JPS6124545B2 - - Google Patents

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 known high-energy ignition device, there is an ignition device proposed in Japanese Patent Application Laid-open No. 7657/1983. In the ignition system 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 as a DC voltage in a capacitor, 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 is determined by the AC output waveform. , the primary current flows for an extra time,
There was a problem that the ignition coil and power transistor consumed a lot of power and caused a large temperature rise.

The present invention was 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 base current of a 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 drive circuit that controls the power transistor at a constant current so that the primary current does not exceed a predetermined current value. A current control circuit and a voltage according to the rotation 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, and the closing angle at which the primary current of the ignition coil is energized is determined. a closing angle expansion circuit that operates to expand the power transistor, a capacitor that is charged in accordance with the time period during which the power transistor is under constant current control, and a discharging time constant that is switched in accordance with the magnitude of the charging voltage of this capacitor. a closing angle that operates to reduce the closing angle at which the primary current of the ignition coil is flowing by changing the switching level of the waveform shaping circuit with respect to the alternating voltage according to the charging voltage of the capacitor; During high-speed rotation, the closing angle expanding circuit expands the closing angle, and the closing angle reducing circuit, in which the power transistor is controlled at a constant current, operates to ensure that the primary current of the ignition coil is always at exactly the same level. The closing angle is controlled so that a predetermined current is reached, and during low speed rotation, the AC output of the alternator is small and the closing angle expansion circuit does not operate, while the closing angle reduction circuit operates in the same way as above and always maintains the By configuring the closing angle control so that the primary current of the ignition coil reaches a predetermined current, the ignition timing can be adjusted when the primary current of the ignition coil reaches a predetermined current from low speed rotation to high speed rotation. It is an object of the present invention to provide a highly reliable internal combustion engine ignition device that performs high-energy ignition by controlling the closing angle so that the ignition coil and power transistor consume less power even during low-speed rotation, and generates less heat. This is the purpose.

The present invention will be explained below based on embodiments shown in the figures. FIG. 1 is a circuit diagram showing an embodiment of the present invention. In Figure 1, 1-11, 13-31, 1
51-153 are resistors, 40 are thermistors, 51-
63 is a transistor, 64 is a power transistor, 71 to 75 are diodes, 81 to 88, 15
4 is a Zener diode, 91 to 95 are capacitors, 100 is an alternator that rotates in synchronization with the internal combustion engine, 101 is an ignition coil, and 102 is a battery. Further, 111, which is surrounded by two-dot chain lines, indicates the approximate components of a closing angle expansion circuit, 112 a closing angle reduction circuit, and 113 a current limiting circuit. In addition, transistors 53, 54, 59
constitutes the main elements of the waveform shaping circuit, and transistors 60, 62, and 63 constitute the main elements of the drive circuit. Transistors 51 and 61 are used as diodes that also serve as temperature compensation for transistors 53 and 62, respectively. Capacitor 91, 9
4 and 95 are used to prevent malfunction. and,
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, the transistor 54 is turned off, and the transistor 59 is turned on.
is off, transistor 60 is on, transistor 62 is off, transistor 63 is on, power transistor 64 is on, and ignition coil 101 is turned on.
energize the primary current. And ignition coil 10
1 increases, the terminal voltage of the current detection resistor 31 increases, and when it finally reaches a predetermined current value,
Current flows into the base of the transistor 62 via the resistors 25 and 26, and the transistors 62 and 63 and the power transistor 64 are controlled in their active regions so that the current flowing through the ignition coil 101 does not exceed a predetermined current value. Ru. The thermistor 40, like the transistor 61, is used for temperature compensation of the current limiting circuit 113. Next, alternator 1
When the AC voltage generated by 00 changes to negative polarity,
Transistor 53 is off, transistor 54 is on, transistor 59 is on, transistor 6 is on.
0 is off, transistor 62 is on, transistor 63 is off, power transistor 64 is off, the primary current of 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, etc., the overvoltage detection circuit composed of resistors 18 and 19 and the voltage regulator diode 84 turns on the transistor 59, and the power transistor 6
4 is turned off to prevent this power transistor 64 from being destroyed.

