JPS6314194B2 - - 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 in particular, to suppress 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. This is how it was done.

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 inside the housing. ). The camshaft 2 rotates in conjunction with the crankshaft of the internal combustion engine and drives the rotor 3. The rotor 3 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 at its center and side electrodes 8 at its periphery in a number corresponding to the number of cylinders of the internal combustion engine. A center carbon 10 is disposed between the center terminal 7 and the rotor electrode 5 via a spring 9, and the center carbon 10 is always in pressure contact with the rotor electrode 5 due to the spring 9.

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 explained 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. Then, when the high voltage value rises to a value sufficient to cause a spark discharge in the discharge gap G, dielectric breakdown occurs in the air in the discharge gap G, causing a spark discharge.

In this case, when the high voltage reaches the above-mentioned 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. Here, the capacitive discharge current refers to the charge accumulated in the stray capacitance between the electrode, etc. near the discharge gap and the ground, which flows at high speed (about a few nanoseconds) and with a sudden rise at the time of dielectric breakdown. say.

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 discharge 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 through a dielectric, and when the rotor electrode 5 approaches the side electrode 8, the third electrode and the side A spark discharge is caused between the electrode 8 and the rotor electrode 5 due to the pioneer discharge.
The electric discharge is caused between the side electrode 8 and the side electrode 8.

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 for 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 strength compared to the reference noise electric field strength) is excellent at 10 dB or more.
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.

That is, in the present invention, the rotor electrode is formed of stainless steel, and the thickness of at least the tip thereof is reduced.
0.1 mm to 1.0 mm, and at least one of the top and bottom surfaces of at least the tip of the rotor electrode is made of glass or resin fiber or cloth as a base, and the base is impregnated with, coated with, or coated with silicone varnish. It is characterized by disposing a dielectric material formed by spraying and curing.

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 tip portion 11 of the rotor electrode 23 facing the side electrode 8 is a thin plate portion with a thickness of 0.1 mm to 1.0 mm,
The vicinity of the central portion of the rotor where the center carbon 10 contacts is made to have a predetermined thickness. Further, the rotor electrode 23 is made of stainless steel, which is a metal with low thermal conductivity. Note that the rotor electrode 23 may be made uniformly thin, but if the thickness is less than 0.1 mm, wear due to discharge will be significant, resulting in poor durability and impractical. It was confirmed through experiments that the noise prevention effect could not 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 the upper surface of the thin plate portion of the rotor electrode 23. These dielectric plates 24 are fixed to the rotor electrode 23 using rivets 25 to form the rotor electrode section 22. In the present invention, the thickness of the dielectric plate 24 is
It has been experimentally confirmed that making the thickness in the range of 0.3 mm to 5.0 mm and thicker than the thickness of the thin plate near the tip of the rotor electrode 23 is effective in reducing noise radio waves. Furthermore, experiments have shown that it is preferable to use a dielectric plate formed based on silicon varnish as the dielectric plate 24, and in particular, it is most preferable to have a structure in which such dielectric plates are laminated. Here, a silicon plate is a substrate made of cloth, glass fiber, resin fiber, etc. (for example, a lattice-shaped substrate), and this substrate is impregnated with silicon varnish.
It is cured by coating or spraying, and has excellent heat resistance, insulation, arc resistance, and corona resistance.

Next, the rotor electrode section 2 constructed in this way
2 is integrally fixed to the insulating member 4 to form the rotor 21 when the insulating member 4 is formed.

FIG. 3 shows the results of measuring the noise electric field strength [dB] generated due to spark discharge in the ignition distributor for each frequency band. Here, solid line A
2 shows a case where the ignition distributor of the present invention is constructed using the rotor 21 shown in FIG. 2. Here, the thin plate portion of the rotor electrode 23 is made of stainless steel with a thickness of 0.3 mm, Each body plate 24 had a thickness of 0.5 mm. The broken line B shows the case where the ignition distributor is constructed using the rotor 3 shown in FIG.
It was formed using brass. Also, the dashed line C is
(A) shows the case where the rotor electrode containing the resistor described above is used. In addition, each ignition distributor has a discharge gap G of 0.75 mm, and is attached to a 4-cylinder, 1600 c.c. engine, and the noise electric field strength is measured.
Shown as 0dB. According to FIG. 3, it can be seen that when the ignition distributor of the present invention is implemented as described above, the noise electric field intensity can be reduced by about 10 to 25 dB in each frequency band compared to the conventional one.

4, 5, 6 and 7 show four other embodiments of the rotor 21 shown in FIG. 2. Fourth
In the figure, the upper and lower surfaces of a rotor electrode 23 having a uniform thickness are covered with a dielectric plate 24. Of the upper dielectric plate 24, the center carbon 10
A hole is provided in a portion facing the center carbon 10 so that the center carbon 10 can come into contact with the rotor electrode 23. In addition, holes are formed in the rotor electrode 23 and the dielectric plate 24 at positions facing the projections 26 protruding from the insulating member 4, and after the projections 26 are inserted into these holes, the projections 26 are inserted into the holes.
The head of rotor 2 is caulked by high frequency heating, etc.
form 1.

