JPS6062660A - Ignition device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To reduce power dissipation and heat radiation and improve reliability by performing the close angle control so as to attain the injection timing when the primary current of an ignition coil reaches a predetermined current and performing high-energy ignition. CONSTITUTION:When the alternating voltage generated by an AC generator 100 is at the positive side, a transistor 53 is turned on, transistors 54, 59 are turned off, a transistor 60 is turned on, a transistor 62 is turned off, a transistor 63 and a power transistor 64 are turned on, thus feeding the primary current of ignition coil 101. When the energizing current of the ignition coil 101 is increased to reach a predetermined current value, a current flows into the base of the transistor 62, the transistors 62, 63 and the power transistor 64 are controlled in an active region, and the energizing current of the ignition coil 101 is controlled. A thermistor 40 is used for the temperature compensation of a current limit circuit 113. Next, when the alternating voltage of the AC generator 100 is changed to the negative side, the primary current of the ignition coil 101 is cut off and an ignition plug is discharged.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition device for an internal combustion engine, and particularly to an ignition device that has high energy ignition performance from low to high rotation speeds.

As a conventionally well-known high-energy ignition device, JP-A-46
There is an ignition device proposed in Japanese Patent No.-7657. In the ignition device according to Japanese Patent Application Laid-Open No. 46-7657, the AC output of an AC generator rotating in synchronization with the internal combustion engine is rectified and stored in a capacitor as a DC voltage, and this DC voltage is used as a bias voltage for the AC output. In addition, by applying it to the waveform shaping circuit, the closing angle at which the primary current of the ignition coil is passed is expanded, and when the primary current of the ignition coil reaches a predetermined current, negative feedback is applied so that the charge in the capacitor is discharged. The closing angle, in other words, the energization start timing is corrected, and the closing angle is controlled so that the ignition timing is reached just when the primary current of the ignition coil reaches a predetermined current value.

Therefore, when the engine speed is low and the AC output voltage of the alternator is small, the charging voltage of the capacitor is almost zero, so the closing angle cannot be controlled as described above, and the closing angle determined by the AC output waveform cannot be controlled. There was a problem in that the current was turned on for an extra time, and the power consumption of the ignition coil and power transistor was large, resulting in a large temperature rise.

The present invention has been made to solve the problems of such conventional devices, and includes: an alternator that rotates in synchronization with an internal combustion engine; a waveform shaping circuit that switches in response to the alternating current voltage generated in the alternator; A drive circuit that controls the Hase current of the power transistor that turns on and off the primary current of the ignition coil in response to the output of the waveform shaping circuit, and a constant current control of the power transistor so that the negative current does not exceed a predetermined current value. a current limiting circuit that applies a voltage corresponding to the rotational speed of the internal combustion engine to the waveform shaping circuit to change the switching level of the waveform shaping circuit with respect to the alternating current voltage, and a closing angle at which the primary current of the ignition coil is energized. a closing angle expansion circuit that operates to expand the primary current of the ignition coil; a closing angle reduction circuit that operates to reduce the closing angle of the power transistor, and a closing angle reduction circuit that operates to reduce the closing angle of the power transistor; - By providing an interruption circuit that interrupts between low-speed rotation and high-speed rotation, the closing angle is controlled so that the ignition timing is reached when the primary current of the ignition coil reaches a predetermined current from low speed rotation to high speed rotation. ignition, and the power consumption of the ignition coil and power transistor is low even during low speed rotation, reducing heat generation.Furthermore, it is possible to prevent oscillation of the waveform shaping circuit, and the negative impact on ignition timing due to the closed angle reduction circuit. It is an object of the present invention to provide a highly reliable ignition device for an internal combustion engine that prevents this from occurring.

The present invention will be explained below based on embodiments shown in the figures.

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

In Fig. 1, 1 to 31 are resistors, 40 is a thermistor,
51 to 63 are transistors, 64 is a power transistor, 71 to 75 are diodes, 81 to 88 are Zener diodes, 91 to 95 are capacitors, 100 is an alternator that rotates in synchronization with the internal combustion engine, 101 is an ignition coil, 1
02 is Hasoteri. Also, 11 is enclosed by a chain double-dashed line.
1 is a closed angle expansion circuit, 112 is a closed angle reduction circuit, 113
The approximate components of each of the current limiting circuits are shown. Further, transistors 53, 54, 59 constitute the main elements of the waveform shaping circuit, and transistors 60, 62 .
63 constitutes the main element of the drive circuit. Transistors 51 and 61 are used as diodes that also serve as temperature compensation for transistors 53 and 62, respectively. Capacitors 9J and 94.95 are used to prevent malfunction. In this embodiment, the time width during which the constant current of the power transistor 64 is controlled is detected by the time width of the collector unsaturated output voltage of the power transistor 64, and the closing angle reduction circuit 112 is operated.

