JPH0474542B2 - - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electronic engine ignition timing control device that automatically and optimally adjusts the ignition timing of an engine according to the engine speed.

Conventional technology Conventionally, as a device that can obtain highly accurate advance angle characteristics that match engine characteristics that cannot be obtained with mechanical governor advance devices, the ignition signal obtained in synchronization with engine rotation is passed through a constant current circuit to a capacitor. When the charging voltage of the capacitor reaches a certain value, a predetermined delayed ignition signal is sent to the switching power transistor provided on the primary side of the ignition coil to control the engine's ignition timing. An electronic engine ignition timing control device has been developed that allows this to be done (see Japanese Patent Publication No. 35893/1983).

However, in such conventional engine ignition timing control devices, the capacitor is charged with a constant current circuit to perform ignition control.
When the engine speeds up to high speeds, the delay in charging the capacitor becomes a problem, resulting in poor response. In addition, while obtaining advance angle characteristics that match the engine characteristics,
It is now impossible to arbitrarily adjust the on-duty of the switching power transistor in accordance with the ignition characteristics of the ignition coil.

Purpose The present invention was made in consideration of the above points, and
In addition to improving responsiveness to increases in engine speed, the two contradictory characteristics of the advance angle characteristic matched to the engine characteristics and the on-duty characteristic of the switching power transistor matched to the ignition coil ignition characteristics are sacrificed at the expense of tracking performance. To provide an electronic engine ignition timing control device that can be satisfied without having to make any changes.

Configuration In order to achieve the object, the present invention takes a pick-up signal synchronized with the rotation of the engine into a frequency-voltage converter, and converts the pick-up signal and a signal obtained by inverting the output signal of the frequency-voltage converter into a first means for performing waveform shaping by comparing with a comparator; means for controlling the on-duty of a power transistor that performs switching on the primary side of the ignition coil by adjusting the time constant of the frequency-voltage converter; A second comparator compares a signal obtained by discharging the output signal of the comparator with a constant current and the output signal of the frequency-voltage converter, and drives the power transistor with the comparison output, thereby converting the power transistor. By controlling the off-timing of the engine, the capacitor is discharged at a constant current, and the ignition timing is controlled while comparing with the output of the frequency-voltage converter, thereby improving the responsiveness to the increase in engine speed. The on-duty characteristics of the power transistor can be changed arbitrarily by making good advance angle adjustment and changing the conversion characteristics of the frequency-voltage converter.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, the engine ignition timing control device according to the present invention includes a sensor 1 consisting of a reluctor and a pick-up coil that generate a pick-up signal synchronized with engine rotation, and a pick-up signal output from the sensor. A signal processing circuit 2 that performs signal processing such as signal noise removal and amplification, and the processed pick-up signal A.
a frequency-voltage converter 3 that performs frequency-voltage conversion; a time constant switching circuit 4 that can change the time constant of the frequency-voltage converter 3 to make its conversion characteristics variable; An inverting circuit 5 that inverts the waveform of the output signal B of the converter 3
, a first comparator 6 that compares the inverted signal with the pick-up signal A output from the signal processing circuit 2, a constant current discharge circuit 7 that discharges the comparison output signal at a constant current through a capacitor, and a constant current Discharge output signal and output signal B of frequency-voltage converter 3
and an amplifier 9 that amplifies the comparison output signal and supplies the amplified signal to the base of the switching power transistor Q provided on the primary side of the ignition coil IGC. It is configured. In the figure, 10 indicates a distributor, and 11 indicates a power supply stabilizing circuit. Further, BAT indicates a battery, and SP1 to SP4 indicate spark plugs.

FIGS. 2a and 2b each show an example of a time chart of various signals in the engine ignition timing control device according to the present invention configured as described above.

In such an engine ignition timing control device, first, a pick-up signal A synchronized with the rotation of the engine is taken into the frequency-voltage converter 3,
The inverted signal of the output signal B and the pick-up signal A
By comparing the two signals in the first comparator 6, the waveform of the pickup signal A is shaped, and a pulsed waveform-shaped signal C is obtained. Figure 2a,
In b, L1 and L2 indicate the threshold values at the time of waveform shaping according to each engine speed, that is, the level of the output signal in the inverting circuit 5, respectively.

At this time, by switching the time constant in the frequency-voltage converter 3 in the time constant switching circuit 4, the on-duty of the power transistor Q can be adjusted as desired.

In FIGS. 2a and 2b, the waveform-shaped signal C2 is obtained by adding the pulse signal C1 for on-duty correction at low engine speeds to the pulse signal C discriminated by the threshold value L1 or L2. The pulse signal C1 is generated according to the set time of the power transistor Q using, for example, a monostable multivibrator.

Next, the waveform shaping signal C output from the first comparator 6 is subjected to constant current discharge in the constant current discharge circuit 7, and the discharge signal D is converted to the output signal of the frequency-voltage converter 3 in the second comparator 8. The base drive signal E of the power transistor Q, in which the advance angle is calculated and the off timing of the power transistor Q is controlled, is obtained. In FIGS. 2a and 2b, F indicates the primary current flowing through the ignition coil IGC due to switching of the power transistor Q in response to the base drive signal E.

As an example, Figure 2 a shows the engine speed
At 1000 rpm, the lead angle is 4.5 degrees and the on-duty of power transistor Q is 35%. Figure b shows the characteristics when the engine speed is 2000 rpm.
This shows the characteristics when the lead angle is 11 degrees and the on-duty of power transistor Q is 50%.

Effects As described above, in the engine ignition timing control device according to the present invention, the ignition timing is controlled by discharging the capacitor at a constant current and comparing it with the output of the frequency-voltage converter. By optimally adjusting the lead angle with good responsiveness to the increase in engine speed, it is possible to easily respond to higher engine speeds, and by changing the conversion characteristics of the frequency-voltage converter, the on-duty characteristics of the power transistor can be improved. It has the excellent advantage of being able to be changed arbitrarily.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an engine ignition timing control system according to the present invention, and FIGS. 2a and 2b are diagrams showing an example of time charts of various signals in the same embodiment. DESCRIPTION OF SYMBOLS 1... Sensor, 2... Signal processing circuit, 3... Frequency-voltage converter, 4... Time constant switching circuit, 5...
...Inverting circuit, 6, 8... Comparator, 7... Constant current discharge circuit, 9... Amplifier, Q... Power transistor.

Claims (1)

[Claims] 1. A pick-up signal synchronized with the rotation of the engine is taken into a frequency-voltage converter, and a first comparator compares the pick-up signal with a signal obtained by inverting the output signal of the frequency-voltage converter to perform waveform shaping. means for controlling the on-duty of a power transistor that performs switching on the primary side of the ignition coil by adjusting the time constant of the frequency-to-voltage converter; and a second comparator compares the output signal with the output signal of the frequency-voltage converter, and controls the off timing of the power transistor by driving the power transistor using the comparison output. An ignition timing control device for an engine.