JPS60187762A - Ignition device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To effect sure igniting operation even in case of operation effected by the combustion of poor mixture, alcohol or the like by a method wherein the time of duration of spark discharge and the time of high energy discharge in an ignition plug upon igniting are elongated so that the high energy discharge is not interrupted and sure igniting operation is effected. CONSTITUTION:When an ignition timing IGN has come, the primary side current of a coil 3 is intercepted by the output of a signal S1, putting a transistor 14 OFF in a circuit 10. Accordingly, a high-voltage pulse is generated in the secondary side L2 of the coil 3 to supply it to the ignition plug and discharge spark. At the same time, high-frequency current is supplied to the primary side of the coil 3 by the signal of a high-frequency oscillator 13 generated by a trigger signal S2 from the circuit 10 and whereby a plural times of the high- voltage pulses P1, P3...Pn are generated in the secondary side. A high-voltage pulse from a high-voltage generating circuit 12 is put on the high-voltage pulses and the time Tb of the high-energy discharge, among the time of duration of discharge, is continued for comparatively long period of time. The high-voltage pulses are generated repeatedly during the high-energy discharging time Tb and the electric discharge will never be interrupted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ignition device for an internal combustion engine that increases the spark discharge energy applied to a spark plug.

(Background of the Invention) Conventionally, as an ignition device for an internal combustion engine that increases the spark discharge energy in a spark plug, there has been a device as shown in Japanese Patent Publication No. 54-4011 (hereinafter referred to as the conventional device). be.

This conventional device has a configuration as shown in FIG.

In the ignition system shown in the figure, a high frequency oscillator 5 is connected to the primary coil L1 of the ignition coil 3, and while the breaker 4 (contact point in the breaker section of the distributor) is closed, the ignition coil 3 is removed from the battery 1. The current flowing in the primary coil L1 is abruptly cut off when force 4 is heard at the ignition timing.

With this interruption of the secondary side current, a high voltage pulse Vρ is generated in the secondary side coil L2 of the ignition coil 3,
This high voltage pulse Vp is distributed by a distributor (path shown) to a spark plug (path shown) attached to each cylinder of the engine.

Then, as the primary side current is cut off, the high frequency oscillator 5 is started, and the high frequency signal f is supplied to the primary side coil L1. As a result, the high-voltage pulse (I) supplied to the spark plug is a high-voltage, high-frequency pulse (indicated by P1 to pn in the figure) as shown in FIG. 2 (A>).
becomes.

In this way, by causing multiple discharges to occur during ignition in one combustion cycle, reliable ignition operation can be obtained and the occurrence of misfire cycles can be prevented.

Note that the transistor 6 in FIG. 1 has an appropriate inverter circuit connected to its base, and operates to compensate for a drop in battery voltage. Also, switch 2
is a switch that is turned on when an ignition switch (not shown) is turned on.

However, as described above, when a configuration is adopted in which multiple consecutive discharges occur at one ignition in one combustion cycle, the total amount of spark discharge energy in one recycle is 1
Although this is larger than when the discharge is performed only once during the cycle, the discharge energy per discharge does not become large as shown in FIG. 2(B).

Therefore, when burning a lean air-fuel mixture or low-cetane fuel such as alcohol, the ignition probability decreases and engine operation becomes unstable.

(Object of the Invention) An object of the present invention is to provide an ignition device for an internal combustion engine that is capable of increasing discharge energy during ignition and more reliable ignition.

(Structure of the Invention) In order to achieve the above object, the present invention provides a high-frequency oscillation means for supplying a high-frequency current to the primary side of the ignition coil when the spark plug is ignited, and a high-frequency oscillation means that supplies a high-frequency current to the primary side of the ignition coil when the ignition plug is ignited. The device is characterized by comprising a high voltage generating means for superimposing a high voltage on the side output.

(Description of an Embodiment) FIG. 3 is a block circuit diagram showing the configuration of an embodiment of an ignition device for an internal combustion engine according to the present invention. In this figure, the same components as those of the conventional device shown in FIG.

As shown in the figure, the device of this embodiment (hereinafter referred to as the first embodiment device) includes an ignition timing control circuit 10 that controls the movement of the breaker 4 in the conventional device shown in FIG. In addition, it is equipped with a high voltage generation circuit 12, a high frequency oscillator 13, etc.

The ignition timing control circuit 10 sets the ignition timing based on the crank angle signal supplied from the crank angle sensor 11, turns off the transistor 14 at this ignition timing, and causes the current to flow to the primary side L1 of the ignition coil 3. This function performs an operation of blocking the current from the dispersion 1 which has been flowing. The ignition timing control circuit 10 also supplies a trigger signal S2 to the high frequency oscillator 13 and the high voltage generation circuit 12 in response to the front ignition timing.

