JPH09329334A - Spark plug with resistance - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a spark plug with resistance, in which segregation of the resistance material hardly occurs even when the resistance material is separated from the aggregate and stable load life characteristics are obtained. SOLUTION: A spark plug P with resistance includes a cylindrical metal shell 1, an insulator 2 with a shaft hole 21 fixed in the metal shell 1, and a terminal electrode 3 inserted into the shaft hole 21.
The center electrode 4 fixed in the shaft hole 21 such that the tip 42 projects from the insulator tip surface 221, the seal portion 31 of the terminal electrode 3 and the base 41 of the center electrode 4 are respectively provided in the shaft hole 21.
Conductive seal glass 5 and 6 to be sealed inside, and located between seal glass 5 and 6, aggregate (lithium borosilicate glass) and resistance material (conductive material, sealing glass, ceramic fine particles, binder, etc.) And a resistor 7 obtained by melting and solidifying a mixture of and, and the maximum particle diameter of the aggregate is 150 μm or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass-sealed spark plug with resistance.

[0002]

2. Description of the Related Art The glass seal of a spark plug with resistance is usually carried out by the following method. The center electrode is fitted into the shaft hole of the insulator, and the conductive glass powder, the resistance material composition, and the conductive glass powder are sequentially poured into the shaft hole, and the glass powder and the like are melted by heating, and face down to the terminal portion. While pressing the terminal electrode, the terminal electrode is pressed and cooled to solidify the glass powder and the like, and the glass sealing of the terminal electrode and the center electrode is completed. The resistance material composition is a mixture of aggregate and resistance material {conductive material, sealing glass, ceramic fine particles, and other additives (binder, etc.)}. Incidentally, Japanese Patent Application Laid-Open No. 62-18001 describes an example of using a ceramic aggregate of 100 μm to 800 μm.

[0003]

The above resistance material composition comprises
The resistance material and the aggregate are weighed in a predetermined weight ratio, added with a binder such as PVA, and mixed (granulated) with a mixer or the like, and the resistance material is easily separated from the aggregate during the granulation. Here, in the conventional aggregate particle size, the separated resistance material is easily separated from the resistance material composition, and when separated, segregation of the resistance material occurs in the resistance body, so current is locally concentrated and burnout of the conductive material is caused. Invite. When the conductive material burns out, the resistance value of the resistor increases and the load life characteristic deteriorates.

An object of the present invention is to provide a resistance-filled spark plug in which segregation of the resistance material hardly occurs even when the resistance material is separated from the aggregate and stable load life characteristics are obtained.

[0005]

In order to solve the above-mentioned problems,
The present invention employs the following configuration. (1) Cylindrical metal shell, an insulator with a shaft hole fixed in the metal shell, a terminal electrode inserted in the shaft hole of the insulator, and fixed in the shaft hole. The center electrode, the seal portion of the terminal electrode and the base portion of the center electrode are respectively sealed with conductive seal glass that seals the shaft hole in the shaft hole and between the seal glasses, and the aggregate and the resistance material In the spark plug with resistance including the resistor obtained by melting and solidifying the mixture, the maximum particle diameter of the aggregate is 150 μm or less.

(2) It has the structure of (1) above, and the aggregate is glass. (3) It has the structure of (1) above, and the aggregate is a mixture of glass and ceramic powder.

(4) The aggregate of any one of the above (1) to (3) has a particle size distribution of σ = 55 μm or less.

[0008]

[Operation and effect of the invention]

[Claim 1] Since the maximum particle size of the aggregate of the resistance material composition is 150 μm or less, the particle size distribution of the aggregate becomes small, and even if the resistance material is peeled from the aggregate, the peeled resistance material causes resistance. It is difficult to separate from the material composition, and segregation of the resistance material can be prevented. Therefore, burning of the conductive material can be prevented, the resistance value of the resistor does not fluctuate, and stable load life characteristics can be obtained.

[Claim 2] When the aggregate is glass, the workability of the glass seal is good, the terminal portion does not float up when the terminal electrode is pressed while applying a downward force to the terminal portion, and the insulator is It can also prevent damage.

[Claim 3] When the aggregate is made of glass and ceramic, the effective length of the resistor can be made long, which is advantageous for preventing the generation of radio noise.

