JPS5928750B2 - 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.
Reference numeral 1 denotes an input signal generator for determining the ignition timing.

This signal generator uses an axle synchronization input signal (rotation signal) obtained from a magnetic induction pickup coil, for example.
is supplied to the detection unit 2.

This detection section 2 shapes the waveform of the input signal to convert it into a "lust" signal, and converts the signal into a 0N10FF duty control section 3.
supply to.

This control section 3 controls the ON (conductivity) period and OFF period of the output transistor 5 in order to cause current to flow through the ignition coil 4 for an appropriate time.
A signal that determines the duty of the (cutoff) period is generated and the signal is supplied 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 40 through resistors 8 to 10, limits the collector current of the output transistor 5 to a constant value, and feeds back a signal to the duty control circuit 3 for subsequent control.

11 in FIG. 1 indicates a spark plug.

By the way, in the above-mentioned ignition system, since the duty control section 3 performs 0N10FF duty control according to the engine speed, it is necessary to create a voltage having a level corresponding to the engine speed.

However, in the past, this voltage was obtained by integrating the input pulse of the axle synchronization, so the response to rotational changes was slow.

Furthermore, since the integrated voltage simply stores input pulses, it is difficult to obtain an accurate voltage value that corresponds to the engine speed.

Further, the duty control is performed by comparing a reference voltage whose level changes depending on the engine speed with a sawtooth wave synchronized with the engine, and a circuit etc. for obtaining this sawtooth wave is separately provided. Because it was necessary, the circuit configuration tended to be complicated.

The present invention has been made in view of the above-mentioned problem, and is achieved by obtaining a feedback circuit configuration that corrects the phase difference between the input signal obtained in accordance with the rotation of the engine and the sawtooth wave. The purpose is to provide an ignition device that can eliminate the problems of the above.

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

FIG. 2 shows the main parts of this embodiment in blocks, and the rotation signal detection section 2 obtains a pulse-like signal at intervals corresponding to the engine rotation speed of the internal combustion engine, as described above.

The voltage storage section 21 is for storing a voltage at a level corresponding to the engine speed.

The sawtooth wave generating section 22 generates a sawtooth wave having a period corresponding to the pulse signal and a slope corresponding to the storage voltage level of the voltage storage section 21.

The comparator 23 compares the voltage level of the sawtooth wave with a reference voltage every cycle of the pulsed signal, and if there is a difference between these two voltages, the storage voltage level of the voltage storage unit 21 is adjusted according to the difference. change.

Fig. 3 shows the configuration shown in Fig. 2 above, in which rotation detection and duty control can be specifically performed, and parts corresponding to Figs. 1 and 2 are given the same reference numerals and explanations are omitted. do.

In FIG. 3, reference numeral 31 denotes a capacitor connected externally to the sawtooth wave generating section 22, and the sawtooth wave is obtained at a terminal A point of the capacitor 31 and becomes a non-inverting input of the comparators 32 and 33.

The reference voltage of the comparator 32 is given from the reference voltage source 34, and the output of the comparator 32 is supplied to the comparison section (phase detection section).
There are 230 inputs.

In the voltage storage section 21, the capacitor 35 is a section that stores a voltage corresponding to the engine speed. Terminal B of the capacitor 35- is connected to the sawtooth wave generation section 22, and is connected to the sawtooth wave generator 22 via a switch 36 and a current source 37. It is connected to the power supply Vcc, and is grounded via a switch 38 and a current source 39.

This part of the voltage storage section 21 is shown in terms of an equivalent circuit, and the switch 36 is closed when the capacitor 35 needs to be charged due to the operation of the comparison section 23, and the switch 38
is closed when it is necessary to discharge the capacitor 35 due to the operation of the comparator 23.

The sawtooth wave generator 22 generates at terminal A a sawtooth wave whose slope corresponds to the voltage of the capacitor 35, but FIG. 4 shows a circuit for that purpose.

That is, a current I proportional to the voltage V flows through the resistor R.

The comparison voltage generator 40 for the ON time of the 0N10FF duty control receives the terminal voltage of the capacitor 35, the power supply voltage, and the output of the constant current control 7 as feedback, and performs duty control according to the engine rotation speed, duty control according to the battery voltage, In order to perform duty control to prevent the output transistor 5 from controlling the ignition coil 4 with a constant current for too long, the reference voltage (threshold voltage) V2 to the comparator 33 is adjusted.

In order to control the ignition current flowing through the output transistor 5 to be constant and the voltage generated on the secondary side of the ignition coil 40 to be constant, the voltage across the resistor 8 must be controlled by the resistor 9,
The voltage is divided by 10 and input into the constant current control circuit 1, compared with the reference voltage level in the constant current control circuit 7, and the output current of the output circuit 6 is changed so that the output current of the output transistor 5 becomes the specified value. Control as follows.

Note that if the constant current control time of the output transistor 5 is too long, the output transistor 50 generates too much heat and there is a risk of destroying the transistor 5. Therefore, it is necessary to correct the duty in order to keep the constant current period to the necessary minimum. There is.

Therefore, the voltage generator 40 compares the voltage according to the constant current period.
The threshold voltage V2 is corrected by adding .

If the internal power supply circuit 41 causes noise in the voltage of the battery 42,
Since there is voltage fluctuation, this is stabilized.

FIG. 5 is a signal waveform diagram showing the operation of the above configuration, and the operation of the circuit shown in FIG. 3 will be explained below with reference to this diagram as appropriate.

The rotation signal detector 2 outputs the rotation signal shown in FIG. A sawtooth waveform (FIG. 5b) with a different slope is obtained.

The discharge time constant of the sawtooth wave is chosen to be well within the pulse width of the input signal of FIG. 5a.

Comparison units 23 and 32 detect whether or not this sawtooth wave has reached the reference voltage v1 at the rising timing of the rotation signal, and if the rotation signal is supplied (rises), the sawtooth wave When the reference voltage V1 has not been reached (there is a phase shift), the capacitor v35 of the voltage storage section 21 is charged as shown at timing t1 in FIG.

This is done by closing switch 36.

On the other hand, when the rotation signal is supplied and the sawtooth wave has already reached the reference voltage V1 (there is a phase shift), the capacitor 35 is discharged as shown at timing t2 in FIG.

This is done by closing switch 38.

In this way, a voltage corresponding to the rotation signal can be obtained at the B end.

On the other hand, since V2 is supplied as the reference voltage of the comparator 33, when the sawtooth wave shown in FIG. The ignition coil current is cut off when the rotation signal falls.

Since the reference voltage V2 changes depending on the B-terminal voltage which changes depending on the engine speed, a predetermined duty control can be performed.

The above configuration has the following advantages.

That is, as shown in FIGS. 5a to 5c, when a change occurs in the engine speed, the sawtooth wave and the voltage stored in the voltage storage section 21 can be corrected within one cycle of the rotation signal, so that the responsiveness to the rotation change is improved. becomes faster.

Further, since the voltage in the voltage storage section 21 is corrected so that the rotation signal and the sawtooth wave exactly match, a voltage corresponding to the accurate rotation speed can be obtained.

Also, just as the voltage at the A terminal of the capacitor 31 is input to the comparators 32 and 33, the sawtooth wave shown in Figure 5 is also used to perform the duty control shown in Figure 5 f, so the circuit Configuration is simplified.

Furthermore, as described above, since a voltage corresponding to the accurate rotational speed can be obtained at the B end, the duty control can be made more accurate.

Note that the present invention is not limited to the above embodiments, and can be applied in various ways.

For example, in the embodiment, the phase shift of the sawtooth wave is detected at the rising point of the rotation signal shown in FIG. 5a, but it may be detected at the falling point of the rotation signal.

As explained above, according to the present invention, a voltage corresponding to an accurate rotation speed can be quickly obtained, and since the sawtooth wave is also used for duty control, the circuit configuration is simplified, and accurate rotation speed can be achieved. It is possible to provide an ignition system that has the advantage of being able to accurately control duty because it can obtain voltage according to the number of lights.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the ignition device, FIG. 2 is a block diagram showing the main parts of an embodiment of the present invention, FIG. 3 is a circuit diagram of the ignition device embodying the same main parts, and FIG. FIG. 4 is a partial detailed circuit diagram of the same circuit, and FIG. 5 is a timing chart showing the operation of the circuit of FIG. 3. 1... Input signal generation section, 2... Rotation signal detection section, 3
...Duty control unit, 4...Ignition coil, 6...
- Output circuit, 21... Voltage storage section, 22... Sawtooth wave generation section, 23... Comparison section, 31.35... Capacitor? , 32° 33... Comparator, 34... Reference voltage source, 36° 38... Switch, 37, 39...
Constant current source, 40... ON time comparison voltage generator, 42
···battery.

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 period corresponding to the pulse-like signal. a sawtooth wave generating section that generates a sawtooth wave having a slope corresponding to the voltage level of the voltage storage section; a comparison section that compares and detects a deviation between the two mold pressures; and a charger that changes the voltage level of the voltage storage section in accordance with the deviation when the comparison section detects the deviation, and changes the slope of the sawtooth wave. comprising a discharge circuit and a duty control section that obtains a threshold voltage corresponding to at least the voltage of the voltage storage section and controls the energization time of the ignition coil based on a comparison result between this voltage and the voltage level of the sawtooth wave. An ignition device featuring: