JP2015056258A - Method of manufacturing spark plug, and spark plug - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an appropriate gap of a spark plug having a sub-combustion space.SOLUTION: A spark plug has a center electrode extending in the axial direction, an insulator having a shaft hole extending in the axial direction, and provided with a center electrode on the tip side of the shaft hole, a main metal fitting arranged on the outer periphery of the insulator, and a cap member having a ground electrode arranged via a gap for the side face of the center electrode, fixed to the tip of the main metal fitting and forming a sub-combustion chamber in conjunction with the main metal fitting. When manufacturing such a spark plug, relative position of the cap member and the center electrode is fixed, while arranging a gap formation member for forming a gap between the side face of the center electrode and the ground electrode. The cap member may have a first member and a second member. The first member is a member having the ground electrode, and a fixing portion being fixed to the tip of the main metal fitting. The second member is a member being fixed to the first member.

Description

  The present invention relates to a spark plug manufacturing method and a spark plug.

  Conventionally, spark plugs have been used in internal combustion engines. For example, a gasoline engine or a gas engine is used as the internal combustion engine. As a spark plug, for example, a spark plug having a sub-combustion space has been proposed (see Patent Document 1). According to the proposed technique, the sub-combustion space is formed by the metal shell and a cap fixed to the tip of the metal shell. The cap is provided with a hole that communicates the auxiliary combustion space with the outside. The air-fuel mixture is introduced into the auxiliary combustion space through the hole of the cap. A center electrode and a ground electrode are disposed in the auxiliary combustion space. Sparks generated in the gap formed by the center electrode and the ground electrode ignite the air-fuel mixture introduced into the auxiliary combustion space. Then, the air-fuel mixture in the combustion chamber is combusted when the flame is ejected to the outside, that is, the combustion chamber of the internal combustion engine through the hole of the cap.

US Pat. No. 1,538,750

  In order to appropriately generate the spark, it is preferable to realize an appropriate gap. However, when the center electrode and the ground electrode are arranged in the sub-combustion space, it is difficult to adjust the relative position between the center electrode and the ground electrode, and an appropriate gap may not be realized.

  The main advantage of the present invention is to achieve a proper gap in the spark plug having a secondary combustion space.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following application examples.

[Application Example 1]
A central electrode extending in the axial direction;
An insulator having an axial hole extending in the axial direction and having the central electrode disposed on a distal end side of the axial hole;
A metal shell disposed on the outer periphery of the insulator;
A cap member that has a ground electrode disposed through a gap between the side surface of the center electrode and the metal shell and is fixed to a tip of the metal shell, and forms a sub-combustion chamber together with the metal shell;
A spark plug manufacturing method comprising:
A first step of fixing a relative position between the cap member and the center electrode in a state where a gap forming member for forming the gap is disposed between a side surface of the center electrode and the ground electrode;
Production method.

  According to this configuration, an appropriate gap of the spark plug having the auxiliary combustion chamber can be realized.

[Application Example 2]
A spark plug manufacturing method according to Application Example 1,
The first step includes a step of welding the cap member to the metal shell.

  According to this configuration, an appropriate gap can be realized by welding the cap member to the metal shell while the gap forming member is disposed between the side surface of the center electrode and the ground electrode.

[Application Example 3]
A method of manufacturing a spark plug according to application example 1 or 2,
The cap member is
A first member having the ground electrode, a through-hole penetrating along the central axis, and a fixing portion fixed to a distal end portion of the metal shell;
A second member fixed to the first member;
Have
The first step includes
Fixing the first member to the metal shell in a state where the gap forming member is disposed between a side surface of the center electrode and the ground electrode;
Removing the gap forming member from between the side surface of the center electrode and the ground electrode through the through hole of the first member;
Fixing the second member to the first member after removing the gap forming member;
Manufacturing method.

  According to this configuration, the gap forming member is removed through the through hole of the first member, and the second member is fixed to the first member after the gap forming member is removed, so that an appropriate gap is realized. The degree of freedom in the configuration of the cap member can be improved.

[Application Example 4]
A method for manufacturing a spark plug according to Application Example 1, further comprising:
After the first step, the step of removing the gap forming member by at least one of heating the gap forming member and dissolving the gap forming member in a specific solvent;
Production method.

  According to this configuration, an appropriate gap can be realized.

[Application Example 5]
A method for manufacturing a spark plug according to Application Example 4, further comprising:
Before the first step, the step of preparing a metal member to which the metal shell and the cap member are fixed,
The first step includes a step of assembling the insulator to which the center electrode is fixed and the metal member.
Production method.

  According to this configuration, an appropriate gap can be realized by assembling the metal member and the insulator in a state where the gap forming member is disposed between the side surface of the center electrode and the inner peripheral surface of the ground electrode.

[Application Example 6]
It is a manufacturing method of a spark plug given in any 1 paragraph of application examples 1-5,
The manufacturing method, wherein a gap distance of the gap in a direction perpendicular to the side surface of the center electrode is 0.3 mm or less.

  Thus, even when the gap distance is small, an appropriate gap can be realized.

[Application Example 7]
A spark plug,
A central electrode extending in the axial direction;
An insulator having an axial hole extending in the axial direction and having the central electrode disposed on a distal end side of the axial hole;
A metal shell disposed on the outer periphery of the insulator;
A cap member that has a ground electrode disposed through a gap between the side surface of the center electrode and the metal shell and is fixed to a tip of the metal shell, and forms a sub-combustion chamber together with the metal shell;
Have
The cap member is
A first member having the ground electrode and a fixing portion fixed to the tip of the metal shell;
A second member fixed to the first member;
Having
Spark plug.

  In addition, this invention can be implement | achieved in various aspects, for example, can be implement | achieved in aspects, such as a spark plug, the manufacturing method of a spark plug, and the spark plug manufactured by the manufacturing method.

It is sectional drawing of the spark plug 100 of 1st Embodiment. 2 is a schematic view of the vicinity of a gap g of a spark plug 100 and a cap member 30. FIG. 3 is a flowchart showing an example of a method for manufacturing the spark plug 100. 3 is a flowchart showing an example of a method for manufacturing the spark plug 100. It is the schematic of the spark plug 100z of 2nd Embodiment. It is a flowchart which shows an example of the manufacturing method of the spark plug 100z. It is a flowchart which shows another example of the manufacturing method of the spark plug 100z. It is the schematic which shows another embodiment of a cap member.

