JPH1032077A - Spark plug installing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the igniting performance of a spark plug, resistance against contamination and breakage, and the yield from the production line by confirming each spark gap formation, etc., simply and accurately in the process of installing an insulator in a metal body. SOLUTION: When an insulator 2 retaining a center electrode 3 is to be installed in a metal body 5 to constitute a single piece structure with an outside electrode 6, each spark gap 7 bounded by the outside electrode 6 and the foremost periphery of the center electrode 3 or insulator 2 is along with its dimension confirmed by an image processing device which incorporates a camera 10, and if the spark gap 7 is positioned outside the set range, the distance of each spark gap 7 is adjusted into the specified dimension by rotating or changing the insulator 2 appropriately, and thereby the correcting work for the spark gap thereafter is lessened and their heights are made even, which should lead to enhancement of the igniting performance and the resistance against contamination and breakage, and an optimum combination of insulator 2 and metal body 5 is obtained, so that it is possible to heighten the yield from the production line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a spark gap between a center electrode held in a shaft hole of an insulator or an outer periphery of a tip of the insulator and one or more outer electrodes integrated with a metal shell. The present invention relates to a method for assembling a spark plug that forms

[0002]

2. Description of the Related Art Conventionally, a set of a metal shell and an insulator in a multipolar spark plug in which a plurality of spark gaps are formed between a center electrode held by the insulator and a plurality of outer electrodes integrated with the metal shell. In the attaching step, the center electrode held by the insulator is somewhat eccentric due to the eccentricity of the molded body itself before firing generated in the insulator or the curvature due to firing, and the metal shell itself is also eccentric due to punching, It is normal that the center axis is somewhat eccentric, and even when such an insulator holding the center electrode and the metal shell are assembled, the spark gap formed between the center electrode and the plurality of outer electrodes is still small. It rarely coincides with the originally designed numerical value (Japanese Patent Application Laid-Open No. 51-95441), so that a spark formed between a plurality of outer electrodes and a center electrode of a metal shell is formed. A spacer is sandwiched between the plurality of outer electrodes and the center electrode so that the gap has a predetermined size, and a minimum eccentricity correction is performed. -37773
No.) is commonly performed.

[0003]

However, in the case of the above-described conventional manufacturing method, generally, an outer electrode integrated with the metal shell, a tip end surface of an insulator inserted into the metal shell, and Since the positional relationship with the held center electrode greatly affects the ignitability of the air-fuel mixture and the anti-fouling property against carbon generated by the ignition of the air-fuel mixture, the insulator that holds the center electrode with respect to the metal shell is required. In assembling, by making the plurality of spark gaps formed between the center electrode and the plurality of outer electrodes integrated with the metal shell as uniform as possible,
Even after correcting the spark gap, it is required to make the protrusion amount of the outer electrode uniform, but at the time of assembling the insulator holding the center electrode to the metal shell,
When the correction amount of the plurality of spark gaps formed by the center electrode held by the insulator and the outer electrode integrated with the metal shell becomes larger, the protrusion amount of the outer electrode after the correction of the spark gap amount becomes larger. The spark plug may be non-uniform, and may have an adverse effect on the ignitability and stain resistance of the spark plug as described above.

Further, like a semi-surface discharge type spark plug, a surface discharge along an insulator front end surface between an insulator holding a center electrode and an outer electrode integrated with a metal shell, and an insulator In the case of forming a spark gap that discharges in the air between the outer periphery of the tip and the outer electrode, the insulator itself holding the center electrode is brittle, so that the gap adjustment by machining is extremely difficult. Therefore, it is inevitable to rely on manual work, and considering the prevention of damage to the insulator by adjusting the gap and the low workability by manual work, the center electrode is integrated with the metal shell integrated with the outer electrode. The smaller the amount of adjustment in the spark gap formed by the outer periphery of the tip of the insulator and the outer electrode during the process of assembling the insulator holding the smaller, the smaller the more it is desirable.

