JPS59103967A - Igniter for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent uneven discharge and electric shock by constituting an igniter for augmenting the firing energy such that a converter will function only during interval including firing timing while employing DC-DC converter. CONSTITUTION:DC-DC converter 7 will function upon turning on of switching circuits 11, 12 while stop upon turning off. A full-wave rectifier 10 will output a signal rectified of signal S1 which will swing to positive side from immediately before firing timing to immediately after firing timing to turn on switching circuits 11, 12 only during said interval. Since DC-DC converter 7 will function only during several tms from immediately before firing timing to immediately after firing timing, it will never cause electric shock even when touching to high voltage section in igniter while keeping a key switch on.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to an ignition system for an internal combustion engine, and more particularly to performance improvement and safety measures in an ignition system that uses a DC-DC converter to increase ignition energy.

(Prior Art) There are two conventional ignition systems that use a DC-DC converter to increase ignition energy, such as the one shown in FIG. (For example, published patent publication No. 53-14242
In FIG. 1, 1 is a battery serving as a power source, 2 is a key switch, and 3 is a four-terminal ignition coil in which a primary winding 3A and a secondary winding 3B are separated. 4 is an electromagnetic pickup that detects ignition timing.

5 is a transistor ignition device, 6 is a primary current cutoff transistor, and 7 is a DC-- which generates a high voltage of about -2 kV.
It is a DC converter. 8 is a power distributor.

9A to 9D are spark plugs provided for each cylinder.

9 when operating when key switch 2 is turned on.
When the electromagnetic pink-up 4 outputs an ignition signal at the ignition timing, the transistor ignition device 5 outputs a signal to turn off the transistor 6. Therefore, the primary current of the ignition coil 30 is cut off, and a high voltage of several tens of kV is generated in the secondary winding 3A, which is applied to the corresponding spark plug via the power distributor 8, causing a spark discharge at that spark plug. Occur.

On the other hand, the output from the DC-DC converter 7 -2.
A high voltage of about kV is constantly applied to the power distributor 8 via the secondary winding 3B. When the discharge occurs as described above, the discharge continues due to the high voltage from the DC-DC converter 7. Therefore, the ignition system on the roadside requires 2 to 4 ms.
Since the discharge duration is increased several times to 10 to 20 ms, the ignition energy per ignition is greatly increased, and even a lean mixture can be reliably ignited.

Therefore, since the engine can be operated with a leaner air-fuel mixture than before, fuel efficiency can be improved.

However, in the conventional device described above, when the key switch 2 is turned on, the DC-DC converter is configured to operate at all times, so high voltage is applied to the power distributor and ignition even at times other than the first ignition timing. Since the voltage is applied to the plug, there is a risk of irregular discharge occurring.

Furthermore, the DC-DC converter operates at unnecessary times other than at the ignition timing, and wasteful power is consumed during this time, thereby reducing the fuel consumption saving effect.

Furthermore, the DC-DC converter continues to operate unless the key switch is turned off, so if an engine stall occurs, for example, if you touch the high-pressure part of the ignition system for inspection with the key switch turned on. , there is a risk of electric shock due to the high voltage of the DC-DC converter.

(Object of the Invention) The present invention has been made to solve the problems of the prior art as described above, and is free from the risk of causing irregular discharge.
Another object of the present invention is to provide an ignition device that can further improve fuel efficiency without the risk of electric shock.

(Summary of the invention) In order to achieve the above object, the present invention has the following features.

A certain period including ignition timing 2 For example, DC-DC only during a period from ms other than ignition timing to several ms to more than ten ms after ignition timing
The converter is configured to operate.

(Embodiments of the Invention) The present invention will be explained in detail based on the following embodiments. Fig. 2 is a circuit diagram of an embodiment of the present invention, and the same reference numerals as in Fig. 11 indicate the same parts. Further, Fig. 3 is an output waveform diagram of the circuit in Fig. 2, where 81 to S5 indicate the output waveforms of the parts with the same symbols in Fig. 2, and +Tl indicates the on/off timing of switching circuit n and 120. .

In Figure 2, the electromagnetic pink-up 4 rotates in synchronization with the crankshaft of the engine (one rotation for every two rotations of the crankshaft), and there are four electromagnetic pin-ups 4 around the circumference at 90° intervals (in the case of a 4-cylinder engine). It consists of a rotary plate with projections made of magnetic material, and one detection coil that corresponds to the projections through a narrow gap. The rotating plate rotates in synchronization with the rotation of the engine, and when the protrusion approaches the detection coil, a voltage is generated in the detection coil by electromagnetic induction.