[Claim 4] The particle size distribution of the aggregate is
Since σ = 55 μm or less, even if the resistance material is separated from the aggregate, the separated resistance material is difficult to separate from the resistance material composition, and segregation of the resistance material can be prevented. Therefore, burning of the conductive material can be prevented, the resistance value of the resistor does not fluctuate, and stable load life characteristics can be obtained.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention (Claim 1,
(Corresponding to 2 and 4) will be described based on FIG. Sample N
o. 1 to No. A spark plug P with resistance (invention product) employing any one of the resistance material compositions of 3 has the following structure. The sample No. A spark plug with resistance (comparative product) that employs the resistance material composition of Nos. 4 and 5 has the same structure.

As shown in FIG. 1, a spark plug P with resistance is inserted into a cylindrical metal shell 1, an insulator 2 with a shaft hole 21 fixed in the metal shell 1, and a shaft hole 21. Terminal electrode 3, the center electrode 4 fixed in the shaft hole 21 so that the tip portion projects from the insulator tip surface 221, and the terminal electrode 3
The seal portion 31 and the base portion 41 of the center electrode 4 are provided with seal glasses 5 and 6 for sealing in the shaft hole 21 and a resistor 7 located between the seal glasses 5 and 6, respectively. The spark plug P with resistance is screwed to a cylinder head (not shown) of an internal combustion engine via a gasket 11, a plug cap (not shown) is fitted to the terminal portion 32, and a high voltage is supplied. .

The metal shell 1 is made of low carbon steel and has a threaded portion 12 having a screw 121 formed on the outer periphery thereof, a body portion 13 having a gasket 11 on the front side, and a hexagonal portion for fitting a plug wrench. 14 and. 141 is a packing,
142 and 143 are rings and 144 is talc.

The insulator 2 is made of a ceramic sintered body mainly composed of alumina, and is located inside the screw portion 12 and inside the leg portion 22 from the hexagonal portion 14 of the metal shell 1 to the inside of the body portion 13. Large diameter part 23 and corrugation 2 on the outer circumference
41 are formed. A shaft hole 21 is formed along the axis of the insulator 2. The diameter of the shaft hole 21 located between the head portion 24 and the large diameter portion 23 is large (φ
The diameter of the shaft hole 21 formed in 4.5) and located in the leg long part 22 is set slightly larger than the center electrode diameter (φ2.6).

The terminal electrode 3 is formed of low carbon steel (nickel plating on the surface) and is sealed with glass in the shaft hole 21 and a terminal portion 32 protruding from the head end surface 242 of the insulator 2. , And a rod-shaped portion 33 that connects the terminal portion 32 and the seal portion 31.

The terminal portion 32 has a small diameter at its central portion in order to prevent the plug cap in the fitted state from coming off. The outer periphery of the seal portion 31 is processed into a screw or knurled shape, and is sealed in the shaft hole 21 by the seal glass 5.

The center electrode 4 includes a nickel alloy sheath material,
It is made of a core material (a good heat conductive metal such as copper) enclosed in the sheath material, and is fitted in the shaft hole 21 so that the tip portion 42 projects from the insulator tip surface 221 and the base portion 41 is sealed. It is sealed in the shaft hole 21 through the glass 6.

The seal glasses 5 and 6 are electroconductive glass powder obtained by mixing (1: 1) copper powder and glass powder, and are electrically conductive, and have electroconductivity. Then, the center electrode 4 is electrically connected to the terminal electrode 3 through the seal glass 6 → the resistor 7 described later → the seal glass 5.

The resistor material composition (granulated product) of the resistor 7 is manufactured as follows. (1) Weigh ZrO ₂ (particle size 5 μm or less), carbon black (primary particle size 0.5 μm or less, secondary particle size 150 μm or less), metallic aluminum (particle size 50 μm), and fine glass, and use a vibration mill. A resistance material is manufactured by dry grinding and mixing (5 hours). (2) The resistance material and the glass raw materials (aggregates; samples No. 1 to No. 5) having the particle sizes shown in Table 1 are in a weight ratio of 30: 7.
It is weighed to about 0, an appropriate amount of 4% aqueous solution of PVA binder is added, and mixed by a mixer for a predetermined time to prepare. In addition, the above predetermined time was set to 2 hours, which is stricter than the usual mixing time (several tens of minutes), in order to make an acceleration test condition in which the resistance material is easily separated from the aggregate during granulation.

