JPS5934486A - Noise prevention ignition system - Google Patents

Abstract

PURPOSE:To suppress noise wave for almost all frequency band by connecting a capacitor to at least one end of primary coil of ignition coil. CONSTITUTION:A capacitor 410 is connected through short lead wire 411 to the end of lead wire 402 while the other end of the capacitor 410 of the outer case is grounded. The capacitance is preferably 1-0.2muF having voltage withstandability higher than 500V and it is a metalized paper capacitor having self recovery function. The lead wire 411 is made as short as possible. The noise wave of frequency band in the proximity of 20-100muHz to be transmitted from the distributor 300 side is bypassed through a capacitor 410 to the ground.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition device for an internal combustion engine, and more particularly to a noise-preventing ignition device that prevents the emission of noise radio waves having almost the same frequency as radio waves from televisions and radios. It is.

As is well known, noise radio waves emitted by spark discharge from the ignition system of internal combustion engines in automobiles etc. cause serious interference with reception of televisions, radios, etc., and in order to prevent this, some Some countries even have laws and regulations regarding noise radio waves.

In addition, it may interfere with the operation of not only televisions and radios but also electronic devices installed in automobiles, such as electronically controlled fuel injection devices, electronic anti-skid devices, electronically controlled automatic transmissions, etc., resulting in safe driving of automobiles, etc. There is also a risk that it may cause problems.

Therefore, it is desired to suppress the generation of such noise radio waves as much as possible, and various methods are being researched and developed.

FIG. 1 shows the configuration of an ignition device in which a conventionally known measure for suppressing radio noise is taken.

Here, the automobile ignition system includes a spark plug 100, high voltage cables 200 and 200', and a distributor 30.
0 and the ignition coil 400, but at the air caps 20 and 20' of the air caps 20 and 20' of the dust distributor 300 and the ignition plug +00, the spark discharge current has a steep rise time, a current, a noise. Discharge the electric skin 4.

This) suppresses the steep large current during the 1-1-ri time, and
In order to suppress the occurrence of the j-branch, improvements have been made to the spark plug 100 and the distributor 300 that have a spark discharge part, and the high-voltage cables 200 and 2 through which the spark discharge current flows.
Various countermeasures against 00' have been taken to date.

First, regarding the ignition plaque 100, a side force electrode 3 is connected to a plug screw thread (2) which is screwed into an internal combustion engine, and a center electrode 4 is opposed to this side electrode 3 via an air cap 20'.
, the structure of the seal ring 5 etc. is the same as that of a normal spark plug, but an IF long low resistance plug is used as the spark plug 1, and a monolithic resistor 7 is connected to its center electrode 4 via a seal old 6. By resistor 7, center conductor 8 and center? li: Electrically coupled to the pole 4. 9 is a shaft head cap.

The resistance value of monolithic resistor 7 has an influence on other parts of the cooperating organization! In order to have the effect of suppressing waste and miscellaneous 8゛ waves, a sieve of 07 m in width from 3 to +5, with a sieve and a length of 8 mm or more shall be used.

The length of the resistance of a normal spark plug with resistance is about 5 to 6 mm, 1&, but in the long resistance plug 100, the length of the entire plug is 75 to 85IIIn, and the resistance is 7 mm.
In order to make the length of the sentence more suitable than 8mm, Q
= 12 to 15 mm.

This long resistance plug 100 is considered to constitute a filter with the electrostatic capacitance between the monolithic resistor 7 and the plug thread part 2 and the resistance of the monolithic resistor 7, but the actual monolithic resistor 7 has a parallel static If this parallel capacitance is large, high frequency current will pass through this capacitance, and the noise suppression effect of the filter will deteriorate.

If the materials that make up the resistance are the same, this parallel capacitance part will be
The longer the resistance length sentence is, the smaller it becomes, sentence = 12 ~ 15 m
This effect becomes even more noticeable when the wavelength is about m, so it is preferable to select the range from -12 nm to about 15+ nm.

Next, as a means to suppress the latent radio waves generated from the high-voltage cables 200 and 200', as shown in No. 11x1, noise-proof high-voltage cables 2°
00', the core wire 201 is set to 8 to 20 Ω/m.
A carbon-impregnated wire with uniformly distributed JI' resistance is used, and its periphery is covered with an insulating sheath 202, and its outer periphery is covered with a kIL wire 203 made of an insulating material.

The distributor 300 consists of a shaft 301, rubber 308, and a cap 309.

The rotor electrode 307 of the rotor 308 is generally made of stainless steel, brass, etc., and a dielectric material 310 made of a silicon-based dielectric material, such as silicon glass, is deposited on its lower end. It is fixed to the rotor 308 by a caulking portion 311.

The silicon glass constituting the dielectric material 310 is coated with silicon ml such as silicon varnish on a base material such as glass fiber.
It is hardened by impregnating or painting 6.
It is most suitable from the viewpoints of frog noise suppression effect, heat resistance, workability, arc and corona resistance, etc.

