CN106415956A

CN106415956A - Spark plug

Info

Publication number: CN106415956A
Application number: CN201580005368.XA
Authority: CN
Inventors: 久野武人; 长泽聪史; 铃木彰
Original assignee: NGK Spark Plug Co Ltd
Current assignee: Niterra Co Ltd
Priority date: 2014-01-23
Filing date: 2015-01-21
Publication date: 2017-02-15
Anticipated expiration: 2035-01-21
Also published as: DE112015000475B4; CN106415956B; JP6033442B2; DE112015000475T5; WO2015111634A1; JPWO2015111634A1

Abstract

This spark plug has both a main metal fitting and an earth electrode which has a base part joined to the tip of the main metal fitting. The earth electrode comprises both an outer layer and a core part disposed on the inner peripheral side of the outer layer. The outer layer forms at least a part of the surface of the earth electrode, is joined to the main metal fitting, and is made of a material which comprises nickel as the main component and contains aluminum in an amount of more than 0 to 2.5wt%. The oxygen content of the surface of the outer layer exceeds 0wt% and is up to 8wt%. The core part includes a first layer made of either copper or a material comprising copper as the main component. In a cross section of the base part of the earth electrode, said cross section including the central axis of the spark plug and the central axis of the earth electrode, at least one of the two boundary lines which show the boundary between the outer layer and the core part includes an oblique line which extends from the main-metal-fitting-side end of the boundary line toward the outer periphery side of the outer layer obliquely against the central axis of the earth electrode.

Description

Spark plug

Technical field

The present invention relates to a kind of spark plug.

Background technology

In the past, spark plug was applied in internal combustion engine.Spark plug has the electrode forming gap.As electricity Pole, for example, propose a kind of ground electrode, and it has the excellent covering material of oxidative resistance and heat conductivity ratio Covering material is excellent and is enclosed in the core within covering material.According to this ground electrode, then pass through Reduce the temperature of ground electrode, oxidative resistance can be lifted.

Prior art literature

Patent documentation

Patent documentation 1：Japanese Unexamined Patent Publication 2001-284013 publication

Content of the invention

Problems to be solved by the invention

However, in engaging ground electrode in the case of base metal housing, there is bond strength relatively low Situation.For example, there is the relatively low situation of bond strength between covering material and base metal housing.

The invention discloses a kind of bond strength that can be lifted between ground electrode and base metal housing Technology.

For solution to problem

The present invention for example discloses applications below example.

[application examples 1]

A kind of spark plug, this spark plug includes：

Central electrode；

Insulator, it keeps described central electrode；

Base metal housing, its configuration is around the radial direction of described insulator；And

Ground electrode, it has the base end part engaging with the top ends of described base metal housing, and Form gap between this ground electrode and described central electrode, wherein,

Described ground electrode comprises：

Outer layer, it forms at least a portion on the surface of described ground electrode, with described base metal housing Engage, and this outer layer by containing nickel as main component, containing more than 0wt% and for 2.5wt% with Under the material of aluminum formed；And

Core, it configures in the inner circumferential side of described outer layer,

Oxygen amount on the surface of described outer layer is more than 0wt% and is below 8wt%,

Described core comprise by copper or containing copper as main component formed the 1st layer of material,

Section in the central axis comprising described spark plug and the central axis of described ground electrode , in the described base end part of described ground electrode, represent boundary between described outer layer and described core Article two, at least one of demarcation line comprises parallax, this parallax from described marginal by described main body The end on metal-back side with respect to described ground electrode described central axis obliquely towards described outer The outer circumferential side of layer extends.

Using this structure, due to the surface of outer layer, i.e. the oxygen amount on the surface of ground electrode be 8wt% with Under, therefore, compared with the situation that is more than 8wt% with oxygen amount, can be lifted outer layer and base metal housing it Between bond strength.Additionally, representing in cross section in two demarcation line of boundary between outer layer and core At least one with comprising the sloped-end from base metal housing side towards outer circumferential side extend parallax, Therefore, it is possible to increase the bonding area between outer layer and base metal housing.As a result, can be lifted connecing Bond strength between ground electrode and base metal housing.

[application examples 2]

Spark plug according to application examples 1, wherein,

Described oxygen amount on the described surface of described outer layer is more than 0wt% and is below 5wt%,

In the described base end part of the described ground electrode in described section,

Described parallax is set to, by the end of described base metal housing side, the end that demarcates,

Would indicate that the outer peripheral face of described outer layer two outer peripheral lines respective by described base metal housing side End be between two outer circumference end, in the direction with the described central axis upright of described ground electrode On distance be set to always apart from W2,

With regard to comprising 1 or two described demarcation line of described parallax, will through described boundary end and with The straight line of described centerline axis parallel of described ground electrode and process are located at when observing from described boundary end Described outer circumference end on the bearing of trend of described parallax and the described central axis with described ground electrode Total distance of the distance between parallel straight line is set to engage apart from W1,

Described joint is always set to ratio t apart from the ratio of W2 apart from W1 with respect to described,

Now, described ratio t is more than 0% and is less than 80%.

Using this structure, because the oxygen amount on the surface of outer layer is below 5wt%, therefore, it is possible to enter one Bond strength between step lifting outer layer and base metal housing.Further, since engaging apart from W1 relatively It is more than 0% and is less than 80% in always ratio t apart from W2, therefore, it is possible to lift ground electrode further Bond strength and base metal housing between.

[application examples 3]

Spark plug according to application examples 1, wherein,

Described core also comprises the 2nd layer, and the part of the 2nd layer configures described 1st layer of inner circumferential side, And the 2nd layer is formed by with containing ratio (weight %) material containing nickel bigger than described outer layer, And the 2nd layer of heat conductivity is higher compared with described outer layer,

Now, described ratio t is more than 0% and is less than 20%.

Using this structure, it is more than 0% and is with respect to always ratio t apart from W2 apart from W1 due to engaging Less than 20%, therefore, it is possible to lift the bond strength between ground electrode and base metal housing further.