Next, the operation will be explained. First, the description will be made while omitting the closing angle expansion circuit 111 and the closing angle reduction circuit 112.

When the AC voltage generated in the AC generator 100 is on the positive side, the transistor 53 is turned on and the transistor 54 is turned off.
Transistor 59 is turned off, transistor 60 is turned on, transistor 62 is turned off, transistor 63 is turned on, power transistor 64 is turned on, and the primary current of ignition coil 101 is conducted. When the current flowing through the ignition coil 101 increases, the terminal voltage of the current detection resistor 31 increases, and when it finally reaches a predetermined current value, the current flows into the base of the transistor 62 via the resistor 25, 26. Transistors 62, 63 and power transistor 64 are controlled in their active regions so that the current flowing through ignition coil 101 does not exceed a predetermined current value. thermistor 40
Similarly to the transistor 61, it is used for temperature compensation of the current limiting circuit 113. Next, when the AC voltage generated in the AC generator 100 changes to negative polarity, the transistor 53
is off, transistor 54 is on, transistor 59
is turned on, the transistor 63 is turned off, the power transistor 64 is turned off, the primary current of the ignition coil 101 is cut off, and the spark plug is discharged via a distributor (not shown).

Furthermore, when the battery voltage rises abnormally due to a surge voltage or the like, the overvoltage detection circuit composed of the resistor 18, 19 and the constant voltage diode 84 turns on the transistor 59, turns off the power transistor 64, and turns off the power transistor 64. prevent the destruction of

Next, the closing angle expansion circuit 111 and the closing angle reduction circuit 11
The operation will be explained with reference to the waveform diagram of FIG. 2 including 2.

In FIG. 2, the waveform diagram (al shows the AC output of the alternator 100, the waveform diagram (b) shows the collector output of the transistor 53, the waveform diagram (C1 shows the primary current waveform of the ignition coil 101, The waveform diagram (dl shows the collector output of the power transistor 64, the waveform diagram tel shows the collector output of the transistor 58, and the waveform diagram (fl shows the charging voltage waveform of the capacitor 93).Now, the rotation speed of the internal combustion engine is sufficient. If high, the AC output of the AC generator 100 is sufficiently large. Therefore, the capacitor 92 is charged with a DC voltage corresponding to the engine speed, and the transistor 53 is in turn charged via the emitter resistor/lower transistor 52 and the resistor 6. directional bias is supplied.Therefore, if the transistor 53 switches in response to the AC output of the alternator 100, the waveform diagram in FIG.
The transistor 53 is turned off at Pl, turned on at Ql, and turned off at P2. In other words, the waveform diagram (a
) The period between Ql and P2 shown in the figure is the energization time of the ignition coil 101. That is, the closing angle is expanded by the closing angle expansion circuit 111. During this energization time, the ignition coil 101
The primary current reaches a constant current after a certain period of time T as shown in the waveform diagram of Fig. 2 (C1), and at that time, the collector output of the power transistor 64 has a non-saturated output voltage as shown in waveform 11 (d1). .In addition, this power transistor 64
When is operating in the non-saturation region, the transistor 54 is off and the transistor 58 is off, so the capacitor 93 is charged with the voltage shown in the waveform diagram (e) in FIG. The charging waveform is as shown in the waveform diagram (f1).

The charging voltage of the capacitor 93 is then negatively fed back to the emitter resistor 8 of the transistor 53 via the Darlington-connected transistors 56 and 57, the resistor IO, and the diode 73. Here, since the transistor 55 is controlled by the collector signal of the transistor 59, the transistor 53
When the transistor 55 is off, the transistor 55 is also off, and negative feedback is applied as described above, so that the transistor 53 receives a reverse bias. Then, during the off period, the transistor 53 receives a reverse bias. This means that after the transistor 53 is turned off at point 22 of the waveform diagram (al) in FIG. 2, the point Q2 at which the transistor 53 is turned on next is determined by the forward bias V1 and reverse bias V2. Then, after the transistor 53 is turned on, the transistor 55 is also turned on, so there is no reverse bias, and the next off point P3 is the forward bias V.
Determined only by 1. That is, this transistor 5
5 performs a positive feedback effect on the switching of the transistor 53, and is particularly effective in preventing oscillations when the alternating current output of the alternator 100 is small at low speeds and the slope is gentle.