Next, the operation including the closing angle expansion circuit 111 and the closing angle reduction circuit 112 will be explained with reference to the waveform diagram of FIG. 2. In FIG. 2, waveform chart a shows the AC output of the alternator 100, waveform chart b shows the collector output of the transistor 53, waveform chart c shows the primary current waveform of the ignition coil 101, and waveform chart d shows the primary current waveform of the ignition coil 101.
shows the collector output of the power transistor 64, the waveform chart e shows the collector output of the transistor 58, and the waveform chart f shows the charging voltage waveform of the capacitor 93. Now, assuming that the rotational speed of the internal combustion engine is sufficiently high, the AC output of the alternator 100 is sufficiently large. Therefore, the capacitor 92 is charged with a DC voltage corresponding to the engine speed, and the transistor 53 is connected to the emitter follower transistor 52 and the resistor 6.
Forward bias is supplied through. Therefore, the level at which the transistor 53 switches with respect to the AC output of the AC generator 100 is lowered by V1 as shown in the waveform diagram a of FIG.
The transistor 53 is turned off at P1, turned on at Q1, and turned off at P2. In other words, the Q shown in the waveform diagram a
1 and P2 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 primary current of the ignition coil 101 reaches a constant current after a certain period of time T as shown in the waveform diagram c in FIG. A non-saturated output voltage is obtained. Here, during a period T during which the power transistor 64 operates in a saturated state, as the current flowing through the current detection resistor 31 increases, a voltage corresponding to the voltage drop is generated at the collector of the power transistor 64. As is generally well known, the resistance value of the resistor 31 is set to a very small value (for example, 50 mΩ).
The voltage drop is about 0.5V at maximum, which is practically negligible with respect to the collector voltage of the power transistor 64 in a non-saturated state (about 9V with a 12V battery), so in Fig. 2d, For convenience, it is expressed as 0V. During this period T, the collector voltage of the power transistor 64 is so small that it can be virtually ignored.
Capacitor 93 is not charged by this voltage. Further, when the power transistor 64 is operating in a 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.
153, the Zener diode 154, and the base current of the transistor 57, resulting in a charging waveform as shown in the waveform chart f in FIG. and,
The charging voltage of capacitor 93 is negatively fed back to emitter resistor 8 of transistor 53 via Darlington-connected transistors 56 and 57, resistor 10 and diode 73. Here, transistor 5
Since the transistor 5 is controlled by the collector signal of the transistor 59, when the transistor 53 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 the transistor 53 at point P2 in the waveform diagram a in FIG.
After turning off, the next point Q2 at which the transistor 53 turns on is determined by the reverse bias V1 and the reverse bias V2. 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 determined only by the forward bias V1. That is, this transistor 55 performs a positive feedback effect on the switching of the transistor 53, and is particularly effective in preventing oscillation when the AC output of the alternator 100 is small at low speeds and the slope is gentle. As mentioned above, the closing angle reduction circuit 11
The reverse bias V2 due to V2 responds to the time width of the collector non-saturation voltage of the power transistor 64, and the on-point of the transistor 53, that is, the ignition coil 1
The closing angle is reduced by changing the energization start point of 01 from the Q1 point, which is determined only by the forward bias V1, to the Q2 point. If the closing angle is reduced too much, the time width of the collector desaturation voltage of the power transistor 64 in the next ignition cycle becomes small, and the reverse bias V
2 becomes smaller, the degree of reduction of the closing angle is corrected, and the energization time is controlled to approximately T.

Next, explanation will be given regarding the low speed rotation of the internal combustion engine.
During low speed rotation, the AC output of the AC generator 100 is very small. Therefore, the closed angle expansion circuit 1
The charging voltage of the capacitor 92 of No. 11 is almost zero, and the forward bias V1 is almost zero,
If the closing angle reduction circuit 112 is not provided, the transistor 53 switches at a point determined by the zero cross point of the AC output of the alternator 100 (points X1 and Y1 in the case of the waveform chart a in FIG. 2). 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 to approximately T.

FIG. 3 is an electrical circuit diagram of a main part showing another embodiment of the closing angle reduction circuit 112 used in the ignition device of the present invention. In Fig. 3, 131 to 135 are resistors;
141 to 144 are transistors, which constitute a discharge current amplification circuit 150.

