JPH0141830B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a measurement circuit suitable for use in measuring the closing angle of an ignition system for an internal combustion engine, particularly a gasoline engine, and is used for inspecting ignition systems in ignition system manufacturing factories and the like.

In an internal combustion engine with an ignition system, the closing angle of the switching circuit on the low-pressure side of the ignition coil has a large effect on ignition performance. If the closing angle is small, the ignition energy will be insufficient, causing a misfire when the internal combustion engine rotates at high speed, while if the closing angle is large, the loss current in the ignition system will increase, causing adverse effects such as heat generation and battery consumption. In order to solve this problem, an ignition device has been developed that has a closing angle control that changes the closing angle of the switching circuit depending on the rotation speed.

In conventional ignition systems that do not perform closing angle control, the closing angle is not affected by the load on the switching circuit, so a resistive load is connected in place of the ignition coil and measured using the method shown in Figure 1. In FIGS. 1 and 2, the output signal 1001' of the switching circuit 1d is level-converted by the level conversion circuit 2', and further inverted by the inverter 121' to become an inverted output 1211'. This inverted output 1211' and the angle pulse 9001' from the angle pulse generator 9' are ANDed by the AND circuit 112' to obtain the pulse to be measured 1121', which causes the counter 7' to add and count. After addition counting is completed,
A storage display circuit 8' displays the added count value of the counter 7', that is, the closing angle.

However, in an ignition system that has closing angle control, the closing angle changes depending on the load condition of the switching circuit 1d, so it is possible to set the closing angle to a condition close to that of an actual vehicle, that is, with the load as the ignition coil and its high voltage side being discharged. Otherwise, the closing angle cannot be measured correctly. Therefore, the voltage waveform at the output end of the switching circuit 1d becomes a very complicated oscillating waveform as shown in FIG. 3, and the conventional measurement method cannot obtain sufficient accuracy. That is, the conventional configuration has a drawback in that it is not possible to distinguish between the closing angle θd of the complex vibration waveform shown in FIG. 3 and the induced voltage Vl, and the induced voltage Vl is also measured by regarding it as the closing angle θd. In addition, in Figure 3, a is 300PPM, b is 2500RPM, and c is
Shows each output signal waveform of switching circuit 1d at 3000 RPM, ON is ON point, OFF is OFF
point, ON _S is the ON point threshold level,
OFF _S indicates the OFF point threshold level.

Therefore, the present invention is composed of a comparator, a monostable circuit, a counter, and a memory display, and uses the output signal of an ignition device whose waveform changes depending on the rotation speed as input, and achieves a closing angle with high accuracy (0.1 degree). The purpose is to measure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing embodiments of the present invention, the principle thereof will be explained below. FIG. 3 shows the output terminal voltage waveform of the switching circuit. The output waveform changes depending on the rotation speed of the ignition device. From these waveforms, there is a clearly distinguishable voltage level at the OFF point, so this voltage level can be detected as the OFF point threshold level. but,
Regarding the ON point, it is difficult to distinguish between the ON point and the induced voltage based on the voltage level, and the time relationship between the ON point and the induced voltage Vl changes when the rotation speed changes, so it is difficult to detect only the ON point. It is.

Therefore, consider a method of measuring the closing angle θd while detecting both the ON point and the induced voltage Vl. The definition of closing angle is the angle from the ON point to the OFF point.
Now, since the OFF point can be detected, the end point of the closed angle can be detected. As for how to detect the starting point, if an ON point threshold voltage is provided as shown in FIG. 3, both the ON point and the induced voltage Vl will be detected. Since the OFF point is the end point, if we consider the point before and closest to the OFF point as the ON point,
The correct ON point can be detected regardless of the rotation speed.

FIG. 4 is a block diagram showing an embodiment of the present invention to which the above principle is applied. In FIG. 4, 1 is an ignition device, and this ignition device 1 includes an ignition coil primary side 1b, a secondary side 1c, and an ignition coil primary side 1b.
The switching circuit 1d is connected to the switching circuit 1d. 2 is an attenuator and switching circuit 1d
The output voltage of the comparator 3 is lowered to the input voltage level of the first and second comparators 3 and 4. Comparators 3 and 4 detect whether the output waveform of attenuator 2 exceeds the ON point voltage level and the OFF point voltage level. Reference numerals 5 and 6 designate first and second monostable circuits which convert the output signals of the comparators 3 and 4 into pulses and output clear signals and latch signals. Reference numeral 9 denotes an angle pulse generator that generates an angle pulse according to the rotation angle of the ignition device (engine). A counter 7 adds and counts the angle pulses, and is cleared by a clear signal generated in the monostable circuit 5.
Reference numeral 8 denotes a storage display which stores and displays the contents of the counter 7 using a latch signal generated in the monostable circuit 6.