A. First embodiment:
A1. Spark plug configuration:
FIG. 1 is a cross-sectional view of the spark plug 100 of the first embodiment. The illustrated line CL indicates the central axis of the spark plug 100. The illustrated cross section is a cross section including the central axis CL. Hereinafter, the central axis CL is also referred to as “axis line CL”, and the direction parallel to the central axis CL is also referred to as “axis line direction”. The radial direction of the circle centered on the central axis CL is also simply referred to as “radial direction”, and the circumferential direction of the circle centered on the central axis CL is also referred to as “circumferential direction”. Of the directions parallel to the central axis CL, the downward direction in FIG. 1 is referred to as a leading end direction D1, and the upward direction is also referred to as a trailing end direction D2. The tip direction D1 is a direction from the terminal fitting 40 described later toward the electrodes 20 and 31a. 1 is referred to as the front end side of the spark plug 100, and the rear end direction D2 side in FIG. 1 is referred to as the rear end side of the spark plug 100.

  The spark plug 100 includes an insulator 10 (also referred to as “insulator 10”), a center electrode 20, a cap member 30, a terminal fitting 40, a metal shell 50, a conductive first seal portion 60, a resistance, The body 70, the electroconductive 2nd seal | sticker part 80, the front end side packing 8, the talc 9, the 1st rear end side packing 6, and the 2nd rear end side packing 7 are provided. The cap member 30 has a ground electrode 31a.

  The insulator 10 is a substantially cylindrical member having a through hole 12 (also referred to as “shaft hole 12”) extending along the central axis CL and penetrating the insulator 10. The insulator 10 is formed by firing alumina (other insulating materials can also be used). The insulator 10 includes a leg portion 13, a first reduced outer diameter portion 15, a distal end side body portion 17, a flange portion 19, and a second reduced outer diameter portion, which are arranged in order from the front end side to the rear end side. 11 and a rear end side body portion 18.

  The flange portion 19 is a maximum outer diameter portion of the insulator 10. The outer diameter of the first reduced outer diameter portion 15 on the front end side with respect to the flange portion 19 gradually decreases from the rear end side toward the front end side. In the vicinity of the first reduced outer diameter portion 15 of the insulator 10 (in the example of FIG. 1, the front end side body portion 17), a reduced inner diameter portion 16 whose inner diameter gradually decreases from the rear end side toward the front end side is formed. Has been. The outer diameter of the second reduced outer diameter portion 11 on the rear end side with respect to the flange portion 19 gradually decreases from the front end side toward the rear end side.

  A center electrode 20 is inserted on the distal end side of the through hole 12 of the insulator 10. The center electrode 20 is a rod-shaped member extending along the center axis CL. The center electrode 20 includes an electrode base material 21 and a core material 22 embedded in the electrode base material 21. The electrode base material 21 is formed using, for example, Inconel (“INCONEL” is a registered trademark) which is an alloy containing nickel as a main component. The core material 22 is formed of a material (for example, an alloy containing copper) having a higher thermal conductivity than the electrode base material 21.

  Focusing on the external shape of the center electrode 20, the center electrode 20 includes a leg portion 25 that forms an end on the front end direction D 1 side, a flange portion 24 provided on the rear end side of the leg portion 25, and a flange portion 24. And a head portion 23 provided on the rear end side. The head portion 23 and the flange portion 24 are disposed in the through hole 12, and the surface of the flange portion 24 on the tip direction D 1 side is supported by the reduced inner diameter portion 16 of the insulator 10. A portion on the distal end side of the leg portion 25 is exposed outside the through hole 12 on the distal end side of the insulator 10.

  A terminal fitting 40 is inserted on the rear end side of the through hole 12 of the insulator 10. The terminal fitting 40 is formed using a conductive material (for example, a metal such as low carbon steel). A metal layer for corrosion protection can be formed on the surface of the terminal fitting 40. For example, the Ni layer is formed by plating. The terminal fitting 40 includes a flange portion 42, a cap mounting portion 41 that forms a portion on the rear end side from the flange portion 42, and a leg portion 43 that forms a portion on the front end side from the flange portion 42. The cap mounting portion 41 is exposed outside the through hole 12 on the rear end side of the insulator 10. The leg 43 is inserted into the through hole 12 of the insulator 10.

In the through hole 12 of the insulator 10, a resistor 70 for suppressing electrical noise is disposed between the terminal fitting 40 and the center electrode 20. The resistor 70 includes glass particles (for example, B ₂ O ₃ —SiO ₂ glass) as main components, ceramic particles other than glass (for example, TiO ₂ ), and a conductive material (for example, a metal such as Mg). And carbon particles).

  In the through hole 12, the first seal portion 60 is disposed between the resistor 70 and the center electrode 20. A second seal 80 is disposed between the resistor 70 and the terminal fitting 40. As a result, the center electrode 20 and the terminal fitting 40 are electrically connected through the resistor 70 and the seal portions 60 and 80. The seal portions 60 and 80 include, for example, glass particles similar to the resistor 70 and metal particles (Cu, Fe, etc.). By using the seal portions 60 and 80, the contact resistance between the stacked members 20, 60, 70, 80, and 40 is stabilized, and the resistance value between the center electrode 20 and the terminal fitting 40 can be stabilized. .

  The metal shell 50 is a substantially cylindrical member having a through hole 59 extending along the central axis CL and penetrating the metal shell 50. The metal shell 50 is formed using a low carbon steel material (other conductive materials (for example, metal materials) can also be used). A metal layer for anticorrosion can be formed on the surface of the metal shell 50. For example, the Ni layer is formed by plating. The insulator 10 is inserted into the through hole 59 of the metal shell 50, and the metal shell 50 is fixed to the outer periphery of the insulator 10. The front end (end on the front end direction D1 side) of the metal shell 50 is located closer to the front end direction D1 than the front end of the center electrode 20. On the rear end side of the metal shell 50, the rear end of the insulator 10 (in this embodiment, the portion on the rear end side of the rear end side body portion 18) is exposed outside the through hole 59.

  The metal shell 50 includes a body portion 55, a seat portion 54, a deformation portion 58, a tool engaging portion 51, and a caulking portion 53, which are arranged in order from the front end side to the rear end side. Yes. The seat part 54 is a bowl-shaped part. A body portion 55 is provided on the distal end side of the seat portion 54. The outer diameter of the trunk portion 55 is smaller than the outer diameter of the seat portion 54. On the outer peripheral surface of the body portion 55, a screw portion 52 for screwing into a mounting hole of an internal combustion engine (for example, a gas engine) is formed. An annular gasket 5 formed by bending a metal plate is fitted between the seat portion 54 and the screw portion 52.

  The metal shell 50 has a reduced inner diameter portion 56 disposed on the distal direction D1 side with respect to the deformable portion 58. The inner diameter of the reduced inner diameter portion 56 gradually decreases from the rear end side toward the front end side. The front end packing 8 is sandwiched between the reduced inner diameter portion 56 of the metal shell 50 and the first reduced outer diameter portion 15 of the insulator 10. The front end side packing 8 is an iron O-ring (other materials (for example, metal materials such as copper) can also be used).