The high-frequency oscillator 13 performs high-frequency oscillation for a predetermined period of time in response to the trigger signal s2 supplied from the ignition timing control circuit 1O, and switches the transistor 15 at high speed.
A high-frequency current is caused to flow through the device for a predetermined period of time.

In response to the arrival of the trigger signal S2, the high voltage generation circuit 12 generates a DC high voltage Vm of a predetermined voltage (for example, -2KV).
is generated and superimposed on the output generated on the secondary side L2 of the ignition coil 3.

The high voltage output generated on the secondary side of the ignition coil 3 at the ignition timing is distributed by the distributor 7 to the spark plugs 8a to 8d attached to each cylinder.

The high voltage generating circuit 12 is, for example, as shown in FIG.
Consists of a C-DC converter. In the figure, when a trigger signal s2 is input to the oscillator drive control circuit 21 at the ignition timing, a drive signal is generated to turn on the oscillator 22 for a predetermined period of time, thereby causing the oscillator 22 to perform an oscillation operation for a predetermined period of time from the ignition timing.

Along with the oscillation operation of the oscillator 22, the transistor 25
performs high-speed switching and causes a high-frequency current to flow through the primary side of the boost coil 23. As a result, a high frequency high voltage is generated on the secondary side, which is rectified by the rectifier circuit 24 and output as a DC high voltage Vm.

When the above ignition occurs! ! The control circuit 10 is, for example, a microcomputer (hereinafter referred to as CPU) as shown in FIG.
32, an input/output interface (hereinafter referred to as Ilo) 31, and a ROM 33.
′@ is provided.

Then, the reference signal S3 from the crank angle pin '+111 (in the case of a 4-cylinder engine, this is output every 180 degrees of crank angle) and the angle A signal $4 (which is output every 2 degrees of crank angle in the case of a four-cylinder engine) is input.

The output operation of the ignition timing control circuit 10 is l
ON-'OFF of transistor 14 via 1031
The configuration is such that the primary side current of the ignition coil 3 is cut off. Further, an operation of outputting the trigger signal S2 is also performed.

The calculation of the ignition timing is performed, for example, by using a crank angle signal from the crank angle sensor 11 and engine operating state parameters obtained based on the crank angle signal (for example,
A data table is provided in the ROM 33 in which the optimum ignition timing at each point in time is stored in advance in accordance with the engine rotational speed), and the optimum ignition timing is determined by looking up the defta table.

In the device of this embodiment configured as described above, when the ignition timing IGN arrives, first, the ignition timing control circuit 10 outputs a signal S1 that turns off the transistor 14, and the primary side current of the ignition fill 3 is cut off. It will be done. Along with this, a high voltage pulse is generated on the secondary side L2 of the ignition coil 3, as shown at 01 in FIG.

Then, with the arrival of the ignition timing IGN, the ignition timing control circuit 10 further supplies the trigger signal S2 to the high frequency oscillator 13 and the high voltage generation circuit 12, so that the high frequency signal generated from the high frequency oscillator 13 causes
A high frequency current is supplied to the primary side L1 of the ignition coil 3, and a plurality of high voltage pulses P2...pn are generated on the secondary side 1..2 as shown in FIG.

At this time, the high voltage output v111 from the high voltage generation circuit 12
is superimposed on the high voltage pulses P2 to pn, the discharge current in the spark plug becomes a continuous waveform as shown in FIG. 〉, the high-energy discharge time is maintained for a relatively long time (e.g., 3 to 4 m5ec). This is longer than the high energy discharge time (approximately 1 to 2 m5ec).

Moreover, during the high-energy discharge time Tb, the high-frequency oscillator 13 repeatedly generates high-voltage pulses, which prevents interruptions in discharge in the spark plug, thereby increasing the duration of the high-energy discharge time. It is made certain.

In this way, in the device of this embodiment, the high energy discharge time is lengthened at each ignition.
The ignition probability is increased, and reliable ignition operation can be achieved especially in engines that operate with combustion of lean mixture or low cetane fuel.

Next, FIG. 7 is a block circuit diagram showing the configuration of another embodiment (hereinafter referred to as the second embodiment) of the present invention, and in the same figure, the first embodiment shown in FIG. Components that are the same as those of the device are designated by the same reference numerals, and their explanations will be omitted.

As shown in FIG. 7, in the device of this embodiment, the oscillation output of the high frequency oscillator 13 is used for the oscillator 22 constituting the high voltage generation circuit 12 in the device of the first embodiment.