[application examples 4]

Spark plug according to application examples 3, wherein,

In described section, described base metal housing is separated with described 1st layer, and outer with described Layer engages with described 2nd layer.

Using this structure, due to separating between base metal housing and the 1st layer, and with outer layer and the 2nd Layer engages, therefore, it is possible to lift the bond strength between ground electrode and base metal housing further.

[application examples 5]

Spark plug according to any one of application examples 1～4, wherein,

Represent described two demarcation line both of which of the described boundary between described outer layer and described core Comprise parallax, this parallax from the described marginal end by described base metal housing side with respect to The described central axis of described ground electrode is obliquely described marginal towards the formation in described outer layer Partial outer circumferential side extends.

Using this structure, and only it is compared with one of two demarcation line comprise the situation of parallax, can Increase the bonding area between outer layer and base metal housing, therefore, it is possible to lift ground electrode and main body Bond strength between metal shell.

In addition, technology disclosed in this specification can be realized in a variety of manners, for example can be with spark Plug, carry the forms such as the internal combustion engine of spark plug, manufacture method of spark plug to realize.

Brief description

Fig. 1 is the sectional view of an example of the spark plug of the 1st embodiment.

Fig. 2 is the skeleton diagram obtained by spark plug 100 is observed in front.

Fig. 3 is the profile of the bonding part between ground electrode 30 and base metal housing 50.

Fig. 4 is the skeleton diagram of an example representing joining process.

Fig. 5 is the profile of an example of the spark plug of the 2nd embodiment.

Fig. 6 is the profile of an example of the spark plug of variation.

Fig. 7 is the profile of an example of the spark plug of variation.

Specific embodiment

A. the 1st embodiment：

A-1. the structure of spark plug：

Fig. 1 is the sectional view of an example of the spark plug of the 1st embodiment.The line CL of diagram represents spark The central axis of plug 100.The section of diagram is the section comprising central axis CL.Hereinafter, by central shaft Line CL is also referred to as " axis CL ", and the direction parallel with central axis CL is also referred to as " axis side To ".The radial direction of the circle centered on central axis CL is also referred to as " radially ", will be with central axis The circumferencial direction of the circle centered on CL is also referred to as " circumferential ".By the direction parallel with central axis CL In, the top of Fig. 1 be referred to as before extreme direction D1, by the direction parallel with central axis CL, Fig. 1 Lower section be referred to as after extreme direction D1r.Front extreme direction D1 be from terminal metal piece 40 described later towards electrode 20, 30 direction.Additionally, the front extreme direction D1 side of Fig. 1 is referred to as the front of spark plug 100, by Fig. 1's Extreme direction D1r side is referred to as the rear end side of spark plug 100 afterwards.

Spark plug 100 include insulator 10 (being also referred to as " insulation electroceramics 10 " below), central electrode 20, Ground electrode 30, terminal metal piece 40, base metal housing 50, resistive element 70, front end side seal 8, Talcum 9, the 1st rear end side seal 6, the 2nd rear end side seal 7, the 1st sealing 60 of electric conductivity and 2nd sealing 80 of electric conductivity.

Insulator 10 be have extend along central axis CL and insertion insulator 10 through hole 12 (with Substantially cylindric component down also referred to as " axis hole 12 ").Insulator 10 is by roasting oxidation aluminum (can also be using the other insulant) being formed.Insulator 10 has from front towards rear end side The leg 13 that is arranged in order to D1r, the 1st contracting outer diameter part 15, front main part 17, flange part 19, 2 contracting outer diameter parts 11 and rear end side main part 18.The external diameter of the 1st contracting outer diameter part 15 is with from rear end side direction Front is gone and is tapered into.Insulator 10 the 1st contracting outer diameter part 15 vicinity (in the example in fig 1 Front main part 17) be formed with contracting inside diameter 16, this contracting inside diameter 16 with from rear end side towards front Side is gone and internal diameter tapers into.The external diameter of the 2nd contracting outer diameter part 11 goes towards rear end side with from front And taper into.

The front of the axis hole 12 of insulator 10 be inserted with along central axis CL extend bar-shaped in Heart electrode 20.Central electrode 20 have the leg 25 being arranged in order towards rear extreme direction D1r from front, Flange part 24 and head 23.The part of the front of leg 25 is exposed to axle in the front of insulator 10 Outside hole 12.The contracting inside diameter 16 of the face insulated body 10 of front extreme direction D1 side of flange part 24 is supported. Additionally, central electrode 20 has outer layer 21 and core 22.The rearward end of core 22 is exposed from outer layer 21, shape Become the rearward end of central electrode 20.The other parts of core 22 are coated by outer layer 21.But it is also possible to It is that core 22 is overall to be covered by outer layer 21.

Outer layer 21 is using the oxidative resistance material more excellent than core 22, i.e. indoor sudden and violent in the burning of internal combustion engine It is exposed to what the less material of consumption during burning gases was formed.The material of outer layer 21 for example can adopt nickel (Ni) or containing nickel as main component alloy (e.g. inconel (" INCONEL " It is registered trade mark)).Here, " main component " refers to the meaning of containing ratio highest composition (below Equally).Containing ratio adopts the value representing with percentage by weight (wt%).Core 22 is by heat conductivity The material higher than outer layer 21, the such as material containing copper (e.g. fine copper or using copper as main component Alloy) formed.

It is inserted with terminal metal piece 40 in the rear end side of the axis hole 12 of insulator 10.Terminal metal piece 40 is to make Formed with conductive material (metal such as such as mild steel).In the axis hole 12 of insulator 10, in terminal It is configured between metalwork 40 and central electrode 20 for suppressing electrical noise, columned resistive element 70. Configure the 1st conductive sealing 60 between resistive element 70 and central electrode 20, in resistive element 70 He The 2nd conductive sealing 80 is configured between terminal metal piece 40.Central electrode 20 and terminal metal piece 40 by resistive element 70 and sealing 60,80 electrical connection.