FIG. 5 shows the rotor 21 shown in FIG. 4 with the dielectric plate 24 covering the top surface of the rotor electrode 23 removed, so that the rotor electrode 23 is exposed over the entire top surface of the rotor 21. be.

FIG. 6 shows the rotor 21 shown in FIG. 4 except for the dielectric plate 24 covering the lower surface of the rotor electrode 23. In FIG.

FIG. 7 shows a dielectric plate 2 on the upper surface of the rotor electrode 23.
4, the hole for the center carbon 10 as shown in FIG. 4 or FIG. The center carbon 10 is made to come into contact with the rotor electrode 23 by standing up near the center of the carbon 21 and further bending it on the upper surface of the insulating member 4.

8A to 8C show an example of how to prevent the rotor electrode portion from coming off when the rotor electrode portion is integrally molded with the rotor insulating member. Only the vicinity of the tip facing the is shown. Here, 31 is a rotor electrode, 32 is a dielectric plate, and the rotor electrode 31 and dielectric plate 32 are respectively formed with constricted portions 31A and 32A having shapes as shown in FIGS. 9A to 9C. In FIGS. 8A to 8C, the shape shown in FIG. 9A is used. Rotor electrode 31 having such a shape
A dielectric plate 32 is arranged on the lower surface of the electrode 31.
If the rotor 34 is formed by molding the dielectric plate 32 integrally with the insulating member 33 when molding the rotor insulating member 33, the resin forming the insulating member 33 is also filled in the constricted portions 31A and 32A. So,
The rotor electrode portion constituted by the rotor electrode 31 and the dielectric plate 32 will not come off from the insulating member 33. Note that the same effect can be obtained even if the constriction is formed only on either the rotor electrode 31 or the dielectric plate 32.

10A and 10B show another example using the retainer shown in FIGS. 8A to 8C. In this example, a narrow rotor electrode 31 is mounted on the upper surface of a dielectric plate 32 formed with a wide width.
are arranged and fixed using rivets 35 to form a rotor electrode portion 36 having the shape shown in FIG. 10A. This rotor electrode portion 36 is molded integrally with the insulating member 37 in the same manner as described above to obtain the rotor 38 shown in FIG. 10B.

FIG. 11 shows an example in which the present invention is applied to an ignition distributor for a two-point ignition engine, where 40 is a rotor, which is driven by a camshaft (not shown) as in the conventional case. The rotor 40 has a first rotor electrode section 4
1 and a second rotor electrode part 51, the first rotor electrode part 41 is made thin only in the vicinity of the tip part 11, and has an annular rotor electrode 42 with which the center carbon 10 comes into contact, and a ring-shaped rotor electrode 42 in the vicinity of the tip part 11. It is composed of dielectric plates 43 disposed on both upper and lower surfaces of a thin plate portion. On the other hand, the second rotor electrode part 51 includes a rotor electrode 52 consisting of a thick plate part with which the center carbon 10 comes into contact and a thin plate part having a tip part 11 facing side electrodes (not shown), and It is constructed by fixing dielectric plates 53 disposed on both sides with rivets 54. The first rotor electrode section 41 and the second rotor electrode section 51 are integrally molded and fixed to the insulating member 44 when the insulating member 44 of the rotor 40 is molded. In addition,
Tips 11 of each of the rotor electrodes 42 and 52
In the tip portion 11A including the tip portions of the dielectric plates 43 and 53, it is desirable that the respective tip portions are on the same plane.

Figure 12 shows the noise prevention effect when the rotor electrodes are configured in various forms at a frequency of 300MHz.
The comparison was made at the measurement points of the conventional rotor electrode shown in Fig. 1, that is, the thickness of 1.5 mm.
The case where the rotor electrode is formed using brass with a diameter of 0 dB is shown as a standard of 0 dB. From FIG. 12, it can be seen that the rotor electrode is made of a metal with low thermal conductivity such as stainless steel, and that the thickness at least at the tip is thin, and
By disposing a dielectric plate formed of silicon varnish on at least one of the upper and lower surfaces of at least the tip of the rotor electrode,
It can be seen that the generation of noise radio waves is suppressed more effectively, and a noise prevention effect superior to that of the conventional method is obtained. In addition, as shown in FIGS. 5 to 7, the dielectric plate 24
Although it is possible to reduce the generation of noise radio waves by disposing only on the upper or lower surface of the rotor electrode 23, as shown in FIG. 2 or 4, if dielectric plates 24 are disposed on both sides of the rotor electrode 23, It turns out to be more effective.

Next, as shown in FIG. 3 and FIG. 12, the reason why the noise prevention effect can be obtained in the present invention will be explained in detail.