  On the rear end side of the seat portion 54, a deformed portion 58 that is thinner than the seat portion 54 is provided. The deformed portion 58 is deformed so that the center portion protrudes outward in the radial direction (in a direction away from the central axis CL). A tool engagement portion 51 is provided on the rear end side of the deformation portion 58. The shape of the tool engaging portion 51 is a shape (for example, a hexagonal column) with which the spark plug wrench is engaged. On the rear end side of the tool engaging portion 51, a caulking portion 53 that is thinner than the tool engaging portion 51 is provided. The caulking portion 53 is disposed on the rear end side of the second reduced outer diameter portion 11 of the insulator 10 and forms the rear end of the metal shell 50 (that is, the end on the rear end direction D2 side). The caulking portion 53 is bent toward the inner side in the radial direction.

  On the rear end side of the metal shell 50, an annular space SP is formed between the inner peripheral surface of the metal shell 50 and the outer peripheral surface of the insulator 10. In the present embodiment, the space SP is surrounded by the crimped portion 53 and the tool engaging portion 51 of the metal shell 50, and the second reduced outer diameter portion 11 and the rear end side body portion 18 of the insulator 10. It is space. A first rear end side packing 6 is disposed on the rear end side in the space SP, and a second rear end side packing 7 is disposed on the front end side in the space SP. In this embodiment, these rear end side packings 6 and 7 are iron C-rings (other materials are also employable). Between the two rear end side packings 6 and 7 in the space SP, powder of talc (talc) 9 is filled.

  When the spark plug 100 is manufactured, the crimping portion 53 is crimped so as to be bent inward. And the crimping part 53 is pressed to the front end direction D1 side. Thereby, the deformation | transformation part 58 deform | transforms and the insulator 10 is pressed toward the front end side in the metal shell 50 through the packings 6 and 7 and the talc 9. The front end side packing 8 is pressed between the first reduced outer diameter portion 15 and the reduced inner diameter portion 56 and seals between the metal shell 50 and the insulator 10. As a result, the gas in the combustion chamber of the internal combustion engine is prevented from leaking outside through the metal shell 50 and the insulator 10. In addition, the metal shell 50 is fixed to the insulator 10.

  Further, a substantially disc-shaped cap member 30 centering on the central axis CL is fixed to the distal end portion of the metal shell 50 (in this embodiment, the portion on the distal end side of the body portion 55). The cap member 30 covers the tip of the metal shell 50. The cap member 30 has a substantially cylindrical ground electrode 31a protruding toward the rear end direction D2. On the inner peripheral side of the ground electrode 31a, the center electrode 20 (in the present embodiment, the leg portion 25) is inserted from the rear end direction D2 side toward the front end direction D1. A discharge gap g (also simply referred to as “gap g”) is formed between the outer peripheral surface (ie, the side surface) of the center electrode 20 and the inner peripheral surface of the ground electrode 31a.

  FIG. 2A is a schematic view of the spark plug 100 in the vicinity of the discharge gap g. FIG. 2B is a schematic view of the spark plug 100 as viewed in the rear end direction D2. FIG. 2C shows a schematic configuration of the cap member 30 viewed from the Ba-Ba cross section of FIG. FIG. 2A shows the central axis CL. On the left side of the central axis CL, a cross section of the metal shell 50 and the cap member 30 (a cross section by a plane including the central axis CL) and the appearance of the insulator 10 and the central electrode 20 are shown. On the right side of the center axis CL, an appearance of a part of the metal shell 50 and the center electrode 20 and a cross section of a part of the cap member 30 are shown.

  As shown in FIG. 2A, the gap g is arranged in a space 90s formed by the metal shell 50 (here, the body portion 55) and the cap member 30 (hereinafter referred to as “sub-combustion chamber 90s”). Called). Specifically, the sub-combustion chamber 90s is insulated from the inner peripheral surface 55si of the metal shell 50 (body 55 in this embodiment) and the inner surface 30s2 (the surface on the rear end direction D2 side) of the cap member 30. It is formed by the surface 10s1 of the body 10 (the leg portion 13 in this embodiment). Hereinafter, the entire portions 55, 30, and 13 forming the sub-combustion chamber 90s among the elements of the spark plug 100 are also referred to as “sub-combustion chamber forming portion 90”.

  As shown in FIGS. 2A to 2C, the cap member 30 includes a first member 31 and a second member 32. The first member 31 includes a cylindrical ground electrode 31 a and a disk portion 31 b as a fixing portion that is fixed to the distal end portion of the metal shell 50. In the present embodiment, the first member 31 is a continuous single member. As shown in FIG. 2A, the ground electrode 31a has a plurality of through holes 31ah extending in the radial direction. The plurality of through holes 31ah are disposed on the tip direction D1 side with respect to the tip surface 20s1 of the center electrode 20, and communicate with the inner peripheral side and the outer peripheral side of the ground electrode 31a.

  The disc part 31b is an annular member that is disposed on the tip end direction D1 side of the ground electrode 31a and that has the central axis CL as the center. The outer diameter of the disc part 31b is substantially the same as the outer diameter of the front end part of the body part 55 of the metal shell 50. The end of the ground electrode 31a on the tip direction D1 side is connected to a portion of the disc portion 31b close to the central axis CL. The edge part of the disc part 31b is connected to the front-end | tip of the metal shell 50 (here trunk | drum 55). At the center of the disc portion 31b, a through hole 31bh is formed which communicates with the inner peripheral side of the ground electrode 31a and the tip direction D1 side of the disc portion 31b. In the portion on the rear end direction D2 side of the through hole 31bh, the inner diameter of the through hole 31bh is the same as the inner diameter of the ground electrode 31a. In the portion on the tip direction D1 side of the through hole 31bh, the inner diameter of the through hole 31bh is larger than the inner diameter of the ground electrode 31a. Thus, the inner diameter of the entire through hole 31bh is equal to or larger than the inner diameter of the ground electrode 31a. The reason for this will be described later.

  As shown in FIG. 2B, the disc part 31b further has through holes H1 to H4 arranged on the outer peripheral side with respect to the ground electrode 31a. These through holes H1 to H4 communicate with the rear end direction D2 side and the front end direction D1 side of the disc portion 31b. FIG. 2C shows a cross section passing through the center of one through hole H1 and parallel to the central axis CL. As shown in the figure, the through hole H1 is inclined obliquely with respect to the central axis CL. Specifically, the direction extending from the rear end direction D2 side of the through hole H1 to the front end direction D1 side is a direction away from the central axis CL. The same applies to the other through holes H2 to H4. The through holes H1 to H4 are arranged isotropically around the central axis CL.

  As shown in FIG. 2A, the second member 32 is a member having the same shape as the through hole 31bh of the disc portion 31b. The 2nd member 32 is being fixed to the 1st member 31 in the state where it was inserted in penetration hole 31bh. The second member 32 has a through hole H5 that communicates with the inner peripheral side of the ground electrode 31a and the tip direction D1 side of the second member 32. The inner diameter of the through hole H5 is smaller than the inner diameter of the through hole 31bh of the disc portion 31b. Thus, the 2nd member 32 is fixed to disc part 31b so that a part of penetration hole 31bh may be plugged up. The inner diameters of the through holes H1 to H4 are also smaller than the through holes 31bh of the disc part 31b.