Base metal housing 50 has along central axis CL extension and insertion base metal housing 50 Substantially cylindric component (in the present embodiment, the central shaft of base metal housing 50 of through hole 59 Line is consistent with the central axis CL of spark plug 100).Base metal housing 50 is to be formed using low-carbon (LC) steel (can also be using other conductive materials (such as metal material)).Insertion in base metal housing 50 It is inserted with insulator 10 in hole 59.Base metal housing 50 is fixed on the periphery of insulator 10.In main body gold Belong to the front of housing 50, the front end of insulator 10 (is the front of leg 13 in the present embodiment Part) it is exposed to outside through hole 59.In the rear end side of base metal housing 50, the rear end of insulator 10 (being the part of the rear end side of rear end side main part 18 in the present embodiment) be exposed to through hole 59 it Outward.

Base metal housing 50 has the main part 55 being arranged in order from front, portions towards rear end side 54th, variant part 58, tool engagement portion 51 and crimp portion 53.Portions 54 are flange shape parts.Leading The outer peripheral face of body 55 is formed with for the installing hole screw thread knot with internal combustion engine (e.g. petrol engine) The threaded portion 52 closed.It is embedded between portions 54 and threaded portion 52 by the formation by metallic plate bending The packing ring 5 of ring-type.

Base metal housing 50 has contracting inside diameter 56, and this contracting inside diameter 56 configures more forward than variant part 58 The position of extreme direction D1 side.The internal diameter of contracting inside diameter 56 gradually becomes with going towards front from rear end side Little.Accompany between the contracting inside diameter 56 and the 1st contracting outer diameter part 15 of insulator 10 of base metal housing 50 Front end side seal 8.Front end side seal 8 is that iron and in alphabetical O shape ring (can also adopt other Material (the e.g. metal material such as copper)).

The shape of tool engagement portion 51 is can be for the shape (e.g. six prisms) of spanner for spark plug engaging. It is provided with crimp portion 53 in the rear end side of tool engagement portion 51.Crimp portion 53 configures in ratio the 2nd of insulator 10 The position of contracting outer diameter part 11 side rearward, forms rear end (the extreme direction D1r after i.e. of base metal housing 50 The end of side).The interior lateral bend that crimp portion 53 is radially oriented.Crimp portion 53 front extreme direction D1 side and It is between the inner peripheral surface and the outer peripheral face of insulator 10 of base metal housing 50, towards front extreme direction D1 It is configured with the 1st rear end side seal 6, Talcum 9 and the 2nd rear end side seal 7 successively.In this embodiment party In formula, the ring that above-mentioned rear end side seal 6,7 is iron and letter-c-shaped (can also be using others Material).

Manufacture spark plug 100 when, by crimp portion 53 by inside lateral bending folding in the way of crimp.Then, will Crimp portion 53 extreme direction D1 side pressing forward.Thus, variant part 58 deforms, by sealing member 6,7 and cunning Stone 9, insulator 10 is pressed towards front in base metal housing 50.Front end side seal 8 is It is pressed between 1 contracting outer diameter part 15 and contracting inside diameter 56, then by base metal housing 50 and insulator 10 Between seal.Operated using above, base metal housing 50 is fixed on insulator 10.

Ground electrode 30 is the bar-shaped electrode with substantially rectangular section in the present embodiment.Ground connection electricity The end face 37 of one end 30x of pole 30 and the end 50x of the front extreme direction D1 side of base metal housing 50 End face 57 engage.Hereinafter, the end 30x of ground electrode 30 is referred to as " base end part 30x ", by cardinal extremity The end face 37 of portion 30x is referred to as " cardinal extremity face 37 ".Additionally, the end 50x of base metal housing 50 is referred to as " top ends 50x ", the end face 57 of top ends 50x is referred to as " top end face 57 ".In the present embodiment, Cardinal extremity face 37 and top end face 57 are all with the central axis CL of base metal housing 50 generally vertically.

Ground electrode 30 extends towards front extreme direction D1 from the top end face 57 of base metal housing 50, Ran Houchao To central axis CL bending, until top ends 31.Top end face 29 in top ends 31 and central electrode 20 Form gap g between (surface 29 of front extreme direction D1 side).Ground electrode 30 has formation ground electrode At least one of outer layer 35 on 30 surface and the core 36 being embedded in outer layer 35.In addition, ground connection electricity The base end part 30x of pole 30 is that the part 38 of the ratio bending in ground electrode 30 leans on base metal housing 50 side Part.

Fig. 2 is the skeleton diagram obtained by spark plug 100 is observed in front.As diagram, central electrode 20th, insulator 10 and base metal housing 50 configure in the same axis centered on central axis CL On.It is bonded to ground electrode 30 in the top end face 57 of base metal housing 50.Cardinal extremity in ground electrode 30 Bonding part between the top end face 57 of face 37 and base metal housing 50 is formed with the width in welding and becomes Wide wide width part 350.Wide width part 350 utilizes at least one of ground electrode 30 and base metal housing 50 , at least one mode in melting and deformation to be forming.

Fig. 3 is the profile of the bonding part between ground electrode 30 and base metal housing 50.This section Figure is the central axis CLx of central axis CL (Fig. 2) and the ground electrode 30 comprising base metal housing 50 Plane P1 at section.Hereinafter, the section comprising two central axis CL, CLx is referred to as " benchmark Section ".Right direction Di of in figure is directed towards the direction (hereinafter referred to as " interior direction Di ") of radially inner side, Left direction Do is directed towards the direction (hereinafter referred to as " outer direction Do ") of radial outside.

The central axis CLx of ground electrode 30 is the central axis of the rod shape of ground electrode 30.As Fig. 3 Shown, what central axis CLx represented is not the central axis of the part 38 of the bending in ground electrode 30, But base end part 30x is (particularly indeformable and maintain part 30s of original form (hereinafter referred to as in welding Make " maintain part 30s ")) central axis.As shown in Fig. 2 from base metal housing 50 When heart axis CL observes, central axis CLx is located at will be from ground electrode 30 (particularly maintaining part 30s) Circumference on one end 301 to the other end 302 angular range AR halve obtained from center direction Position.In the present embodiment, central axis CLx is big with the central axis CL of base metal housing 50 Body is parallel.In addition, the 1st width Wa in Fig. 2 represent the section of ground electrode 30 substantially rectangular in The length of the 1st side Sa, the 2nd width Wb represent the section of ground electrode 30 substantially rectangular in the 1st side The length of the 2nd orthogonal side Sb of Sa.1st side Sa is substantially vertical with plane P1, is halved by plane P1.

