JPS5810580B2 - Automotive ignition system diagnostic device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a diagnostic device for an ignition system of an automobile, and more particularly to a diagnostic device suitable for automatically detecting the number of cylinders and diagnosing each cylinder.

Conventional automobile ignition system diagnostic devices employ a method in which the number of cylinders, which varies depending on the vehicle, is specified using a selection switch or the like.

In addition to the inconvenience of having to specify the number of cylinders one by one before diagnosis with such a device,
If the designation is incorrect due to forgetting the designation, correct diagnosis cannot be made, and furthermore, providing a selection switch increases the cost and has the drawbacks that the design of the device is not good.

An object of the present invention is to provide a diagnostic device for an automobile ignition system that can automatically detect the number of cylinders.

The present invention attempts to automatically detect the number of cylinders by counting the number of ignition pulses for all cylinders, that is, the number of voltage pulses generated by the ignition device during the period of the ignition pulse of a given cylinder.

Examples of the present invention will be described below.

A typical ignition system circuit diagram is shown in FIG.

In the figure, the ignition device includes a battery 1, a switch 2.1
An ignition coil 3 including a secondary coil 4 and a secondary coil 5, an interrupter 6, a capacitor 7, a high voltage cord 8, a distributor 9 including a center electrode 10, a plug cord 11,
12, 13, 14, spark plugs 15, 16, 17, 18
It is composed of

Figure 1 shows the case of an ignition system for a four-cylinder engine.
Since its operation is well known, its explanation will be omitted.

In diagnosing this ignition system, signals extracted at points A, B, and C are used.

The signal taken out from point A is the voltage generated in the secondary coil 5 transmitted by the high voltage cord 8 and detected by the secondary voltage sensor 19. The signal taken out from point B is the signal taken out from the primary coil 4.
The signal extracted from signal point C, which directly detects the primary voltage generated in , is a signal obtained by detecting the ignition pulse of an arbitrary cylinder from the plug cord 11 by the reference cylinder sensor 20.

FIG. 2 shows a diagnostic device according to an embodiment of the present invention, which diagnoses an ignition system based on signals taken out from points A, B, and C in FIG.

In the figure, the signal at point A is input to the waveform shaping section 30, the signal at point B to the waveform shaping section 22, and the signal at point C to the waveform shaping section 25.

The signal waveform-shaped by the waveform shaping section 30 is sent to a discharge duration processing circuit 31a and a peak value hold circuit 31.
b, and the outputs of the discharge duration processing circuit 31a and the peak value hold circuit 31b are input to the data processing section 21.

On the other hand, the output from the waveform shaping circuit 22 is
1, the peak value hold circuit 31b and the counter 23.1 through the inverter 22a. The signals are input to one input terminal of the AND circuit 29, respectively.

A flip-flop 26 is connected to the other input terminal of the AND circuit 29.
6 is configured so that the signal taken out from point C is inputted via a waveform shaping circuit 25.

Further, a signal from the flip-flop 26 is input to the counter 23 via a delay circuit 27, and the output of the counter 23 is input to the data processing section 21 via a latch circuit 24 connected to the counter 23.

Further, a differentiation circuit 28 is connected to the latch circuit 24, and the output of the flip-flop 26 is differentiated and input to the latch circuit 24.

Further, the output of the AND circuit 29 is input to the data processing section 21.

Now, the primary voltage signal at point B is waveform-shaped by the waveform shaping section 22 and separated into two signals.

One is a primary voltage waveform with noise removed and sent to the data processing unit 21, and the other is a rectangular wave and is sent to the inverter 22a.
and is sent to one input terminal of the AND circuit 29.

The output of the inverter 22a is sent to the input terminal of the counter 23, where the number of primary voltage pulses is counted.

The output of the counter 23 is latched by a latch circuit 24 and then sent to the data processing section as a cylinder number signal.

The output signal of the reference cylinder sensor 20 taken out from point C is shaped by the waveform shaping section 25 to become a rectangular wave and sent to the flip-flop 26.

The flip-flop 26 inverts its output every time it receives an output pulse from the waveform shaping section 25.

The output is sent to the other input terminal of the AND circuit 29, the delay circuit 27, and the differentiating circuit 28.

The delay circuit 27 delays the output of the flip-flop 26 and inputs the delayed output to the reset terminal of the counter 23.

The output pulse of the differentiating circuit 28 is given to the latch circuit 24 and becomes a timing pulse for latching the count value of the counter 23, that is, the cylinder number signal.

The time difference between this pulse and the output pulse of the delay circuit 27 becomes a latch time, and a cylinder number signal is sent to the data processing section 21 during this time.

The secondary voltage signal taken out from point A is shaped by the waveform shaping section 30 and then separated by the peak value hold circuit 31b and the discharge duration processing circuit 31a, and the respective separated signals are sent to the data processing section 21.

The peak value hold circuit 31b is driven by a rectangular wave signal from the waveform shaping section 22, as will be described later.

The waveform shaping section 22 has a configuration as shown in FIG. 3a.

That is, in the figure, the other end of the resistor 32, one end of which is connected to the terminal for taking out the signal from point B in Figure 1,
The positive input terminals of a resistor 33, a capacitor 36, and a comparator 37 are connected to each other.

The other ends of the resistor 33 and capacitor 36 are both grounded.

Resistors 34 and 35 are connected to the negative input terminal of the comparator 37.
A constant voltage is applied to the other end of the resistor 34, and the other end of the resistor 35 is grounded.

Now, when a voltage waveform as shown in FIG. 3 taken out from point B is input, the resistors 32 and 33 and the capacitor 36
By removing noise etc., a waveform as shown in FIG. 3C is obtained.

Furthermore, this waveform is applied to the + input terminal of the comparator 37, and the sign (+) is applied to the - input terminal by resistors 34 and 35.
In response to the constant voltage shown in FIG. 3c, a voltage at a level 39a shown by a two-dot chain line is applied.

As a result, the waveform outputted from the output terminal of the comparator 37 becomes a rectangular wave as shown in FIG. 3d.

The primary voltage waveform as shown in FIG. 3c appearing on the input line 38 of the positive input terminal of the comparator 37 is input to the data processing section 21 in FIG.

On the other hand, the waveform shaping section 25 has a circuit configuration as shown in FIG. 4a.

That is, in the figure, one end of the resistor 41 is connected to the terminal for taking out the signal from point C in FIG.
A resistor 42, a capacitor 45, and an inverter 46 are connected to each other.

The other ends of the resistor 42 and capacitor 45 are both grounded.

The output terminal of the inverter 46 is connected to the positive input terminal of a comparator 47, and the negative input terminal of the comparator 47 is connected to resistors 43 and 44, respectively.

A constant voltage is supplied to the other end of the resistor 43, and the other end of the resistor 44 is grounded.

Now, when a voltage waveform as shown in FIG. 4 taken out from point C is inputted, noise etc. are removed by resistors 41 and 42 and a capacitor 45 and inverted by an inverter 46, and then the voltage waveform shown in FIG. The voltage is shaped as shown in c.

Resistors 43 and 44 receive a constant voltage indicated by the sign (+).
As a result, a reference level signal shown by a two-dot chain line in FIG. 4c is generated as a line 49.

The voltages on lines 48 and 49 are compared by comparator 47, which outputs a pulse as shown in FIG. 4d at output 50.

Now, the voltage waveforms at points A, B, and C in the first diagram and the output signals from the main elements are shown in FIG. 5.

That is, in the figure, the voltages shown at a, b, and c are the first
The voltages at point B, point A, and point C in the figure are shown, respectively.

Also, d is the output signal of the flip-flop 26, and e
is the output signal of the AND gate 29, f is the output signal of the inverter 22a, and g is the count state of the counter 23 expressed as a staircase wave.

τA is the delay time of the delay circuit 27.

The reason for providing this delay time τA is to secure the signal latch time necessary for sending the count value of the counter 23, ie, the cylinder number signal, to the data processing section 21.

Therefore, the time at which the counter 23 starts counting the number of primary voltage rectangular wave pulses is delayed by τB from τA.

This allows automatic detection of the number of cylinders to be performed correctly.

e is the data necessary for diagnosis to the data processing unit 21, for example, the primary voltage waveform signal shown in FIG.
This is a synchronization command signal for sending the output signal of the discharge duration processing circuit 31a separated from the next voltage, the output signal of the peak value hold circuit 31b, etc.

Therefore, according to this embodiment, the number of cylinders can be automatically detected based on the voltage pulse generated by the ignition device, such as the primary voltage, and the ignition pulse signal of an arbitrary cylinder.

Further, according to this embodiment, it is possible to easily perform diagnostic processing on ignition signals for each cylinder, and to obtain an inexpensive and smart diagnostic device.

The voltage pulse generated by the ignition device may be a secondary voltage before being supplied to the distributor as at point A.

As described above, according to the present invention, the number of cylinders can be automatically detected.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a typical ignition system related to the diagnostic device for an automobile ignition system of the present invention, FIG. 2 is a block diagram of the diagnostic device of the present invention, and FIGS. FIG. 5 is an operational diagram of FIG. 2. 22...Waveform leveling unit, 22a...Inverter, 23...Counter, 25...
Waveform leveling unit, 26...Flip-flop, 27
... Delay circuit, 29 ... AND gate, 21 ... Data processing section, 37 ... Comparator.

Claims (1)

[Claims] 1. An ignition system diagnostic device that extracts a signal from the ignition system of a multi-cylinder internal combustion engine and diagnoses the ignition system, which includes means for detecting voltage pulses generated by the ignition system, and an ignition voltage supplied to any one cylinder. A diagnostic device for an ignition system for an automobile, comprising means for counting the number of voltage pulses generated by the ignition system during a pulse period.