JP2665794B2 - Ignition device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition device for an internal combustion engine, and more particularly to an ignition device provided with a misfire detecting means.

2. Description of the Related Art Generally, an ignition device for an internal combustion engine responds to an output signal of a signal generation device that generates a signal in accordance with rotation of the internal combustion engine.
The power transistor is driven by the control circuit, and the primary current of the ignition coil is turned on and off. Thus, the high voltage generated in the secondary coil of the ignition coil is supplied to a spark plug provided in each cylinder of the internal combustion engine through a power distribution device to generate a spark discharge, and ignite an air-fuel mixture in each cylinder. And

In recent years, internal combustion engines equipped with an electronically controlled fuel injection device have become widespread. In this case, it is necessary to stop fuel injection immediately when misfire occurs due to malfunction of an ignition device or the like. For this reason, various means for detecting misfire are taken. For example, in the device described in Japanese Patent Application Laid-Open No. 60-19962, a current flowing through a power transistor for interrupting a primary current is detected by an impedance element. An abnormal primary current detection circuit is disclosed. This makes it difficult to determine whether a misfire has occurred by detecting the primary voltage of the ignition coil, and monitors the primary current.

[Problems to be Solved by the Invention] However, since the primary current of the ignition coil is not affected by a change in the state of the secondary side, in the above-described prior art, a misfire caused by the secondary side of the ignition coil, such as a defective spark plug, It is not possible to detect a misfire due to detachment of the high tension cord or the like.

Further, since the resistance connected to the emitter side of the power transistor as the impedance element is selected to have a small resistance value, the detection accuracy changes due to the variation in the resistance value, and therefore some kind of correction means must be provided. .

Therefore, the present invention is based on the premise that the primary voltage of the ignition coil is detected, and provides an ignition device including a misfire detecting means capable of detecting misfire caused by not only the primary side but also the secondary side of the ignition coil. With the goal.

Means for Solving the Problems To achieve the above object, the present invention provides a control circuit 1 for outputting an ignition signal in accordance with the rotation of an internal combustion engine, as shown in FIG. A power transistor 2 for intermitting a primary current of an ignition coil 3 in response to an ignition signal.
A first detection circuit 10 for comparing a primary voltage generated when the primary current is interrupted with a predetermined reference voltage to detect a surge voltage equal to or higher than the reference voltage, and setting a duration of the output surge voltage of the first detection circuit 10 to a predetermined time And a second detection circuit 20 for detecting a surge voltage that lasts for a predetermined time or more when the primary voltage is detected to be equal to or lower than the reference voltage, and when the surge voltage is maintained for a predetermined time or more. When it is detected, a predetermined misfire signal is output.

[Operation] In the ignition device for an internal combustion engine having the above configuration, an ignition signal is output from the control circuit 1 shown in FIG. 1 according to the rotation of the internal combustion engine. The power transistor 2 is driven by this ignition signal, and the primary current of the ignition coil 3 is interrupted. As a result, a high voltage having a waveform as shown in FIG. 2A is induced in the secondary coil of the ignition coil 3.

The primary voltage generated by the operation of the power transistor 2 is compared with a predetermined reference voltage V _P at the first detection circuit 10, the reference voltage V _P or more surge voltage is detected, the second
Does not reach the reference voltage V _P as shown in FIG. (B) is distinguished from the primary voltage. This surge voltage is compared with a predetermined duration t ₀ in the second detection circuit 20, and a surge voltage that lasts for the predetermined time t ₀ or more as shown in FIG. 2C is detected.

And Thus, when the above-mentioned primary voltage does not reach the reference voltage V _P is detected, the misfire signal is outputted when the words misfire due to the primary side is detected. When it is detected that the surge voltage has continued for a predetermined time or more,
That is, when a misfire caused by the secondary side is detected, a misfire signal is similarly output.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

FIG. 3 shows an embodiment of an ignition device for an internal combustion engine according to the present invention, in which a control circuit 1 has an input terminal IN connected to a signal generation device (not shown), and a pulse according to the rotation of the internal combustion engine (not shown). A signal is input, waveform shaping, closing angle control, and the like are performed, and an ignition signal is output. As a signal generator, besides the electromagnetic power generation system, photoelectric system or Hall IC
Various devices are known, such as a magnetically responsive rectangular wave signal generator using the same. The control circuit 1 also has a known configuration.