  In a state where the spark plug 100 is attached to the internal combustion engine, at least the surface of the cap member 30 on the tip direction D1 side is exposed to the combustion chamber of the internal combustion engine (not shown). During the operation of the internal combustion engine, an air-fuel mixture containing fuel and oxygen flows from the combustion chamber into the auxiliary combustion chamber 90s of the spark plug 100 through the through holes H1 to H5. The air-fuel mixture can also flow into the inner peripheral side of the ground electrode 31a through the through hole H5, the gap g, and the through hole 31ah of the ground electrode 31a. In this state, a voltage is applied to the spark plug 100, and discharge is performed in the gap g. By this discharge, the air-fuel mixture in the sub-combustion chamber 90s is ignited, the air-fuel mixture is combusted, and the pressure in the sub-combustion chamber 90s increases. As a result, the flame is ejected from the auxiliary combustion chamber 90s to the combustion chamber through the through holes H1 to H5. The air-fuel mixture in the combustion chamber is ignited by the jetted flame, and the internal combustion engine operates.

  In the present embodiment, the directions of the through holes H1 to H5 are different from each other. Accordingly, flames are ejected from the through holes H1 to H5 in different directions. As a result, combustion of the air-fuel mixture in the combustion chamber of the internal combustion engine can be realized appropriately.

  The inner diameters of the through holes H1 to H5 are all smaller than the inner diameter of the through hole 31bh of the disc part 31b. Accordingly, the pressure in the sub-combustion chamber 90s when the air-fuel mixture burns in the sub-combustion chamber 90s can be increased compared to the case where the through hole 31bh remains without being blocked. Therefore, the momentum of the flame ejected from the through holes H <b> 1 to H <b> 5 can be increased, so that the reach of the flame can be extended to a position far from the spark plug 100 in the combustion chamber of the internal combustion engine. As a result, combustion of the air-fuel mixture in the combustion chamber of the internal combustion engine can be realized appropriately.

A2. Production method:
3 and 4 are flowcharts showing an example of a method for manufacturing the spark plug 100. FIG. FIG. 4 shows a continuation of FIG. In the drawing, a schematic diagram of an assembly (that is, a part obtained in the middle of manufacturing) formed in each step is shown in a rectangle indicating each step. The schematic view of the assembly is shown in the same format as FIG.

  In the first step S100, the center electrode 20, the first seal portion 60, the resistor 70, the second seal portion 80, and the terminal fitting 40 are provided in the through hole 12 of the insulator 10 (FIG. 1). Then, the metal shell 50 is fixed to the insulator 10. As a method for forming the members 60, 70, and 80 in the through hole 12, various known methods can be employed. For example, the center electrode 20 is disposed at a position (FIG. 1) supported by the reduced inner diameter portion 16 in the through hole 12. Next, the material powder of the first seal part 60, the material powder of the resistor 70, and the material powder of the second seal part 80 are filled in the through hole 12 in this order. Then, the insulator 10 is heated to a predetermined temperature higher than the softening point of the glass component contained in each material powder, and in a state of being heated to the predetermined temperature, the terminal fitting is opened from the opening on the rear end direction D2 side of the through hole 12 40 is press-fitted into the through-hole 12. As a result, each material powder is compressed and sintered to form the first seal portion 60, the resistor 70, and the second seal portion 80. As a method for fixing the insulator 10 and the metal shell 50 (that is, an assembling method), the method described in FIG. 1 is employed.

  In the next step S <b> 110, the first member 31 is disposed at the tip of the metal shell 50. At this time, the tip of the center electrode 20 is inserted on the inner peripheral side of the ground electrode 31a. In the present embodiment, the edge portion of the surface 30s2 (inner surface 30s2) on the rear end direction D2 side of the disc portion 31b of the first member 31 contacts the front end surface 55s1 of the body portion 55 of the metal shell 50. At this stage, the center electrode 20 and the ground electrode 31a can be in contact with each other.

  In the next step S120, the cylindrical spacer 200 passes through the through hole 31bh of the disc portion 31b and connects the inner peripheral surface of the ground electrode 31a and the outer peripheral surface of the center electrode 20 from the tip direction D1 side of the disc portion 31b. Arranged between. The inner diameter of the spacer 200 is approximately the same as the outer diameter of the center electrode 20, and the outer diameter of the spacer 200 is approximately the same as the inner diameter of the ground electrode 31a. Further, as described above, the inner diameter of the through hole 31bh of the disc portion 31b is equal to or larger than the inner diameter of the ground electrode 31a over the entire through hole 31bh. Therefore, the spacer 200 can be easily inserted between the center electrode 20 and the ground electrode 31a through the through hole 31bh.

  The radial thickness of the spacer 200 is the same as the appropriate distance of the gap g (the distance in the direction perpendicular to the side surface of the center electrode 20) over the entire circumference. Therefore, by arranging the spacer 200 between the outer peripheral surface of the center electrode 20 and the inner peripheral surface of the ground electrode 31a, an appropriate distance of the gap g can be realized over the entire circumference.

  Further, the portion of the surface of the metal shell 50 that contacts the first member 31 is only the front end surface 55 s 1 of the metal shell 50. Accordingly, the first member 31 can freely move in a direction perpendicular to the central axis CL while being in contact with the front end surface 55s1 of the metal shell 50. In step S120, the position of the first member 31 in the direction perpendicular to the central axis CL is adjusted so that the spacer 200 can be inserted between the central electrode 20 and the ground electrode 31a. In addition, as a material of the spacer 200, various materials, such as resin and a metal plate, are employable.

  In the next step S <b> 130 of FIG. 4, the first member 31 is fixed to the metal shell 50. In the present embodiment, the portion W1 on the outer peripheral side of the portion where the front end surface 55s1 of the metal shell 50 and the inner surface 30s2 of the first member 31 (here, the disc portion 31b) are in contact with each other over the entire circumference. Welded by welding. This step S130 is performed in a state where the spacer 200 is disposed between the outer peripheral surface of the center electrode 20 and the inner peripheral surface of the ground electrode 31a. Accordingly, the first member 31 can be fixed to the metal shell 50 while realizing an appropriate gap g.

  In the next step S140, the spacer 200 is removed through the through hole 31bh. In the next step S150, the second member 32 is fitted into the through hole 31bh of the disc portion 31b, and the second member 32 is fixed to the first member 31. In the present embodiment, the portion W2 on the tip direction D1 side of the portion where the first member 31 and the second member 32 are in contact is welded by laser welding over the entire circumference. Thus, the spark plug 100 is completed.

