JPS6138351B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric spark ignition type ignition power distribution device for an internal combustion engine, and particularly to suppressing the generation of noise radio waves caused by discharge between a rotor electrode and a side electrode that face each other at a predetermined period. It was designed to do so.

An ignition system for an electric spark ignition internal combustion engine, such as an automobile internal combustion engine, has an ignition coil, an ignition distributor, a spark plug, etc. Current flows. Noise radio waves caused by this spark discharge may interfere with communications such as television and radio, and in some countries,
The noise radio waves generated by this type of vehicle are regulated by law.

In addition, this type of noise radio waves not only affect communications, but also affect electronic devices installed in automobiles, such as electronically controlled fuel injection devices, electronic anti-skid devices, and electronically controlled automatic transmissions. There is also a risk that this may impede safe driving.

For this reason, there is a demand for reducing the noise radio waves generated from spark ignition devices, and various devices and devices have been researched and developed or put into practical use.

FIG. 1 shows an example of a conventional ignition power distribution device used in a spark ignition device, where 1 is a housing, and the housing 1 is connected to an internal combustion engine (not shown) together with a camshaft 2 housed therein. is installed on. The camshaft 2 rotates in conjunction with the crankshaft of the internal combustion engine and drives the rotor 3. The rotor 3 is
It has an insulating member 4 connected to the camshaft 2, and a rotor electrode 5 made of brass or the like fixed to the upper surface of the insulating member 4. Reference numeral 6 denotes a cap attached to the housing 1, which has a central terminal 7 in its center, and side electrodes 8 in a number corresponding to the number of cylinders of the internal combustion engine on its periphery.
have. A center carbon 10 is disposed between the center terminal 7 and the rotor electrode 5 via a spring 9.
Therefore, it is always in pressure contact with the rotor electrode 5.

In the ignition distributor configured in this way, high voltage generated in the ignition coil (not shown) is supplied to the central terminal 7 via a high voltage cable (not shown). This high voltage is guided to the rotor electrode 5 via the spring 9 and the center carbon 10, and each time the rotor electrode 5 and the side electrode 8 face each other, the high voltage introduced to the rotor electrode 5 is introduced to the rotor electrode 5. The dielectric breakdown occurs in the air in the discharge gap G between the tip 11 and the side electrode 8, and as a result, a high voltage is distributed to the side electrode 8. High voltage is then supplied to the spark plug via a high voltage cable (not shown).

The spark discharge phenomenon between the rotor electrode 5 and the side electrode 8 will be described in more detail. That is, the high voltage supplied from the ignition coil does not reach its maximum value in steps, but increases with a time constant determined by circuit constants of the ignition coil, high voltage cable, etc. When the high voltage value rises to a value sufficient to cause a spark discharge in the discharge gap G, the discharge gap G
dielectric breakdown occurs in the air and spark discharge occurs.

In this case, when the high voltage reaches the above value, rapid dielectric breakdown occurs, and the discharge current flows rapidly with a short pulse width and becomes an unstable current with a high peak value, which is harmful. A large amount of high-frequency components are generated, which are radiated to the outside using high-voltage cables as antennas and become radio noise.

It is generally believed that the noise electric field radiated from the noise source due to this seed spark discharge is proportional to the noise current. Therefore, in order to suppress the generation of noise radio waves, it is necessary to reduce the capacitive discharge current flowing through the discharge gap between the rotor electrode and the side electrode. Note that the capacitive discharge current here refers to the electric charge accumulated in the stray capacitance between the electrode, etc. near the discharge gap and the ground that flows at high speed (about a few nanoseconds) and with a sudden rise when dielectric breakdown occurs. means.

Therefore, in order to suppress the generation of noise radio waves in the ignition distributor, the measures described in (A) to (C) below have been proposed.

(A) A resistor is provided in the rotor electrode This is a resistor embedded in the rotor electrode 5 between the center carbon 10 and the tip 11 of the rotor electrode 5.

(B) A device with a larger discharge gap This is a device with a larger discharge gap G between the rotor electrode 5 and the side electrode 8.
The plate electric gap G, which is about 0.75 mm, is set to about 1.524 to 6.35 mm.

(C) A third electrode arranged near the rotor electrode The third electrode is attached to the rotor electrode 5 via a dielectric, and when the rotor electrode 5 approaches the side electrode 8, the third electrode A spark discharge is caused between the rotor electrode 5 and the side electrode 8, and a spark discharge is caused between the rotor electrode 5 and the side electrode 8 by the precursor discharge.