As shown in figure 3, ground electrode 30 comprises outer layer 35 and core 36.Outer layer 35 forms ground electrode 30 Surface, engage with base metal housing 50.Outer layer 35 is by the oxidative resistance material shape more excellent than core 36 Become.In the present embodiment, outer layer 35 is by containing chromium, aluminum and the material of nickel as main component, tool Say that the nichrome being to the addition of aluminum is formed body.By adding aluminum, Neng Gouti so in nichrome Rise oxidative resistance.Core 36 configures the inner circumferential side in outer layer 35, engages with base metal housing 50.Core 36 are formed by the high material of thermal conductivity ratio outer layer 35.In the present embodiment, core 36 is to use fine copper Formed.

Two demarcation line L10, L20 of in figure represent the boundary between outer layer 35 and core 36.1st boundary Line L10 represents the demarcation line of interior direction Di side, and the 2nd demarcation line L20 represents the demarcation line of outer direction Do side. 1st boundary end P11 is the end by base metal housing 50 side of the 1st demarcation line L10.2nd boundary end P21 It is the end by base metal housing 50 side of the 2nd demarcation line L20.Additionally, the two of in figure outer peripheral lines L30, L40 represent the outer peripheral face of outer layer 35.1st outer peripheral lines L30 represent the outer peripheral lines of interior direction Di side, 2nd outer peripheral lines L40 represent the outer peripheral lines of outer direction Do side.1st outer circumference end P32 is the 1st outer peripheral lines L30 End by base metal housing 50 side.2nd outer circumference end P42 is the 2nd outer peripheral lines L40 by base metal shell The end of body 50 side.

As diagram, two demarcation line L10, L20 are remaining big with central axis CLx at part 30s Body is parallel.Wide width part the 350, the 2nd demarcation line L20 with closer to base metal housing 50 then further away from The mode of heart axis CLx bends, until the 2nd boundary end P21.Form the reason of such 2nd demarcation line L20 By seeing below.

1st demarcation line L10 in wide width part 350 at the part of maintenance part 30s with the 2nd demarcation line L20 similarly bends.But, in wide width part 350 at the part of base metal housing 50, 1 demarcation line L10 by closer to base metal housing 50 then closer to central axis CLx in the way of bend, directly To the 1st boundary end P11.In other words, the 1st demarcation line L10 comprises sloping portion L11, this sloping portion L11 The central axis CLx that end P11 is with respect to ground electrode 30 demarcate from the 1st obliquely towards the shape outer layer 35 The outer circumferential side becoming the part of the 1st demarcation line L10 extends.So, in the interior direction Di side of ground electrode 30, Outer layer 35 extends along the top end face 57 of base metal housing 50 towards central axis CLx.Thus, outer layer Bonding area between 35 and base metal housing 50 increases.

So, the bonding area between outer layer 35 and base metal housing 50 increases such that it is able to lifting connects Weld strength between ground electrode 30 and base metal housing 50.Its reason is as follows.In general, copper Heat conductivity is higher than the heat conductivity of nickel alloy.That is, compared with nickel alloy, copper is easy to radiate.Thus, When to welding between ground electrode 30 and base metal housing 50, on composition surface, with nickel alloy The temperature of (i.e. outer layer 35) is compared, and the temperature of copper (i.e. core 36) is easy to reduce.As a result, with outer Bond strength between layer 35 and base metal housing 50 is compared, between core 36 and base metal housing 50 Between bond strength can reduce.Thus, between the outer layer 35 on composition surface and base metal housing 50 The large percentage of bonding area in the case of, compared with situation less with its ratio, ground connection can be lifted Bond strength between electrode 30 and base metal housing 50.

Method as forming bonding part as Fig. 3, can adopt various methods.Fig. 4 is to represent joint The skeleton diagram of the example processing.The order of (F) according to (A)～Fig. 4 of Fig. 4 for the joining process is entered OK.In figure show ground electrode 30 a part (part engaging with base metal housing 50) and A part (part engaging with ground electrode 30) for base metal housing 50.Additionally, illustrating in figure The baseline cross-section same with Fig. 3 (section at plane P1).

First, as shown in (A) of Fig. 4, (B) of Fig. 4, by cutting off one end of ground electrode 30, Thus forming cardinal extremity face 37.Demarcation line L10u, L20u of in figure respectively with engage before demarcation line L10, L20 (Fig. 3) is corresponding, outer peripheral lines L30u, L40u respectively with engage before outer peripheral lines L30, L40 phase Corresponding.Each line L10u, L20u, L30u, L40u are all parallel with central axis CLx.

By make cutting off tool 920 with respect to the ground electrode 30 being bearing in support tool on 910 to in Heart axis CLx moves, thus ground electrode 30 is sheared in vertical direction.Cutting off tool 920 is from ground connection electricity The interior direction Di side of pole 30 is moved towards outward direction Do.Cut section and cardinal extremity face 37 using what this cut-out was formed Corresponding.

(C) of Fig. 4 represents the ground electrode 30 after cut-out.In the vicinity in cardinal extremity face 37, ground electrode 30 Each key element (here is outer layer 35 and core 36) because of the cutting off tool 920 with outward direction Do movement Contact and deform in the way of towards outward direction Do bending.For example, the 1st demarcation line L10u is in cardinal extremity face 37 Vicinity by closer to cardinal extremity face 37 then closer to central axis CLx in the way of deform.

Then, as shown in (D) of Fig. 4, ground electrode 30 is configured on the top of base metal housing 50 On face 57.Established part on the top end face 57 of the cardinal extremity face 37 of ground electrode 30 and base metal housing 50 Contact.Then, will be engaged between ground electrode 30 and base metal housing 50 using resistance welding.Now, With base metal housing 50, the power parallel with central axis CLx is applied to ground electrode 30.Specifically, Ground electrode 30 is applied with the power in the direction (extreme direction D1r afterwards) towards base metal housing 50, to master Body metal shell 50 applies the power towards front extreme direction D1.

