of a capacitor 203. 1 by this thyristor 20
Another closed circuit consisting of the next coil 162, the thyristor 20, and the resonance capacitor 15 is formed.

The ignition coil 16 includes a first coil 161, a second primary coil 162, a secondary coil 163, and an iron core 16.
Consists of 4. FIG. 6 shows the structure of the ignition coil 16. In FIG. 6, the number of turns of the first and second primary coils 161, 162 is approximately 40 turns each, and the number of turns of the secondary coil 163 is approximately 6000 turns.
Both are wound on an iron core 164, and the turns ratio between the primary coils 161, 162 and the secondary coil 163 is set to about 150. The first and second primary coils 161 and 162 are wound on the iron core 164 so that their respective portions partially overlap so that they are closely magnetically coupled to each other. Further, the two primary coils 161, 162 are connected so that one end of each of the two primary coils 161, 162 is common so that magnetic fields are generated in the same direction in the iron core 164 when energized. It has a point (midpoint of the primary coil) 160.

The first and second primary coils 161, 162 are magnetically coupled to a secondary coil 163 via an iron core 164, and boost the voltage generated in the two primary coils 161, 162 to It is output from the coil 163.

Further, in FIG. 1, one end of the secondary coil 163 is grounded (GND), and the other end is connected to the center electrode of the distributor 22 that distributes high voltage to each cylinder.

The distributor 22 has a well-known configuration, and uses a shaft that rotates synchronously at one half of the engine speed and a distribution rotor 23 that rotates in unison to control the ignition provided in a predetermined cylinder. High tension cords 251, 252, 253, 254 to plugs 241, 242, 243, 244
Distributes high voltage through.

The following semiconductor devices were used in the apparatus shown in FIG.

One shot multi 711...Toshiba TC4528BP Noah Gate 714, 715, 718
...Toshiba TC4001BP up-down counter 717
...Toshiba TC4516BP inverter 719,720 ...Toshiba TC4049BP one shot multi 721,728
...74LS221 manufactured by TI Next, the operation of the device shown in FIG. 1 will be explained.

FIG. 4 is a signal waveform diagram of each part of the device shown in FIG. 1,
1 is the electromotive force of the coil 533, 2 is the output voltage of the pickup 53, 3 is the ignition period signal which is the output of the shaping circuit 6, and 4 is the one shot multi 71.
1 is the ignition timing period signal which is the output, 5 is the output signal of the NOR gate 714, 6 is the _QD output signal of the counter 717, and 7 is the inverter buffer 719, 720.
8 represents the waveform of the trigger signal S(A), and 9 represents the waveform of the trigger signal S(B).

First, when engine key switch 2 is turned on, DC power supply 1 is connected to DC-DC converter 3.
A DC voltage of ⁺ 12V is supplied and boosted to ⁺ 200V, and this 200V DC voltage is constantly stored in the capacitor 4.

The signal rotor 51 rotates in accordance with the rotation of the engine, and the fourth
An electromotive force having the waveform shown in FIG. 1 is generated. The point at which this electromotive force switches from positive to negative is the ignition timing. Since the coil 533 is biased by the bias voltage Vb by the shaping circuit 6, the output voltage of the pickup 53 becomes a value where the potential generated by the coil 533 is increased by the bias voltage Vb, as shown in FIG. . This signal is shaped by the shaping circuit 6 and becomes a signal that rises to "1" at the ignition timing shown in FIG. 4.

The output signal of the shaping circuit 6 is sent to the trigger signal generation circuit 7.
The one-shot multi 711 is triggered at the rising edge of the signal to generate a pulsed ignition period signal with a pulse width of approximately 2 msec as shown in FIG. This pulse width is defined as the ignition period. The ignition period signal enters the Noah gate 714 and the Noah gate 71
4,715 flip-flops are inverted. As a result, the output of the NOR gate 714 becomes "0" as shown in FIG. 4.

The output of NOR gate 714 is led to the reset terminal of counter 717, and when this output is "0", counter 717 is released from reset. Upon release of this reset, the counter 717 starts counting at a clock frequency of about 80 KHz from the clock generating circuit 716. Here, the counter 717 is a 4-bit binary counter and is set to down-count mode, so the contents of the counter 717 change from 0 to 15 at the first rising edge of the clock signal.
Changes to That is, the _QD output of the counter 717 changes from "0" to "1". From then on, the countdown is repeated every time a clock signal arrives,
The contents change periodically as 0, 15, 14, ..., 2, 1, 0, 15, .... At this time, the _QD output, which is a 1/16 frequency division output, has the contents of the counter 717 from 8 to
15, it becomes "1", so the clock frequency of 16
A square wave with a duty ratio of 50% as shown in FIG. The width of one pulse in FIG. 4 is 100 μsec, and the interval between pulses is 100 μsec.

