JPH08326642A - Ignition timing control device for internal combustion engine - Google Patents

Abstract

PURPOSE: To prevent missing out of ignition signals at the time of sudden change of engine speed to constantly generate optimum ignition signals in an ignition signal generating device used for internal combustion engines. CONSTITUTION: When a rotational angle sensor signal of an internal combustion engine is compared to a threshold value using a comparator 10, and the elapsed time from the side of start of waveform shaped pulse signal coincides with a preliminarily calculated ignition timing, an ignition timing signal is outputted to an ignition device. With the threshold value, the elapsed time from the start of pulse signal obtained by differenciating output of the comparator 10 by a differentiation circuit 11 is measured by a timer 12, the value of the threshold is changed in response to the elapsed time by a correction circuit 13 and a D/A converter 14, and thus an optimum value is obtained according to the level of sensor signals. Data trains to be outputted from the D/A converter are preliminarily stored, and according to the operating state, either one of the data trains is selected to be outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition timing control device for an internal combustion engine by digital signal processing.

[0002]

2. Description of the Related Art FIG. 4 is a schematic block diagram showing an example of a conventional ignition timing control device for an internal combustion engine. In FIG. 4, 10 is a comparator, 16 is an input terminal, 17 is an output terminal,
40 is an F / V converter. A sensor signal output from a rotation angle sensor of an internal combustion engine (not shown) is input to the input terminal 16 and is subjected to signal processing by an ignition signal generator configured by the comparator 10 and the F / V converter 40, and an output terminal An ignition signal is output from 17. The ignition timing starts when the igniter starts charging when the internal combustion engine reaches a certain rotation angle and when the internal combustion engine reaches the vicinity of the top dead center. The timing for starting charging the igniter and the timing for igniting are determined by the ignition timing control device.

Next, the operation of the conventional ignition timing control system for an internal combustion engine will be described. Conventionally, in an internal combustion engine control system using a microprocessor (MPU), a magnetic detection type sensor is often used as a rotation angle sensor of the internal combustion engine. This magnetic detection type sensor uses the fact that the voltage across the detection coil changes due to the change in magnetic flux due to the rotation of the shaft, so the sensor output, that is, the sensor signal, is a function of the internal combustion engine speed. Become. In order to use the sensor signal as an ignition signal, it is necessary to shape the waveform using the comparator 10. However, since the level of the sensor signal is low at low revolutions, the threshold of the comparator 10 is lowered, and induced noise etc. at high revolutions. It is necessary to increase the threshold value of the comparator 10 in order to avoid the influence of.

Further, in order to generate the energy required for ignition, it is necessary to optimally control the energization time from the timing of starting the charging of the igniter to the timing of outputting the ignition signal. It is necessary to measure the engine speed of the internal combustion engine and generate a threshold value corresponding to the engine speed to determine the timing to start charging the igniter. The F / V converter 40 generates this threshold value. The F / V converter 40 converts the frequency (F) of the sensor signal indicating the internal combustion engine speed into a voltage (V), and the converted voltage (V) is a comparison voltage (threshold value) of the comparator 10. I am trying.

[0005]

However, in the above-mentioned conventional ignition timing control system for an internal combustion engine, the optimum threshold value is set when the rotational speed change, that is, the output voltage change of the magnetic detection type sensor is large, such as during cranking. However, there is a problem in that it is difficult to obtain the optimum ignition timing. For example, when the rotation speed suddenly drops, the output voltage of the sensor becomes a value smaller than the threshold voltage, resulting in signal loss and misfire.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an excellent ignition timing control device for an internal combustion engine capable of generating an accurate ignition signal without signal omission. .

[0007]

In order to achieve the above object, the present invention compares the internal combustion engine rotation angle sensor signal with a threshold value and shapes the waveform so that an optimum ignition timing can be obtained.
The threshold value of the comparator is changed according to the elapsed time from the pulse signal obtained by differentiating the output, and a plurality of sets of data strings of the threshold value of the comparator that is changed according to the elapsed time from the pulse signal are stored. However, one of them is used.

[0008]

Therefore, according to the present invention, an optimum threshold value can be obtained, and an accurate ignition signal can be generated without signal omission.

[0009]

1 is a block diagram showing the structure of an ignition timing control system for an internal combustion engine according to an embodiment of the present invention, in which constituent elements having the same functions as those in FIG. 4 are designated by the same reference numerals. 2 is a waveform diagram showing the operation of the main part of the ignition timing control device shown in FIG. 1, and FIG. 3 is a timer, a correction circuit, and D in FIG.
It is a block diagram which shows the relationship with a / A converter.

In FIG. 1, reference numeral 10 is a comparator, which shapes the waveform of the internal combustion engine rotation angle sensor signal. Reference numeral 11 is a differentiating circuit, which differentiates the output of the comparator 10 to detect a change point. Reference numeral 12 is a timer, which is at regular time intervals (for example, 0, 5 m
every s) and count up the time. Reference numeral 13 is a correction circuit, a correction circuit for decoding the digital value of the timer in accordance with the predetermined relationship shown in FIG. 3, and 14 is a D / A converter,
The decoding result by the correction circuit 13 is converted into an analog voltage, and the threshold value of the comparator 10 is generated. Reference numeral 15 is a hysteresis generating resistor, which prevents an error in threshold setting caused by noise or power supply voltage fluctuation. Reference numeral 16 is an input terminal, and 17 is an output terminal. Reference numeral 18 is an input terminal for the count pulse.