One of the features of the present invention is that the discharge time constant of the capacitor 93 is switched according to the charging voltage, and this will be explained using FIGS. 4 to 7. First, resistor 152 and Zener diode 15
The operation of the discharge current amplification circuit 150 shown in FIG. 3 in the case where there is no series circuit with 4 will be described with reference to the waveform diagrams of FIGS. 4 and 5. Combination of transistors 141 and 142 and transistor 14
The combinations 3 and 144 are current amplification circuits that perform temperature compensation using transistors of the same type, and amplify current so that the voltage drops across resistors 133 and 134 and the voltage drops across resistors 131 and 132 are equal, respectively. . Therefore, capacitor 93
As long as the discharge current of is flowing through the resistors 135, 134 and the transistor 144, the resistor 131,
A reverse bias is supplied to transistor 53 via transistor 141 and diode 73. 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 Ve, as shown by the waveform i shown in FIG. In FIGS. 4 and 5, the horizontal axis is time, and the vertical axis is voltage. In addition, the waveform g in FIGS. 4 and 5 is for the AC generator 1.
00 represents the positive polarity peak voltage V of the AC output.
Generally, the output of the alternator 100 increases linearly with the engine speed, so the peak voltage is inversely proportional to the waveform period. Since the waveform period has the unit of time and is a quantity representing the time width, the peak voltage is at time t.
It can be regarded as a function of Waveform g shows this function, that is, the function of 1/t. On the other hand, in the case of the circuit shown in FIG. 1, the reverse bias is supplied via the emitter follower formed by the transistors 56 and 57, the resistor 10, and the diode 73, so that the charging voltage of the capacitor 93 is If the forward voltage drop is less than the forward voltage drop, reverse bias cannot be supplied. Therefore, the actual reverse bias becomes zero at time to as shown in the waveform h shown in FIG. No directional bias. 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 at the waveform period corresponding to time t, the transistor 53 cannot be turned on, resulting in an ignition error. . That is, the reverse bias voltage waveforms h and i in FIGS. 4 and 5 must be below the waveform g. Therefore, if the discharge time constant of the capacitor 93 is increased as shown in the waveform h' shown in FIG. 4, an ignition error will occur in the rotational speed section of the waveform period corresponding to the time t of the waveform h'>waveform g. On the other hand, in waveforms g and i shown in FIG.
Since the waveform g is a function of 1/t and the waveform i is an exponential function, the quotient thereof has a minimum value. Therefore, if the circuit constants are set so that the waveform i does not exceed the waveform g at the minimum point, the capacitor 9
As long as the discharge current of No. 3 is flowing through the resistors 135, 134 and the transistor 144, a reverse bias is supplied to the transistor 53, so the closing angle is reduced by the reverse bias even when the engine is running at an extremely low speed. Since the energization time of the ignition coil 101 is controlled to approximately T, controllability is high.

In the present invention, as shown in the circuits of FIGS. 1 and 3, a series circuit of a resistor 152 and a Zener diode 154 is inserted into the discharge circuit of the capacitor 93. 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. Therefore, the reverse bias is set higher when t is small, such as waveform j shown in FIG. 6 and waveform k shown in FIG. 7, for waveform h shown in FIG. 4 and waveform i shown in FIG. 5, respectively. can. This indicates that a large reverse bias can be applied when t is small, that is, when the engine rotates at high speed, and the control performance during high speed rotation is further improved. Furthermore, if the idea of this embodiment is applied and the reverse bias waveform is made into a multi-stage polygonal line approximation curve to approximate waveform g, control performance can be further improved.

In addition, in the time constant circuit of the closing angle expansion circuit 111 and the closing angle reduction circuit 112, each capacitor 92, 93
It is also possible to improve the temperature characteristics by placing a thermistor in parallel with.

Further, in the embodiment of the present invention, the closing angle expansion circuit 111 rectifies the AC output of the AC generator 100 to generate a DC voltage that changes with the rotation speed of the internal combustion engine, and applies it to the transistor 53 of the waveform shaping circuit as a forward bias. However, for example, the differential signal of the output of the waveform shaping circuit may be rectified and charged, or a monostable multivibrator may be triggered by the output of the waveform shaping circuit, and a 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 112 operates according to the time width of the collector unsaturated output voltage while the power transistor 64 is under constant current control. 3
The closing angle reduction circuit 112 may be operated by detecting the time width during which the power transistor 64 is controlled to have a constant current by a terminal voltage of 1.