Approximately 2 msec after the ignition timing signal rises,
The input of the NOR gate 714 becomes "0". If the counter 717 is reset immediately at this time, the time width of the _QD output "1" immediately before that reset will be shortened, and the commutation of the thyristor, which will be described later, will not be carried out properly. As a countermeasure for this, by leading the output of the one-shot multi 711 and the output of the counter 717 to the input of the NOR gate 718, the Q _D
Only when the output is "0", the output of the NOR gate 718 becomes "1", inverting the flip-flop consisting of the NOR gates 714 and 715, thereby setting the output of the NOR gate 714 to "1" and resetting the counter 717. I have to.

As explained above, an integral number of square waves of 1/16 of the clock frequency (5KHz) are generated at the _QD output at least during the ignition period with a delay of less than one clock signal period (12.5μsec) from the ignition timing signal. . This signal is inverted by inverter buffers 719 and 720 to become the signal shown in FIG. 7.

The one-shot converter 721 is triggered by the falling edge of the inverter buffer 719, generates a pulse of about 5 μsec, turns on the transistor 726, and outputs the trigger signal S(A) shown in FIG. 4 to the terminal 702. Also, the one-shot multi 728 is triggered by the rising edge of the output of the inverter buffer 720, generates a pulse of about 5 μsec, turns on the transistor 733, and outputs the trigger signal S(B) shown in FIG. 4 to the terminal 703. do. In other words, the trigger signals S(A) and S(B) have a period with a phase difference of 180° from each other.
It is a signal with a pulse width of 200μsec and a pulse width of 5μsec.

Next, the operation of the high pressure generator will be explained. FIG. 5 is a waveform diagram showing the signals of each part in this embodiment in a temporally enlarged manner compared to FIG. 4. In FIG. 5, 1 is the trigger signal S(A), 2 is the trigger signal S(B), 3 is the terminal voltage of the capacitor 15, 4 is the cathode voltage of the thyristor 13, and 5 is the thyristor 1
3 represents the current flowing through the thyristor 20, 6 represents the anode voltage of the thyristor 20, and 7 represents the waveform of the current flowing through the thyristor 20.

The trigger signal S(A) shown in FIG.
trigger. Similarly, the trigger signal S(B) shown in FIG. 52 triggers the thyristor 20 via the pulse transformer 21 and the noise prevention circuit.

First, when the thyristor 13 is triggered and turned on, current flows through a closed circuit consisting of the capacitor 4 , the thyristor 13 , the primary coil 161 , and the capacitor 15 . At this time, since the capacitance of capacitor 4 is sufficiently larger than that of capacitor 15, capacitor 4 can be considered as a constant voltage (200V) power source. Furthermore, since the resistance of the circuit consisting of the resistance of the primary coil 161 and the resistance of the thyristor 13 is sufficiently small, this first closed circuit consists of the capacitance C of the capacitor 15 (for example, 2 μF) and the inductance L of the primary coil ( For example, it resonates under conditions determined by 50μH).

The current at resonance flows through the positive terminal of capacitor 4, thyristor 13, primary coil 161, and
It flows in the direction of the ground terminals of capacitor 15 and capacitor 4, forming a half-sine waveform as shown in FIG. Its peak current value is approximately 150A, and the energizing time is approximately
It is 20μsec. Due to this energization, the voltage applied to the capacitor 15 increases to about 600V as shown in FIG. 5.

The thyristor 13 remains on only when i>0, but as shown in FIG. 5, when i≦0, the thyristor 13 commutates and becomes off.

In this way, in the device shown in FIG. 1, since an oscillating current due to resonance flows through the circuit including the primary coil, capacitor, switching element, and DC power supply, the thyristor 13 automatically commutates, so a special commutation circuit is used. There is no need to add .

When thyristor 13 turns off, capacitor 15
The voltage stored in the power source is about 600V, which is about three times the DC power supply voltage of 200V, and this is due to the amplification effect based on the resonance phenomenon.