(E) of Fig. 4 represents an example of the profile after welding.As diagram, base metal shell Top ends 50x of body 50 along ground electrode 30 cardinal extremity face 37 to the direction vertical with central axis CLx Extension.Equally, the base end part 30x of ground electrode 30 along base metal housing 50 top end face 57 to The vertical Directional Extension of central axis CLx.The power that base end part 30x and top ends 50x are applied in welding In the presence of can deform as (E) of Fig. 4.

Core 36 is pressed against the top end face 57 of base metal housing 50 in welding, therefore with along top Face 57 deforms to the mode of the Directional Extension away from central axis CLx.As a result, after welding, the 2nd Demarcation line L20 can be formed as closer to top end face 57 then further away from central axis CLx.On the other hand, 1st demarcation line L10 as below.Demarcation line as illustrated using (C) of Fig. 4, before welding L10u cardinal extremity face 37 to be formed about be then closer to central axis CLx closer to cardinal extremity face 37.Its knot Really, in welding, in the vicinity of the 1st demarcation line L10u, core 36 is difficult to extend, and outer layer 35 can court To central axis CLx extension.As a result, the 1st demarcation line L10 the 1st boundary end P11 can be formed in The 2nd boundary end P21 of the 2nd demarcation line L20 compares the position close to central axis CLx.

After welding, remove the unnecessary part producing in bonding part, then engage and complete.Fig. 4's (F) represent the state completing that engages, identical with the profile of Fig. 3.(F) in (E) of Fig. 4, Fig. 4 Example in, remove than the 1st datum level Si inner direction Di side part 35i, 50i.1st datum level Si With by inner peripheral surface (inner peripheral surface before welding near top end face 57) the forward end side of base metal housing 50 It is substantially the same to face obtained from D1 prolongation.Additionally, removing than the 2nd datum level So outer direction Do side Part 35o, 50o.2nd datum level So and by the outer peripheral face of base metal housing 50 (near top end face 57 Welding before outer peripheral face) forward extreme direction D1 extend obtained from face be substantially the same.

In addition, the manufacture method of ground electrode 30 can also adopt various methods.For example can adopt following Method.The external member of the cup-shaped that preparation is formed by the material of outer layer 35, inserts by core in this external member The inner member that the material in portion 36 is formed.By shaping the outer of external member in the state of inserting inner member Shape, thus before forming the bar-shaped component of external member that there is inner member and cover inner member, bending Ground electrode.According to the step being illustrated using Fig. 4 by the bar-shaped engaging ground electrode obtaining In base metal housing 50.Then, bend ground electrode in the way of forming suitable gap g, thus Form ground electrode 30.In addition, in order that ground electrode 30 be readily bent it is also possible to will bending before Bar-shaped ground electrode annealing.

Additionally, the joint between ground electrode 30 and base metal housing 50 can be in the system of spark plug 100 Various stage execution during making.For example, it is also possible to be fixed on centering electrocardio in base metal housing 50 After the insulator 10 that pole 20 and terminal metal piece 40 are kept, by the bar-shaped ground connection electricity before bending Pole is engaged with base metal housing 50.Furthermore, it is also possible to form suitable gap g after this joint Mode bend ground electrode.Replace it is also possible to by bending before bar-shaped ground electrode with After base metal housing 50 engages, base metal housing 50 is fixed on to central electrode 20 and terminal gold Belong to the insulator 10 that part 40 is kept.

A-2. evaluation test：

In evaluation test, using the ground electrode 30 with the 1st embodiment and base metal housing 50 Component sample evaluating bond strength.Table 1 below shows surface oxygen amount, ratio t and intensity Evaluation result between relation.

[table 1]

" surface oxygen amount " be welding before the surface of outer layer 35 of ground electrode 30 on, oxygen containing than Rate (unit is percentage by weight).The measuring method of surface oxygen amount as below.Using electron probe Microscopic analyses (Electron Probe Micro Analysis：EPMA) to the ground electrode 30 before welding In outer layer 35 surface from the partly different part that melting or deformation occur in welding on element Species and amount be analyzed.The region being analyzed is the foursquare region of 500 μm of 500 μ m.So Afterwards, calculate the ratio with respect to oxygen element and the total amount of the element constituting outer layer 35 for the amount of oxygen element, as Surface oxygen amount.Employ SEM/EDS (scanning electron microscope/energy dispersion type in this analysis X-ray analysis equipment) JSM-6490LA of Jeol Ltd. (specifically).Here, Accelerating potential is set as 20kV.

The element on the surface of ground electrode 30 can be (e.g. empty by the environmental gas around ground electrode 30 Gas) contained by oxygen aoxidized.Particularly in the case that outer layer 35 contains aluminum, the surface of outer layer 35, I.e. the surface of ground electrode 30 is easily oxidised.Additionally, in the case of carrying out above-mentioned annealing, surface The amount of oxide can increase.This oxide can lead to weld defect.Thus, the oxygen amount on surface is more In the case of, there is a possibility that weld strength declines.

In evaluation test shown in table 1, as surface oxygen amount, test 1,2,4,5,8,9, This 7 values of 10 (wt%).Because " 1wt% " is identical with the evaluation result of the intensity of " 2wt% ", because This, unified representation in Table 1.Further, since the evaluation result of the intensity of " 4wt% " and " 5wt% " Identical, therefore, unified representation in Table 1.Adjusted by adjusting the time of the temperature annealed and annealing Surface oxygen amount.In addition, the method for control surface oxygen amount is not limited to adjust the temperature and time of annealing Method, can adopt various methods.For example, it is also possible to adjust the oxygen in environmental gas when being annealed Concentration.Additionally, in order to reduce surface oxygen amount it is also possible in container after being exhausted using vacuum pump Annealed.