However, the conventional proposals (A) to (C) each have the following drawbacks.

Regarding (A), due to the stray capacitance in parallel with the resistor, the noise suppression effect on high frequency bands of about 300 MHz or higher is small, and the ignition energy loss due to the resistor (several kilohms to tens of kilohms) is large.

Regarding (B), the noise prevention effect (the effect of reducing the noise electric field compared to the reference noise electric field) is excellent at 10 dB or more, but the ignition energy loss becomes extremely large. Therefore, there is a risk that reliable ignition, which is essential for exhaust purification and improved fuel efficiency in recent years, may be impaired. Furthermore, if a higher voltage than conventional ones is used to ensure ignition, it becomes difficult to take measures against high voltage leaks.

Regarding (C), the structure is complicated and there are problems with long-term reliability.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ignition power distribution device for an internal combustion engine that eliminates such conventional drawbacks, exhibits a sufficient noise prevention effect, and suppresses the generation of noise radio waves.

In order to achieve such an objective, the present invention
It has a rotor electrode that rotates in conjunction with the rotation of the internal combustion engine, and a plurality of side electrodes that face the rotor electrode with a predetermined gap in between. In an ignition distributor that supplies and distributes power to a spark plug connected to a side electrode through discharge between A dielectric plate made of silicone varnish and having dimensions within the range of 0.3 mm to 5.0 mm and thicker than the thickness of the rotor electrode tip is disposed on at least one of the top and bottom surfaces of the tip. It is characterized by the fact that it has been established.

The present invention will be explained in detail below based on the drawings. In the following description, parts similar to those in FIG. 1 are denoted by the same reference numerals.

FIG. 2 shows an example of the structure of the rotor in the ignition distributor of the present invention, together with the center carbon 10 and the side electrodes 8. Here, 21 is a rotor, and this rotor 21 has an insulating member 4 and a rotor electrode part 22. Rotor electrode section 22
has a rotor electrode 23 and two dielectric plates 24, and the rotor electrode 23 is formed of a thin metal material having a thickness of 0.1 mm to 1.0 mm. In addition, the rotor electrode 23
It is preferable to use a metal with low thermal conductivity such as stainless steel or Nitarom. Furthermore, as in this example,
Instead of having a uniform thickness, at least the thickness of the tip portion 11 facing the side electrode 8 may be set to 0.1 mm to 1.0 mm, but if the thickness is thinner than 0.1 mm, wear due to discharge will be significant. It was confirmed through experiments that the durability deteriorates and it is not practical, and that if the thickness exceeds 1.0 mm, the desired noise prevention effect cannot be obtained.

Further, one of the dielectric plates 24 is connected to the rotor electrode 23.
so as to cover the entire lower surface of the other dielectric plate 24.
covers a portion of the upper surface of the rotor electrode 23 except for the vicinity where the center carbon 10 contacts. These dielectric plates 24 are fixed to the rotor electrode 23 using rivets 25 to form the rotor electrode part 22.
form. Next, when molding the insulating member 4, the rotor electrode portion 22 is integrally fixed to the insulating member 4 to form the rotor electrode 21.

In the present invention, the dielectric plate 24 is made of silicone, which is made of cloth, glass fiber, resin fiber, or the like as a base (for example, a lattice-shaped base), and is made by impregnating, coating, or spraying silicon varnish or the like onto this base and hardening it. It is formed as a dielectric plate formed on the basis of varnish. This dielectric plate has superior heat resistance, insulation, arc resistance, and corona resistance compared to other dielectric plates such as silicone rubber and silicone grease, and is also highly effective in preventing noise due to a reduction in discharge voltage. .

Further, as a result of experimenting with various thicknesses of the dielectric plate 24 disposed on at least one of the upper surface and the lower surface of the tip portion 11 of the rotor electrode 23, the applicant found that the dielectric plate 24 was
It was confirmed that when the thickness is set to be thicker than 3 and within the range of 0.3 mm to 5.0 mm, a more effective noise prevention effect can be obtained.