Furthermore, the rise time of the primary current of the ignition coil 101 changes due to fluctuations in the power supply voltage, etc., and the time it takes to reach a constant current also changes, causing the time during which the power transistor 64 operates in the non-saturation region to change. The magnitude of the reverse bias V2 applied to will also vary, but
During the period when the power transistor 64 is conductive, the reverse bias (2) is interrupted by the transistor 55;
Fluctuations in ignition timing due to fluctuations in reverse bias V2 are prevented.

As described above, the reverse bias V2 by the closing angle reduction circuit 112 responds to the collector non-saturation voltage time width of the power transistor 64, and the ON point of the transistor 53, that is, the starting point of energization of the ignition coil 101, is controlled by the forward bias V1 alone. Change the determined Ql to 02 points and reduce the closing angle. If the closing angle is reduced too much, the collector non-saturation voltage time width of the power transistor 64 in the next ignition cycle will become smaller, and the reverse bias 2 will become smaller.As a result, the closing angle reduction liquid will be corrected and the energization time will be reduced. It is controlled to approximately 'r.

Next, explanation will be given regarding the low speed rotation of the internal combustion engine.

During low speed rotation, the AC output of the alternator 1oO is very small. Therefore, the charging voltage of the capacitor 92 of the closing angle expansion circuit 111 is almost zero, and the forward bias V1 is almost zero, and if there is no closing angle reduction circuit 112, the zero cross point of the AC output of the alternator 100 (
The transistor 53 switches at a point determined by the waveform diagram in FIG. 2 (X1, 71 points in case of al). Since the ignition coil 101 rotates at a low speed, the energization time of the ignition coil 101 at that time is much longer than the time T. In the conventional device, the closing angle could not be corrected at all in this case, but in the device of the present invention, the closing angle reduction circuit 112 supplies a reverse bias to the transistor 53 in the same manner as explained during high-speed rotation, and the energization time is reduced. Control it to T.

FIG. 3 shows a closed angle reduction circuit 11 used in the ignition device of the present invention.
FIG. 2 is a main part electrical circuit diagram showing another embodiment of the second embodiment. In FIG. 3, 131 to 135 are resistors, and 141 to 144 are transistors, which constitute a discharge current amplification circuit 150.

The operation of the discharge current amplification circuit 150 shown in FIG. 3 will be explained with reference to the waveform diagrams of FIGS. 4 and 5.

First, the combination of transistors 141 and 142 and the combination of transistors 143 and 144 are current amplifier circuits in which temperature compensation is performed using transistors of the same type. Amplify the current so that the voltage drop is equal. Therefore, the discharge current of capacitor 93 is
Provides reverse bias to transistor 53 through resistor 131, transistor 141 and diode 73 as long as it flows through 35, 134 and transistor 144. Therefore, the emitter resistance 8 of the transistor 53
The reverse bias voltage supplied to is a voltage that changes in an exponential curve from the initial voltage VO as shown in the waveform shown in Figure 5 (11). In Figures 4 and 5, the horizontal axis is time, and the vertical axis is In addition, the waveforms in FIGS. 4 and 5 (gl are the positive peak voltage V of the AC output of the AC generator 100 plotted against the waveform gap t. In general, AC power generation Since the output of the engine 100 increases linearly with the engine speed, it becomes a function of the waveform + gl = 1/l.On the other hand, in the case of the circuit shown in Figure 1, the reverse bias is provided by the transistors 56 and 57. Since the charging voltage of the capacitor 93 is supplied through the emitter follower, the resistor 10, and the diode 73, the charging voltage of the capacitor 93 is
When the forward voltage drop of the diode 73 is lowered or lower, a reverse bias cannot be supplied. Therefore, the substantial reverse bias is determined by the waveform shown in FIG.
Since it becomes zero at O, no reverse bias is applied when the AC generator 100 rotates at an extremely low speed in which the waveform period of the AC output is equal to or higher than To. On the other hand, if the reverse bias voltage value at time t exceeds the positive peak voltage of the AC output of the AC generator 100 with a waveform period of t, the transistor 53 is turned on, resulting in a flaw ignition error. That is, Figures 4 and 5
The reverse bias voltage waveform (hl, (1) in the figure must be below the waveform (gl). Therefore, if the discharge time constant of the capacitor 93 is increased as shown in the waveform (++') shown in Figure 4, An ignition error occurs in the rotation speed section of the waveform period corresponding to time t of waveform (h')>waveform tg+.On the other hand, in the waveforms (gl and (1) shown in FIG. 5), the waveform (
Since gl is a function of 1/l and waveform (1) is an exponential function, its quotient has a minimum value. Therefore, if the circuit constants are set so that the waveform (1) does not exceed the waveform tg at the minimum point, the discharge current of the capacitor 93 will flow through the resistor 135, 134 and the transistor 144 as described above. As far as it goes, since a reverse bias is supplied to the transistor 53, the closing angle is reduced by the reverse bias and the energization time of the ignition coil 101 is controlled to approximately T even when the engine is running at a very low speed, so the controllability is high.

