JPS5857630B2 - igniter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition system equipped with a delayed ignition signal generation circuit that generates a delayed ignition signal at a time point delayed by a predetermined engine crank angle from a reference ignition timing that occurs in synchronization with engine rotation. In particular, the present invention relates to improvements in delayed ignition signal generation circuits.

Conventionally, the delayed ignition signal generation circuit of this type of ignition system has been constructed with a monostable multi-vibration brake driven for a predetermined time by the generation of a reference ignition signal.

However, the capacitors that make up the monostable multi-bibreak operate so as to have a large negative voltage with respect to ground potential during non-stable operation.

For this reason, the allowable negative voltage with respect to ground potential is 0.7
Monostable multivibrators could not be used in monolithic IC circuits that are on the order of volts.

Therefore, a charging/discharging capacitor connected so as not to generate a negative voltage with respect to the ground potential is installed, and the current flowing through this capacitor is reversed when the reference ignition signal is generated, and from that point on, the terminal voltage of the capacitor changes to a predetermined value. An ignition system was proposed in Japanese Patent Application No. 119350/1983 in which a delayed ignition signal is generated by determining the delayed ignition warm-up period.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ignition system equipped with a comparator suitable for detecting the terminal voltage of a capacitor in a delayed ignition signal generation circuit of this type of ignition system.

A feature of the present invention is that a comparator is constructed using a PNP transistor whose base is connected to the opposite end of the capacitor to ground.

In a second ignition signal generation circuit that generates a second ignition signal by delaying a first ignition signal synchronized with the rotation of the engine, the time for charging and discharging a capacitor with a constant current is detected when the ignition signal is generated. The ignition system for this method is shown in FIG.

In other words, in the figure, the circuit indicated by the dashed line is composed of seven J-sick ICs (hereinafter referred to as MIC), and when the changeover switch 5 is ON, the ignition timing is set at an appropriate angle from the first ignition timing determined by the output of the pickup coil 3. An internal MIC circuit that performs ignition at a delayed point in time, stops the operation of the circuit constituted by the internal MIC circuit when the selector switch 5 is OFF, and performs ignition at the first ignition timing determined by the output of the pickup coil 3. is an integrated circuit of the ignition device section, and in this embodiment, the power transistor 7 has a current so that it can output good characteristics as a so-called ignition device even when the delay angle determined by the MIC internal circuit is large. A limiting circuit is provided to limit the maximum current of the power transistor 7 no matter what the delay angle is, and also to limit the maximum current generated during current limiting.

A current limit time reduction circuit 4 is provided for the purpose of reducing collector loss of the power transistor 7.

That is, in FIG. 1, the pickup coil 3, the resistor 10.1
1, 12, 13, 15, diode 90°91.92,
By capacitors 50 and 51 and transistor 60,
A pickup coil generated voltage detection circuit is configured, a signal amplification circuit is configured by resistors 14, 16, 17° 18.19, 20, 22, 23, transistors 61, 62, 63, 64, 65, and a power transistor 7, A high voltage generating circuit is constituted by a high voltage Zener diode 8 and an ignition coil 1, and ignition is performed by a spark plug 2.

On the other hand, the maximum current limiting circuit of the power transistor 7 is composed of current detection resistors 40, 41, 42 and a transistor 66, and the current limiting time shortening circuit 4 is configured to reduce the collector loss of the power transistor 7. A resistor 21 and a Zener diode 110 are also connected for the purpose of stabilizing the signal amplification section of the ignition device.

On the other hand, the ignition timing delay circuit is a diode 95°96.9
7, 98, resistor 26, PNP transistor 68, 69.
A trigger circuit consisting of PNP transistors 81, 82゜83 and a small capacitor 54 serves as an input signal, and the NPN
Transistor 70°71, PNP transistor 84,8
5. A bistable circuit consisting of resistors 27゜28 operates, resistors 34゜35.36, NPN transistors 75, 76゜77, PNP transistors 86, 87, and diode 1.
00, 101, 102, and the inclination direction of the triangular wave generation circuit made up of the capacitor 53 is reversed.

The output of the comparator 6 is composed of an NPN transistor with a common emitter and an open collector. This becomes another trigger signal input for the bistable circuit.