Next, a case where the thyristor 20 is triggered will be explained. When this thyristor 20 is turned on, the capacitor 15, the second primary coil 162,
A closed circuit consisting of the thyristor 20 is formed, and the charge stored in the capacitor 15 flows in the direction of the upper terminal of the capacitor 15, the second primary coil 162, the thyristor 20, and the lower terminal of the capacitor 15.
The waveform becomes a half-sine wave as shown in FIG. 5 and FIG. As with the thyristor 13, the thyristor 20 has a peak current value of about 150 A and a current conduction time of about 20 μsec. The voltage applied to the capacitor 15 due to this energization ranges from about 600V to about -400V as shown in FIG.
decreases to When the current waveform of the thyristor 20 shown in FIG. 5 becomes zero, the thyristor 1
As in case 3, natural commutation occurs, so no special commutation circuit is required.

Thereafter, by successively and alternately triggering the thyristor 13 and the thyristor 20, current alternately flows through the first primary coil 161 and the second primary coil 162.

First and second primary coils 161, 162 and 2
Since the turns ratio of the secondary coil 163 is set to approximately 150, a voltage approximately 150 times the voltage applied to the primary coils 161 and 162 is generated in the secondary coil 163.

Since the voltage applied to the first and second primary coils 161, 162 is approximately 600V, the turns ratio is approximately
It is calculated that a high voltage of 600 (V) x 150 = 90 (KV) is generated in the secondary coil 163 from 150, but in reality, about 40 (KV) is generated due to losses in the ignition coil 16, and due to discharge. The voltage is sufficient to ignite.

The voltage generated by the secondary coil 163 is distributed to predetermined cylinders by the distributor 22, and is supplied to the spark plugs 241, 242, 243, 244 via high tension cords 251, 252, 253, 254 to ground the spark plugs. Ignition occurs by discharging to the electrodes.

Once a discharge path is formed by the discharge, the air in the vicinity is ionized and becomes an arc discharge, and the induced discharge continues until the voltage drops below the discharge sustaining voltage (approximately 500V to 1KV). Although this duration is shorter than that of a normal ignition device (approximately 2 msec), the next cycle starts immediately after this inductive discharge ends, so the ions remaining between the discharge gap can easily cause a re-discharge. occurs, and the discharge continues almost without interruption. Since this duration can be determined by the ignition period electrically set in the trigger signal generation circuit 7, it is easy to set it to a sufficiently long time to achieve complete ignition.

Furthermore, since the other thyristor is in the reverse blocking state for about half of the time that one thyristor is on, the repetition period of the trigger signals S(A) and S(B) can be shortened. As described above, the apparatus shown in FIG. 1 can continuously generate a plurality of sparks in extremely short cycles over an appropriate period of time in the ignition control of an internal combustion engine for an automobile, thereby improving the ignition performance of the internal combustion engine.

Next, in the anode voltage waveform of the thyristor 20 shown in FIG. 5 and FIG. 6, a peak voltage V _p occurs when the thyristor 13 ends energization. This peak voltage
V _p is related to the length l of the overlapping portion of the first and second primary coils 161, 162 of the ignition coil 16 shown in FIG. 6 (i.e., the degree of magnetic coupling between both primary coils 161, 162). do. This relationship is shown in FIG. From the relationship shown in Figure 7, the length of the overlapping part l
When l is set below a certain value l ₀ , the peak voltage V _p becomes zero. Therefore, if we set the length of the overlapping part l to ₀ ,
The forward blocking voltage of the thyristor 20 only needs to be 600V or more, and is reduced by the peak voltage _Vp .

On the other hand, the same applies to the thyristor 13 shown in FIG. 5, and the peak voltage _Vp can be eliminated by setting the length of the overlapping portion to _l0 .

Note that if the length l of the overlapping portion shown in FIG. 6 is made too small, each primary coil 161, 162
As the magnetic coupling between the secondary coil 163 and the secondary coil 163 becomes smaller,
Since there is a problem that the output voltage of the secondary coil 163 decreases, it is better not to make the length l of the overlapping portion smaller than necessary.

As a result, the first and second 1 shown in FIG.
By changing the length l of the overlapping portion of the secondary coils 161, 162 and appropriately setting the length of the portion where the two primary coils 161, 162 are tightly magnetically coupled to each other, the thyristors 13, 20 can be The applied peak voltage can be reduced or eliminated,
Even a thyristor with a low forward blocking voltage can be used in the device shown in FIG. 1, resulting in cost reduction.

