JPS6139385A - Ignition plug - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an improvement in a spark plug used in a high-voltage ignition circuit of an internal combustion engine, and more specifically, to an improvement in a spark plug used in a high-voltage ignition circuit of an internal combustion engine, and specifically, to effectively suppress the generation of noise radio waves from the spark plug. It is something.

[Conventional technology]

High-frequency noise radio waves generated from a spark plug can be suppressed by, for example, connecting a resistor in series between a terminal fitting fitted to one end of the inner hole of the spark plug and a center electrode fitted to the other end.
This can be done by configuring a high frequency absorption circuit.

Conventionally, as the above-mentioned resistor, one in which a mixture of carbon, zirconia (or alumina, or magnesia), and glass is baked into the inner hole is known. this is,
As shown in FIG. 7, a high-resistance glass 41 is placed in carbon (conductor), and the current path 43 is formed in a zigzag shape to suppress noise current (hereinafter, the effect of suppressing noise current by forming the current path 43 in a zigzag shape) (The suppressing effect on this is called the structural effect)
The aim is to increase the Here, zirconia has the function of attaching carbon, which forms the current path 43, to the glass 41 to suppress variations in resistance and increase durability. ' However, the noise radio wave suppression effect of the above-mentioned resistor made of a mixture of carbon, zirconia, and glass is still insufficient, and further improvements are desired in view of the increase in the number and precision of electronic devices installed in vehicles. There is.

(Problems to be Solved by the Invention) The present invention has been devised in view of the above-mentioned circumstances, and aims to provide a spark plug with further improved noise radio wave suppression effect by improving the above-mentioned resistor. That is.

[Means for solving problems]

The present invention uses zinc oxide, an oxide magnetic material, and glass with a small particle size instead of carbon and zirconia as materials for forming the current path in the conventional spark plug resistor described above, and on the other hand, the current path is formed in a zigzag pattern. The high-resistance material used to form the shape is glass with a large particle size, as in the past.

FIG. 1 is a sectional view showing an example of the spark plug of the present invention, and FIG. 2 is a schematic diagram illustrating the structure of a resistor used in the spark plug.

That is, the present invention provides an insulator 1 having an inner hole penetrating in the axial direction.
, a terminal fitting 2 fitted into an opening at one end of the inner hole of the insulator, a center electrode 3 fitted into an opening at the other end of the inner hole of the insulator, and the insulator. A spark plug having a resistor 4 disposed within the inner hole and between the terminal fitting and the center electrode, wherein the resistor contains 5 to 40 wt% of zinc oxide and an oxide magnetic material. 10~40w
t% and glass 20-8 with a softening temperature of 300-600°C
Current path 42 forming material consisting of 5 wt% 10 to 40 wt%
And, the softening temperature is 300-600℃ and the particle size is 100-50℃.
The spark plug is characterized by comprising 41.60 to 90 wt% of glass having a diameter of 0 μm.

In the spark plug of the present invention, conventional components such as the insulator 1, terminal fitting 2, center electrode 3, etc. other than the resistor 4 can be used as they are.

The resistor 4 consists of a current path 42 and a high resistance portion 41 that forms the current path 42 in a zigzag shape. The electric wire 42 is made of zinc oxide, oxide magnetic material, and glass with small particle size. The proportion of the current path 42 in the resistor 4 is 10 to 4.
It is set to 0wt%. This is because if it is less than 10 wt%, the resistance becomes too high, and if it is more than 40 wt%, the above structural effect cannot be obtained.

Zinc oxide reduces the amplitude of noise current by its rectifying effect. The proportion of zinc oxide in the current path forming material (zinc oxide, oxide magnetic material, glass with small particle size) is 5 to 5.
It is set to 40wt%. This is because if it is less than 5 wt%, the energy necessary for ignition cannot be obtained, and if it is more than 40 wt%, the amount of glass with small particle size decreases, making it impossible to weld the oxide magnetic material to glass with large particle size. Also,
The particle size of zinc oxide is 10 to 100 microns. This is because if the thickness is less than 10 μm, the melt penetration into the glass will result in high resistance.
This is because a conductive path cannot be formed if the thickness is 100 μm or more.

The oxide magnetic material suppresses the high frequency components of noise radio waves due to its high frequency absorption ability. A typical example of oxide magnetic material is ferrite (M
O・FetO3). M1 (divalent metal) includes manganese (Mn), iron (, Fe), Balt (CO), nickel (Ni), copper (CLI), magnesium (M(]), zinc (Zn), Calcium (Ca
) etc. The proportion of the oxide magnetic material in the current path forming material is 10 to 40 wt%. This is because if it is less than 10 wt%, the high frequency absorption ability will be too low, and if it is more than 40 wt%, the energy loss will be large. Further, the particle size of the oxide magnetic material is 10 to 50 μm. This is because if it is less than 10 μm, it will react with the glass during the heating process, become fused into the glass, become a non-magnetic material, and reduce its high frequency absorption ability.
This is because when the temperature exceeds .mu.m, the magnetic material does not soften at high temperatures, but the glass softens, so gaps are likely to form around the magnetic material, which impairs the stability and durability of the resistor.