The energy lost in one discharge between the rotor electrode and the side electrodes is several millijoules, and the number of discharges per unit time is expressed as the product of the number of rotations of the rotor electrode and the quantity of the side electrodes. . for example,
When a car is running normally, the number of discharges is approximately 100 times/second. Therefore, several hundred millijoules of thermal energy is generated per second, which heats the rotor electrodes. Conventional rotor electrodes used a good thermal conductor such as brass or aluminum, so the average temperature of the discharge electrode surface was about 100°C. However, the rotor electrode used in the present invention is thinner than the conventional one at least at its tip and is made of a metal material with low thermal conductivity, so the thermal resistance is large and the rotor electrode temperature becomes higher than the conventional one. Therefore, an effect of active electron emission (hereinafter referred to as thermionic effect) can be obtained. In addition, since a dielectric plate is disposed on either the upper or lower surface of at least the tip of the rotor electrode, this dielectric plate acts as a heat insulator, and the above-mentioned thermionic effect is further enhanced. . In this way, when the temperature of the rotor electrode increases and the thermionic effect becomes active, the discharge voltage decreases and the capacitive discharge current decreases, which is thought to suppress the generation of noise radio waves generated by spark discharge. .

Furthermore, since a dielectric plate is disposed on at least one surface of the rotor electrode, a so-called residual charge effect occurs in which electric charge is accumulated between the conductor part of the rotor electrode and the dielectric plate, which reduces the risk of spark discharge. It is believed that the discharge voltage can be significantly reduced, thereby suppressing the generation of noise radio waves.

As for the dielectric plate, it has been experimentally confirmed that a dielectric plate formed from silicon varnish is the best in terms of durability and noise prevention effect, as described above. In addition, this type of dielectric plate generally has a thickness of about 0.15 mm to 0.2 mm, so in order to obtain the desired thickness of the dielectric plate, several pieces of this type of dielectric plate are laminated. Because of its shape, it is also thought to have a better noise prevention effect than silicone rubber or silicone grease.

An example of a method for manufacturing this type of dielectric plate will be described below. That is, a dielectric plate of this type is made into a square with a size of, for example, about 1 m ² , and dielectric plates of the same size are bonded together using an adhesive or the like to obtain a laminated dielectric plate. Next, it can be hollowed out using a mold of a desired shape. Also,
One such 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, manufacturing using the latter method is advantageous in terms of productivity. In addition, as the above-mentioned adhesive, epoxy resin type, alkylene resin type, silicone rubber, acrylic resin type, phenolic resin type, etc. can be used.

Furthermore, for example, in FIG. 10A, it has been experimentally confirmed that it is most preferable for the tip 31B of the rotor electrode 31 and the tip 32B of the dielectric plate 32 to be on the same plane. However, although no particular difference was observed even if the deviation was within the manufacturing error range, it was confirmed through experiments that the noise prevention effect was reduced if the dielectric plate was set back by 2 mm or more from the tip of the rotor electrode.

As explained above, according to the ignition power distribution device of the present invention, generation of noise radio waves can be sufficiently suppressed without causing ignition energy loss, and reliability can be maintained at the same level as conventional ignition power distribution devices. be able to.

Further, by applying the present invention to an ignition distributor for two-point ignition, it is possible to suppress radio noise generated from this type of distributor.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing an example of a conventional ignition distributor, FIG. 2 is a vertical cross-sectional view showing an example of the rotor according to the present invention together with a center carbon and side electrodes,
Fig. 3 is a characteristic curve diagram showing the noise electric field intensity generated from the ignition distributor corresponding to each frequency, and Figs. 4 to 7 show four examples of the rotor according to the present invention, together with the center carbon and side electrodes. Figure, Figure 8A
is a perspective view showing an example of preventing the rotor electrode and dielectric plate from coming off; FIG. 8B is a plan view thereof; FIG. ~
FIG. 10A is a plan view showing three examples of the shape of the rotor electrode or dielectric plate shown in FIG.
FIG. 10B is a cross-sectional view of a rotor formed using the rotor electrode portion shown in FIG. 10A, FIG. FIG. 12 is a diagram comparing the noise prevention effects. 1...Housing, 2...Camshaft, 3...Rotor, 4
...Insulating member, 5...Rotor electrode, 6...Cap, 7
...Central terminal, 8...Side electrode, 9...Spring, 10...Center carbon, 11,11A...Tip part, 21,3
4, 38, 40...Rotor, 22, 36, 41, 5
1... Rotor electrode part, 23, 31, 42, 52... Rotor electrode, 24, 32, 43, 53... Dielectric plate,
25, 35, 54...Rivet, 26...Protrusion, 31
A, 32A... Constricted portion, 31B, 32B... Tip portion, 33, 37, 44... Insulating member.

Claims (1)

[Claims] 1. It has 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 the high voltage generated from the ignition coil is connected to the rotor electrode. In the 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 rotor electrode is formed of stainless steel, and at least the thickness of the tip thereof is increased. 0.1mm~1.0mm
At the same time, at least one of the top and bottom surfaces of at least the tip of the rotor electrode is made of glass or resin fiber or cloth as a base, and the base is impregnated with, applied or sprayed with silicone varnish and cured. An ignition power distribution device for an internal combustion engine, characterized in that a dielectric plate formed by the above-mentioned method is disposed.