[0021]

[Table 1]

The glass sealing of the terminal electrode 3 and the center electrode 4 is performed as follows. (1) With the insulator 2 fixed such that the long leg 22 is on the lower side, the center electrode 4 is fitted from the shaft hole 21 on the head 24 side of the insulator 2 and locked to the step seat 222. 42 is projected from the tip end surface 221 of the insulator 2.

(2) Insulator 2 with the long leg portion 22 facing downward
With the fixed, the conductive glass powder (seal glass 6
A suitable amount of the resistance material composition (which becomes the resistor 7) is adjusted to 0.
An appropriate amount of 5 g of conductive glass powder (which will become the seal glass 5) is sequentially poured into the shaft hole 21 on the head 24 side of the insulator 2. (3) With the insulator 2 fixed so that the long leg 22 is on the lower side, the terminal electrode 3 is attached to the shaft hole 21 from the head 24 side of the insulator 2.
Fit inside.

(4) Insulator 2 so that the long leg portion 22 faces downward
Insulation 2 is heated at 900 ° C. for 20 minutes (the conductive glass powder and the resistance material composition are melted), and the terminal electrode 3 is pressed while applying a downward force to the terminal 32, The bottom surface of 32 is brought into contact with the head end surface 242 of the insulator 2.

(5) The insulator 2 is cooled to solidify the molten seal glass or the like, and the glass sealing of the terminal electrode 3 and the center electrode 4 is completed. In addition, the insulator 2 with the glass seal completed is fitted into the metal shell 1 through the packing 141, the rings 142, 143 and the talc 144 are loaded, and the metal fitting 1 is tightened by crimping the caulking portion 145. It can be assembled.

Next, each sample No. The evaluation of each spark plug with resistance manufactured by using the resistance material composition will be described. Sample No. A spark plug P with resistance (invention product) manufactured using the resistance material compositions of 1, 2, and 3 (100 pieces each), and Sample No. The resistance value of each spark plug (comparative product) manufactured by using the resistance material composition of 4 and 5 (100 pieces each) was measured, and the resistance value 3σ was calculated after confirming an average of 5 kΩ. did.
No. The aggregate particle size distribution σ of the aggregates of the resistance material compositions 1 to 5 was measured.

A load life test was conducted on 10 randomly selected wires out of 100 wires in accordance with JIS B8031-1995, and the load life change rate (shown in Table 1).
I asked. Further, a load life test was conducted by extending the time for 50 hours and the load life change rate (shown in Table 1) was obtained.

Next, sample No. The advantages of the spark plug P with resistance manufactured by using the resistance material compositions 1, 2, and 3 will be described. [A] Since the maximum particle size of the aggregate (borosilicate glass) of the resistance material composition is 150 μm or less, the aggregate particle size distribution σ
Becomes smaller (aggregate grain size σ ≦ 55 μm), and even if the resistance material is separated from the aggregate, the separated resistance material is difficult to separate from the resistance material composition, and segregation of the resistance material can be prevented. Therefore,
The conductive material in the resistance material can be prevented from burning, the resistance value of the resistor 7 does not fluctuate little, and the resistance spark plug P exhibits stable load life characteristics (see Table 1).

[B] Since the aggregate is glass (borosilicate glass), the workability of the glass seal is good, and the terminal portion 3
When the terminal electrode 3 is pressed while applying a downward force to the terminal 2, the terminal portion 32 does not float up, and damage to the insulator 2 can be prevented.

Next, a second embodiment of the present invention (claim 1,
(Corresponding to 3 and 4) will be described. Sample No. 6-No.
Method for manufacturing a spark plug Q with resistance (invention product) that employs any one of the resistance material compositions of 8 (including glass seal)
And the structure are the same as those of the spark plug P with resistance (other than the items described below). The sample No. A spark plug with resistance (comparative product) that employs a resistance material composition of 9, 10 also has the same structure.