  As described above, according to the manufacturing method of the present embodiment, the spacer 200 for forming the gap g is disposed between the outer peripheral surface (that is, the side surface) of the center electrode 20 and the ground electrode 31a. The relative position between the first member 31 and the center electrode 20 (and thus the relative position between the cap member 30 and the center electrode 20) is fixed (FIG. 3: S120, FIG. 4: S130). Accordingly, an appropriate gap g can be realized. The step of fixing the relative position between the cap member 30 and the center electrode 20 includes a step of welding the first member 31 to the metal shell 50 (FIG. 4: S130). Here, the center electrode 20 is fixed to the metal shell 50 via the insulator 10. Therefore, since the positional deviation of the first member 31 with respect to the metal shell 50 and, consequently, the positional deviation of the ground electrode 31a with respect to the center electrode 20 is suppressed, an appropriate gap g can be realized.

  As described with reference to FIG. 2, the cap member 30 includes the first member 31 and the second member 32 fixed to the first member 31. The first member 31 includes a ground electrode 31a, a through hole 31bh penetrating along the central axis CL, and a disc portion 31b fixed to the tip end surface 55s1 of the metal shell 50. The step of fixing the relative position between the cap member 30 and the center electrode 20 is to fix the first member 31 to the metal shell 50 in a state where the spacer 200 is disposed between the side surface of the center electrode 20 and the ground electrode 31a. (FIG. 4: S130), removing the spacer 200 from between the side surface of the center electrode 20 and the ground electrode 31a through the through hole 31bh of the first member 31 (FIG. 4: S140), and removing the spacer 200. And a step of fixing the second member 32 to the first member 31 after removal (FIG. 4: S150). Therefore, it is possible to improve the degree of freedom of the configuration of the cap member 30 while realizing an appropriate gap g. For example, in the present embodiment, the second member 32 is fitted into the through hole 31bh used for removing the spacer 200, and the through hole H5 having a smaller diameter than the through hole 31bh is provided. Therefore, the spacer 200 can be easily removed. Furthermore, the spark plug 100 having the through holes H1 to H5 suitable for the ejection of flame can be easily realized.

In the present embodiment, the through hole 31bh used for removing the spacer 200 is arranged coaxially with the center electrode 20, and therefore the spacer 200 can be easily removed. However, the through-hole used for removing the spacer 200 may be disposed at a position away from the central axis (here, the central axis CL) of the central electrode 20. In general, the through hole used for removing the spacer 200 only needs to communicate with the gap g. In this way, the spacer 200 can be removed from the gap g through the through hole.

B. Second embodiment:
B1. Spark plug configuration:
FIG. 5 is a schematic view of a spark plug 100z according to the second embodiment. The difference from the spark plug 100 of the first embodiment shown in FIGS. 1 and 2 is that the configuration of the tip portion of the trunk portion 55z of the metal shell 50z is different from the tip portion of the trunk portion 55 of the metal shell 50 of the first embodiment. They are only different from the configuration and the configuration of the cap member 30z is different from the configuration of the cap member 30 of the first embodiment. Other configurations of the spark plug 100z are the same as the configuration of the spark plug 100 of the first embodiment. Hereinafter, among the elements of the spark plug 100z of the second embodiment, the same elements as those of the spark plug 100 of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  FIGS. 5A to 5C show schematic views of the same format as FIGS. 2A to 2C, respectively. As shown in FIG. 5A, the cap member 30z is a continuous single member having a ground electrode 31a and a disk portion 33. The shape of the disc portion 33 is the same as the shape obtained by reducing the outer diameter of the disc shape formed by the disc portion 31b and the second member 32 in FIG. In addition, the outer diameter Da of the disc part 33 is larger than the inner diameter Db of the inner peripheral surface 55si of the portion of the body 55z of the metal shell 50z that forms the sub-combustion chamber 90s. The ground electrode 31a is the same as the ground electrode 31a in FIG.

  As shown in FIG. 5A, the configuration of the body portion 55z of the metal shell 50z is the same as the configuration obtained by adding the large inner diameter portion 55zL to the distal end side of the body portion 55 in FIG. . The large inner diameter portion 55zL is a substantially cylindrical portion centered on the central axis CL. The thickness of the large inner diameter portion 55zL in the distal direction D1 is substantially the same as the thickness of the disc portion 33 of the cap member 30. The inner diameter of the large inner diameter portion 55zL is substantially the same as the outer diameter Da of the disk portion 33. The disc portion 33 of the cap member 30z is fitted on the inner peripheral side of the large inner diameter portion 55zL. The disc portion 33 is welded to the large inner diameter portion 55zL. As described above, the disk portion 33 corresponds to a fixing portion that is fixed to the distal end portion of the metal shell 50. The structure of the other part of the metal shell 50z is the same as that of the metal shell 50 shown in FIGS.

  As shown in FIG. 5A, the spark plug 100z of the second embodiment forms the same auxiliary combustion chamber 90s as the spark plug 100 of the first embodiment. The auxiliary combustion chamber 90s includes an inner peripheral surface 55si of the metal shell 50z (in the present embodiment, the body portion 55z), an inner surface 30s2 (the surface on the rear end direction D2 side of the disc portion 33) of the cap member 30z, and an insulator. 10 (in this embodiment, the leg portion 13) and the surface 10s1. Hereinafter, the whole of these portions 55z, 30z, and 13 is also referred to as “sub-combustion chamber forming portion 90z”. Further, as shown in FIG. 5A, the arrangement of the center electrode 20 and the ground electrode 31a in the auxiliary combustion chamber 90s is the same as that in the embodiment of FIG. And as shown to FIG. 5 (B) and FIG.5 (C), the same through-holes H1-H5 as 1st Embodiment are formed in the cap member 30z. As described above, the spark plug 100z of the second embodiment can appropriately realize the combustion of the air-fuel mixture in the combustion chamber of the internal combustion engine, similarly to the spark plug 100 of the first embodiment.

B2. Production method:
B2-1. First production method:
FIG. 6 is a flowchart showing an example of a method for manufacturing the spark plug 100z. In the drawing, a schematic diagram of an assembly (parts obtained in the course of manufacturing) formed in each step is shown in a rectangle indicating each step. The schematic view of the assembly is shown in the same format as FIG.

  In the first step S200, the center electrode 20, the first seal portion 60, the resistor 70, the second seal portion 80, and the terminal fitting 40 are provided in the through hole 12 of the insulator 10 (FIG. 1). Then, the surface of the front end portion of the center electrode 20 (particularly, the outer peripheral surface where the gap g is to be formed) is coated with the wax 300. As the wax 300, for example, a wax that is solid at room temperature (for example, paraffin wax) can be used. In this case, the wax 300 may be applied to the surface of the center electrode 20 with the wax 300 softened by heating. The amount of the wax 300 is such that the radial thickness of the wax 300 on the surface of the center electrode 20 (that is, the thickness in the direction perpendicular to the side surface of the center electrode 20) is approximately the same as the appropriate distance of the gap g. To be adjusted. In addition, the formation method of the members 60, 70, and 80 in the through hole 12 is the same as the formation method of the first embodiment.