Here, an example of a method for manufacturing a dielectric plate formed from silicon varnish will be described. First, a dielectric plate made of silicon varnish is made into a square with a size of, for example, about 1 m ² , and a dielectric plate of the same size made of silicon varnish is crimped using an adhesive or the like to form a laminated dielectric. Get a body plate. Next, it can be formed by hollowing out using a mold having a desired shape. Alternatively, one dielectric plate may be hollowed out using a mold having a desired shape, and then bonded and laminated using an adhesive. However, if this type of dielectric plate is to be as thick as, for example, 3 mm, it is advantageous in terms of productivity to manufacture it by the latter method. Note that, as the above-mentioned adhesive, an epoxy resin-based adhesive, an alkylene resin-based adhesive, a silicone rubber-based adhesive, an acrylic resin-based adhesive, a phenol resin-based adhesive, or the like can be used.

In FIG. 3, using the roll 21 shown in FIG. 2,
The rotor electrode 23 is formed using stainless steel with a thickness of 0.3 mm, and the thickness of the dielectric plate 24 is
The noise electric field strength is shown when the thickness is changed from 1/3 to 10 times (0.1 mm to 3.0 mm). An ignition distributor having such a rotor 21 was installed in a 6-cylinder, 2000 c.c. engine with a discharge gap G of 0.75 mm, and the noise electric field strength was measured. In Figure 3, 1μV/m
is shown as 0dB.

In FIG. 3, solid line A represents the case where the thickness of the dielectric plate 24 is 1/3 times that of the rotor electrode 23 (0.1 mm).
The dashed line B is also 1/2 times (0.15mm), and the dashed line C is 1x
Double (0.3mm), solid line D is double (0.6mm), dashed line E
indicates the case of 5 times (1.5 mm), and the broken line F shows the case of 10 times (3.0 mm). Note that the two-dot solid line G is the first
In the conventional rotor 3 shown in the figure, the rotor electrode 5 is formed using brass with a thickness of 1.5 mm. From FIG. 3, it can be seen that when the thickness of the dielectric plate 24 is approximately equal to or thicker than the thickness of the rotor electrode 23, the value of the noise electric field strength suddenly decreases.

Based on the experimental results shown in FIG. 3, FIG. 4 shows the ratio of the thickness of the dielectric plate 24 to the thickness of the rotor electrode 23 on the horizontal axis, and the noise in the conventional rotor 3 on the vertical axis. The electric field strength, that is, the degree to which the noise electric field strength has decreased with respect to curve G in Figure 3, is shown by taking the average value of 24 points from 20 to 100 MHz, and is shown as the noise prevention effect. be. From FIG. 4, it can be clearly seen that when the thickness of the dielectric 24 is made equal to or thicker than the thickness of the rotor electrode 23, the noise radio waves are effectively reduced.

The experimental results shown in FIGS. 3 and 4 are for the case where the thickness of the rotor electrode 23 is 0.3 mm, but if the thickness of the rotor electrode 23 is in the range of 0.1 mm to 1.0 mm, the third Almost similar results were obtained using the ratios shown in the figure and FIG.

FIG. 5 shows another example of the rotor according to the present invention, and unlike the case shown in FIG. 2, the rotor electrode 2
Only the thickness of the dielectric plate 24 disposed on the upper surface of the rotor electrode 3 is made approximately equal to the thickness of the rotor electrode 23. That is, the dielectric plate 24 disposed on the lower surface of the rotor electrode 23 is made by stacking and pressing 20 dielectric plates formed based on silicone varnish with a thickness of 0.2 mm to a thickness of about 3.5 mm. dielectric plate 2
No. 4 was made by stacking two dielectric plates formed based on the same silicon varnish and pressing them together to give a thickness of about 0.3 mm. In this case as well, the same noise prevention effect as in the case where thick dielectric plates 24 were provided on both sides could be obtained.

Further, even if the thick dielectric plate 24 was provided only on either the upper surface or the lower surface of the rotor electrode 23, substantially the same effect as described above could be obtained.