" ratio t " in table 1 is that the joint shown in Fig. 3 is (single with respect to the always ratio apart from W2 apart from W1 Position is %).Always apart from W2 in Fig. 3 shown in baseline cross-section in be that two outer peripheral lines L30, L40 are respective By between outer circumference end P32, P42 of base metal housing 50 side and ground electrode 30 central axis Distance on the vertical direction of CLx.Engaging apart from W1 is the distance between straight line LP1 and straight line LP3, This straight line LP1 is by the boundary end P11 of base metal housing 50 side and electric with ground connection through sloping portion L11 The central axis CLx of pole 30 is parallel, and this straight line LP3 is through being located at sloping portion when the end P11 that demarcates observes Outer circumference end P32 on the bearing of trend of L11 and parallel with the central axis CLx of ground electrode 30.This joint Distance on the direction that W1 is vertical with the central axis CLx of ground electrode 30.

2nd demarcation line L20 does not comprise from the boundary end P21 of the 2nd demarcation line L20 with respect to ground electrode 30 Central axis CLx obliquely towards the outer circumferential side of the part of formation the 2nd demarcation line L20 in outer layer 35 The sloping portion extending.Thus, the boundary end P21 of the 2nd demarcation line L20 and the 2nd of the 2nd outer peripheral lines L40 the The distance between outer circumference end P42 is not included in engaging in W1.

In the evaluation test of table 1, as ratio t, test 0,5,10,30,50,80,90 (%) This 7 values.Have rated this 7 values for each surface oxygen amount one by one.That is, in this evaluation test, evaluate 49 respective samples of combination between 7 surface oxygen amount and 7 ratios t.In addition, being mainly adjusted by When the nose angle of cutting off tool 920 ((A) of Fig. 4), welding, the load that applies and welding current are adjusting Whole ratio t.Nose angle is bigger, then more being capable of scaling up t.Load is bigger, then more being capable of scaling up t. Welding current is less, then more being capable of scaling up t.

The evaluation result of the intensity in table 1 as below determine.That is, ground electrode 30 and master are entered to be about to Body metal shell 50 is to the stretching making both separated from one another and the direction parallel with central axis CLx stretches Test, measurement tensile strength (the maximum tension load that i.e. sample can bear).A evaluates and represents that stretching is strong Spend for 450N/mm²More than, B evaluates and represents that tensile strength is 350N/mm²Above and tensile strength Less than 450N/mm², C evaluation expression tensile strength is less than 350N/mm².In addition, tension test makes Carried out with the AG-5000B of Shimadzu Scisakusho Ltd.

In addition, the measurement of ratio t and tension test are come using the multiple samples made at identical conditions Carry out.Ratio t of the sample being adopted as tension test, using by the sample made at identical conditions Product are with baseline cross-section cut-out thus measuring obtained ratio t.That makes at identical conditions is multiple Between sample, ratio t is substantially the same.

Between 49 kinds of samples, the structure in addition to surface oxygen amount and ratio t is identical.For example, with Under structure be identical in 49 kinds of samples.

As shown in table 1, in the case that surface oxygen amount is 9wt% or 10wt%, regardless of ratio t, by force The evaluation result of degree is all that C evaluates.On the other hand, in the case that surface oxygen amount is below 8wt%, energy Enough realize more preferable evaluation result (A evaluates or B evaluates).So, by suppressing surface oxygen amount in 8wt% Hereinafter, weld strength can be lifted.Furthermore it is possible to it is more little to be inferred as surface oxygen amount, weldering more can be lifted Connect intensity, but be difficult to for surface oxygen amount to be set to 0 in reality.Thus, surface oxygen amount can be using than 0wt% Big various values.

In addition, the surface oxygen amount being capable of good evaluation result is 1,2,4,5,8 (wt%). Arbitrary value in these values can be used as the preferred scope (more than lower limit, below the upper limit) of surface oxygen amount The upper limit.For example, surface oxygen amount can adopt 8wt% value below.Furthermore, it is possible to by these values The upper limit below arbitrary value be used as surface oxygen amount preferred scope lower limit.For example, surface oxygen amount can With the value using more than 1wt%.

Additionally, in the case that surface oxygen amount is below 5wt%, being capable of particularly preferred A and evaluate.Separately Outward, the surface oxygen amount being capable of A evaluation is 1,2,4,5 (wt%).Thus, particularly preferably from this The upper and lower bound of the preferred scope of surface oxygen amount is selected in 4 values.Additionally, it is each in this 4 surface oxygen amount From in the case of, obtain A evaluation ratio t be 5,10,30,50,80 (%).Can be by these values In arbitrary value be used as ratio t preferred scope the upper limit.For example, ratio t can adopt less than 80% Value.Furthermore it is possible to be inferred as with ratio t be 0% situation compared with, ratio t be more than 0% in the case of Weld strength can be lifted.Thus, ratio t can be using the various values bigger than 0%.In addition it is also possible to The lower limit of selection percentage t from ratio t (5,10,30,50,80 (%)) obtaining A evaluation.For example, Ratio t can also adopt more than 5% value.

B. the 2nd embodiment：

B-1. the structure of spark plug：

Fig. 5 is the profile of an example of the spark plug of the 2nd embodiment.In in figure in the same manner as Fig. 3 Show connecing between the base end part 30bx of ground electrode 30b and top ends 50x of base metal housing 50 Close the profile of part.It is only that ground electrode 30b's with the discrepancy of the 1st embodiment shown in Fig. 3 Core 36b comprises the 1st layer of 34a and configuration the 2nd layer of 34b in the inner circumferential side of the 1st layer of 34a.Ground electrode 30b Structure in, the structure in addition to core 36b identical with the structure of the ground electrode 30 shown in Fig. 3.With Under, key element in the key element of the ground electrode 30b of the 2nd embodiment and Fig. 3 ground electrode 30 Identical key element marks identical reference, and omits the description.Additionally, the spark of the 2nd embodiment The structure in addition to ground electrode 30b in the structure of plug 100b and the structure of the spark plug 100 shown in Fig. 1 Identical.Hereinafter, in the key element of the spark plug 100b of the 2nd embodiment and Fig. 1 spark plug 100 Key element identical key element mark identical reference, and omit the description.