  In the next step S <b> 210, the metal shell 50 is fixed to the insulator 10. The fixing method is the same as the method in step S100 in FIG. Note that step S200 may be performed after step S210.

  In the next step S220, the cap member 30z is fixed to the metal shell 50z. Specifically, the disc part 33 of the cap member 30z is fitted on the inner peripheral side of the large inner diameter part 55zL of the metal shell 50z. At this time, the tip of the center electrode 20 is inserted on the inner peripheral side of the ground electrode 31a. And the part W3 by the side of the front end direction D1 of the part which the inner peripheral surface of the large inner diameter part 55zL and the outer peripheral surface of the disc part 33 contact is welded by laser welding over the perimeter. This step 220 is performed in a state where the wax 300 is disposed between the outer peripheral surface of the center electrode 20 and the inner peripheral surface of the ground electrode 31a. Accordingly, the cap member 30z can be fixed to the metal shell 50 while realizing an appropriate gap g.

  In the next step S230, the wax 300 is removed. In the present embodiment, the wax 300 is washed away by boiling the sub-combustion chamber 90s with hot water. The wax 300 is melted by heating with hot water. The melted wax 300 is discharged out of the auxiliary combustion chamber 90s together with hot water. As described above, the spark plug 100z is completed by removing the wax 300.

  As described above, according to the manufacturing method of FIG. 6, the wax 300 for forming the gap g is disposed between the cap member 30 z and the center in a state where the wax 300 is disposed between the outer peripheral surface of the center electrode 20 and the ground electrode 31 a. The relative position with respect to the electrode 20 is fixed (FIG. 6: S220). Accordingly, an appropriate gap g can be realized. The step of fixing the relative position between the cap member 30z and the center electrode 20 includes a step of welding the cap member 30z to the metal shell 50 (FIG. 6: S220). Here, the center electrode 20 is fixed to the metal shell 50z via the insulator 10. Therefore, the positional deviation of the cap member 30z with respect to the metal shell 50z, and hence the positional deviation of the ground electrode 31a with respect to the center electrode 20, is suppressed, so that an appropriate gap g can be realized.

  Further, after the step of fixing the relative position between the cap member 30z and the center electrode 20 (FIG. 6: S220), the wax 300 is removed by heating the wax 300 (S230). Therefore, it is possible to suppress the wax 300 from remaining in the gap g while realizing an appropriate gap g.

B2-2. Second manufacturing method:
FIG. 7 is a flowchart showing another example of a method for manufacturing the spark plug 100z. In the drawing, a schematic diagram of an assembly (parts obtained in the course of manufacturing) formed in each step is shown in a rectangle indicating each step. The schematic view of the assembly is shown in the same format as FIG.

  Step S300 is the same as step S200 of FIG. The surface of the tip of the center electrode 20 is coated with wax 300. Step S310 is a process performed independently of step S300, and is a process of fixing the cap member 30z to the metal shell 50z. Specifically, the cap member 30z is fitted on the inner peripheral side of the large inner diameter portion 55zL of the metal shell 50, and the cap member 30z is fixed to the metal shell 50 by laser welding. Hereinafter, a member composed of the metal shell 50z and the cap member 30z fixed to the metal shell 50z is referred to as an “assembled metal member 530”. In step S310, the metal shell 50z is not yet fixed to the insulator 10. Note that a metal layer for corrosion protection may be formed on the surface of the assembled metal member 530 after the assembled metal member 530 is formed and before the next step S320. For example, the Ni layer may be formed by plating.

  After steps S300 and S310 are performed, the assembled metal member 530 (that is, the metal shell 50z) is fixed to the insulator 10 in step S320. The fixing method is the same as the method of step S100 in FIG. At this time, the tip of the center electrode 20 is inserted on the inner peripheral side of the ground electrode 31a. This step S320 is performed in a state where the wax 300 is disposed between the outer peripheral surface of the center electrode 20 and the inner peripheral surface of the ground electrode 31a. Therefore, the metal shell 50z can be fixed to the insulator 10 while realizing an appropriate gap g.

  The next step S330 is the same as step S230 in FIG. As described above, the spark plug 100z is completed by removing the wax 300.

  As described above, according to the manufacturing method of FIG. 7, the wax 300 for forming the gap g is disposed between the cap member 30z and the center in a state where the wax 300 is disposed between the outer peripheral surface of the center electrode 20 and the ground electrode 31a. The relative position with respect to the electrode 20 is fixed (FIG. 6: S320). Accordingly, an appropriate gap g can be realized. Further, before the step of fixing the relative position between the cap member 30z and the center electrode 20, an assembled metal member 530 in which the metal shell 50z and the cap member 30z are fixed to each other is prepared (S310). Then, in the step of fixing the relative position between the cap member 30z and the center electrode 20, the assembled metal member 530 (the metal shell 50z with the cap member 30z) and the insulator 10 to which the center electrode 20 is fixed are assembled. Step (S320) is included. Therefore, the positional deviation of the cap member 30z with respect to the metal shell 50z, and hence the positional deviation of the ground electrode 31a with respect to the center electrode 20, is suppressed, so that an appropriate gap g can be realized.

  In addition, after the step of fixing the relative position between the cap member 30z and the center electrode 20 (FIG. 7: S320), the wax 300 is removed by heating the wax 300 (S330). Therefore, it is possible to suppress the wax 300 from remaining in the gap g while realizing an appropriate gap g.

C. Another embodiment of the cap member:
FIG. 8 is a schematic view showing another embodiment of the cap member. FIGS. 8A to 8C show cap members 30w, 30x, and 30y that can be used in place of the cap member 30 shown in FIGS. FIG. 8A to FIG. 8C each show a cross section including the central axis CL. In the figure, the same elements as those of the cap member 30 in FIG.

  A cap member 30w shown in FIG. 8A has a first member 31 and a second member 32w. The first member 31 is the same as the first member 31 in the embodiment of FIG. The shape of the second member 32w is the same as the shape obtained by omitting the portion on the rear end direction D2 side from the second member 32 in FIG. 2 (the portion whose outer diameter is substantially the same as the inner diameter of the ground electrode 31a). is there. That is, the shape of the second member 32w is a flat and substantially disk shape. The second member 32w is welded to the disc portion 31b in a state of being fitted into the through hole 31bh of the disc portion 31b, similarly to the second member 32 of FIG. Thus, the second member 32w is fixed to the disc portion 31b so as to block a part of the through hole 31bh, and forms a through hole H5w having a smaller diameter than the through hole 31bh.

  A cap member 30x shown in FIG. 8B includes a first member 31x and a second member 32x. The first member 31x includes a ground electrode 31a and a disc portion 31c. The disc portion 31c has the same shape as that obtained by omitting the portion on the tip direction D1 side (the portion whose inner diameter is larger than the inner diameter of the ground electrode 31a) from the disc portion 31b in FIG. . That is, the shape of the disc portion 31c is a flat, substantially disc shape having a through hole 31ch having the same inner diameter as the inner diameter of the ground electrode 31a. In step S140 of FIG. 4, the spacer 200 is removed through the through hole 31ch. Although not shown, the disc portion 31c has four through holes corresponding to the through holes H1 to H4 in FIG. 2B (referred to as “rear end side holes”). In the example of FIG. 8B, the first member 31x is a continuous single member.

  The shape of the second member 32x is approximately the same as the shape obtained by expanding the outer diameter of the second member 32w of FIG. 8A to the outer diameter of the disk portion 31c of the first member 31x. The 2nd member 32x is arrange | positioned on the surface by the side of the front end direction D1 of the disc part 31c. And the part W4 of the outer peripheral side of the part which the disc part 31c and the 2nd member 32x contact is welded by laser welding over the perimeter. Thus, the second member 32x is fixed to the disc portion 31c so as to block a part of the through hole 31ch of the disc portion 31c, and forms a through hole H5w having a smaller diameter than the through hole 31ch. In addition, although illustration is abbreviate | omitted, the 2nd member 32x has four through-holes corresponding to the through-holes H1-H4 of FIG. 2 (B) (it is called a "front end side hole"). And arrangement | positioning of the 2nd member 32x with respect to the 1st member 31x is determined so that the rear end side hole which the disc part 31c does not illustrate and the front end side hole which the second member 32x does not illustrate communicate.

  The cap member 30y shown in FIG. 8C has a first member 31x and a second member 32w. The first member 31x is the same as the first member 31x in FIG. The second member 32w is the same as the second member 32w in FIG. The second member 32w is disposed on the surface on the tip direction D1 side of the disc portion 31c of the first member 31x. And the part W5 of the outer peripheral side of the part which the disc part 31c and the 2nd member 32w contact is welded by laser welding over the perimeter. Thus, the second member 32w is fixed to the disc portion 31c so as to block a part of the through-hole 31ch of the disc portion 31c, and forms a through-hole H5w having a smaller diameter than the through-hole 31ch.

  Note that the disc portions 31b and 31c of the cap members 30w, 30x, and 30y in FIGS. 8A to 8C are similar to the disc portion 31b in FIG. It is fixed to the tip of 55. As described above, the disk portions 31 b and 31 c correspond to a fixing portion fixed to the metal shell 50.

D. Variation:
(1) As a structure of a cap member, not only the structure of said each embodiment but a various structure is employable. For example, the through holes 31 bh and 31 ch of the first members 31 and 31 x shown in FIGS. 2 and 8 are used for removing the spacer 200. Therefore, the inner diameters of the through holes 31bh and 31ch are preferably equal to or larger than the outer diameter of the spacer 200, that is, the inner diameter of the ground electrode 31a. The inner diameters of the through holes H5 and H5w of the second members 32, 32w, and 32x are preferably smaller than the inner diameters of the through holes 31bh and 31ch of the first members 31, 31x. In this way, the pressure in the sub-combustion chamber 90s when the air-fuel mixture burns in the sub-combustion chamber 90s can be increased, so that the flame reachable range is far from the spark plug in the combustion chamber of the internal combustion engine. Can be expanded to The inner diameters of the through holes 31bh and 31ch of the first members 31 and 31x may be less than the inner diameter of the ground electrode 31a. In this case, the spacer 200 may be deformed and removed.

(2) The through hole provided in the cap member (the hole that communicates the auxiliary combustion chamber 90s and the outside) may be provided only on one of the inner peripheral side and the outer peripheral side of the ground electrode 31a. For example, in the embodiments of FIGS. 2, 5, and 8, the through holes H1 to H4 (not shown in FIG. 8) may be omitted. Instead, the through holes H5 and H5w may be omitted. Further, the total number of through holes provided in the cap member is not limited to five, but may be four or less, or may be six or more.

(3) In the embodiments of FIGS. 2 and 8, the through holes H5 and H5w of the second members 32, 32w, and 32x may be omitted. Also in this case, at the time of manufacturing the spark plug, before fixing the second members 32, 32w, 32x to the first members 31, 31x, the gap forming members (for example, through the through holes 31bh, 31ch of the first members 31, 31x) , Spacer 200) can be removed. The second members 32, 32w, 32x are preferably fixed to the first members 31, 31x so as to close the through holes 31bh, 31ch of the first members 31, 31x. Generally, when a through hole is provided in the first member of the cap member, the second member of the cap member is configured to close at least a part of the through hole of the first member, that is, to reduce the through hole. It is preferable to be fixed to one member. By doing so, the pressure in the auxiliary combustion chamber when the air-fuel mixture is combusted in the auxiliary combustion chamber can be increased, so that the flame reachable range can be extended far from the spark plug in the combustion chamber of the internal combustion engine. However, the second member may be fixed at a position away from the through hole on the first member. Also in this case, the degree of freedom of the configuration of the cap member can be improved by using the first member and the second member.

(4) As a configuration of the cap member of the spark plug manufactured according to the procedure of FIGS. 3 and 4, a configuration that is fitted on the inner peripheral side of the metal shell as in the embodiment of FIG. 5 may be adopted. Further, as a configuration of the cap member of the spark plug manufactured according to the procedure of FIG. 6 or FIG. 7, a configuration that is fixed to the front end surface of the metal shell as in the embodiment of FIG.

(5) The configuration of the ground electrode is not limited to a substantially cylindrical configuration like the ground electrode 31a of each of the above embodiments, and various configurations can be employed. For example, a bar extending from the surface 30s2 (FIGS. 2 and 5) on the rear end direction D2 side of the cap member to a position facing the outer peripheral surface of the center electrode 20 may be employed as the ground electrode. The ground electrode may be a separate member from other parts of the cap member. For example, in the embodiment of FIG. 2A, the ground electrode 31a may be fixed to the disc portion 31b by welding.

(6) A noble metal tip may be provided in a portion of the center electrode where the gap g is formed. Further, a noble metal tip may be provided in a portion of the ground electrode where the gap g is formed. As a material for the noble metal tip, an alloy containing a noble metal such as iridium or platinum can be employed.

(7) The spark plug manufacturing method is not limited to the method described with reference to FIGS. 3, 4, 6, and 7, and various methods can be employed. For example, in the manufacturing method of FIGS. 6 and 7, the method for removing the wax 300 is not limited to boiling, and any method can be employed. For example, the wax 300 may be washed away using a solvent capable of dissolving the wax 300 (for example, toluene (C ₆ H ₅ CH ₃ )). Moreover, you may perform both the removal by heating (for example, boiling) and the removal by melt | dissolution using a solvent. Here, the order of heating and melting may be adopted, or the order of melting and heating may be adopted. Further, at least one of heating and dissolution may be performed a plurality of times.