FIG. 5 is an electrical circuit diagram showing a detailed embodiment of the closed angle measuring circuit shown in FIG. 4 above.
In FIG. 5, A indicates the output terminal of the switching circuit 1d in FIG. 4, and the voltage at this point (FIG. 6a) becomes the input to the attenuator circuit 2. The attenuator circuit 2 is composed of a voltage dividing circuit of resistors 22 and 23 and a buffer circuit 21, and lowers the voltage at point A to the input voltage level of the comparators 3 and 4. The diodes 24 and 25 are for protection of the buffer circuit 21.

The comparator 3 compares the ON point threshold voltage set by the variable resistor 31 with the output voltage level of the attenuator circuit 2, and outputs a signal having the waveform shown in FIG. 6b. The monostable circuit 5 is triggered by the falling edge of the output signal of the comparator 3, and generates a pulse signal of 1 μs width as shown in FIG. 6c. The comparator 4 compares the OFF point threshold voltage set by the variable resistor 41 with the output voltage level of the attenuator circuit 2, and outputs the signal shown in FIG. 6d. The monostable circuit 6 is triggered by the falling edge of the output signal of the comparator 4, and outputs a latch signal with a width of 100 μs as shown in FIG. 4e. This latch signal is ANDed with the angle pulse (FIG. 6(g)) generated by the angle pulse generator 9 consisting of a rotary encoder at the AND gate 113, stops the counting of the counter 9, and is also input to the delay circuit 100. be done. The delay circuit 100 delays the latch signal output from the monostable circuit 6 by 1 μs,
A timing signal is generated to cause the output of the counter 7 to be stored in the storage display 8. The NAND gate 112 converts the signal shown in FIG. 6c generated by the monostable circuit 5 and the signal shown in FIG. 4 e generated by the monostable circuit 6 to the inverter 1.
By performing NAND with the signal inverted by 11, a clear signal (FIG. 6f) is generated by removing the pulse immediately after the OFF point from FIG. 6c. The counter 7 counts the angle pulses (Fig. 6g) generated from the rotary encoder 9 and outputs the NAND gate 1.
It is cleared by the clear signal (FIG. 6f) generated by the monostable circuit 6, and stopped by the latch signal generated by the monostable circuit 6. The output signal of the monostable circuit 5 (Fig. 6c) is connected to the induced voltage Vl generation point shown in Fig. 3.
However, the clear signal (FIG. 6 f) that is the output of the NAND gate 112 is valid only at the ON point that is close to the OFF point before the OFF point.
Counter 7 is cleared at the ON point and counts the angle pulse (Fig. 6 (g)), and stops counting at the OFF point.
The contents are stored and displayed on the storage display 8.

As described above, in the present invention, the ON point and OFF point are determined based on the vibration waveform of the ignition switching circuit 1d.
The induced voltage Vl is detected by the comparators 3 and 4, and the induced voltage immediately after the OFF point is detected by the monostable circuit 6 regardless of the rotation speed of the ignition device 1, and the induced voltage Vl whose time relationship changes depending on the rotation speed is detected by the comparators 3 and 4. By paying attention to the order of the voltages and combining the counter 7 and the memory display 8, the effect of induced voltage is removed, which has the excellent effect of accurately and easily measuring the closing angle.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a conventional closing angle measuring circuit, Fig. 2 is a signal waveform diagram used to explain the operation of the circuit shown in Fig. 1, Fig. 3 is an output voltage waveform diagram of the ignition system, and Fig. 4 is a diagram of the main circuit. A block diagram showing an embodiment of the closed angle measuring circuit according to the invention, FIG. 5 is an electric circuit diagram showing a specific example of the circuit shown in FIG. 4, and FIG. 6 shows waveforms of various parts of the circuit shown in FIG. 5. It is a diagram. 1...Ignition device, 2...Attenuator, 3,4
... Comparator, 5, 6 ... Monostable circuit, 7 ... Counter, 8 ... Memory display, 9 ... Angle pulse generator.

Claims (1)

[Claims] 1. A first comparator that takes the voltage at the output end of the switching circuit of the ignition device as an input signal, and detects that the input signal has decreased below the ON point threshold voltage when the switching circuit is turned ON; a second comparator that detects that the input signal has risen above the OFF point threshold voltage when the switching circuit is turned OFF; and a second comparator that converts the outputs of the first and second comparators into pulses, respectively. 1. A second monostable circuit, a counter that is cleared by the output generated in the first monostable circuit when the switching circuit is turned on, and adds and counts angular pulses, and when the switching circuit is turned off. and a storage display that stores and displays the output of the counter based on the output generated in the second monostable circuit.