As shown in Fig. 2, there is a strong correlation between the strength of the noise radio wave and the magnitude of the emitted 7L voltage. (If the gap between the two is 0.75+n+n)
When the dielectric material 310 is added to the rotor electrode 307, the discharge voltage is reduced, and the generation of noise radio waves can be significantly suppressed.

For example, the rotor electrode 307 is made of stainless steel with a thickness of 0.8 mm, and the dielectric material 310 is made of stainless steel with a thickness of 0.5 mm.
When using silicon glass of mm, the discharge voltage was 4
At ~5 kV, a noise suppression effect of about 15 dB could be obtained compared to the case of a 0.6 mm thick brass rotor electrode without the additional dielectric 310.

Note that in the 112th position, the center electrode 303 of the distributor 300 is connected to the ignition coil 400 via the resistance string high voltage cable 200'.

FIG. 3 shows the results of measuring the noise electric field strength in an actual vehicle. Here, the solid line 30 is the noise radio wave regulation 8j+
Indicates the level of Further, each of the curves 31 to 34 shows the noise and electric field intensity when the ignition device shown in Table i1 is used.

(7) The characteristics in Figure 3 show the results of measurements of the ignition system of a 1500cc engine installed in 717 bonnet-type passenger cars, and IpLV/m is expressed as OdB.

As is clear from Fig. 3, when using an ignition system that has areas where no noise suppression is applied, as in the case of curves 31, 32, and 33, the areas where noise suppression measures have been taken are Even if there is, it will be masked by large noise components from areas where no other noise suppression measures have been taken, and there will be almost no noise suppression effect.

By simultaneously applying the three noise countermeasures described above to each location, a noise prevention effect of 10 to 30 dB can be achieved.

Furthermore, as is clear from Fig. 3, 20 to I00MHz
In the current range, even if countermeasures are taken at each location, the noise prevention effect in this range is small, and the absolute level of noise is high, so the margin is small compared to the legal regulation level 30.

FIGS. 4(A) and 4(B) show the measurement results of noise intensity (8) in an actual vehicle. Figure 4 (CA) shows an example of a cab-over type truck (2000cc 4-stroke engine), and Figure 4 (B) shows an example of a 2-box Honnet type passenger car (1500cc 4-cycle engine). As in the case of curve 34, the measurement results are shown in curve 35 using noise prevention measures taken at all locations.

As is clear here, in the lower frequency band of about 20~loOMHz, the noise prevention effect is small, and depending on the vehicle, it may exceed the legal regulation level 30, which may interfere with communications such as radio and television. There is a need to further suppress the generation of noise radio waves.

Conventional ignition devices that take various noise radio wave suppression measures as described above have not been able to effectively suppress noise radio waves having frequency components in the vicinity of 20 to 100 MHz.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks and effectively suppress noise radio waves in a frequency range that could not be suppressed with conventional ignition devices. An object of the present invention is to provide a prevention type ignition device.

In order to achieve such a goal, the present invention.

A capacitor is connected to at least one of both ends of the primary coil of the ignition coil.

Hereinafter, the present invention will be described in detail with reference to the drawings.

As a result of studying the mechanism of noise radio wave generation, the present inventors found that in FIG.
Resistance paper high voltage cable 200 between and spark plug +00
It has been found that the noise flows through both the resistance paper high voltage cable 200' between the distributor 300 and the ignition coil 400, and each of these cables 200 and 200' acts as an antenna, and the noise radio waves are radiated.

At this time, the cable 200 usually has a length of 60 to 70 cm or more, and there is a long resistance plaque 10 at the end.
0 is connected, the spark current from the distributor 300 is attenuated and ultimately flows through the air cap 20' of the plug 100 to ground. Furthermore, since the effective length of the antenna is short, the generation of all 11 sound waves is reduced. On the other hand, the cable 200' has a short length, usually around 30 cm, and the ignition coil 400 is connected to the end of the cable 200'.
and the primary side lead wire 401 are connected, so
There is little attenuation in the vicinity of 20~loOMHz, which has a long wavelength, and the ignition coil 400 and primary lead wire 4
It was revealed that a strong spark current flows up to 0.01, and that this part acts as an antenna, emitting radio noise.

Therefore, even if the noise radio waves are suppressed by attaching a dielectric added rotor to the rotor 308 and sufficiently lowering the broadcast voltage, depending on the frequency, the noise suppression is still insufficient and the noise radio waves are radiated. Therefore, it is desirable to further reduce the emission of such noise radio waves.

Therefore, in the present invention, focusing on the above-mentioned points, in order to suppress noise (11) from the primary lead wire 401 of the ignition coil 400 and radio wave radiation, at least one of both ends of the primary coil of one ignition coil is Connect a capacitor to the power.