The core 36 of the 1st layer of 34a and Fig. 3 is equally formed by the high material of thermal conductivity ratio outer layer 35.At this In embodiment, the 1st layer of 34a is to be formed using fine copper.The part configuration of the 2nd layer of 34b is at the 1st layer The inner circumferential side of 34a.2nd layer of 34b is by with containing ratio (wt%) the material shape containing nickel bigger than outer layer 35 Become.That is, the containing ratio of the nickel of the 2nd layer of 34b is higher than the containing ratio of the nickel of outer layer 35.Additionally, the 2nd The heat conductivity of layer 34b is higher than the heat conductivity of outer layer 35.In the present embodiment, the 2nd layer of 34b is to make With pure nickel formation.

As shown in figure 5, the internal structure of ground electrode 30b is outer layer 35 in the part comprising cardinal extremity face 37 With 2 Rotating fields of the 2nd layer of 34b, other parts be outer layer 35, the 1st layer of 34a and the 2nd layer of 34b 3 Rotating fields.1st layer of 34a is not engaged with base metal housing 50, and the 2nd layer of 34b is connect with base metal housing 50 Close.In addition, though omitting diagram, the top ends of ground electrode 30b are (corresponding with the top ends 31 of Fig. 1 Part) internal structure be also outer layer 35 and 2 Rotating fields of the 2nd layer of 34b.But, the 1st layer of 34a Extend to the top ends of ground electrode 30b.

Demarcation line L10b, L20b of in figure equally represents outer layer 35 with demarcation line L10, L20 of Fig. 3 respectively Boundary and core 36b between.P11b, P21b are same with boundary end P11, P21 of Fig. 3 respectively at boundary end It is the end by base metal housing 50 side of demarcation line L10b, L20b.As diagram, demarcation line The 1st demarcation line L10 of L10b and Fig. 3 is same, comprises from the 1st boundary end P11b with respect to ground electrode 30b Central axis CLx obliquely towards the outer circumferential side of the part of formation the 1st demarcation line L10b in outer layer 35 The sloping portion L11b extending.Thus, the bonding area between outer layer 35 and base metal housing 50 increases, Therefore, the situation phase with not forming sloping portion L11b, the 1st layer of 34a being engaged with base metal housing 50 Ratio can lift the weld strength between ground electrode 30b and base metal housing 50.

Additionally, as described above, compared with copper, the weld strength of nickel is stronger.Additionally, in this embodiment party In formula, separate between 34a and base metal housing 50 for the 1st layer containing copper.And, outer containing nickel 35 and the 2nd layers of 34b of layer are engaged with base metal housing 50.Thus, with the 1st layer of 34a and base metal housing The situation of 50 joints is compared, and the welding that can be lifted between ground electrode 30b and base metal housing 50 is strong Degree.

Method as forming bonding part as Fig. 5, can adopt and (the A)～Fig. 4 using Fig. 4 The same method of (F) method of illustrating.Here, conduct makes the 1st layer of 34a and base metal housing 50 Between the method separated, various methods can be adopted.For example, as the ground electrode 30b before cut-out, Manufacture and include there is outer layer 35, the part of 3-tier architecture of the 1st layer of 34a and the 2nd layer of 34b and have outer The component of the part of 2 Rotating fields of 35 and the 2nd layers of 34b of layer.Then, (B) with (A) of Fig. 4, Fig. 4 Similarly cut off the part of 2 Rotating fields.Then, by base in the same manner as (D) of Fig. 4, (E) of Fig. 4 The top end face 57 of end face 37b and base metal housing 50 welds together.Then, (E), the figure with Fig. 4 4 (F) similarly removes the part exceeding from datum level Si, So ((E) of Fig. 4), thus completing Joining process.

In addition, as the manufacture method of ground electrode 30b, can be using the ground connection electricity with the 1st embodiment The same method of the manufacture method of pole 30.Additionally, as the manufacture method of spark plug 100b, can adopt The method same with the manufacture method of the spark plug 100 of the 1st embodiment.

B-2. evaluation test：

In evaluation test, using the ground electrode 30b with the 2nd embodiment and base metal housing 50 Component sample evaluating bond strength.Table 2 below shows ratio t, 100-t and intensity Relation between evaluation result.

[table 2]

Ratio t is engaging apart from W1 with respect to always apart from the ratio (unit is %) of W2 shown in Fig. 5.? In the embodiment of Fig. 5, always always identical apart from W2 apart from W2 and the embodiment of Fig. 3.Engage distance W1 is two straight lines the distance between LP1b, LP3.Straight line LP3 is identical with the straight line LP3 of Fig. 3.Straight line LP1b is by the boundary end P11b of base metal housing 50 side and electric with ground connection through sloping portion L11b The parallel straight line of the central axis CLx of pole 30b.

2nd demarcation line L20b does not comprise from the boundary end P21b of the 2nd demarcation line L20b with respect to ground electrode The central axis CLx of 30b obliquely towards formation the 2nd demarcation line L20b in outer layer 35 part outer The sloping portion that the week side of boss extends.Thus, the 2nd boundary end P21b and the 2nd outer peripheral lines of the 2nd demarcation line L20b The distance between the 2nd outer circumference end P42 of L40 is not included in engaging in W1.

In the evaluation test of table 2, as ratio t, have rated 0,5,10,20,30,50,80, This 8 values of 90 (%).That is, in this evaluation test, have rated 8 kinds of samples.

" 100-t (%) " is to deduct value obtained from ratio t from 100.This value is bigger, then outer layer 35 Bonding area and base metal housing 50 between is less, and the 2nd layer of 34b and base metal housing 50 it Between bonding area bigger.

The evaluation methodology of the intensity of table 2 is identical with the evaluation methodology of the intensity of above-mentioned table 1.But, evaluate Threshold value different.That is, A evaluates and represents that tensile strength is 550N/mm²More than, B evaluates and represents stretching Intensity is 450N/mm²Above and tensile strength be less than 550N/mm², C evaluation expression tensile strength Less than 450N/mm².