[0005] Therefore, in a spark plug once assembled as a product, a spark gap formed by a front end face of a center electrode held by an insulator fixed in a metal shell and an outer electrode integrated with the metal shell. (Japanese Patent Publication No. Hei 6-58820) has been proposed, but it is only a fine adjustment for a spark plug completed as a product. If the adjustment amount of the spark gap is outside the allowable range, it cannot be adjusted and must be eliminated as a defective product, and the outer electrode is vertically deformed by mechanical pressing to adjust the spark gap. Therefore, in a multipolar spark plug having a plurality of outer electrodes, it is difficult to use an image processing system, and workability is extremely low. It is those that result in.

Accordingly, the present invention has been made to solve the above-mentioned conventional problems, and is intended to improve the yield as a product and to manufacture a multi-polar spark plug having an appropriate spark gap by using an image processing system. It is to be.

[0007]

For this purpose, the outer electrode integrated with the metal shell and the center electrode or the outer periphery of the distal end of the insulator protruded from the front end face into the shaft hole of the insulator. In an assembling step of a spark plug for forming one or a plurality of spark gaps, an insulator is inserted into a metal shell, and the center electrode or the outer periphery of the distal end of the insulator held in a shaft hole of the insulator is connected to the main body. That a spark gap was formed between the metal fitting and the outer electrode integrated with the metal fitting,
In the confirmation of the formation of the spark gap and the confirmation of the formation of the spark gap, when the average value of the distances of the plurality of spark gaps is α, the distance of the plurality of spark gaps is within the average value α ± 20%. While confirming this by the spark gap detecting means by image processing using a camera from the firing part side, the insulator is assembled in the metal shell by the fixing means.

Further, when the insulator for holding the center electrode inserted in the metal shell in the shaft hole is temporarily pressed for image processing for confirming the formation of the spark gap, the insulator is used. Is performed by temporary holding packing made of iron or aluminum, and the confirmation of the formation of the spark gap by the center electrode and the plurality of outer electrodes by the image processing is performed. In the confirmation of the distance between the plurality of spark gaps, the center electrode inserted into the metal shell is held in the shaft hole in order to keep the distance between the spark gaps within the average value α ± 20%. If the average value is other than α ± 20%, adjust the insulator by holding the center electrode inserted in the metal shell in the shaft hole. It is changed to an insulator.

[0009] In the punching diameter D (mm) of the arc surface of the outer electrode which is the discharge surface coaxial with the center electrode, the diameter of the center electrode is d, and the distance of the spark gap of the finished product is g.
(Mm), D = ｛(g + 0.1) × 1.2 ×
After the step of assembling the insulator holding the center electrode with respect to the metal shell, the distance between the plurality of spark gaps is adjusted to g ± 0.1.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In practicing the present invention,
Formation of a spark gap between the center electrode or outer periphery of the distal end of the insulator which is inserted into the metal shell and held by the insulator, and the outer electrode integrated with the metal shell, and confirmation of the formation of this spark gap At the same time, while confirming that the distance of the spark gap is within a predetermined dimension by the spark gap detecting means by image processing using a camera from the firing part side, the insulator is assembled into the metallic shell by fixing means such as caulking. By performing the attachment, even in the fine adjustment of the spark gap after the product is completed as a spark plug, the unevenness of the height due to the correction of the bending or the like of the outer electrode can be suppressed to a minimum. Height can be made uniform.

Further, in order to confirm the formation of the spark gap by the center electrode and the plurality of outer electrodes by the spark gap detecting means by image processing using a camera, and to keep the average value of the distance between the plurality of spark gaps within a predetermined dimension. By rotating the insulator holding the center electrode inserted in the metal shell in the shaft hole, the insulator is adjusted, or otherwise, the shaft electrode is inserted in the metal shell. By changing the insulator holding the center electrode with another insulator, the combination of the insulator holding the center electrode and the metal shell integral with the outer electrode forming a proper spark gap without waste can be obtained. It is possible to easily and reliably select and combine them, and it is also possible to improve the yield of products as spark plugs. In particular, assuming that the diameter of the center electrode is d and the distance of the spark gap of the finished product is g (mm), D = D in the punching diameter D (mm) of the arc surface of the outer electrode which is the discharge surface coaxial with the center electrode.
After {(g + 0.1) × 1.2 × 2 + d}, after the step of assembling the insulator holding the center electrode to the metal shell, the distance between the plurality of spark gaps is adjusted to g ± 0.1. Therefore, the spark gap can be easily corrected.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and 2 show an insulator (2) which holds a center electrode (3) constituting a multipolar spark plug (1) in a shaft hole (21) so as to protrude from a tip surface (22).
In the metal shell (5) integrated such that the plurality of outer electrodes (6) face the outer periphery (31) of the center electrode (3) protruding from the end surface (54), the plurality of spark gaps are formed. In fixing to form (7), the insulator (2) projecting from the tip and holding the center electrode (3) is attached to the metal shell (4) integrated with the plurality of outer electrodes (6). 5) The seating surface (23) is inserted into the step (55) via the packing (15), and is temporarily pressed by the packing holding jig (13) by the temporary holding packing (8). Filling (9) and crimping jig (14)
Thus, the upper end portion (56) of the metal shell (5) is subjected to an assembling process by fixing means for caulking inward.

The metal shell (5) is made of low-carbon steel by cold forging, has a cylindrical shape, and has a screw portion (51), a large-diameter body portion (52) and a hexagonal portion (53) on the outer periphery of the tip. Further, a wire of Ni alloy is protruded from the distal end surface (54) by resistance welding so as to face the distal end, and the distal end portion is bent inward. Then, the outer periphery (31) of the distal end of the center electrode (3) is formed. ) To form a spark gap, a coaxial arc surface (6
1). Outer electrode (6) punched out of (61).
(6) is formed.

The insulator (2) is made of an alumina sintered body containing alumina as a main component, and has a center electrode (3) projecting from a tip surface (22) in a shaft hole (21). The glass seal is integrally sealed with the terminal electrode (4) via a conductive glass seal material and a resistor. In addition, the insulator (2) has a leg (25), a middle body (26), a large-diameter body (27) and a corrugation which are exposed to the combustion chamber via the seat surface (23) on the tip side. It has the shape of a head (28).

In the method of manufacturing a multi-polar spark plug according to an embodiment of the present invention, as shown in FIG. 3, the multi-polar spark plug (1) is inserted into the metal shell (5) in the assembling step. A spark gap (7) is formed between a center electrode (3) held in a shaft hole (21) of the fitted insulator (2) and a plurality of outer electrodes (6) integrated with the metal shell (5). ) Has been formed and the formation of the spark gap (7) has been confirmed, and when the average value of the distances of the plurality of spark gaps (7) has been set to α together with the confirmation of the formation of the spark gap (7), It is confirmed by the spark gap detecting means, that is, the image processing apparatus (A) using the camera (10) from the firing part (11) that the distance between the plurality of spark gaps (7) is within the average value α ± 20%. After doing Clamping jig (14) caulked upper end portion of the metal shell (5) and (56) inwardly by those comprising performing assembled thin portion (57) is plastically deformed.

Since the method of manufacturing the multipolar spark plug according to the embodiment of the present invention is as described above, after the product as the multipolar spark plug (1) is completed, the insulator (2) is used.
In the fine adjustment of the distance of the spark gap (7) formed by the center electrode (3) held by the metal shell and the plurality of outer electrodes (6) integrated with the metal shell (5), the metal shell (5) is also used. Since the unevenness of the height of the outer electrode (6) caused by the correction of the bending or the like of the outer electrode (6) integrated with the outer electrode (6) can be minimized, the height of the outer electrode (6) can be reduced. By making the spark plug as uniform as possible, it is possible to improve the ignitability and the stain resistance of the spark plug.

