JPS59101584A - Ignition device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent interruption of feeding the discharging energy from a DC-DC converter, by repeating putting-on and off of the current flowing in the primary side of an ignition coil, which is equipped with a DC-DC converter to reinforce the secondary side, several cycles for a combustion stroke. CONSTITUTION:A waveform shaping circuit 11 trims a signal S1 from a signal generator 17 and emits resultant ignition signals S2 having a period of cycle of 180 deg.. A pulse signal S5 is emitted by an AND gate 15, which takes the logical product of pulse signals S3, S4 from single-stable multis 12, 13 and an oscillator 16, to be fed into a power transistor Q through an OR gate 14 together with the above-mentioned ignition signal S2. This signal feed serves turning-on and off of the current flowing through the primary side of ignition coil 1 two or three cycles per combustion stroke of each cylinder. In the secondary winding 1b, a high voltage is generated every time the transistor Q is turned off and distributed to ignition plugs 8. Thus blowing-off of discharge sparks, likely to occur caused by the eddy current generated in the combustion chamber, will be well covered by a reignition.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an ignition system for an internal combustion engine, which is equipped with a DC-DC converter for reinforcing ignition energy into the secondary side of an ignition coil in addition to a normal ignition circuit.

As a conventional ignition device of this type, for example, Japanese Patent Application Laid-Open No. 1986-
There are those described in specifications such as No. 124672 and US Pat. No. 4,033,316 and No. 4,136,301.

The basic configuration of these conventional devices will be explained with reference to FIG. 1. For example, one end of the primary winding 1a of the ignition coil 1 is connected to a power source (+12V), and the other end is connected to an electromagnetic type. A full-torque ignition circuit is connected to the ground through an igniter 4 that is turned on and off based on an ignition signal generated from a pickup coil 3 in accordance with the rotation of a rotor 2 that rotates in synchronization with the rotation of the signal generator engine. It is a provision.

As this ignition circuit, in addition to the full-type ignition circuit, a current interrupting type such as a semi-type or Kettering type, or a capacitive discharge type (CDI) type may be used.

On the other hand, at one end of the secondary winding 1b of the ignition coil 1, a center cord 5. A spark plug 8 for each cylinder is connected via a distributor 6 and a high tension cord I, and an output terminal of a DC/DC converter 10 is connected to the other end via a high voltage line 9, respectively.

The effect is that by switching the igniter 4, the current flowing through the primary winding 1a of the ignition coil 1 is interrupted according to the ignition timing, and at that time, a high voltage (-15 to -25 KV) is generated in the secondary winding 1b. Center code 5. The spark plug is introduced between the electrodes of the spark plug 8 via the distributor 6 and the high-tensile cord 7, and dielectric breakdown occurs between the electrodes in order to start spark discharge.

When this spark discharge starts, the high voltage (-
2KV) is high voltage line 9. Secondary winding 1b, center cord 5. It is guided between the electrodes of the spark plug 8 via the distributor 6° and the high tension cord γ, thereby creating a sustained discharge and reinforcing the ignition energy.

In addition, when ignition energy is reinforcingly injected by the DC-DC converter 10, the discharge duration is 2 to 4 msec, which is more than twice that of the case where only electromagnetic induction energy is used.
Since the discharge energy is extended to a certain extent, the total discharge energy is 10
07? lJ or more, thereby improving engine performance, especially fuel efficiency, and stabilizing combustion during operation with a lean mixture.

By the way, even with the ignition device equipped with the -DC converter as described above, there are the following drawbacks.

That is, by switching the igniter 4, the collector voltage Vc of the power transistor Q in the igniter 4 increases.
When the voltage changes as shown in Figure 2, the discharge voltage Vs and current Is usually change as shown in Figure 2, Figure 2, (C).
When the discharge spark is blown out by
Since the ignition energy injected from the converter cannot cause dielectric breakdown between the electrodes of the spark plug, the discharge voltage Vs and current Is are interrupted in the middle as shown in Figure 2) and (e), respectively, and the combustion is improved by the DC-DC converter. The effect will be lost.

This invention has been made in view of the above points, and has an object to prevent injection of discharge energy from a DC-DC converter from being interrupted due to blowing out of discharge sparks caused by eddy currents in a combustion chamber or the like. With the goal.

Therefore, the ignition device for an internal combustion engine according to the present invention achieves the above object by turning on and off the primary side of the ignition coil a plurality of times per - explosion stroke.

Hereinafter, embodiments of the present invention will be described with reference to FIG. 3 and subsequent figures of the drawings.

FIG. 3 is a block circuit diagram showing one embodiment of the present invention. In this figure, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and explanations of these parts will be omitted.