When ignition is performed at the first ignition timing determined by the rising slope of the pickup coil 3, the selector switch 5
becomes OFF, and the NPN transistor 67 becomes 0FFL.
, NPN transistor 72°79 is 0NL75 is OFF
In order to do this, 76 starts a constant current sinking operation, and the capacitance value CI of the capacitor 53, the sinking current (1) of the NPN l-range staff 6, and the initial voltage (2) of the capacitor 53.

The time t determined by

After (to-V.-C, / I, ), capacitor 53
The terminal voltage becomes approximately Ov, and the charging/discharging operation of the capacitor 53 is stopped.

Furthermore, since the transistor 72 is ON, the signal output from the diode 98 is not input to the bistable circuit.

Figure 2 is a waveform diagram of each part of Figure 1, Figure 3 is at low speed rotation,
The waveform diagram of each part during high-speed rotation and FIG. 4 are diagrams showing advance angle characteristics, and the detailed operation will be explained below with reference to these and FIG. 1.

A positive and negative alternating current signal as shown in FIG. 2a is generated at one end of the pickup coil 3 at point A, and the negative appropriate section transistor 60 is turned off.

The transistors 60 and 61 have a Schmitt circuit configuration in which a microresistance 15 is connected to the external emitter, and the rising and falling waveforms of the transistors 60 and 61 are steep.

The transistor 62 is similar to the transistor 60, and has a waveform as shown in FIG. 2 with respect to the pickup coil waveform.

When the transistor 62 is turned OFF, the transistor 63 is ONL, the transistors 64 and 65 are OFFFL, the power transistor 7 is energized, and the primary current flows through the ignition coil 1.

Transistor 68 is in opposite phase to transistor 62,
The waveform is as shown in FIG. 2C, and the collector voltage waveform of the transistor 69 is generated with a delay of several microseconds between the rising and falling waveforms due to the capacitor 54 connected between the collector and the base.

In the end, the collector voltage waveform of the transistor 69 is as shown in FIG.
It becomes as shown in.

PNP l-transistor 80.81, 82, 83, 84
, 85 is called a current mirror circuit, and PN
The same current as the collector current of the P transistor 84 becomes the same as each collector current.

This is a constant current circuit unique to MIC, and in this configuration, each circuit is set to have a constant current of several tens of microamperes.

Since the diode 96.97 is an AND circuit, each anode voltage waveform of the diode 96.97 is as shown in FIG. It is configured to be input.

When the selector switch 5 is OFF, the transistor 61
is OFF and the transistor 72 is ONL, so the trigger signal is not input to the base of the transistor 70, and the transistor 70 is stable in the OFF1 state and the transistor 71 is ON, so the transistor 73 is stable. continues to be OFF.

In this state, when the transistor 62 is turned on, the transistor 63 is set to 0FFL, and 64 and 65 are turned on, so that the power transistor 7 is turned off.

That is, the electromagnetic energy stored in the ignition coil 1 is discharged at the ignition plug 2, producing a spark discharge.

(Spark discharge at first ignition timing T1.

) On the other hand, when the selector switch 5 is ON,
Since the transistor 12 is OFF, the trigger signal passing through the diode 98 is input to the base of the transistor 70, and the transistor 70 becomes ONL, and the transistor 71
is turned OFF, and therefore the ON state of the transistor 70 is stabilized.

When transistor 70 turns on, transistor 75 turns on.
The so-called current mirror type constant current circuit consisting of the diode 102, the transistor 76, and the resistor 36 operates, discharging the charge in the capacitor 53 with a constant current 1. Therefore, the terminal voltage of the capacitor 53 has a constant slope. It will start to fall down.

On the other hand, this constant current ■1 is However, ■ Zener voltage of Z-zener diode 111 VP=forward voltage of diode 102 is given.

When the terminal voltage of the capacitor 53 falls and becomes equal to the divided potential of the low paper 31 and 32, the output of the comparator 6 becomes low level.

That is, the output transistor in the comparator 6 is turned on.

Therefore, the collector current of the transistor 70 becomes bi-level and 75 turns on, so the collector current of the transistor 76 becomes
1 disappears, and the constant current falling phenomenon of the capacitor 53 disappears.

Further, the base voltage of the transistor 73 becomes Ov,
73 is turned off.

On the other hand, a so-called current mirror circuit consisting of the diode 101, the transistor 77, and the transistors 87 and 86 connects the collector of the transistor 86 to the resistor 35.
Since a constant current ■2 determined by
The terminal voltage of 3 is charged at a constant slope determined by constant current 2.

The constant current value 2 is as follows: C: Capacitance value of capacitor 53 t: Time Vref: Dividing point voltage of resistors 31 and 32 It increases according to the above formula, and when the signal corresponding to the first ignition timing signal is input, Then, discharge starts with a constant current, and the terminal voltage Vc2 starts decreasing at the voltage value before the capacitor starts discharging.

Here, the reason why the discharge current is expressed as I-I is that the constant current (2) always continues to flow.

Eventually, the terminal voltage of the capacitor 53 becomes a triangular wave as shown in FIG. 2g.

That is, during the falling time of the triangular wave, the transistor 1 is in the OFF state, and therefore the transistor 73 is in the ON state, so that the base voltage of the transistor 64 becomes as shown in FIG. While the base voltage of the transistor 64 falls to a low level, conduction occurs and a current flows through the primary side of the ignition coil 1 as shown in FIG. When the change becomes positive, transistor 3 turns off, transistors 64 and 65 become conductive, and
The power transistor 7 is turned off and a high voltage is generated, that is, a spark discharge occurs in the ignition plug 2 at the second ignition timing.

On the other hand, the negative current is detected by the current detection resistor 40°41.42
．． The maximum current limit circuit consisting of the 1-range transistor 6 limits the maximum value as shown in FIG.

That is, when the current limit time is long, by applying a current proportional to the length to the base of the transistor 60, the time when the transistor 60 is turned off, that is, the ignition coil 1
This means that the start of energization is delayed.

On the other hand, the phase angle α0 between the first ignition timing T1 and the second ignition timing T2 is determined by the following equation.

From Fig. 2 f2g, if the rising slope is m1, the falling slope is n1, the falling time width is tl, and the period is T, then m= (T
-tl ) = ntl while N-T = 15 (4 chito-distributors),
From the relationship, it can be seen that the above α becomes α-cons, and the delay angle α is constant regardless of the rotation speed.

That is, as shown in FIG. 3, during low speed rotation, the terminal voltage of the capacitor 53 becomes as shown by the solid line in FIG. , at high speed rotation, the waveform shows the rising edge of the solid line and the falling edge of the dotted line of a, and the transistor 7
1 is like d, and the primary current is like e, but the delay angle α
0 remains constant regardless of rotation.

Further, due to the effect of the current limit time reduction circuit 4, the energization time of the ignition coil 1 hardly changes.

However, as can be seen from Fig. 3g, when the distonopy 2 rotation speed (hereinafter referred to as dist rotation) becomes extremely slow (during startup), the terminal voltage of the capacitor reaches the supply voltage of the current mirror. Then, a constant voltage is maintained, and the charge in the capacitor becomes saturated.

Therefore, the terminal voltage of the capacitor 53 no longer becomes a triangular wave, and the delay angle α decreases as the rotational speed decreases.

When the selector switch 5 is 0FFj, the transistor 72 is on, so the trigger signal corresponding to the first ignition timing T1 is not transmitted to the bistable circuit, and the transistor 74 is ONL and the transistor 75 is OFF. Therefore, the current mirror transistor 76 becomes conductive, the terminal voltage of the capacitor 53 becomes approximately Ov, the collector voltage of the transistor 71 continues to be at a low level, and the current mirror transistor 76 also becomes 0FF1. ,continue.

That is, the advance angle characteristic when the changeover switch 5 is OFF is the fourth
The advance angle characteristic is determined by the centrifugal advance mechanism and negative pressure advance mechanism of the distributor, and when the selector switch 5 is on, it becomes as shown in FIG. 4B.

On the other hand, the capacitor 50 is a countermeasure against minute noise on the input signal, and the capacitor 51 is a speed-up capacitor.

In this configuration, there is no trigger circuit using an AC coupling capacitor, which is often used as a bistable trigger, so the moment the power is applied to the circuit, the bistable circuit operates in the direction of passing current. There is no damage caused by the so-called trigger capacitor.

The Zener diode 112 has a standard around 12 to 13 V, and is provided to determine the maximum voltage of the MIC and protect the MIC from various surges.

The capacitor 52 is a monolithic ICM in the ignition system section.
It is configured in the IC 200 and delays the turn-off of the transistor 63 by several μsec.

That is, in contrast to the collector voltage waveform of the transistor 62 shown in FIG. 5a, the collector voltage waveform of the transistor 63 is as shown in FIG.

When the transistor 13 is in the OFF state (the selector switch 5 is OFF), the collector voltage waveform of the transistor 65 becomes as shown in FIG. 5C.

More precisely, as shown in FIG. 5C, the first ignition timing signal occurs when the transistor 73 is turned off and the transistor 65 is turned on.

The reason why the turn-off of the transistor 63 is delayed by the so-called Miller integration circuit made of the capacitor 52 is that the transistor 62 is turned on, the transistor 68 is turned off, the transistor 70 is turned on, and the transistor 71 is turned off.
F, until transistor 73 turns on, there is a time delay of several hundred nanoseconds due to the switching delay of each transistor, and ignition occurs temporarily at the first ignition timing before ignition occurs at the second ignition timing. This is to prevent things from happening.

That is, the operation time of transistors 62, 63, 64 in MICI is changed from transistors 68 to 73 in MIC2.
By making the operation time longer than the previous operation time, the above-mentioned malfunction can be prevented.

That is, with respect to the collector voltage waveform of the transistor 62 at turn-on shown in FIG. 5a, the collector voltage waveform of the transistor 63 is as shown in FIG. 5, and the collector voltage waveform of the transistor 73 is as shown in FIG. If you set it to
When ignition occurs at the second ignition timing,
.

At time t1.C of FIG. 5, the transistor 65 starts to turn off. The OFF state remains stable at t2, and the OFF state of the transistor 65 is established until time t3, at which time ignition occurs.

In the ignition system shown in FIG. 1, t2-t, = Jt1, and J
Since t is approximately 1 μsec, t4−t,=Jt2 is set to 1, and J t2mvl is set to approximately 2 μsec.

The reason why we configured a so-called Miller integration circuit between the collector bases of transistors 63 and 69 was to use a capacitor with a capacity that could be configured within the MIC.
Its capacitance value is 10 to 30 PF, and even if it is configured within the MIC, the chip size of the MIC does not need to be extremely large.

In the ignition system shown in FIG. 1, even if the Zener voltage of the Zener diode 111 changes somewhat, the delay angle α hardly changes.

That is, the slope m. In other words, the delay angle α is determined by the ratio of the resistors 35 and 36.

By the way, the diode 100 is activated when the engine is started with the changeover switch 5 being switched to the ON state where ignition is performed at the second ignition timing, that is, when the key switch 300 is repeatedly turned ON and OFF. When the charge is accumulated in the capacitor 53, the key switch 3
At the moment when 00 is turned on, the transistor 73 is turned on, the ignition coil is energized, and after an appropriate time, it is a diode that prevents false ignition, and the key switch is turned off.
F, and when the power line of the ignition device becomes low level, the electric charge stored in the capacitor 53 is discharged through the diode 100.

The above is an explanation of the operation of the ignition system shown in Figure 1. During extremely low speed operation (starting) of the engine, the capacity of the capacitor used during steady operation is 10 to 20 times larger. If used (e.g. 2.2μF for 0.1uF capacitance)
capacity), the rotation speed at which the delay angle starts to decrease is 1/10.
It is clear from the above explanation that it can be reduced to ~1/20.

In the example shown in FIG. 1, two capacitors 53 and 530 are connected directly and sub-connected, and the capacitance of capacitor 53 is set to 10 to 530.
20 times, turn on the transistor 531 at startup, and charge/discharge only the capacitance of the capacitor 53, so that the two capacitors 53 and 530 are
By increasing the combined capacity by 10 to 20 times, the desired delay angle can be obtained even at startup.

FIG. 6 shows an embodiment of the invention.

That is, FIG. 6 is a circuit diagram of the comparator of the ignition device described above.

In the figure, this embodiment has P at the input stage of the comparator 6.
This uses NP transistors 601 and 602.

FIG. 7 is a circuit diagram when a conventional comparator 600 is used, and the input stage of this comparator 600 has an NPN
l-Randistaro 10°620 was used.

The terminal voltages of the terminals CI and C2 of the capacitor in each figure can be set equal to (BE+■f), but as the terminal voltages C1 and C2 increase, vBEl and vBE2 increase because Vf is almost constant.

Here, the reverse voltage between the base and emitter of the NPN (EBo) is around 7V, and if the value of the terminal voltage C2 becomes around 8V, this will lead to destruction of the NPN transistor.

Therefore, if a PNP transistor is used, the reverse resistance EvEBo
can be made equal to the withstand voltage of the IC chip, so the terminal voltage of the capacitor can be set to 20V or more.

Being able to increase the terminal voltage of the capacitor allows the capacitance of the capacitor to be reduced, which has a great effect on increasing the packaging density.

Furthermore, in the case of a conventional comparator using an NPN transistor, a base current IB must be supplied when charging the capacitor.

This base current is determined by the collector current and the current amplification rate hFE, but since the temperature change of hFE is around ±50% between -30° and 100°C, set ■1 to a minute current of 5 to 10 μ. The effect on the angle is large when

Therefore, according to this embodiment, although the base current of the comparator affects (1) as described above, it is instantaneous and only when the terminal voltage of the capacitor drops below the reference voltage, so no error occurs.

Further, according to this embodiment, the influence on the constant charging current to the capacitor can be reduced.

Further, according to this embodiment, since the vBE withstand voltage is high, the terminal voltage of the capacitor can be increased, and the detection voltage can be detected in a wide range from around Ov to 20V, so that the terminal voltage of the capacitor can be increased. The difference can be increased.

Furthermore, according to this embodiment, the charging voltage of the capacitor varies depending on the rotational speed, and when the rotational speed is high, the charging time is short and the voltage is also low.

) 20V at 10rpm, 50V at 400rpIl
mV, and the capacitor capacity is normally switched at 200 rl) Im, but since this capacitor switching becomes unnecessary and only one capacitor is required, the number of capacitors increases and the volume of the ignition control circuit module increases. This can be prevented from increasing.

As explained above, according to the present invention, by configuring the detection input stage of the comparator for detecting the voltage across the charge/discharge capacitor with a PNP transistor, the voltage value that can be charged to the charge/discharge capacitor can be increased. Therefore, it is possible to obtain an ignition device for an internal combustion engine that can accurately control the ignition timing without malfunction over a range from low speed rotation to high speed rotation of the engine.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of the ignition system, Figure 2 is a waveform diagram of each part of the circuit in Figure 1, Figure 3 is a waveform diagram of each part at high and low speed rotation, and Figure 4 is a diagram of the waveforms of each part of the circuit in Figure 1. 5 is a diagram showing details of the collector voltage waveform of some transistors in the circuit of FIG. 1, FIG. 6 is a diagram showing an embodiment of the present invention, and FIG. The figure is a circuit diagram of the input stage of a conventional comparator. 6.600...Comparator, 601,602
・・・・・・PNP transistor, 610, 620・
...NPN transistor.

Claims (1)

[Scope of Claims] 1. A reference ignition signal generation circuit that generates a first ignition signal serving as a reference for ignition timing synchronized with the rotation of the engine; a delayed ignition signal generation circuit that generates a second ignition signal for generating ignition at a time delayed by a predetermined crank angle, responsive to output signals from the reference ignition signal generation circuit and the delayed ignition signal generation circuit; and an ignition circuit that conducts and interrupts the current flowing through the primary winding of the ignition coil, wherein the delayed ignition signal generation circuit includes a charging/discharging capacitor;
means for switching the direction of a current flowing through the capacitor in response to a first ignition signal output from the reference ignition signal generation circuit; and means for generating the second ignition signal while detecting a terminal voltage of the capacitor. An ignition device comprising a comparator for controlling and switching the direction of current to the capacitor, further comprising a PNP transistor as a transistor constituting a detection input stage of the comparator. 2. In claim 1, the detection input stage of the comparator is constituted by a pair of PNP transistors, a reference voltage is applied to the control input terminal of one of the PNP transistors, and a reference voltage is applied to the control input terminal of the other PNP transistor. is connected to the anti-ground side end of the capacitor, and the other PNP transistor to which the anti-ground side end of the capacitor is connected is in a non-conducting state during a period in which the voltage across the capacitor is higher than the reference voltage. An ignition device characterized by: