Spark plug production method, spark plug production device and assembly inspection method

Patent metadata

Field	Value
Publication number	US-10270229-B2
Application number	US-201615557847-A
Country	US
Kind code	B2
Filing date	Mar 17, 2016
Priority date	Mar 18, 2015
Publication date	Apr 23, 2019
Grant date	Apr 23, 2019

Abstract

A method of producing a spark plug comprises (a) a step of combining a metallic shell and an insulator; (b) a step of inserting a portion of the assembly on its forward end side into a pressure container; (c) a step of bringing an insulating member into contact with the outer circumferential surface of a base side portion of the insulator over the entire circumference thereof, and pressing the assembly so as to close the opening by the assembly; and (d) a step of pressurizing the interior of the pressure container and applying a predetermined voltage between the terminal electrode and the metallic shell, wherein the step (b) includes a step of inserting the portion of the assembly on the forward end side into the pressure container such that a gap formed between the outer surface of the insulator and the inner surface of the metallic shell on the forward end side of the assembly is disposed in the pressure container.

First claim

Having described the invention, the following is claimed:

1. A method of producing a spark plug comprising:
(a) a step of combining a tubular metallic shell and an insulator such that the metallic shell covers an outer circumferential surface of a forward end side of the insulator so as to obtain an assembly, the metallic shell having a ground electrode at its forward end portion, the insulator having an axial hole and holding a terminal electrode in the axial hole such that a portion of the terminal electrode on its base end side is exposed from the axial hole;
(b) a step of inserting a portion of the assembly on its forward end side into a pressure container through an opening of the pressure container;
(c) a step of bringing an insulating member into contact with an outer circumferential surface of a base end side of the insulator over the entire circumference of the base end side in a state in which an axial line of the assembly and an axial line of the opening coincide with each other, and pressing the assembly so as to close the opening by the assembly; and
(d) a step of pressurizing an interior of the pressure container and applying a predetermined voltage between the terminal electrode and the metallic shell,
wherein the step (b) includes a step of inserting the portion of the assembly on the forward end side into the pressure container such that a gap formed between an outer circumferential surface of the insulator and an inner circumferential surface of the metallic shell on the forward end side of the assembly is disposed in the pressure container.

2. A method of producing a spark plug according to claim 1 , wherein the step (c) includes a step of bringing the assembly into close contact with the pressure container in the direction of the axial line of the assembly through a seal provided around the opening.

3. A method of producing a spark plug according to claim 1 , further comprising (e) a step of photographing or observing the terminal electrode and the metallic shell applied with the predetermined voltage from a position on the pressure container opposite the opening.

4. A method of producing a spark plug according to claim 1 , wherein the step (c) includes a step of bringing an electrically conductive member into contact with a base end portion of the terminal electrode, the electrically conductive member being used for applying the predetermined voltage.

5. A method of producing a spark plug according to claim 4 , wherein the step (c) includes a step of pressing the metallic shell, along the axial line of the assembly, in a direction from a base end toward a forward end of the assembly to thereby close the opening by the assembly.

6. A method of producing a spark plug according to claim 4 , further comprising (f) a step of, after the step (d), displacing at least one of the electrically conductive member and the insulating member such that the insulating member relatively moves, along the axial line of the assembly, in relation to the insulator in a direction from a forward end toward a base end of the assembly.

7. A method of producing a spark plug according to claim 6 , wherein the step (f) is performed by causing the electrically conductive member to press the terminal electrode, along the axial line of the assembly, in the direction from the base end toward the forward end of the assembly and displacing the insulating member in the direction from the forward end toward the base end of the assembly.

8. A method of producing a spark plug according to claim 1 , wherein the step (c) includes a step of fitting the insulating member onto the terminal electrode from a base end side of the terminal electrode and pressing the insulating member, along the axial line of the assembly, toward the forward end side of the assembly, to thereby bring the insulating member into close contact with at least either of an outer circumferential surface of the terminal electrode and an outer circumferential surface of a base end side of the insulator.

9. A method of producing a spark plug according to claim 1 , wherein the step (d) includes a step of bringing an earthing electrode into contact with the metallic shell on a base end side of the assembly in relation to a seat surface of the metallic shell, the seat surface closing the opening and maintaining a gas tightness of the pressure container.

10. A method of producing a spark plug according to claim 1 , wherein
the insulator holds a center electrode in a forward end side of the axial hole such that a portion of the center electrode on its forward end side is exposed from the axial hole; and
the method further comprising (g) a step of, after the step (d), bending the ground electrode toward the forward end portion of the center electrode.

11. A method of producing a spark plug according to claim 1 , further comprising (h) a step of, after the step (d), disposing a gasket on the metallic shell at a position located forward of and adjacent to a seat surface of the metallic shell along the axial line of the assembly, the seat surface closing the opening and maintaining a gas tightness of the pressure container.

12. A method of producing a spark plug according to claim 1 , wherein
the pressure container includes the opening as a sole opening; and
the step (b) includes a step of inserting forward-end-side portions of a plurality of the assemblies different from each other into a plurality of the pressure containers.

13. A method of producing a spark plug according to claim 1 , further comprising (i) a step of bringing an earthing electrode into contact with the metallic shell,
wherein the step (c) includes a step of bringing an electrically conductive member into contact with a base end portion of the terminal electrode, the electrically conductive member being used for applying the predetermined voltage, and
wherein at least one of the earthing electrode and the electrically conductive member is chamfered.

Assignees

• Ngk Spark Plug Co

Inventors

• Okuda Masafumi
• Otsuki Toshiyuki
• Nishiyama Kanako

Classifications

• G01N27/205

  in insulating materials · CPC title

• H01T13/60 Primary

  of electrical properties · CPC title

• H01T21/02

  of sparking plugs · CPC title

• F02P17/12

  Testing characteristics of the spark, ignition voltage or current (testing of sparking plugs H01T13/60) · CPC title

• H01T13/36

  characterised by the joint between insulation and body, e.g. using cement · CPC title