FIG. 5 shows an example of the structure of the present invention, and FIG. 6 shows its electric circuit diagram. In the figure, 402 is a primary REIT wire terminal. 403 is an ignition switch connected to the lead wire 401, and 404 is a battery that sends current from the swift 403 to the ignition coil 400 via the primary lead wire 401. 405 is a connection from the ignition coil 400 to the contact point l-408, 407 is an arc extinguishing capacitor for the contact point 406, 4
08 is a primary side coil.

In the present invention, a capacitor 410 is connected to the lead wire terminal 402 via a short lead wire 411, and the other power terminal of the capacitor 410 serves as an outer case and is connected to ground.

The capacitance of the capacitor 410 is 1nF-0.2gF.
It is preferable to use a metalized paper capacitor (12), which has a withstand voltage of 500 V or more and has a self-healing effect. The reason for this is that when the primary current is cut off, a self-induced electromotive force reaching several hundreds of volts is generated in the ignition coil 400, which may destroy the capacitor 410.

The length of the lead wire 411 of the capacitor 410 is made as short as possible in order to prevent the impedance of this portion from increasing due to the inductance of the lead wire 411 and deteriorating the spark current bypass effect as much as possible.

Since the present invention is configured as described in -1- above, the noise radio waves in the frequency band around 20~loOMHz caused by the spark discharge transmitted from the distributor 300 side are
Before being radiated through primary lead 401, it is bypassed by capacitor 410 and dropped to ground. That is, the existence of this capacitor 410 makes it possible to reduce noise radio waves.

FIG. 7 shows another configuration example of the present invention, and FIG. 8 shows an electric circuit diagram thereof. Here, two ground wires 412 and 41 are connected to the terminal of the capacitor 410 that is not on the ground side.
3, and one lead wire 412 connects to the ignition coil 40.
Connect the reed spring 413 of another J to the primary side terminal 402 of No. With this configuration, the bypass effect becomes even better.

8. To add the capacitor 410, 2 of the ignition coil
Which side of the primary side terminals 402 to select is determined by
Both terminals 402 are determined depending on the vehicle, frequency, etc.
It is desirable to add it to

FIGS. 9(A) and 9(B) show measurement results when the present invention is applied to an actual car. The foot measurement conditions are the fourth
The curve 30 is the same as in Figures (A) and (B), but in the Figure, the curve 30 is the legal regulation value, (A) is the case when the conventional ignition device is used, and (B) is the case where the conventional ignition device is used. 7 shows curves of measurement results when capacitors with a capacity of 1.05#F are added to both primary side terminals of the ignition coil in the embodiment shown in FIG. As is clear from FIGS. 9(A) and 9(B), according to the present invention, the noise level is significantly reduced in the frequency band around 20 to 100 MHz, and no noise level exceeds the legal regulation value of 30.

As described above, 1. According to the present invention, the generation of noise radio waves can be sufficiently suppressed over a wider frequency band, that is, almost all frequency bands where noise may occur, compared to the conventional method. I can do it.

[Brief explanation of the drawing]

Figure 1 is a diagram showing a configuration example of a conventional ignition system, Figure 2 is a characteristic curve diagram showing the relationship between discharge voltage and noise voltage, and Figures 3, 4 (A) and (B) are conventional 5 and 7 are perspective views showing two sides of the structure of the ignition device of the present invention, and FIG. 6 and FIG. Figure 8 is an equivalent electric circuit diagram corresponding to Figures 5 and 7, respectively, and Figures 9 (A) and (B) are characteristics showing actual measurement examples of the relationship between frequency and noise electric field strength, demonstrating the effects of the present invention. It is a curve diagram. 100... Spark plug (long resistance plug), (15) 200, 200'... High voltage cable, 300... Distributor, 400... Ignition coil, 2... Plug screw portion, 3 ... Side electrode, 4 ... Center electrode, 5 ... Seal ring, 6 ... Seal benefit, 7 ... Monolithic resistor, 8 ... Center shaft conductor, 9 ... Shaft head cap , 201... Carbon-impregnated wire, 202... Insulating sheath, 203... Satin wire, 301... Limb, 302... Rubber cap, 303... Center electrode, 304... Side Electrode, 305... Spring. 306...Contactor, (16) 307...Rotor electrode, 308...Rotor, 308...Cap, 310...Applying dielectric material, 311...Caulking portion, 20, 20'・・・Discharge cap, 401 ・・
Primary lead wire, 402... Primary lead wire terminal, 403... Ignition switch, 404...
Battery, 405... Primary lead wire, 406... Contact point, 407... Arc extinguishing capacitor, 408... 1
Next coil, 410... Capacitor, 411.412, 413... Lead wire. (17) -541 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] A spark plug having a monolithic resistor, a disc (distributor) for breaking the rotor formed by adding a dielectric to the end face of at least one bra of a rotor electrode, and a core wire including a resistor, the spark plug and the distributor An ignition device comprising a first high-voltage cable to be connected and an ignition coil for supplying high-voltage output to the distributor, characterized in that a capacitor is connected to at least one of both ends of a first coil of the ignition coil. Noise-preventing ignition device.