The resistance material composition (granulated product) of the resistor 7 is prepared as follows. ZrO ₂ (particle size 5 μm or less), carbon black (primary particle size 0.5 μm or less,
Secondary particle size 150 μm or less), metallic aluminum (particle size 50 μm), and fine glass are weighed, and 5 with a vibration mill.
The resistance material is manufactured by Hr dry pulverization and mixing.

A glass / alumina raw material (aggregate; sample No. 6 to No. 6) having the above-mentioned resistance material and the particle sizes shown in Table 2 was used.
8) and 8) are weighed at a weight ratio of about 30:70, an appropriate amount of a 4% PVA binder aqueous solution is added, and mixed for a predetermined time with a mixer to prepare. For the same reason, the above predetermined time was set to 2 hours, which was stricter than the normal mixing time (tens of minutes).
The glass / alumina raw material is a mixture of lithium borosilicate glass and alumina powder having the same particle size distribution in a ratio of 3: 1.

[0033]

[Table 2]

Next, each sample No. The evaluation of each spark plug with resistance manufactured by using the resistance material composition will be described. Sample No. Spark plug Q with resistance manufactured by using 6 to 8 resistance material compositions (100 pieces each)
(Invention product), and Sample No. The resistance value of each spark plug (comparative product) manufactured using the resistance material composition of 9, 10 (100 pieces each) was measured, and the resistance value 3σ was calculated after confirming an average of 5 kΩ. did.
No. The aggregate particle size distribution σ of the aggregate of the resistance material composition of 6 to 10 was measured.

A load life test was conducted on 10 randomly selected wires out of 100 wires in accordance with JIS B8031-1995 and the load life change rate (shown in Table 2).
I asked. Further, a load life test was conducted by extending the time for 50 hours and a load life change rate (shown in Table 2) was obtained.

Next, sample No. The advantages of the spark plug P with resistance manufactured by using the resistance material compositions 6, 7, and 8 will be described. [C] Since the maximum particle size of the aggregate (borosilicate glass + alumina) of the resistance material composition is 150 μm or less, the aggregate particle size distribution σ becomes small (aggregate particle size distribution σ ≦ 55 μ
m), even if the resistance material is separated from the aggregate, the separated resistance material is difficult to separate from the resistance material composition, and segregation of the resistance material can be prevented. Therefore, the conductive material in the resistance material can be prevented from being burnt down, the resistance value of the resistor does not fluctuate, and the spark plug Q with resistance exhibits stable load life characteristics (see Table 2).

[D] Since the aggregate of the resistor material composition is borosilicate glass and alumina, the effective resistor length can be long, which is advantageous in preventing the generation of radio noise.

The present invention includes the following embodiments in addition to the above embodiments. a. In addition to borosilicate glass, the glass raw material may be barium borate glass, lithium borate-calcium glass, or the like.

B. The heating temperature and heating time at the time of glass sealing may be appropriately determined according to the glass material and the like. For example, 800 ° C to 950 ° C, 5 minutes to 40 minutes. c. The ceramic powder used for the aggregate may be a ceramic powder other than alumina. d. The mixing time of the mixer at the time of preparing the resistance material composition may be appropriately determined. For example, 2 minutes to 2 hours

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a spark plug with a resistor employing a resistor composition of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal shell 2 Insulator 3 Terminal electrode 4 Center electrode 5 and 6 Seal glass 7 Resistor 21 Shaft hole 31 Seal part 41 Rear end part (base part) 221 Insulator tip surface P, Q Spark plug with resistance

Claims (4)

[Claims] 1. A tubular metal shell, an insulator with a shaft hole fixed in the metal shell, a terminal electrode inserted into the shaft hole of the insulator, and fixed in the shaft hole. A central electrode, a conductive electrode sealing glass that seals the terminal electrode sealing portion and the central electrode base portion in the shaft hole, respectively, and between the sealing glass, the aggregate and the resistance material. A spark plug with resistance, comprising: a resistor obtained by melting and solidifying a mixture with the spark plug with resistance, wherein the maximum particle diameter of the aggregate is 150 μm or less. 2. The resistance-filled spark plug according to claim 1, wherein the aggregate is glass. 3. The spark plug with resistance according to claim 1, wherein the aggregate is a mixture of glass and ceramic powder. 4. The spark plug with resistance according to claim 1, wherein a particle size distribution of the aggregate is σ = 55 μm or less.