JPS5925025Y2 - Spark hydrant pre-ignition tester circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pre-ignition tester circuit for detecting pre-ignition due to ion current of a spark plug installed in an internal combustion engine.

A conventional pre-ignition tester circuit, as shown in the circuit diagram shown in FIG. Then, a circuit 11 is connected in series with a diode D1, a resistor R1, and a DC power source B1 for measuring ion current whose polarity matches that of the spark plug P. It had a circuit configuration connected to the input terminal of an oscilloscope S.

In this pre-ignition tester circuit, a delicate voltage waveform due to pre-ignition and a sharp voltage rising waveform due to spark discharge are connected, making it difficult to recognize the presence or absence of pre-ignition.

In addition, the display of the oscilloscope S is swept with the spark discharge signal, and the presence or absence of preignition is measured by the presence or absence of the ion current waveform that appears before the next spark discharge. It is not possible to detect the presence or absence of the color.

Furthermore, when measuring the pre-ignition of a spark plug containing a resistor, the rise of the voltage due to spark discharge is slow, making it difficult to accurately determine whether there is an ionic current.

The object of the present invention is to eliminate such drawbacks and to provide a preignition tester circuit that can accurately detect all preignitions that occur during spark discharge.

The pre-ignition tester circuit of the present invention has a circuit in which a diode D1, a resistor R1, and a DC power source whose polarity matches the polarity of the spark plug are connected in parallel with the spark plug. In the pre-ignition tester circuit, the pre-ignition tester circuit is configured such that the input signal is input to the display device via the capacitor C, and the intermediate point 2 between the capacitor C and the display device is connected to the collector of the transistor T, and the base of the transistor T is triggered by a spark discharge signal.・By connecting the output terminal of a constant ratio split monostable vibrator that divides the time between spark discharge signals at a fixed ratio, the above point 2 is grounded for a fixed period of time from the point of occurrence of spark discharge, and the resistor R2 A DC power source having a polarity opposite to that of the DC power source is connected through the DC power source, so that a preignition waveform appears at the rear end of the pulse waveform.

Next, the present invention will be explained based on an embodiment shown in FIGS. 2 to 5.

The same reference numerals as in Fig. 1 indicate the same elements, T is a transistor whose collector is connected to the input terminal 2 of the oscilloscope S and whose emitter is grounded, and 3 is a constant ratio division type monostable connected to the base of the transistor T. The vibrator 12 is a circuit in which a diode D2, a resistor R2, and a DC power supply ratio arranged in opposite polarity to the DC power supply B1 for ion current measurement are connected in series, and the diode D2 side is connected to the input terminal 2 of the oscilloscope S. has been done.

The constant ratio division type monostable bi-break 3 is a constant current circuit (1) as shown in the circuit example shown in FIG. ■2, transistor Tr1. Tr□, resistors R3, R4, capacitor C
1. It consists of a diode D3, and the power supply terminal 4 has a constant voltage V.
cc is applied, and the trigger signal shown in FIG. As shown in the figure, a pulse signal is generated by dividing the period between spark discharges at a fixed ratio t1:t2, regardless of the length of the period between spark discharges.

Figure 4A shows the spark discharge waveform. In the constant ratio division type monostable vibrator 3, in a stable state, the transistor Tr1 is OFF (non-conducting), the transistor Tr2 is ON (conducting), and the capacitor C1 is charged with a constant current 1.

When the negative polarity trigger shown in FIG. 6A is applied to the base of the transistor Tr2 via the diode D3, the transistor Tr2 turns OFF, and the transistor Tr1
becomes ON.

At this time, the base voltage of the transistor Tr2 is negative as shown at the beginning of Figure 6, but as it is discharged by the constant current I2, it approaches the O potential, and eventually becomes positive, and when the current starts flowing to the base of the transistor Tr2, it becomes stable. The transistor Tr in the state.

is turned OFF, and the transistor Tr2 returns to the ON state.

As a result, the base voltage of the transistor Tr2 changes as shown in Figure 6, and the collector voltage of the transistor Tr2 is always divided into a constant ratio regardless of the frequency change of the trigger signal, as shown in Figure 6C and the Figure 4. It becomes a pulse.

FIG. 6 shows changes in the collector voltage of the transistor Tr2.

Note that the slope of the voltage rise of the base voltage of the transistor Tr2 and the collector voltage of the transistor Tr1 is determined by the capacitance of the capacitor C1 and the constant currents (2) and (1), so it remains constant regardless of changes in the engine speed. .

The output of the monostable vibrator 3 causes the transistor T to conduct for an hour t1 after the spark discharge, and for the next 12 hours the transistor T ceases to conduct.

An input signal having a pulse waveform shown in FIG. 4 is supplied to the input terminal 2' of the oscilloscope.

When pre-ignition is generated by the ion current in the spark plug P, the waveforms a, l), and c in the waveform diagram of the conventional pre-ignition tester shown in Fig. 4-2 are as follows.
A small ion current waveform occurs before the waveform due to the spark discharge.

This ion current waveform is the input terminal 2' of the oscilloscope S.
is added with the pulse waveform shown in 8 of Figure 4 above to obtain the fourth pulse waveform.
As shown in E of the figure, a protrusion a due to pre-ignition,
l), and c are input as pulse-like voltage waveforms.

As a result, when preignition does not occur, the oscilloscope displays the pulse shown in Figure 5 A, and when preignition occurs, the oscilloscope displays the pulse with a protrusion like the mouth in Figure 5, making it very clear that preignition is not occurring. I can recognize Siyeon.

As mentioned above, the pre-ignition tester circuit of the present invention is
Since the input terminal of the oscilloscope is grounded through a transistor that is turned on by the output of a fixed-ratio monostable vibrator that operates in synchronization with the spark discharge, (a) the voltage drops at the location of the spark discharge, causing a The position of the waveform produced by the ignition becomes clear and can be clearly distinguished from the rising waveform of the pre-ignition waveform.

(b) There is no need to adjust the position of the trigger signal in response to changes in engine speed.

All pre-ignitions that occur during spark discharge can be accurately detected.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a conventional pre-ignition tester circuit, Fig. 2 is a schematic diagram of a pre-ignition tester circuit according to the present invention, Fig. 3 is a circuit diagram of a constant ratio split monostable vibrator, and Fig. 4 5 shows a voltage waveform diagram, FIG. 5 shows an oscilloscope display, and FIG. 6 shows a waveform diagram for explaining the operation of the monostable bi-break. In the figure, P... Spark plug, B1. B2...
Constant voltage power supply, R1゜R2...Resistance, C...
・Condenser, Dl, B2...Diode,
S...Oscilloscope, 3...Constant ratio split type monostable bi-break.

Claims (1)

[Scope of utility model registration request] A circuit in which a diode D1, a resistor R1, and a DC power supply whose polarity matches that of the spark plug are connected in series is connected in parallel with the spark plug, and input to the display device via the capacitor C from the intermediate point 1 between the resistor R1 and the diode D1. In the pre-ignition tester circuit, an intermediate point 2 between the capacitor C and the display device is connected to the collector of the transistor T,
By connecting to the base of the transistor T the output terminal of a monostable vibrator that is triggered by a spark discharge signal and divides the time between spark discharge signals at a constant ratio, The point 2 is grounded and connected to a DC power source having a polarity opposite to that of the DC power source via a resistor R2, so that a preignition waveform appears at the rear end of the pulse waveform. Spark plug pre-ignition tester circuit.