Glass with a small particle size (hereinafter referred to as glass △) is dissolved in the zinc oxide and oxide magnetic material, and the glass with a large particle size (hereinafter referred to as glass B) is dissolved in the zinc oxide and oxide magnetic material. ) and stabilize the current path. The glass has a softening temperature of 300°C to 6
A temperature of about 00°C is used. The spark plug is 25 when used.
The softening point of glass A is 300°C because it is heated to about 0°C.
The softening temperature of the glass A should preferably be 600°C or lower in order to bake or weld the resistor into the inner hole of the insulator 1 without oxidizing the terminal fitting 2 and the center electrode 3. This is because it is desirable.

Examples of such glass A include silicic acid glass containing lithium <Li), silicic acid (SiOz) glass, soda zinc glass, and the like. If the zinc oxide and oxide magnetic material account for less than 85 wt% in the current path forming material, the above-mentioned zinc oxide and oxide magnetic material cannot be welded to glass B with a large particle size, which will be described later. This is because it is impossible to make the most of it.

Note that the above function can be achieved if the particle size of the glass A having a small particle size is 5 μm or less.

As described above, the glass B having a large particle size and high resistance functions as an obstacle to the current, making the current path zigzag. As glass B, a glass similar to glass A having a small particle size is used for the same reason as above. The proportion of glass B with large particle size in the resistor 4 is 60~g□wt%
shall be. This is because if it is less than 60 wt%, the above structural effect cannot be sufficiently obtained, and if it is more than 90 wt%, the amounts of zinc oxide and oxide magnetic material become too small. The appropriate particle size of glass B having a large particle size is approximately 100 μm to 500 μm. If it is less than 100 μm, the glass tends to soften during normal use and the current path becomes unstable.
This is because if the resistor 4 is baked into the inner hole of the insulator 1 when the particle diameter is .mu.m or more, a gap is likely to be formed between the glass B having a large particle size and the current path during welding.

In the spark plug of the present invention, a resistor 4 made of the above-mentioned components is filled in the inner hole of the insulator 1 between the terminal fitting 2 and the center electrode 3, and then baked and welded to the inner wall of the inner hole. Manufactured by The baking and welding temperature is generally around 900°C.

[Effect]

The spark plug of the present invention not only has the above-mentioned structural effect of creating a zigzag current path with the glass B having a large particle size, but also reduces the amplitude of noise current with zinc oxide, and suppresses high frequency components with the oxide magnetic material. Therefore, the generation of noise radio waves can be further suppressed.

〔Example〕

Hereinafter, the present invention will be explained in detail based on specific examples.

(B) Production of products Example products and comparative example products were each produced according to the following procedure. The shape of each product was as shown in FIG.

(1) Preparation of current path forming materials Zinc oxide (particle size 50 μl), ferrite (particle size 20 μl)
FA) and Glass A (particle size: 411 m, 200 mesh bath) were mixed in various proportions shown in the table and dry-pulverized to obtain a current path forming material. The glass used is sodium silicate glass (SiOz52wt%, 3tO'337wt).
%, CaO7wt%, [1204wt%], and nickel zinc ferrite (NiQ3) was used as the ferrite.
9mo1%, Zn611m01%, Fet 0350
mo1%) was used.

(2) Preparation of resistor raw materials Glass B shown in the table (particle size 200 μm) is used as the current path forming material.
A lithium silicate glass (with the same composition as glass A) was added to the solution shown in Table 1, mixed with an aqueous solution of dextrin and CMC, dried, and passed through a 24-mesh sieve. did.

(3) Insert the center electrode 3 into the lower end of the inner hole of the connecting insulator (made of alumina) 1 of the resistor, and place the glass (SiO264wt%, Alz0
36wt%, B20323wt%, Naz07wt%)
Copper glass mixed with copper powder in a ratio of 1 = 1 was placed at 0.26 (+), and from above, using a φ4.75 push bottle, 250klll
After that, 0.5o of the above resistor raw material was charged in two parts and pressurized, and then the copper glass was added on top of it at 0.46O.
Every 17 minutes, pressurize at 200 kO using a stem. In this state, place it in a furnace at 850°C to 870°C for 30 minutes and heat it to soften the copper glass and the glass in the resistor raw material.
Immediately after removal from the furnace, the stem was pressurized with 60 Jl. Through this operation, the resistor raw material became the resistor 4, and the copper glass became the copper glass electrodes 51 and 52, respectively. Further, the resistance value of the resistor 4 was set to be the resistance value determined by J[SM rating.

After the insulator 1 was cooled, a housing 6 to which a ground electrode 8 was fixed was attached to the outer periphery of the insulator 1 to obtain a spark plug having the structure shown in FIG. 1.

