JPH04140481A - Ignition device for internal combustion engine - Google Patents

Abstract

PURPOSE:To eliminate a reset signal, formed by a noise induced by ignition high voltage, by providing a detecting means for detecting a combustion condition of an internal combustion engine by a signal corresponding to discharge time in the internal combustion engine and a mask means for masking an output of the detecting means. CONSTITUTION:In a normal operational condition, a fuel injection control signal is supplied to an injector 14 from a control unit 1 synchronously with a signal, generated at a fixed period from a signal generator 19, and also turning off a power transistor 2 to ignite a spark plug 5 by generating negative high voltage in a secondary side by positive voltage generated in a primary side of an ignition coil 3. An ion current following combustion of a mixture by this ignition is detected by a diode 6 and input to a comparator 11. A compared output of the comparator is collated with an output of a comparator 23, responding to ignition high voltage, in an AND circuit 24, to output a reset signal to an output side of the AND circuit 24, and on the other hand, to mask the reset signal by a noise.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides an internal combustion engine ignition system that can prevent malfunctions caused by noise induced by high voltage flowing during discharge of a spark plug. It is connected to the engine ignition system.

[Prior Art] FIG. 3 is a configuration diagram showing a conventional ignition device for an internal combustion engine. In the figure, (1) is an ignition timing control unit as a control means for controlling fuel injection timing and ignition timing in the internal combustion engine in synchronization with the rotation of the internal combustion engine; (2)
is a power transistor, (3) is an ignition coil, (4) is a backflow prevention diode, and (5) is a spark plug. The primary side of the ignition coil (3) is grounded via the collector-emitter of the power transistor (2), and the base of the power transistor (2) is connected to the control unit (1). Further, the secondary side of the ignition coil (3) is connected to the spark plug (5) via a reverse diode (4). The spark plug (5) is further connected to the negative electrode of a DC power source (8) via an ion current detection diode (6) and a resistor (7). A capacitor (9) and a resistor (10) connected in series are connected in parallel to the resistor (7) and the DC power supply (8). A connection point between the capacitor (9) and the resistor (10) is connected to one input terminal of a comparator (11), and a reference voltage is applied to the other input terminal of the comparator (11). The output signal of the comparator (11) is supplied to the counters (12) and 13) as a reset signal. In addition, ku6) to ku13
) constitutes a detection means for detecting the state of fuel in the internal combustion engine.

Further, a fuel injection signal is supplied from the control unit (1) to an injector (14) of the internal combustion engine. (15) is the cylinder of an internal combustion engine, (16)
is the piston of an internal combustion engine, (7) is the piston rod, (1
8) is a crankshaft, (19) is a signal generator that generates signals at predetermined intervals in synchronization with the rotation of the internal combustion engine, and the signal from this signal generator (19) is supplied to the control unit (1). and is also supplied to the counter (12) via the comparator (20).

Next, the operation of the conventional ignition system for an internal combustion engine shown in FIG. 3 will be explained with reference to FIG. 4.

Now, under normal operating conditions, the control unit (1) performs fuel injection control on the injector (4) in synchronization with the signal shown in Figure 4A that is generated from the signal generator (19) at regular intervals. When the signal is supplied, the power transistor (2) is controlled by the control unit (1) and turned off, thereby generating a back electromotive voltage as shown in Figure 4B on the primary side of the ignition coil (3). At the same time, a negative high voltage as shown in Fig. 4C is generated on the secondary side, and the ignition plug (5) ignites.When the air-fuel mixture in the cylinder (15) is ignited by the ignition of the ignition plug (5), the air-fuel mixture in the cylinder (15) is combusted. , an ion current is generated, which is detected by the diode (6) and is obtained as an ion current I as shown in Figure 4 at the input side of the comparator (11).

At this time, the noise N appearing in the fourth diagram is due to the high voltage for ignition. These signals are fed to a comparator (11) and become a reset signal as shown in FIG. 4E. That is, in this case, two types of reset signals exist during one cycle of the clock shown in FIG. 4A: a reset signal due to noise and a reset signal due to ion current. Then, the counter (12) that rises with the clock in Figure 4A and falls with the reset signal will always be reset by the reset signal due to noise, and therefore the output side of the counter (12) will have the counter (12) shown in Figure 4F. As a result, the counter (13) generates a low level signal as shown in FIG. 4G.

[Problems to be Solved by the Invention] The conventional ignition device for an internal combustion engine is configured as described above, and there are counters (12), (13) that continuously monitor the presence or absence of ion flow.
is in operation, so that if a misfire occurs, for example, between time t2 and t3, there is a problem in that it is not possible to detect this and generate a misfire detection signal.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide an ignition device for an internal combustion engine that can prevent malfunctions due to noise induced by high voltage for ignition.

[Means for Solving the Problems] An ignition device for an internal combustion engine according to the present invention includes a control means for controlling ignition timing in the internal combustion engine in synchronization with the rotation of the internal combustion engine, and a control means for detecting a combustion state in the internal combustion engine. The apparatus includes a detection means, and a mask means connected to the detection means and masking the output of the detection means at the time of discharge by a signal corresponding to the time of discharge in the internal combustion engine.