Next, in the device shown in FIG. 1, since the primary windings 161 and 162 of the ignition coil 16 are inserted between the thyristor 13 and the thyristor 20, the thyristor 13 and the thyristor 20 may be damaged by noise or the like. Even if the primary windings 161 and 1
The inductance and resistance component 62 prevents a sudden increase in current and overcurrent, thereby preventing destruction of the thyristor and switching elements other than the thyristor due to di/dt of the thyristor or overcurrent.

In addition, the capacitor 15 is connected to the primary coils 161, 1
62, the rate of increase dV/dt of the voltage applied in the forward direction to the thyristors 13 and 20 is determined by the time constants of the capacitor 15 and the primary coil 162, and the time constants of the capacitor 15 and the primary coil 161, respectively. Determined by the time constant, its rate of increase dV/dt
can be set to a low value of 100V/μsec or less.

Furthermore, malfunctions caused by dv/dt applied to the other thyristor due to the operation of one thyristor can be eliminated.

Furthermore, the primary coils 161 and 162 are wound in the same direction and are configured to generate magnetic fields in the same direction, thereby reducing the dv/dt applied to the switching element and ensuring the safety of the switching element. Reliable operation can be obtained.

(Effects of the Invention) According to the present invention, when igniting an internal combustion engine, a plurality of sparks can be generated continuously for an appropriate period in an extremely short cycle, and ignition energy is ensured so as not to run out at high speeds. In addition, flame duration is ensured to prevent flame growth or misfire at low speeds, thereby improving ignition performance.

In addition, while reducing the drop in the output voltage of the secondary coil, the voltage induced in the second primary coil at the end of energization to the first primary coil and the voltage induced in the second primary coil at the end of energization to the second primary coil are reduced. The voltage induced in the first primary coil can be reduced or made zero, and therefore the voltage applied to the first and second switching elements can be reduced accordingly, reducing the forward blocking voltage. Even if inexpensive switching elements such as thyristors with a relatively low resistance are used, malfunctions and destruction can be prevented, and these elements can be operated safely and reliably.

[Brief explanation of drawings]

Fig. 1 is an electric circuit diagram showing an ignition system for an internal combustion engine as an embodiment of the present invention, Fig. 2 is a detailed electric circuit diagram of a shaping circuit in the apparatus shown in Fig. 1, and Fig. 3 is a trigger circuit diagram in the apparatus shown in Fig. 1. A detailed electric circuit diagram of the signal generation circuit, FIG. 4 is a signal waveform diagram of each part in the apparatus shown in FIG. 1, and FIG. 5 is a waveform diagram of the signal waveform of each part in the apparatus shown in FIG.
FIG. 6 is a schematic structural diagram of the ignition coil in the device shown in FIG. 1, and FIG. 7 is a characteristic diagram showing the relationship between the length of the overlapping portion of each primary coil of the ignition coil and the peak voltage applied to the thyristor. . 1, 3, 4...battery that constitutes the DC power supply,
DC-DC converter, capacitor, 5...Ignition timing detection device, 7...Trigger signal generation circuit, 13,
20... Thyristor forming the first and second switching elements, 15... Resonance capacitor, 16...
Ignition coil, 161, 162...Primary coil, 1
60...Middle point of the primary coil, 163...Secondary coil, 241-244...Spark plug.

Claims (1)

[Claims] 1. A DC power supply that generates a DC voltage; an ignition coil having two primary coils, a first and a second coil, and one secondary coil; connected to the secondary coil; The spark plug and the first and second primary coils are connected to a middle point of the primary coils with one end of each of the primary coils connected in common so that the first and second primary coils generate magnetic fields in the same direction when energized. a first switching element that forms a closed circuit together with the first primary coil, the capacitor, and the DC power supply; a second switching element that forms a closed circuit together with the second primary coil and the capacitor; comprising a switching element, and a signal generation circuit that operates according to an ignition instruction signal and generates an energization signal so that the first switching element and the second switching element are alternately rendered conductive at a predetermined timing; An ignition device for an internal combustion engine, in which the two primary coils, the first and second coils, are wound around the same core together with the secondary coil with only a portion overlapping each other.