  Moreover, you may manufacture the spark plug demonstrated in FIG.1, FIG.2, FIG.8 according to the following methods similar to FIG. That is, the first members 31, 31x of the cap members 30, 30w, 30x, 30y are fixed to the metal shell 50. The center electrode 20, the first seal portion 60, the resistor 70, the second seal portion 80, and the terminal fitting 40 are provided in the through hole 12 of the insulator 10 independently of the fixing of the first members 31 and 31 x. After these steps, the insulator 10 and the metal shell 50 are temporarily assembled, and the spacer 200 is disposed between the outer peripheral surface of the center electrode 20 and the ground electrode 31a. Then, the metal shell 50 is fixed to the insulator 10 in a state where the spacer 200 is disposed between the outer peripheral surface of the center electrode 20 and the ground electrode 31a. Thereby, the relative position between the center electrode 20 and the ground electrode 31a is fixed. Thereafter, the spacer 200 is removed through the through holes 31bh, 31ch of the first members 31, 31x. Then, the second members 32, 32w and 32x are fixed to the first members 31 and 31x so as to block a part of the through holes 31bh and 31ch of the first members 31 and 31x.

  Generally, as a spark plug manufacturing method, a gap forming member (for example, the spacer 200 in FIGS. 3 and 4 or the wax 300 in FIG. 6) is disposed between the side surface of the center electrode 20 and the ground electrode 31a. In this state, various methods for fixing the relative position between the center electrode 20 and the ground electrode 31a can be employed. By adopting such a method, the gap g having a small distance in the direction perpendicular to the side surface (that is, the outer peripheral surface) of the center electrode 20 can be easily realized by reducing the thickness of the gap forming member in the radial direction. it can. For example, a distance of 0.3 mm or less may be adopted as the distance of the gap g. In this way, the voltage required for discharge can be reduced. Moreover, even if the compression rate of the internal combustion engine is high, it is possible to suppress an increase in the voltage required for discharge. For example, the compression rate of a gas engine is often higher than that of a gasoline engine. When a spark plug is applied to such a gas engine, it is possible to suppress an increase in voltage required for discharge. As the lower limit of the distance of the gap g, any distance that can be realized according to the accuracy of the dimension of the spark plug can be adopted. For example, 0.05 mm may be adopted.

(8) The configuration of the spark plug is not limited to the configuration shown in FIGS. 1, 2, 5, and 8, and various configurations can be employed. For example, the resistor 70 may be omitted. Further, the head 23 of the center electrode 20 may be omitted.

  As mentioned above, although this invention was demonstrated based on embodiment and a modification, embodiment mentioned above is for making an understanding of this invention easy, and does not limit this invention. The present invention can be changed and improved without departing from the spirit and scope of the claims, and equivalents thereof are included in the present invention.

5 ... gasket, 6 ... first rear end packing, 7 ... second rear end packing, 8 ... front end packing, 9 ... talc, 10 ... insulator (insulation) Insulator), 11 ... second reduced outer diameter portion, 12 ... through hole (shaft hole), 13 ... leg portion, 15 ... first reduced outer diameter portion, 16 ... reduced inner diameter portion , 17 ... Front end side body part, 18 ... Rear end side body part, 19 ... Gutter part, 20 ... Center electrode, 21 ... Electrode base material, 22 ... Core material, 23 ... head, 24 ... collar, 25 ... leg, 30, 30w, 30x, 30y, 30z ... cap member, 31, 31x ... first member, 31a ... grounding Electrode, 31b, 31c ... disc part, 31ah, 31bh, 31ch ... through hole, 32, 32w, 32x ... second member, 33 ... disc part, 40 ... terminal fitting, 41 ... Cap mounting part, 42 ... Bridge part, 43 ... Leg part, 50, 50z ... Metal fitting, 51 ... Tool engaging part, 52 ... Screw part, 53 .. . Fastening part, 54 ... seat part, 55, 55z ... trunk part, 55zL ... large inner diameter part, 55si ... inner peripheral surface, 56 ... reduced inner diameter part, 58 ... deformed part, 59 ... through hole, 60 ... first seal part, 70 ... resistor, 80 ... second seal part, 90, 90z ... sub-combustion chamber forming part, 90s ... sub-combustion Chamber (space), 100, 100z ... Spark plug, 200 ... Spacer, 300 ... Wax, 530 ... Assembly metal member, g ... Gap (discharge gap), H1-H5 ... Through hole

Claims (7)

A central electrode extending in the axial direction;
An insulator having an axial hole extending in the axial direction and having the central electrode disposed on a distal end side of the axial hole;
A metal shell disposed on the outer periphery of the insulator;
A cap member that has a ground electrode disposed through a gap between the side surface of the center electrode and the metal shell and is fixed to a tip of the metal shell, and forms a sub-combustion chamber together with the metal shell;
A spark plug manufacturing method comprising:
A first step of fixing a relative position between the cap member and the center electrode in a state where a gap forming member for forming the gap is disposed between a side surface of the center electrode and the ground electrode;
Production method. It is a manufacturing method of the spark plug according to claim 1,
The first step includes a step of welding the cap member to the metal shell. It is a manufacturing method of the spark plug according to claim 1 or 2,
The cap member is
A first member having the ground electrode, a through-hole penetrating along the central axis, and a fixing portion fixed to a distal end portion of the metal shell;
A second member fixed to the first member;
Have
The first step includes
Fixing the first member to the metal shell in a state where the gap forming member is disposed between a side surface of the center electrode and the ground electrode;
Removing the gap forming member from between the side surface of the center electrode and the ground electrode through the through hole of the first member;
Fixing the second member to the first member after removing the gap forming member;
Manufacturing method. The method of manufacturing a spark plug according to claim 1, further comprising:
After the first step, the step of removing the gap forming member by at least one of heating the gap forming member and dissolving the gap forming member in a specific solvent;
Production method. The method for manufacturing a spark plug according to claim 4, further comprising:
Before the first step, the step of preparing a metal member to which the metal shell and the cap member are fixed,
The first step includes a step of assembling the insulator to which the center electrode is fixed and the metal member.
Production method. A method for manufacturing a spark plug according to any one of claims 1 to 5,
The manufacturing method, wherein a gap distance of the gap in a direction perpendicular to the side surface of the center electrode is 0.3 mm or less. A spark plug,
A central electrode extending in the axial direction;
An insulator having an axial hole extending in the axial direction and having the central electrode disposed on a distal end side of the axial hole;
A metal shell disposed on the outer periphery of the insulator;
A cap member that has a ground electrode disposed through a gap between the side surface of the center electrode and the metal shell and is fixed to a tip of the metal shell, and forms a sub-combustion chamber together with the metal shell;
Have
The cap member is
A first member having the ground electrode and a fixing portion fixed to the tip of the metal shell;
A second member fixed to the first member;
Having
Spark plug.

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