The output waveform of the electromagnetic pickup 4 described above is 81 in FIG.
As shown in Figure 2, when the protrusions first approach, it is on the positive side, and when it moves away, it is on the negative side. And the signal S1 of the electromagnetic pickup 4 starts to swing to the positive side at the 1st ignition timing.

The negative side output returns to 0 immediately before the ignition timing (varies depending on the rotation speed, but more than 10 ms before), and the negative side output returns to 0 one ignition timing later. Immediately after (also after 10-odd ms).

DC again! - The DC converter 7 is a self-commutated converter composed of switching transistors 7A and 7B, a step-up transformer 7C, a rectifying diode 7D, and a capacitor 7E, and operates when the switching circuits 11 and 12 are on. When the switching circuits 11 and 12 are turned off, the boosting operation is stopped.

On the other hand, the full-wave rectifier circuit 10 outputs a signal S4 obtained by full-wave rectifying the signal S1.

This signal S4 is generated at one ignition timing t as shown in FIG. 384.
. The output swings to the positive side from just before to just after.

The switching circuits 11 and 12 are turned on only while the signal S4 is output on the positive side (actually, while the level of the signal S4 is above a certain threshold), and are turned off otherwise.

Therefore DC! -DC converter 7 is τ1 in FIG.
Alternatively, it operates only during τ2, that is, several tens of milliseconds from immediately before to immediately after the ignition timing.

Note that (a) and (b) in Figure 3 show the changes in waveforms depending on one rotational speed, and (a) shows the change in the waveform at low rotational speed, and (b) shows the one at high rotational speed. Regardless of K, the DC-DC converter operates only in a short period including one ignition timing and generates the output s6.

In the case of a self-excited converter, it takes some time (several milliseconds) for the output voltage to rise completely after starting one operation.
), but as can be seen from Fig. 3, the signal S1 rises several dozen ms before the ignition timing to, and from that point on, the DC-D
C! 1 ignition timing t since the converter starts operating. In this case, the output has risen completely and no problem occurs (・.

Also, the ignition timing t. Since the I) C-DC converter continues to operate for several tens of milliseconds thereafter, sufficient ignition energy can be injected after the start of discharge.

(Effects of the Invention) As explained above, in the present invention, the DC-DC converter is configured to operate only during the necessary time from immediately before to immediately after one ignition timing.

Therefore, there is no possibility of irregular discharge occurring, and unnecessary power consumption is eliminated. Therefore, fuel efficiency is further improved. In addition, even if the key switch is turned on, the DC-DC converter only operates while the engine is rotating, so there is no risk of electric shock when inspecting the engine when it stalls, etc., making it safe. It is.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional ignition device, FIG. 2 is a circuit diagram of an embodiment of the present invention, and FIG. 3 is an output waveform diagram of the circuit shown in FIG. Explanation of symbols 1...Battery 2...Key switch 3...
・Ignition coil 3A...Primary winding 3B...Secondary winding 4...Electromagnetic pickup 5...Transistor ignition device 6...Transistor 7...DC-DC! Converter 8...Distributor 9A to 9D...Spark plug 10...Full wave rectifier circuit 11.12...Switching circuit Patent attorney Junnosuke Nakamura 11■1 f2 Figure 11'3 ( b) (b)

Claims (1)

[Claims] 1. A four-terminal ignition coil in which a primary winding and a secondary winding are separated, a first means for detecting one ignition timing, and a primary current of the ignition coil at one ignition timing; means for generating high voltage in the secondary winding by interrupting the secondary winding; a power distributor connected to one end of the secondary winding for distributing the high voltage to the spark plugs of each cylinder; In an ignition device equipped with a DC high voltage generating means connected between one end and ground, the signal from the first means is received only during a limited period from just before the ignition timing to after the ignition. The device as claimed in claim 1, further comprising second means for operating the generating means. 2. The first means is an electromagnetic pickup consisting of a rotary plate having a magnetic protrusion that rotates in synchronization with the crankshaft of an internal combustion engine, and a detection coil that faces the protrusion of the rotary plate through a narrow gap. The second means includes a rectifier circuit for full-wave rectification of the output of the electromagnetic pickup and pickup;
2. The apparatus according to claim 1, further comprising a circuit for operating said high voltage generating means only while there is an output from said rectifying circuit.