Further, in the embodiment of the method for manufacturing a multipolar spark plug, the insulator (2) for holding the center electrode (3) inserted in the metal shell (5) in the shaft hole (21).
Is temporarily pressed for image processing by the camera (10) for confirming the formation of the spark gap (7).
The temporary holding member (12) made of iron or aluminum is used to hold the temporary holding member (12).
Spark gap (7) having an appropriate size by image processing by camera (10) by crushing
The positioning of the insulator (2) to be inserted into the metal shell (5) in which the formation of the powder (9) is confirmed can be performed after the powder (9) is filled and assembly processing such as crimping is performed. Failure due to swinging of the insulator (2) in the metal shell (5) can be prevented.

Further, the center electrode (3) held on the insulator (2) by the image processing by the camera (10).
And a plurality of outer electrodes (6) integrated with the metal shell (5)
When the average value of the distances of the plurality of spark gaps (7) is set to α together with the confirmation of the formation of the spark gaps (7), the individual spark gaps (7 In order to keep the distance of ()) within the average value α ± 20%, the insulator (2) holding the center electrode (3) inserted in the metal shell (5) in the shaft hole (21) is rotated. Or average value α ± 2
If it is other than 0%, the insulator (2) holding the center electrode (3) in the shaft hole (21) inserted into the metal shell (5) is replaced with another insulator (2 '). ), An insulator (2) holding a center electrode (3) that forms an appropriate spark gap (7) without waste, and a metal shell integral with the outer electrode (6). The combination with (5) can be easily and reliably selected and combined, and the product yield as the spark plug (1) can be improved.

In particular, assuming that the diameter of the center electrode is d and the distance of the spark gap of the finished product is g (mm) in the punching diameter D (mm) of the outer electrode, D = ｛(g + 0.1)
× 1.2 × 2 + d｝, and after the step of assembling the insulator holding the center electrode to the metal shell, the distance between the plurality of spark gaps is adjusted to g ± 0.1. , Metal shell (5) of insulator (2) such as caulking
If the spark gap (7) after completion of the assembling process is less than the range set as the finished product, the outer electrode (6) integrated with the metallic shell (5) is used to correct the spark gap (7). It is necessary to correct the spark gap (7) due to the cause, and it becomes difficult to correct the spark gap (7) by machining. On the other hand, if the spark gap (7) is out of the set range, the height of the outer electrode (6) integrated with the metal shell (5) is insufficient. By defining the dimensions in this way, the modification of the spark gap (7) can be made easier and more accurate, since it becomes uniform and poses a problem for the ignitability of the mixture or the resistance to fouling.

The method of manufacturing a multipolar spark plug according to an embodiment of the present invention is particularly directed to an insulator (2) holding a center electrode (3) and an outer electrode (6) integrated with a metal shell (5). ) And the spark gap (7) is an insulator (2)
And a semi-surface discharge type spark plug (100) which forms a surface discharge along the front end surface (22) and an air discharge (g) between the outer periphery (24) of the front end of the insulator (2) and the outer electrode (6) [ 5 (a)] and an insulator (2) between an annular electrode (12) integrally formed at the tip of the metal shell (5) and a center electrode (3) held by the insulator (2). (2)
This is also effective in a full surface discharge type spark plug (200) formed with a spark gap (7) along 2) (see FIG. 5B). In particular, in the case of the semi-surface discharge type spark plug (100), the air discharge gap (g) between the outer periphery (24) of the distal end of the insulator (2) and the discharge surface (61) of the outer electrode (6) is set. The insulator (2) is assembled in the metal shell (5) while confirming by image processing.

In the above embodiment, the means for fixing the insulator (2) in the metal shell (5) is so-called powder caulking, in which the powder (9) is filled and caulked. Without being limited to the above, the thin portion (57) of the metal shell (5) is heated without filling with the powder (9), and the upper end portion (56) of the metal shell (5) is crimped inward. So-called heat crimping can be used.

[0022]

As described above, when assembling the insulator holding the center electrode into the metal shell integrated with the outer electrode, the existence and dimensions of the spark gap formed by the center electrode and the plurality of outer electrodes are provided. By using image processing with a camera to confirm that the spark plug is ignitable and fouling resistant, the insulator holding the center electrode is rotated or changed so as to have an appropriate spark gap. This has an excellent effect that the yield as a product can be significantly improved while improving the yield.