[Operation] In the present invention, the noise induced by the high voltage for ignition is masked to eliminate the reset signal formed thereby, and the reset signal formed in response to the ion current is used to generate the misfire detection signal in the event of a misfire. to occur.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a configuration diagram showing one embodiment of the present invention, and (1) to
(20) is similar to the above. In this embodiment, a resistor (21) and a capacitor (22) are connected in series between the secondary side of the ignition coil (3) and the ground, and the connection point between the two is connected to the negative input terminal of the comparator (23). Comparator (23)
Apply a reference voltage to the other input terminal of the comparator (23), connect the output terminal of the comparator (23) to one input terminal (negative logic terminal) of the AND circuit (24), and connect the other input terminal of the AND circuit (24). Connected to the output terminal of the comparator (11) and connected to the AND circuit (
The only difference from FIG. 3 is that the output terminal of 24) is connected to the reset terminal of the counters (12) and (13). still,
(21) to (24) constitute a masking means that generates a signal corresponding to the discharge period in the internal combustion engine, transmits it to the detection means, and masks the output of the detection means.

Next, the operation of the embodiment of the present invention shown in FIG. 1 will be explained with reference to FIG. 2. Now, under normal operating conditions, a fuel injection control signal is supplied from the control unit (1) to the injector (14) in synchronization with a signal generated periodically by the signal generator (19), and the control unit (14) The power transistor <2> is controlled and turned off by the unit (1), and as a result, a positive voltage as shown in Figure 2B is generated on the primary side of the ignition coil (3), and a positive voltage is generated on the secondary side of the ignition coil (3). A negative high voltage as shown in Figure 2C is generated, and the spark plug (5) ignites. When the air-fuel mixture in the cylinder (15) is ignited by the ignition plug (5), an ionic current is generated, which is connected to the diode (6).
The ion current is detected at the input side of the comparator (11) and is obtained as an ion current shown in the second diagram. At this time, the noise N appearing in the second diagram is due to the high voltage for ignition.

These signals are fed to a comparator (11) and become a reset signal as shown in FIG. 2E. In other words, in this case the second
Two types of reset signals exist during one cycle of the clock shown in FIG. A: a reset signal due to noise and a reset signal due to ion current.

On the other hand, a signal as shown in FIG. 2C' is obtained on the output side of the comparator (23) in response to the ignition high voltage shown in FIG. 2C. This signal is supplied to one input terminal of the AND circuit (24) and is logically processed with the signal shown in FIG. 2E from the comparator (11). As a result, a signal as shown in FIG. 2E' is taken out at the output side of the AND circuit (24) as a true reset signal. In other words, the reset signal due to noise is masked by the signal shown in FIG. 2 C', and only the reset signal due to the ion current is taken out as the true reset signal. This reset signal is supplied to counters (12) and (13). Therefore, the counter (12) generates signals as shown in 1 to t2 during the times shown in FIG. 2F, which rise with the clock shown in FIG. 2A and fall with the reset signal generated by the ion current. At this time, the output of the counter (13) is at a low level as shown in FIG. 2G.

Next, if a misfire occurs, for example, between time t2 and t3, no ion current is generated, so no reset signal is generated on the output side of the AND circuit (24) as shown in FIG. 2E. Then, the output of the counter (12) that started up at the clock at time t2 (A in FIG. 2) is reset at the next clock (at time t3), as shown in FIG. (13) generates a signal that rises at time 3 and falls at the reset signal caused by the next ion current, as shown in FIG. 2G. In other words, a misfire detection signal is output.

[Effects of the Invention] As described above, according to the present invention, the control means for controlling the ignition timing in the internal combustion engine in synchronization with the rotation of the internal combustion engine, the detection means for detecting the combustion state in the internal combustion engine, and the above-mentioned The detection means is connected to the primary side of the ignition coil, and the mask means is connected to the detection means and masks the output of the detection means at the time of discharge by a signal corresponding to the time of discharge in the internal combustion engine. This has the effect of providing an ignition device for an internal combustion engine that can mask noise induced by high voltage and reliably generate a misfire detection signal in the event of a misfire.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a waveform diagram for explaining the operation of FIG. 1, FIG. 3 is a configuration diagram showing a conventional ignition system for an internal combustion engine, and FIG. This figure is a waveform diagram for explaining the operation of FIG. 3. In the figure, (1) is the fuel injection timing/ignition timing control unit, (5) is the spark plug, <6) is the ion current detection diode, (8) is the DC power supply, (11) is the comparator, and (12) is the ion current detection diode. , (13) is a counter, (23) is a comparator, and (24) is an AND circuit. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] A control means for controlling ignition timing in the internal combustion engine in synchronization with the rotation of the internal combustion engine; a detection means for detecting a combustion state in the internal combustion engine; and a control means connected to the detection means for the internal combustion engine. an ignition device for an internal combustion engine, comprising: masking means for masking the output of the detection means at the time of discharge with a signal corresponding to the time of discharge.