In this embodiment, the igniter 4 in FIG. 1 is replaced by a waveform shaping circuit 11. Monostable multivibrator (hereinafter abbreviated as "monostable multi") 12, 13° OR gate 1
4. ANDGATE 15. and an ignition circuit consisting of a control means consisting of an oscillator 16 and a power transistor Q as a switch means, the power transistor Q is set to -
The secondary winding 1a and the secondary winding 1b are connected between the primary winding 1a of the ignition coil 1 separated from each other and the ground, and the power transistor Q is connected to the power transistor Q for each explosion stroke of each cylinder of the engine. I am trying to control it to turn on and off multiple times.

That is, the waveform shaping circuit 11 shapes the waveform signal Sl synchronized with the rotation of the engine from the /gnardier generator (crank angle sensor) 17 configured similarly to that shown in FIG. ), an ignition signal S2 with a period of 180° is outputted at the engine crank angle as shown in ().

The monostable multi 12 is triggered at each falling edge of the ignition signal S2 to output a pulse signal with a pulse width τl, and the monostable multi 13 is triggered at each falling edge of the pulse signal output from the monostable multi 12. Then, a pulse signal S3 having a pulse width τ2 as shown in FIG. 4(b) is output.

For example, after an ignition switch (not shown) is turned on, the oscillator 16 always outputs a pulse signal S4 as shown in FIG. 4, so that the pulse signal S3. The AND gate 15 which takes the logical product of S4 outputs a pulse signal S5 as shown in FIG.

Therefore, if this pulse signal S5 and the ignition signal S2 are input to the base of the power transistor Q through the OR gate 14, this power transistor Q will be activated twice or three times per one explosion stroke for each cylinder of the engine. ignition coil 1
The current flowing through the primary winding 1a is interrupted.

Therefore, the ignition coil 1 is connected to the secondary winding 1b of the ignition coil 1 every time the power transistor Q is turned off, that is, every time the collector voltage VC of the power transistor Q rises as shown in FIG. -15 to - by mutual induction of 1
A high voltage of about 25 KV is generated, and this high voltage, which is generated two or three times per - explosion stroke, is distributed by the distributor 6 to the spark plug 8 of each cylinder.

Therefore, after the dielectric breakdown occurs between the electrodes of the spark plug 8 of each cylinder due to the high voltage induced by the -th line, and spark discharge starts, -2 from the DC-DC converter 10
If a sustained discharge is caused by a high voltage of about ψ, the discharge voltage VS and current Is will change as shown in Figures 4 (f) and (g), respectively, but the Even if the spark discharge is blown out by the eddy current and the discharge voltage VS and current Is are interrupted at the point shown in the example in Figure 4 (see the * mark on the force), the high voltage induced by the second or third shot will ignite it again. Therefore, the ignition energy can be subsequently injected and strengthened by the high voltage from the DC-DC converter 10, so that the combustion improvement effect is not inhibited.

In the above embodiment, the current flowing through the primary winding 1a of the ignition coil 1 is intermittent two or three times per - explosion stroke, but the pulse width τ2 of the pulse signal s3 and the period of the pulse signal s4 By adjusting , it is also possible to always intermittent the primary current the same number of times per - number of explosion strokes.

Further, in the above embodiment, an example in which the ignition circuit is of a full-circuit type has been described, but the invention can be similarly applied to other types of ignition circuits such as a set-type ignition circuit, for example.

Furthermore, if the spark discharge is not blown out, the second

A high voltage is applied to the spark plug 8 due to the third induction, but at this time the spark plug 8 is in a conductive state, so
Radio noise generated when dielectric breakdown occurs between electrodes does not increase unnecessarily.

As described above, according to this invention, the primary side of the ignition coil is turned on and off multiple times per one explosion stroke of the engine, so even if the spark discharge is blown out by the vortex in the combustion chamber, the ignition will not occur again. Therefore, the combustion improvement effect based on the injection of ignition energy by the DC-DC converter can always be achieved.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram showing an example of an ignition device equipped with a conventional DC-DC converter. Figures 2 (A) - (One is a signal waveform diagram of each part to explain the operation of Figure 1, respectively. Figure 3 is a block circuit diagram showing an embodiment of the present invention. Figure 4 (A) ~(IJ) are signal waveform diagrams of each part for explaining the operation of Fig. 3. 1...Ignition coil 1a...-Next winding 1b...
Secondary winding 2...Rotor 3・Pickup coil 6...Distributor 8...Spark plug 10
...DC-DC converter 11... Waveform shaping circuit 12.13... Monostable multivibrator 14...
OR gate 15...AND gate 16...Oscillator 17...Signal generator -5
5 艷ζ; 口 ；１１ 廿Fig. 4

Claims (1)

[Claims] 1. In an ignition system for an internal combustion engine equipped with a DC-DC converter that reinforcingly injects ignition energy into the secondary side of the ignition coil in addition to the normal ignition circuit, the ignition energy flows through the ignition circuit and on the primary side of the ignition coil. 1. An ignition device for an internal combustion engine, comprising a switch means for turning on and off a current, and a control means for driving the switch means a plurality of times per one explosion stroke of the engine.