[Brief description of the drawings]

FIG. 1 is a view showing a state in which an insulator is inserted into a metal shell in a method of manufacturing a multipolar spark plug according to an embodiment of the present invention.

FIG. 2 is a view showing a method for manufacturing a multipolar spark plug according to an embodiment of the present invention.

FIG. 3 is a diagram showing a method for manufacturing a multi-polar spark plug by image processing according to an embodiment of the present invention.

FIG. 4 is a diagram of image processing by a camera used in a method of manufacturing a three-pole spark plug according to an embodiment of the present invention.

FIG. 5A is a front view of a semi-surface discharge spark plug manufactured by the method for manufacturing a multipolar spark plug according to the embodiment of the present invention, and FIG. It is sectional drawing of a surface discharge type spark plug.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multi-polar spark plug 2 Insulator 3 Center electrode 5 Metal shell 6 Outer electrode 7 Spark gap 8 Temporary holding packing 9 Powder 10 Camera 11 Firing part 12 Ring electrode 13 Packing holding jig 14 Caulking jig 15 Packing 21 Shaft hole 22 Tip Surface 23 Seating surface 24 Tip outer periphery 54 Tip end surface 55 Step 56 Upper end 61 Discharge surface of outer electrode 100 Semi-surface discharge spark plug 200 Full surface discharge spark plug

Claims (6)

[Claims] 1. A plurality of spark gaps are formed between an outer electrode integrated with a metal shell and a center electrode or an outer periphery of a distal end of the insulator protruding from a distal end surface into a shaft hole of the insulator. In the spark plug assembling step, an insulator is inserted into the metal shell, and the outer electrode integrated with the center electrode or the outer periphery of the insulator tip and the metal shell held in a shaft hole of the insulator. Assembling of a spark plug that attaches the insulator to the metallic shell by fixing means while confirming that the spark gap has been formed by the spark gap detecting means by image processing from the ignition part side Method. 2. In the confirmation of the formation of a plurality of spark gaps by the center electrode and the plurality of outer electrodes by the image processing, when the formation of the spark gaps is confirmed and the average value of the distances of the plurality of spark gaps is α. , The distance between these spark gaps is an average value α ± 20%
2. The method for assembling a spark plug according to claim 1, further comprising, after confirming that the temperature is within the range, temporarily holding down the insulator, and then crimping the upper end of the metal shell inward. 3. An average value of the distances of the plurality of spark gaps, which is determined together with the confirmation of the formation of the spark gaps by the image processing, is α, and the confirmation of the distances of the plurality of spark gaps is not an average value α ± 20%. 3. The method for assembling a spark plug according to claim 1, wherein, in the case, the insulator formed by holding the center electrode inserted into the metal shell in the shaft hole is replaced with another insulator. 4. An insulator for holding a center electrode inserted in a metal shell in a shaft hole and temporarily holding the insulator for image processing for confirming formation of a spark gap. 3. The method for assembling a spark plug according to claim 1, wherein the temporary holding is performed by temporary holding packing made of iron or aluminum. 5. A method of confirming the formation of a spark gap by a center electrode and a plurality of outer electrodes by the image processing and confirming the distance of the plurality of spark gaps by setting an average value of the distances of the plurality of spark gaps to α. 3. The method according to claim 1, wherein the distance between the spark gaps is within an average value .alpha .. ± .20% by rotating an insulator that holds the center electrode inserted into the metal shell in the shaft hole.
And a method for assembling the spark plug according to 3. 6. In the punching diameter D (mm) of the arc surface of the outer electrode which is between the discharge coaxial with the center electrode, the diameter of the center electrode is d, and the distance of the spark gap of the finished product is g (mm).
D = {(g + 0.1) × 1.2 × 2 + d}
The distance between the plurality of spark gaps is adjusted to g ± 0.1 after the step of assembling the insulator holding the center electrode with respect to the metallic shell.
Assembling method of the described spark plug.