Of course, in FIG. 7, the high frequency oscillator 16 performs a high frequency oscillation operation for a predetermined period of time in response to the arrival of the trigger signal 32 from the ignition timing control circuit 10, and the high frequency signal generated thereby is transmitted to the internal One is supplied to the transistor 15 and the other is supplied to the back pressure transformer 23 via two high frequency amplification circuits.

As for the operation of the device of this embodiment, as in the device of the first embodiment, when the ignition timing IGN arrives, the OFF signal S1 of the transistor 14 is sent from the ignition timing control circuit 10.
is output, and the trigger signal S2 is output.
The signal is supplied to a high frequency oscillator 16.

As a result, a high frequency current is supplied to the primary side L1 of the ignition coil 3, and the high voltage output Vm is superimposed on the output of the secondary side L2.

As described above, the device of this embodiment includes a high-frequency oscillator for supplying a high-frequency current to the primary side L1 of the ignition coil 3, and a high-voltage generation circuit for superimposing a high voltage on the output of the secondary side L2. By using the same oscillator as the component, it is possible to reduce the number of component parts and to greatly reduce the number of noise sources.

Next, FIG. 8 is a block circuit diagram showing the configuration of still another embodiment (hereinafter referred to as the third embodiment) according to the present invention,
In this figure, the same components as those of the first embodiment shown in FIG. 3 are denoted by the same reference numerals, and the explanation thereof will be omitted.

The device of this embodiment is configured to cause the ignition timing control circuit 18 to perform an oscillation operation, and is also configured to serve as an ignition coil as a booster coil constituting the high voltage generation circuit.

That is, in the ignition timing control circuit 18, as shown in FIG. 9, with the arrival of the ignition timing IGN, a high frequency pulse train signal S7 which turns ON-OFF at a predetermined duty ratio is output, and the primary side of the ignition coil 17 is The configuration is such that a high frequency current is supplied to L1.

Further, on the secondary side of the ignition coil 17, two secondary windings L2. L3 is provided. Therefore, as the high frequency current is applied to the negative side L1, high frequency high voltage pulses are generated in the two secondary windings L2 and L3, and among them, high voltage pulses are generated in the secondary winding L3. The high-voltage, high-frequency pulse is rectified by the rectifier 24 to become a DC high voltage, which is superimposed on the high-frequency, high-voltage pulse generated at L2.

Therefore, in the operation of the apparatus of this embodiment, the discharge current of the spark plug at the time of one ignition is set as shown in FIG.
The high-energy discharge time shown in Fig. 1 is assumed to be long.

Furthermore, in the device of this embodiment, there is no need to separately provide a step-up transformer for a high-frequency oscillator or a high-voltage generation circuit, and the number of parts and storage space can be reduced.

(Effects of the Invention) As explained in detail above, in the ignition device for an internal combustion engine according to the present invention, the duration of the spark discharge in the ignition plug and the high energy discharge time are lengthened at the time of ignition,
Moreover, reliable ignition operation can be performed without interruption of high-energy discharge. As a result, reliable ignition operation can be performed especially in an engine that operates by burning a lean air-fuel mixture or a low-cetane fuel such as alcohol.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the configuration of a conventional ignition device for an internal combustion engine, FIG. 2 is a waveform diagram showing its ignition operation, and FIG. 3 is a configuration of an embodiment of the ignition device for an internal combustion engine according to the present invention. 4 is a block circuit diagram showing the configuration of the high voltage generation circuit of the same device, FIG. 5 is a block diagram showing the configuration of the ignition timing control circuit of the same device, and FIG. 6 is the ignition operation of the same device. FIG. 7 is a block circuit diagram showing the configuration of another embodiment of the present invention, FIG. 8 is a block circuit diagram showing the configuration of still another embodiment of the present invention, and FIG. 9 is the same. FIG. 3 is a waveform diagram showing the output of the ignition timing control circuit of the device. 3.17...Ignition coil 8a-8d
... Spark plug 10.18 ... Ignition timing control circuit 12 ...
・・・・・・・・・High pressure generation circuit 13.16...
... High frequency oscillator 22 ... ... ... ... Oscillator 23 ...
・・・・・・・・・・・・4 pressure transformer 24・・・・・・
・・・・・・・・・Rectifier Special W1 Applicant Nissan Motor Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] (1) - An ignition coil that generates a high voltage pulse on the secondary side when the current flowing to the secondary side is cut off and sends the high voltage pulse to the ignition plug; ignition timing control means for cutting off side current; high-frequency oscillation means for supplying a high-frequency current to the primary side of the ignition coil when the spark plug is ignited; An ignition device for an internal combustion engine, comprising: high voltage generating means for superimposing a high voltage on the output.