(b) Evaluation For each of the products manufactured above, the noise electric field strength was measured and the noise suppression effect was evaluated. The results are shown in Figures 3 to 5.
As shown in the figure. The noise electric field strength was measured as shown in Figure 6. After each spark plug was placed under 4 atmospheres, which is the same atmospheric pressure as inside the engine, and discharged and aged for several minutes at a rotational speed of 200 rpm, the noise measuring device was used. This was done by measuring the noise electric field strength at each frequency using a still,
The measured value was the maximum value of the noise electric field strength at each frequency.

FIG. 3 shows an example product 23 of the present invention (23 corresponds to No. 23 shown in Table 1. The same applies hereinafter) and a conventional product 24 (the conventional product has a resistor material of carbon 0.9 wt% and zirconia 22. 1wt%, glass A4.5wt%, glass B72
．． 5 wt %) is a graph comparing the noise electric field strength with that of 5 wt %. As can be seen from FIG. 3, the noise electric field strength of the product 23 according to the embodiment of the present invention is significantly reduced at each frequency compared to the conventional product 24. That is, the noise radio wave suppression effect is improved.

Figure 4 shows Example product 2.3.4 of the present invention and Comparative example product 5.
．． 6.7 is a graph showing the noise electric field strength. From the comparison between Example Product 4 and Comparative Example Product 5.6.7, if the amount of zinc oxide is too large, the noise electric field strength increases. I understand.

In addition, in the table, Example product 3.8 and Comparative example product 9.10
Comparing these, it can be seen that if the amount of ferrite is too large, the 1 energy loss increases too much. FIG. 5 is a graph showing the noise electric field strength of Comparative Example Product 20 and Example Products 2, 21, and 22. It can be seen from FIG. 5 that if the amount of glass B is too small, the noise electric wave suppressing effect due to the above-mentioned structural effect becomes small, so that the noise electric field strength increases.

Note that each of the above products uses nickel-zinc ferrite as the ferrite, but various ferrites such as nickel ferrite, manganese-zinc ferrite, barium ferrite, and strontium ferrite can also be used as the ferrite. When similar experiments were conducted on these various ferrites, similar trends were obtained.

However, when the other components other than ferrite were the same, the effect of reducing the noise electric field strength when using nickel-zinc ferrite and YIG ferrite was slightly better than the others.

〔Effect of the invention〕

In summary, the present invention provides an ignition plug in which a resistor is connected in series between a terminal fitting and a center electrode to form a low-pass filter circuit to suppress noise radio waves. Zinc, oxide magnetic material, glass with small particle size, and glass with large particle size are used.

As is clear from the examples described, in the spark plug of the present invention, the amplitude of the noise current is reduced by zinc oxide, the high frequency component is absorbed by the oxide magnetic material, and the current path is formed by glass with a large particle size. The zigzag pattern is used to suppress radio noise. Therefore, compared to conventional spark plugs, the noise radio wave suppression effect 111J is significantly enhanced. Therefore, when the spark plug of the present invention is used in the high-voltage ignition circuit of an internal combustion engine, the adverse effects of noise radio waves on various electronic devices installed in a vehicle can be effectively prevented (OI
llp is within the scope of the present invention, x is outside the range, and the conventional product is one in which the conductive path is formed of carbon and zirconia, the glass is sodium borosilicate glass, and the ferrite is Ni-Zn ferrite).

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of the spark plug of the present invention, and FIG. 2 is a schematic diagram illustrating the structure of a resistor used in the spark plug of the present invention. FIG. 3 is a graph comparing the noise electric field strength between the product 23 according to the embodiment of the present invention and the conventional product 24. FIG. 4 is a graph showing the noise electric field strength of Example product 2.3.4 of the present invention and Comparative example product 5.6.7. FIG. 5 shows comparative product 20 and example product 2 of the present invention.
21.22 is a graph showing the noise electric field strength of 21.22. FIG. 6 is a diagram illustrating a method of measuring noise electric field strength. FIG. 7 is a diagram showing the structure of a resistor of a conventional spark plug. 1... Insulator 2... Terminal fitting 3...
Center superposition 4... Resistor patent applicant
Nippondenso Co., Ltd. representative J...1 person Patent attorney Hiroma Okawa Patent attorney Shudo Fujitani Patent attorney Akio Sumi Maruyama Constant frequency (MHr) 4th measurement 8: Jfl wave @ (MHz)

Claims (1)

[Scope of Claims] An insulator having an inner hole penetrating in the axial direction, a terminal fitting fitted into an opening at one end of the inner hole of the insulator, and the other end of the inner hole of the insulator. a center electrode fitted into an opening of the insulator; and a resistor disposed within the inner hole of the insulator and between the terminal fitting and the center electrode, wherein the resistor is 5-40wt% zinc oxide and 10-40w oxide magnetic material.
t% and glass 20-8 with a softening temperature of 300-600°C
10 to 40 wt% of a current path forming material consisting of 5 wt% and a softening temperature of 300 to 600°C and a particle size of 100 to
A spark plug comprising 60 to 90 wt% of glass having a diameter of 0 μm.