Moreover, FIG. 8 is a main part electric circuit showing still another embodiment of the closing angle reduction circuit 112 used in the present ignition device. In FIG. 8, 65 is a transistor, and 32 is a resistor. In this embodiment, the switching level is changed by extracting the base 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, in the ignition device of the present invention,
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 by the alternator, and an ignition coil primary current that turns on and off in response to the output of this waveform shaping circuit. a drive circuit that controls the base current of the power transistor, a current limiting circuit that performs constant current control with the power transistor so that the primary current does not exceed a predetermined current value, and a current limiting circuit that controls the base current of the power transistor so that the primary current does not exceed a predetermined current value; In addition to the 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; It is equipped with a capacitor that is charged according to a constant current controlled time width, and a discharging circuit whose discharging time constant is switched according to the magnitude of the charging voltage of this capacitor. Since the internal combustion engine is provided with a closing angle reduction circuit that operates to change the switching level of the waveform shaping circuit and reduce the closing angle at which the primary current of the ignition coil is energized, the internal combustion engine can operate at a low speed. Even when the AC output of the alternator is small, the closing angle reduction circuit operates and controls the closing angle so that the energization time is a predetermined time, thereby reducing the ignition coil and power during low speed rotation. The transistor has excellent effects such as low power consumption, low heat generation, and high reliability. 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, so that 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 battery voltage, the energization time becomes longer until the power transistor is controlled at a constant current. It has the excellent effect of being able to reach a predetermined primary current value and increasing the ignition energy without increasing the heat generation of the power transistor. Further, the closing angle reduction circuit changes the switching level of the waveform shaping circuit with respect to the alternating current voltage according to the charging voltage of a capacitor charged according to the time width during which the power transistor is under constant current control; By configuring the ignition coil so as to reduce the closing angle through which the primary current flows, there is an excellent effect that the closing angle reducing circuit can be configured with a simple and inexpensive circuit.

Furthermore, since the capacitor is configured to discharge through a discharge circuit whose discharge time constant changes depending on the magnitude of the charging voltage of the capacitor, the discharge curve of the capacitor corresponds to the waveform period of the AC output voltage of the alternator. Since the characteristic curve can be approximated, the control performance for reducing the closing angle is improved, and there is an excellent effect that the closing angle can be controlled with good response from high-speed rotation to extremely low-speed rotation.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram showing an embodiment of the device of the present invention, and FIG. 2 is a waveform diagram of each part to explain its operation.
3 and 8 are principal electrical circuit diagrams showing other embodiments of the closed angle reduction circuit 112 applied to the device shown in FIG. 1, and FIGS. 4, 5, 6, and 7 respectively. 1 and 3 are characteristic diagrams for explaining the operation of the circuits shown in FIGS. 1 and 3, respectively. 53, 54, 59...Transistors as main components of the waveform shaping circuit, 60, 62, 63...
...Transistor as main component of drive circuit, 64...Power transistor, 93...Capacitor, 100...Alternator, 101...Ignition coil, 102...Battery, 111...Closing angle expansion circuit, 112... ...Closed angle reduction circuit, 113
...Current limiting circuit, 151-153...Resistor and Zener diode forming the discharge circuit.

Claims (1)

[Claims] 1. An ignition coil, a power transistor that turns on and off the primary current of this ignition coil, an alternator that rotates in synchronization with an internal combustion engine, and an alternating current generation voltage generated in this alternator. a waveform shaping circuit that switches in response; a drive circuit that controls the base current of the power transistor in response to the output of the waveform shaping circuit; and a drive circuit that controls the primary current of the ignition coil to a predetermined value or less. a current control circuit that controls a constant current of the ignition coil; and a current control circuit that applies a voltage according to the rotational speed of the internal combustion engine to the waveform shaping circuit, and changes the switching level to the waveform shaping circuit for the alternating current voltage to control the primary current of the ignition coil. A closing angle expansion circuit that operates to expand the closing angle at which the power transistor is energized, a capacitor that is charged in accordance with the time period during which the power transistor is controlled with constant current, and a magnitude of the charging voltage of this capacitor. A discharging circuit whose discharging time constant is switched according to the charging voltage of the capacitor is provided, and a switching level of the waveform shaping circuit with respect to the alternating current voltage is changed depending on the charging voltage of the capacitor, and a closing angle at which the primary current of the ignition coil is energized is determined. An ignition device for an internal combustion engine, comprising a closed angle reduction circuit that operates to reduce the angle. 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 system for internal combustion engines consisting of: