JPS5951671B2 - igniter - Google Patents

Description

[Detailed description of the invention] The present invention relates to an ignition device for an internal combustion engine.

FIG. 1 is a block diagram showing an ignition system for an internal combustion engine.

In the figure, 1 is an input signal generator for determining ignition timing.

This signal generating section 1 supplies an axle-synchronized input signal (rotation signal) obtained from, for example, a magnet 1 to an inductive pickup coil to a rotation signal detecting section 2 .

The detection section 2 shapes the input signal into a pulse, and supplies this pulse signal to the 0N10FF duty control section 3.

In order to cause current to flow through the ignition coil 4 for an appropriate time, the control section 3 generates a signal that determines the duty of the ON period and OFF period of the output 1 to the transistor 5, and supplies the signal to the output circuit 6.

This output circuit 6 actually performs switching control of the output transistor 5.

The constant current control circuit 7 detects the current flowing through the ignition coil 4 through resistors 8 to 10, limits the collector current of the output transistor 5 to a constant value, and sends a signal to the 0N10FF duty control section 3 for subsequent control. Give feedback.

Further, on the secondary side of the ignition coil 4, an ignition plug 11 is provided for causing spark discharge.

By the way, in the ignition system as described in -, the duty control unit 3 performs 0N10FF duty control according to the engine speed, so the reference voltage whose level changes depending on the engine speed and the sawtooth wave of engine synchronization are used. I'm comparing.

FIGS. 2a to 2c show conventional signal waveforms at various parts when performing a -4- comparison.

The signal waveform shown in FIG. 2a is the input signal output from the input signal generator 1, FIG. 2 is a sawtooth wave signal synchronized with the engine, and FIG. This is the signal obtained by comparing .

As shown in the figure, conventionally, the sawtooth wave signal shown in FIG. 2 is converted into tl+t2. Although it is attempted to fall instantaneously to zero at each timing of t3t..., in reality, this falling time does not fall to zero, but falls to zero at a predetermined slope.

Therefore, this fall time cannot be ignored and becomes a cause of error during high speed rotation when the period of the sawtooth wave signal becomes short.

In addition, since the above-mentioned sawtooth wave signal is generally obtained by charging and discharging a capacitor, the above-mentioned 1. , 12.13. At each timing, the capacitor is discharged with a large current.

For this reason, the conventional method has the disadvantage of requiring a large-area transistor for discharging, and also has the disadvantage that the ground potential rises due to the large current flowing through the grounding wiring, causing errors. be.

This invention was made in consideration of the above-mentioned circumstances, and its purpose is to provide an ignition system that does not require a large area transistor for discharging, and that has less error, especially when the engine rotates at high speed. The purpose is to supply equipment.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a block diagram showing the configuration of one embodiment of the ignition device according to the present invention, and parts corresponding to those of the conventional device shown in FIG.

In FIG. 3, reference numeral 21 denotes a voltage storage section, and this voltage storage section 21 is for storing a voltage at a level corresponding to the engine speed, and as the voltage storage means, a capacitor 22 is used as shown in the figure. It is used.

Reference numeral 23 denotes a sawtooth wave generating section, which has a period that is an integral multiple of the period of the pulse signal and generates a rising time corresponding to the storage voltage level of the capacitor 22 in the voltage storage section 2. A sawtooth wave is generated having a slope of , and a slope at the time of falling that is in a fixed ratio relationship with this slope.

Reference numeral 24 denotes a comparison unit, which compares the voltage level of the sawtooth wave with the reference voltage level every cycle of the pulsed signal, and if there is a deviation between these two levels, the comparison unit 24 compares the voltage level of the sawtooth wave with the reference voltage level, and if there is a deviation between these two levels, it to change the storage voltage level of the capacitor 22 in the voltage storage section 21.

The sawtooth wave generated by the sawtooth wave generator 23 is supplied to voltage comparators 25A, 25B, and 26.

The one voltage comparator 25A has a reference voltage source 27.
A reference voltage (1) is applied from A, and its comparison output is supplied to the comparator 24 as a phase comparison power.

Another voltage comparator 25B has a reference voltage source 27
A reference voltage (3) is applied from B, and its comparison output is supplied to the comparator 24 as a phase comparison input.

The ON time comparison voltage generation unit 28 for 0N10FF duty control is supplied with the storage voltage of the capacitor 22 in the voltage storage unit 21, the power supply voltage Vcc, and the output of the constant current control circuit 7, and performs duty control according to the engine speed. In order to perform duty control according to the battery voltage and duty control that prevents the output I transistor 5 from controlling the ignition coil 4 with a constant current for a long time, the reference voltage 2 to the voltage comparator 16 is set. Adjust.

The power supply circuit 29 stabilizes the voltage of the battery 30 since there is noise and voltage fluctuation.

FIG. 4 is a circuit diagram showing the detailed configuration of the sawtooth wave generating section 23. As shown in FIG.

In the figure, a terminal of the capacitor 22 in the voltage storage section 2 is connected to a non-inverting input terminal of a voltage comparator 31.

Also, the output terminal of this voltage comparator 31 is npn)
Connected to the base of transistor 32.

The emitter of this transistor 32 is connected to the inverting input terminal of the voltage comparator 31, and a resistor 33 is connected between this connection point and a ground potential point.

That is, - the voltage comparator 31. npn) A circuit consisting of a transistor 32 and a resistor 33 constitutes a voltage-current conversion circuit 34 that flows a current (2) proportional to the terminal voltage (2) of the capacitor 22.

The collector of the L transistor 32 is composed of four PNP transistors 35. 36. 37.38
connected in parallel to the base of

Moreover, only the above l transistor 35 has its collector
The bases are shorted.

The collector of the transistor 36 is connected to the collector of an npn transistor 39 and the base of an npn transistor 40.

The emitter of the transistor 39 is connected to the ground potential point, and the switching signal S from the comparator 24 is supplied to the base of the transistor 39 via a resistor 41.

There are two npn in the collector of the above I transistor 37.
The bases of l-transistors 42 and 43 are connected.

Further, the emitters of both transistors 42 and 43 are connected to the ground potential point, and the collector and base of one transistor 42 are short-circuited.

The collector of the transistor 42 is connected to the collector of an NPN L-transistor 44 whose emitter is connected to the ground potential point, and the base of the transistor 44 is supplied with the switching signal S via a resistor 45. .

The collector of the transistor 38 is connected to the collector of the transistor 40 and the anode of the diode 46.

The cathode of this diode 46 is connected to the collector of the transistor 43.

Further, the emitter of the transistor 40 is connected to a ground potential point, and a capacitor 47 is connected between the collector of the transistor 43 and the ground potential point.

That is, the four 1-herald transistors 35, 36, 37
, 38 constitute a current mirror circuit which takes the output current I of the voltage-current conversion circuit 34 as an input and obtains a current proportional to this.

Similarly, the two transistors 42 and 43 constitute a current mirror circuit that causes a current proportional to the output current of the L-transistor 37 to flow through the transistor 43.

In this case, the current ratio of the former current mirror circuit is 1:
1, and the latter is set at 1:2.

That is, a current I can be passed through the collector of the transistor 38, and a current 2, which is twice this, can be passed through the collector of the transistor 43.

Next, the operation of the sawtooth wave generator 23 configured as shown in FIG. 4 will be explained using the waveform diagrams shown in FIGS. 5a and 5l).

First, if it is assumed that the period T of the human input signal from the input signal generating section 1 is constant as shown in FIG. The output current I also remains constant.

Here, at the timing ta, the switching signal S output from the comparator 24 becomes high level.

When signal S goes high, transistor 44 turns on.
However, since the input current (2) to the transistor 42 flows to this I transistor 44, the output current of the transistor 43 becomes zero.

At this time, transistor 39 is on, transistor 40
is turned off, so the current I flowing through the transistor 38 charges the capacitor 47 through the diode 46.

Therefore, the terminal voltage of the capacitor 47 rises at a predetermined slope as shown in FIG.

Next, at the peak timing, the switching signal S is inverted from high level to low level.

When the signal S becomes low level, transistors 1 to 39 are turned off and transistors 1 to 40 are turned on, so that the current I flowing through the transistor 39 flows to this transistor 40.

Therefore, the capacitor 47 is not charged by the current (2).

On the other hand, when the signal S is at a low level, the transistors 1 to 44 are turned off, and the input terminal I flows to the transistor 42.

When the input current ■ flows through the transistor 42, the current 2■ flows through the transistor 43, so that the capacitor 47, which has been charged to a predetermined voltage by the current ■, is now discharged by the current 2■.

Therefore, at this time, the terminal voltage of the capacitor 47 falls at twice the slope of the rise.

Below, each timing tc. When te, tg,..., the terminal voltage of the capacitor 47 rises at a predetermined slope,
At each timing td, tf, . . . , a sawtooth wave having a period equal to the period of the input signal is obtained, falling at twice the slope at the time of rising.

Note that there is a relationship MTl-T2 between the fall time T1 and the rise time T2 in FIG.

Further, this relationship is satisfied even if the terminal voltage (2) of the capacitor 22 is not constant.

Next, the operation of the overall apparatus shown in FIG. 3 is shown in FIG.
This will be explained using the waveform diagram shown in f.

The rotation signal detection section 2 outputs a pulsed rotation signal as shown in FIG. 6a.

Further, as described in in, the sawtooth wave generating section 23 generates a sawtooth wave as shown in FIG.

This sawtooth wave is detected by a voltage comparator 25A and a comparator 24 to which the output of the comparator 25A is supplied, in synchronization with the rising-low retiming of the rotation signal, to determine whether or not it has reached the reference voltage ■1. If the rotation signal is supplied (
When the sawtooth wave has not reached the reference voltage v1 even though it has been raised (rise), that is, when there is a phase shift, the sixth
As shown at timing t1 in the figure, the voltage storage section 21
The inner container 22 is charged.

On the other hand, when the rotation signal is supplied, the sawtooth wave is already
1, that is, when there is a phase shift, the capacitor 22 is discharged as shown at timing t2 in FIG.

Then, after the sawtooth wave reaches the reference voltage ■1 or to
1, and only after the rotation signal rises and falls, the switching signal S is inverted, and the sawtooth wave starts to fall.

Then, the comparison unit 24 detects whether the sawtooth wave has reached the reference voltage V3, and if it has reached V3, the sawtooth wave will now rise.

Claims (1)

[Claims] 1. A rotation signal detection unit that obtains a pulse-like signal at an interval corresponding to the engine speed of the internal combustion engine, a voltage storage unit that stores a voltage at a level corresponding to the engine speed, and a voltage storage unit that has a period corresponding to the pulse-like signal. and a sawtooth wave that generates a sawtooth wave having a slope at the time of bean soup rising and a slope at the time of falling that are in a fixed ratio relation to this slope in accordance with the voltage level stored in the voltage storage section. A generating section compares the voltage level of the sawtooth wave with a first reference level every cycle of the pulsed signal, and if there is a difference between these two voltage levels, the voltage level is stored in the voltage storage section according to the difference. The present invention is characterized by comprising a comparison section that changes the voltage level, and a duty control section that compares the voltage level of the sawtooth wave with a second reference level and controls the energization time of the ignition coil based on the comparison result. ignition device.