Next, the operation of this embodiment will be described with reference to FIGS. FIG. 2 shows the waveform of each part. In FIG. 2, 20 is a waveform of the internal combustion engine rotation angle sensor signal input to the input terminal 16. 24 is a threshold value. Reference numeral 21 is a waveform of the waveform shaping output obtained by shaping the waveform 20 by the comparator 10. 20a is the point at which the waveform 20 of the internal combustion engine rotation angle sensor intersects the threshold value 24,
Similarly, 20b is a point (zero cross) at which the waveform 20 crosses the zero level. The waveform shaping output 21 whose waveform has been shaped by the comparator 10 is differentiated by the differentiating circuit 11. Two
2 is the differentiated waveform, that is, the waveform of the output pulse of the differentiating circuit 11. Reference numeral 23 is a count pulse for the timer which is generated at intervals of 0.5 mS. The timer 12 has a count pulse 23 from the count pulse input terminal 18.
Is input and counts up. The timer 12 is reset by the plus side of the waveform 22 of the output pulse of the differentiating circuit 11, and when reset, starts counting up again by the count pulse 23. The correction circuit 13 includes a read-only memory having conversion contents as shown in FIG. 3, and converts the output value of the timer 12 into an appropriate digital value. This digital value is converted into an analog voltage value by the D / A converter 14 according to the relationship shown in FIG. The output of the D / A converter 14 is the threshold value 24 and is given to the comparator 10.

In this way, as is clear from the relationship between the waveform 20 of the internal combustion engine rotation angle sensor signal shown in FIG. 2 and the output of the D / A converter 14, that is, the threshold value 24, the level of the sensor signal is Even if it changes, the threshold value changes, so that D / D shown in FIG.
By setting the A output value, the start side timing 21a of the waveform shaping output 21 can be optimally set.

FIG. 3 shows that the starting side timing 21a of the waveform shaping output 21 is located at a position further advanced from the position where the ignition timing is most advanced when the operating state changes in advance for each rotational speed. The D / A output value shown is set, and the rotation speed and the start side timing 21a of the waveform shaping output 21 are set.
The relationship is stored in advance as data. The ignition timer value 25 is calculated from the relationship between the ignition timing, the rotation speed stored as data, and the start side timing 21a of the waveform shaping output 21 by detecting the operating state from various sensors.
a is calculated as the time from the start side timing 21a of the waveform shaping output 21. Then, the waveform shaping output 21
Ignition is performed by outputting an ignition timing signal to the ignition device at the time when the elapsed time from the start side timing 21a matches the ignition timer time.

Even if the D / A output value is set for each rotation speed as described above, the ignition timing can actually be set, for example, considering the range of engine coolant temperature from extremely low to extremely high. It is conceivable that the range becomes longer and the ignition timer setting time becomes considerably longer.

Therefore, a plurality of sets of D / A output values for each rotation are stored in accordance with the ignition timing calculated based on the input values of various sensors, and the ignition timing is retarded when the ignition timing is on the retarded side. For D
/ A output value, if the ignition timing is on the advance side D for advance
/ A output value is used.

As described above, according to this embodiment, since the setting time of the ignition timer is short, there is little delay in the actual ignition timing from the target ignition timing even during acceleration, and the output drop during drivability and drivability during acceleration. It is possible to provide a simple ignition timing control device that does not cause deterioration of the ignition timing.

Further, although the above embodiment does not refer to the instruction of the energization start timing to the ignition timing control device, it is assumed that the instruction of the energization start timing is given at a time as far back as possible from the ignition timing to secure the energization time. The specific method is determined according to the system to which the present invention is applied.

[0018]

As is apparent from the above embodiments, the present invention compares the internal combustion engine rotation angle sensor signal with a threshold value, shapes the waveform, and differentiates the output from the pulse signal. Since the threshold value of the comparator is changed according to the information of, the threshold value becomes the optimum value according to the level of the sensor signal, and the optimum one is selected from multiple data strings according to the operating state. Since it is used, it has an effect that an optimum ignition signal is always generated.

[Brief description of drawings]

FIG. 1 is a block diagram of an ignition timing control device for an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is an output waveform diagram of the same embodiment.

FIG. 3 is a configuration diagram showing a relationship between a timer, a correction circuit, and a D / A converter.

FIG. 4 is a block diagram of a conventional ignition timing control device for an internal combustion engine.

[Explanation of symbols]

 10 comparator 11 differentiation circuit 12 timer 13 correction circuit 14 D / A converter 15 hysteresis resistance 16 input terminal 17 output terminal 18 count pulse input terminal 21 waveform shaping output 25 ignition signal 40 FV converter

Claims (1)

[Claims] 1. A comparator for comparing an input signal from an internal combustion engine rotation angle sensor with a threshold value, a differentiation circuit for differentiating the output of the comparator, and a time elapsed from generation of an output pulse of the differentiation circuit. Timer, a correction circuit for reading a threshold value according to the elapsed time as a digital value, and a D / A for converting the output of the correction circuit into the threshold value.
A waveform shaping circuit comprising a converter, which outputs a pulse signal from the comparator, and a target ignition timing from the operating state of the internal combustion engine, is calculated as an ignition timer time from the start timing of the pulse, and the pulse In the ignition timing control device that outputs the ignition timing signal to the ignition device at the time when the elapsed time from the start side timing matches the ignition timer time, the threshold value according to the elapsed time from the output pulse generation of the differentiating circuit is An ignition timing control device for an internal combustion engine, wherein a plurality of sets are stored and one set is selected from a plurality of sets of data based on inputs from various sensors and output.