The control circuit 1 is connected to the base of a power transistor 2 formed by connecting two transistors in Darlington. The emitter of the power transistor 2 is grounded, and the collector is connected to one end of the primary coil of the ignition coil 3. The other end of the primary coil of the ignition coil 3 is connected to a power source V _B with the secondary coil. Thus, the power transistor 2 is driven by the output ignition signal of the control circuit 1,
The primary current of the ignition coil 3 is interrupted. As a result, a high voltage is induced in the secondary coil of the ignition coil 3, and this high voltage is applied to a spark plug (not shown) provided in each cylinder of the internal combustion engine via a distributor (not shown), and a spark discharge is generated in the spark plug. The resulting mixture in each cylinder is ignited.

In the ignition device of the present embodiment, the first detection circuit 10 and the second detection circuit 20 shown in FIG. 3 are connected to the power transistor 2 and the control circuit 1 connected to the ignition coil 3. I have.

The first detection circuit 10 has a resistor 11 and a resistor 12 connected to a connection point between the power transistor 2 and the ignition coil 3, and the primary voltage of the ignition coil 3 is divided and input to the inverting input terminal of the comparator 15. I have. The non-inverting input terminal of the comparator 15 is supplied with a constant voltage power supply V _{CC divided} by the resistors 13 and 14, and the reference voltage _VP is set.

The second detection circuit 20 receives the output of the comparator 15 as the J terminal input, and outputs the output of the control circuit 1 to the K terminal via the inverter 21a.
It has a JK flip-flop 21 (hereinafter simply referred to as a flip-flop 21) as a terminal input, and a Q output is used as a base input of a transistor 23 via a resistor 22. The emitter of the transistor 23 is grounded and the collector through a resistor 24 is connected to a constant voltage source V _CC, one end is connected to the base of the capacitor 25 and the transistor 26 is grounded. The emitter of the transistor 26 is grounded, it is connected to the base of transistor 28 with its collector is connected through a resistor 27 to a constant voltage source V _CC. Transistor 28 is similarly grounded emitter and a collector connected to the output terminal OUT is connected to a constant voltage source V _CC through a resistor 29. The output terminal OUT is connected to an electronic circuit unit for an electronically controlled fuel injection device (not shown).

The operation of the ignition device having the above configuration will be described with reference to the waveform diagram shown in FIG. 4A to 4F show operation waveforms at points a to f in the circuit of FIG.

The primary coil of the ignition coil 3 as described above is connected to a power source V _B, the primary current is supplied to the time of conduction of the power transistor 2. Then, the pulse signal shown in FIG. 4A is output from the control circuit 1 in accordance with the rotation of the internal combustion engine (not shown), and the base current of the power transistor 2 is turned on and off.
As a result, the power transistor 2 is turned on and off, and the primary current of the ignition coil 3 is interrupted. When the primary current is interrupted, a high voltage is induced in the secondary coil, and a spark discharge occurs in a spark plug (not shown).

Thus, a pulse voltage is output to the primary coil of the ignition coil 3 every time the pulse signal of FIG. 4 (a) falls, and this voltage is divided by the resistors 11 and 12 and the signal of FIG. Become. This signal is input to the inverting input terminal of the comparator 15 is compared with the resistance 13 and the predetermined voltage V _P which is set by a resistor 14, a surge voltage having a value equal to or greater than a predetermined voltage V _P is detected. That is, the signal of FIG. 4 (c) is output. The output signal (c) is supplied as the J terminal input of the flip-flop 21 and the signal of FIG. 4 (a) is supplied as the K terminal input via the inverter 21a.
The Q output signal of 21 is as shown in FIG.

The Q output of the flip-flop 21 is applied to the transistor 23 via the resistor 22, and the transistor 23 is turned on or off. As a result, the capacitor 25 charges and discharges via the resistor 24, and the signal shown in FIG. 4E is output. When the charging voltage of the capacitor 25 reaches the operation level of the transistor 26, the transistor 26 is turned on, and thus the transistor 26 is turned on.
28 is cut off, and the signal shown in FIG. 4 (f) is output from the output terminal OUT.