FIG. 6 shows an example in which the present invention is applied to an ignition distributor for a two-point ignition engine, where 31 is a rotor, which is driven by a camshaft (not shown) as in the conventional case. The rotor 31 has a first rotor electrode section 32
and a second rotor electrode part 41, the first rotor electrode part 32 is made thin only near the tip part 11, and has an annular rotor electrode 3 which the center carbon 10 contacts.
3, and dielectric plates 34 which are disposed on both upper and lower surfaces of a thin plate near the tip 11 and are thicker than the thin plate. On the other hand, the second rotor electrode section 4
Reference numeral 1 denotes a rotor electrode 42 consisting of a thick plate part on which the center carbon 10 comes into contact and a thin plate part having a tip facing a side electrode (not shown); It is constructed by fixing a thicker dielectric plate 43 with rivets 44. These first rotor electrode portion 32 and the second
The rotor electrode portion 41 is connected to the insulating member 35 of the rotor 31.
When molding, they are molded integrally and each is fixed to the insulating member 35. Also in this example, the thickness of the thin plate portions of the rotor electrodes 33 and 42 is the same as described above.
It is preferable to set the thickness to 0.1 mm to 1.0 mm, and to use a metal material with low thermal conductivity such as stainless steel or nichrome. On the other hand, the dielectric plates 34 and 43 are silicon plates of 0.3 mm to 5.0 mm, and are made thicker than the thin plate portions of the rotor electrodes 33 and 42. Even when the ignition distributor for two-point ignition was configured using the rotor 31 shown in FIG. 6, the generation of noise radio waves could be suppressed in the same way as described above. Note that, in the tip portion 11A including the tip portions 11 of the rotor electrodes 33 and 42 and the tip portions of the dielectric plates 34 and 43, it is desirable that the tip portions thereof are on the same plane.

As explained above, according to the ignition distributor of the present invention, the dielectric plate formed based on silicon varnish disposed on the top or bottom surface of at least the tip of the rotor electrode is thicker than the tip of the rotor electrode. By increasing the thickness, the generation of noise radio waves originating from the ignition distributor can be further suppressed compared to the case where a dielectric plate having a thickness equal to or less than the thickness of the rotor electrode is provided.

Further, according to the present invention, even when the rotor electrode is thin, the thin rotor electrode can be reinforced because a thick dielectric plate is stacked on the rotor electrode. This prevents the rotor electrode from bending even if large pressure (up to about 200 kg/cm ² ) is applied when molding the rotor electrode and dielectric plate together with the insulating mold member.
Further, as a result, there is no problem in manufacturing that the resin forming the insulating member flows out in areas other than the mold around the rotor electrodes. Furthermore, even if a small amount of mold resin flows out to the tip of the dielectric plate, the entire front surface thereof will not be covered, and the noise prevention effect will not be impaired.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an example of a conventional ignition distributor, FIG. 2 is a longitudinal sectional view showing an example of a rotor according to the present invention, together with a center carbon and side electrodes.
Figure 3 is a characteristic curve diagram showing the noise electric field intensity generated from the ignition distributor using the ratio of the thickness of the rotor electrode to the dielectric plate as a parameter. Figure 4 shows the results shown in Figure 3, FIGS. 5 and 6 are longitudinal cross-sectional views showing two other examples of the rotor according to the present invention. be. DESCRIPTION OF SYMBOLS 1... Housing, 2... Camshaft, 3... Rotor, 4... Insulating member, 5... Rotor electrode, 6...
Cap, 7...center terminal, 8...side electrode, 9...
...Spring, 10...Center carbon, 11,11
A... Tip, 21, 31... Rotor, 22, 3
2, 41... Rotor electrode section, 23, 33, 42...
...Rotor electrode, 24, 34, 43...Dielectric plate,
25,44...Rivets.

Claims (1)

[Scope of Claims] 1. A rotor electrode that rotates in conjunction with the rotation of an internal combustion engine, and a plurality of side electrodes that face the rotor electrode with a predetermined gap in between, and a high voltage generated from an ignition coil. In an ignition distributor configured to supply and distribute power to a spark plug connected to the side electrode via discharge between the rotor electrode and the side electrode, the thickness of at least the tip portion of the rotor electrode is 0.1 mm to 1.0 mm, and at least one surface of the top or bottom surface of at least the tip of the rotor electrode has a dimension in the range of 0.3 mm to 5.0 mm, and the thickness of the tip of the rotor electrode. An ignition power distribution device for an internal combustion engine characterized by having a dielectric plate formed based on silicone varnish that is thicker than that of an internal combustion engine. 2. The ignition power distribution device for an internal combustion engine according to claim 1, wherein the dielectric plate has a plurality of laminated structures. 3. In the ignition distributor for an internal combustion engine according to claim 1 or 2, the dielectric plate has a glass or resin fiber or cloth as a base, and the base is impregnated with silicone varnish, An ignition distributor for an internal combustion engine characterized by being formed by coating or spraying and curing.