6 and 7 are main part electric circuit diagrams showing still another embodiment of the closing angle reduction circuit 112 used in the ignition device of the present invention. In FIG. 6, 151.152.153 is a resistor; is a Zener diode; in FIG. 7, 161 and 162 are resistors, and 163 is a Zener diode.

FIGS. 8 and 9 are waveform diagrams for explaining the circuit operations shown in FIGS. 7 and 8, respectively. Figures 6 and 7
In the circuit shown in the figure, the resistor 152 or 16 is connected to the discharge circuit of the capacitor 93 in the circuits shown in FIGS.
2 and a Zener diode 154 or 163 in series. Therefore, the discharge time constant changes depending on whether the charging voltage of the capacitor 93 is higher or lower than the Zener voltage of the Zener diode 154 or 163. Therefore, the reverse bias can be set higher in the circuits of FIGS. 6 and 7, and the waveform (J) shown in FIG. 8 and the waveform (J) shown in FIG. 9 (when t is small like kl), respectively. This shows that a large reverse bias can be applied when the engine is small, that is, when the engine rotates at high speed.
Control performance during high-speed rotation is further improved. moreover,
By applying the idea of this embodiment, the control performance can be further improved by making the reverse bias waveform into a multi-stage polygonal line approximation curve to approximate the waveform (gl).

Furthermore, in the time constant circuits of the closing angle expansion circuit 111 and the closing angle reduction circuit 112, it is also possible to improve the temperature characteristics by arranging a thermistor in parallel with each capacitor 92, 93.

Further, in the embodiment of the present invention, the closing angle expansion circuit 11
1 rectifies the AC output of the AC generator 100 to create a DC voltage that changes with the rotational speed of the internal combustion engine and applies it as a forward bias to the transistor 53 of the waveform shaping circuit. The differential signal may be rectified and charged, a monostable multi-high break may be triggered by the output of the waveform shaping circuit, and the DC voltage obtained by smoothing the output may be used as the forward bias.

Further, in the embodiment of the present invention, the closing angle reduction circuit 11
2 operates according to the time width of the collector unsaturated output voltage while the power transistor 64 is under constant current control, but the power transistor 4 is under constant current control by the terminal voltage of the current detection resistor 31. The closing angle reduction circuit 112 may be operated by detecting the time width in between.

In addition, Fig. 10 shows the closing angle reduction circuit 1 used in this ignition system.
12 is a main part electric circuit showing still another embodiment of No. 12. In FIG. 10, 65 is a transistor and 32 is a resistor. In this embodiment, the switching level is changed by extracting the Hase current of the transistor 53 by the transistor 65, and the closing angle is reduced by applying a reverse bias to the transistor 53.