In the above operation, 4 in FIG t ₁ to the case where spark discharge occurs in the spark plug (not shown) through the ignition coil 3
time primary voltage as time t ₂ is equal to or more than a predetermined voltage V _P is short, not the capacitor 25 is charged to a predetermined value at which the transistor 26 can be driven. Therefore, transistor 26
Is maintained in the cutoff state.

On the other hand, if no spark discharge occurs due to a cause of the secondary side of the ignition coil 3 such as a defective spark plug or detachment of the high tension cord, for example,
Surge voltage becomes longer time than the predetermined voltage V _P as time t ₃ to t ₄ in large next Fig. 4 (d), the charging voltage of the capacitor 25 becomes equal to or higher than the operation level of the transistor 26,
A pulse signal indicating a misfire shown in FIG. 4 (f), that is, a misfire signal is output.

Alternatively, when the surge voltage to be at 3 in the drawing t ₅ to t ₆ does not reach the predetermined voltage V _P level, the transistor 23
Since the input to the transistor becomes as shown in Fig. 3 (d), the transistor
23 is cut off, the pulse signal between t ₅ to t ₆ of FIG. 3 (f) is output. Therefore, even if the primary current to the control circuit 1 becomes insufficient for some reason, a misfire signal is output. When the misfire signal is output in this manner, the electronic circuit unit (not shown) stops the fuel injection operation of the electronically controlled fuel injection device (not shown).

FIG. 5 shows another embodiment of the present invention, in which two ignition coils 6, 7 are juxtaposed, and the collectors of the power transistors 4, 5 are connected to each of them. The bases of the power transistors 4 and 5 are connected in parallel to the control circuit 1, and an OR circuit 8 is connected to the connection point between each base and the control circuit 1.
Is connected to the second detection circuit 20 via. Other configurations are the same as those of the embodiment of FIG.

Thus, according to the present embodiment, the output signal of the control circuit 1 is alternately distributed to the power transistors 4 and 5, and high voltages are alternately output from the ignition coils 6 and 7 to each cylinder. Misfire detection of the ignition plug in each of the ignition coils 6 and 7 is performed in the same manner as in the embodiment of FIG. 1, but when it is determined that a misfire has occurred, a signal is output to the above-described electronic circuit unit and the fuel injection operation is stopped. At the same time, an output signal is supplied to the control circuit 1 and one of the power transistors 4 and 5 on the misfire side is forcibly shut off.

[Effects of the Invention] The present invention is configured as described above, and has the following effects.

That is, in the ignition device of the present invention, the first detection circuit and the second detection circuit not only cause misfire due to the primary side of the ignition coil, but also, for example, defective ignition plug, detachment of the high tension cord, etc. A misfire caused by the secondary side can also be detected. Thus, in response to the output misfire signal, for example, the fuel injection operation at the time of misfire of the electronically controlled fuel injection device can be reliably stopped.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an ignition device of the present invention, and FIG. 2 is a waveform diagram of a primary voltage in the ignition device of the present invention, wherein (a) is a normal surge voltage, and (b) is a predetermined voltage. (C) is a waveform diagram showing a surge voltage that lasts for a predetermined time or more, FIG. 3 is an electric circuit diagram showing an embodiment of the ignition device of the present invention, and FIG. 4 is an embodiment of FIG. FIG. 5 is a waveform diagram of a signal at each point in the example, and FIG. 5 is an electric circuit diagram showing another embodiment of the ignition device of the present invention. 1 ... control circuit, 2,4,5 ... power transistor, 3,6,7 ... ignition coil, 10 ... first detection circuit, 20 ... second detection circuit

Claims (1)

(57) [Claims] An ignition device for an internal combustion engine, comprising: a control circuit that outputs an ignition signal in accordance with the rotation of the internal combustion engine; and a power transistor that interrupts a primary current of an ignition coil in accordance with the ignition signal of the control circuit. A first detection circuit for comparing a primary voltage generated at the time of primary current interruption of the power transistor with a predetermined reference voltage to detect a surge voltage equal to or higher than the reference voltage, and maintaining the output surge voltage of the first detection circuit; A second detection circuit that compares a time with a predetermined time and detects a surge voltage that lasts for the predetermined time or more, and when it is detected that the primary voltage is equal to or less than the reference voltage, and when the surge voltage is equal to or more than the predetermined time. An ignition device for an internal combustion engine, which outputs a predetermined misfire signal when it is detected that the ignition is continued.