As explained above, the ignition system of the present invention includes an alternator that rotates in synchronization with the internal combustion engine, a waveform shaping circuit that switches according to the alternating current voltage generated in the alternator, and a waveform shaping circuit that performs switching according to the alternating current voltage generated in the alternator. A drive circuit that controls the Hose current of the power transistor that turns on and off the primary current of the ignition coil in response to the output of the circuit, and a current that controls the power transistor at a constant current so that the negative current does not exceed a predetermined current value. A limiting circuit and a voltage corresponding to the rotational speed of the internal combustion engine are applied to the waveform shaping circuit to change the switching level of the waveform shaping circuit with respect to the alternating current voltage to expand the closing angle at which the primary current of the ignition coil is energized. The switching level of the iiS waveform shaping circuit with respect to the AC voltage is changed according to the time width during which the power transistor is under constant current control, and the primary current of the ignition coil is energized. Since it is equipped with a closing angle reduction circuit that operates to reduce the closing angle of The closing angle is controlled so that the energization time is a predetermined time, and as a result, the ignition coil and power transistor consume less power during low speed rotation, generate less heat, and are highly reliable. Furthermore, since the closing angle enlargement circuit and the closing angle reduction circuit are controlled so that the energization time is a predetermined time from low speed rotation to high speed rotation, the primary current of the ignition coil when the ignition timing is reached is the predetermined current. It has the excellent effect of achieving high energy ignition. Further, the closing angle reduction circuit changes the switching level of the waveform shaping circuit with respect to the AC voltage according to the time width while the power transistor is under constant current control, and the primary current of the ignition coil is energized. Therefore, even if the rise of the primary current of the ignition coil becomes gradual due to a drop in the battery voltage, the current conduction time becomes longer until the power transistor is controlled with a constant current, and the specified primary current is reduced. This has the excellent effect of increasing the ignition energy without increasing heat generation due to power l-run risk.

Furthermore, since it includes an interruption circuit that interrupts the change in the switching level of the waveform shaping circuit by the closing angle reduction circuit during the conduction period of the power transistor, regardless of the output of the closing angle expansion circuit. Not only can the oscillation of this waveform shaping circuit be prevented by performing a positive feedback effect, but also the ignition timing can be adjusted even if the switching level of the waveform shaping circuit due to the closing angle reduction circuit fluctuates due to fluctuations in the power supply voltage, etc. It has the excellent effect of preventing adverse effects on

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram showing one embodiment of the device of the present invention, and FIG.
The figure is a waveform diagram of each part to explain its operation, and FIGS. 3, 6, 7, and 10 are main parts showing other embodiments of the closed angle reduction circuit 112 applied to the device shown in FIG. 1. The electrical circuit diagrams of FIGS. 4, 5, 8 and 9 are characteristic diagrams for explaining the operation of the circuits shown in FIGS. 1, 3, 6 and 7, respectively. 53.54.59...Transistor as a main component of a waveform shaping circuit, 55...Transistor as a main component of an interruption circuit, 60,62.63...Transistor as a main component of a drive circuit , 64・
・・Power transistor, 93 ・・2L capacitor, 1
00... Alternator, 101... Ignition coil, 10
2...Battery, 111...Closing angle expansion circuit. 112...Closing angle reduction circuit, 113...Current limiting circuit. Representative Patent Attorney Takashi Okabe Figure 2 Figure 3 Figure 11 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10

Claims (1)

[Claims] 1. Turn on the ignition coil and the primary current of the ignition coil;
a power transistor that turns off, an alternator that rotates in synchronization with the internal combustion engine, a waveform shaping circuit that switches in response to the alternating current voltage generated in the alternator, and a waveform shaping circuit that switches in response to the output of the waveform shaping circuit. a drive circuit for controlling the Hose current of the power transistor; a current limiting circuit for controlling the power transistor at a constant current to limit the primary current of the ignition coil to a predetermined value or less; In addition to the waveform shaping circuit, a closing angle expansion circuit operates to change the switching level of the waveform shaping circuit with respect to the alternating current voltage to expand the closing angle at which the primary current of the ignition coil is energized; A closing angle that operates to change the switching level of the waveform shaping circuit with respect to the alternating voltage according to the time width during which the transistor is under constant current control, and to reduce the closing angle at which the primary current of the ignition coil is energized. An internal combustion engine comprising: a reduction circuit; and an interruption circuit that interrupts a change in the switching level of the waveform shaping circuit by the closed angle reduction circuit during the conduction period of the power transistor, regardless of the output of the closed angle expansion circuit. ignition device. 2. In the ignition device for an internal combustion engine according to claim 1, the closing angle reduction circuit applies a reverse bias to the transistor of the waveform shaping circuit in accordance with the time width during which the power transistor is under constant current control. An ignition device for an internal combustion engine that operates to change the switching level of the waveform shaping circuit with respect to the alternating current voltage applied to the alternating current voltage, and to reduce the closing angle through which the primary current of the ignition coil is conducted.