In addition, between 8 kinds of samples, the structure in addition to ratio t (i.e. 100-t) is identical.Example If structure below is identical in 8 kinds of samples.

As shown in table 2, compared with the situation that ratio t is larger, in the case of ratio t is less, there is intensity Evaluation result be preferably inclined to.May infer that its reason is as follows.In welding containing nickel as main component Material in the case of, the one-tenth branch in addition to nickel in this material leads to weld defect.Thus, exist The stronger tendency of the more high then weld strength of containing ratio (wt%) of nickel.Then, in the embodiment party of Fig. 5 In formula, ratio t is less, then the containing ratio of nickel 2nd layer 34b and the base metal housing 50 higher than outer layer 35 Between bonding area bigger.Therefore, it is possible to the more little then weld strength of the ratio t of being inferred as is higher.In addition, In the case that ratio t is 0%, the evaluation result of intensity is not that A evaluates but B evaluation.It is considered that its Reason for this is that, may in the section different from the baseline cross-section of measurement scale t the 1st layer of 34a and base metal Housing 50 engages.

In addition, ratio t being capable of A evaluation is 5,10,20 (%).Therefore, it is possible to by these values In arbitrary value be used as ratio t preferred scope the upper limit.For example, ratio t can adopt less than 20% Value.Furthermore it is possible to be inferred as, with ratio t be 0% situation compared with, ratio t be more than 0% situation Under, extend to suppress the 1st layer of 34a and base metal towards central axis CLx by outer layer 35 in welding Joint between housing 50, therefore, it is possible to lift weld strength.Thus, ratio t can adopt bigger than 0% Various values.In addition it is also possible to select ratio from ratio t (5,10,20 (%)) obtaining A evaluation The lower limit of example t.For example, ratio t can also adopt more than 5% value.

Additionally, as described above, surface oxygen amount is less, then more can lift weld strength.Thus, than The above-mentioned preferred scope of example t can apply to the various surfaces oxygen amount of below 5wt%.

In addition, in the embodiment of Fig. 5, separating between base metal housing 50 and the 1st layer of 34a, And engage with outer layer 35 and the 2nd layer of 34b.Replace, base metal housing 50 can also with outer layer 35, 1st layer of 34a and the 2nd layer of 34b engages.In this case it is also possible to be inferred as, can be by making Ratio t less increasing the 2nd layer of bonding area between 34b and base metal housing 50, therefore, it is possible to carry Rise bond strength.Thus, in this case it is also possible to be inferred as being capable of the above-mentioned excellent of application percentage t Select scope.

C. variation：

(1) in the above-described embodiment, the 1st demarcation line L10, L10b (Fig. 3, Fig. 5) comprises to incline Inclined portion divides L11, L11b.Generally, it is preferable on the basis of outer layer 35 in section and core 36,36b Between at least one of two demarcation line there is sloping portion.Using this structure, with two demarcation line Both of which does not have a case that sloping portion is compared, can increase outer layer 35 and base metal housing 50 it Between bonding area, therefore, it is possible to be lifted between ground electrode 30,30b and base metal housing 50 Bond strength.

For example, it is also possible to be, two demarcation line both of which contain sloping portion.This structure is being applied In the case of the embodiment of Fig. 3, Fig. 5, the 2nd demarcation line L20, L20b comprise from the 2nd demarcate end P21, The sloping portion that P21b obliquely extends towards outward direction Do.In this case, engage and adopt apart from W1 With the 1st boundary end P11, P11b and the 1st outer circumference end P32 between the 1st distance (joint of Fig. 3, Fig. 5 away from From W1) and the 2nd boundary end P21, P21b and the 2nd outer circumference end P42 between the 2nd with a distance from aggregate value.The 2 distances are through the 2nd boundary end P21, P21b and straight line LP2, the LP2b parallel with central axis CLx With through the 2nd outer circumference end P42 and the distance between the straight line LP4 parallel with central axis CLx.Additionally, Can also be that the 1st demarcation line L10, L10b of interior direction Di side does not comprise sloping portion, outer direction Do side The 2nd demarcation line L20, L20b comprise sloping portion.

Fig. 6 is the sectional view of an example of the spark plug of variation.The spark plug 100c of this variation is Two demarcation line both of which are comprised the such structure of sloping portion be applied to the embodiment of Fig. 3 and obtain The example of the spark plug arriving.In figure show in the same manner as Fig. 3 ground electrode 30c base end part 30cx and The profile of the bonding part between top ends 50x of base metal housing 50.Real with the 1st shown in Fig. 3 The discrepancy applying mode is only that, two boundary between the outer layer 35c and core 36c of ground electrode 30c 2nd demarcation line L20c of the outer direction Do side in line L10, L20c comprises sloping portion L21c.Fig. 6's The part than central axis CLx inner direction Di side in variation, in the bonding part of ground electrode 30c Structure and the bonding part of Fig. 3 in the part than central axis CLx inner direction Di side structure phase With.Additionally, the ratio central axis CLx in the variation of Fig. 6, in the bonding part of ground electrode 30c The knot of the part of the structure of part of outer direction Do side and contrast central axis CLx inner direction Di side The structure obtained from mirror transformation that structure is carried out with central axis CLx as axis of symmetry is substantially the same.

The structure of the other parts of ground electrode 30c and the big body phase of structure of the ground electrode 30 shown in Fig. 3 With.For example, the structure of outer layer 35c and core 36c is except the 2nd demarcation line L20c's at base end part 30cx Outside shape, it is substantially the same with the outer layer 35 of Fig. 3 and the structure of core 36 respectively.Additionally, variation The structure in addition to ground electrode 30c in the structure of spark plug 100c and the spark plug 100 shown in Fig. 1 Structure is identical.Hereinafter, in the key element of the spark plug 100c of variation and Fig. 1, Fig. 3 spark plug 100 and the key element identical key element mark identical reference of ground electrode 30, and omit the description.

The sloping portion L11 of the 1st demarcation line L10 tilts with respect to central axis CLx from the 1st boundary end P11 The outer circumferential side (here is interior direction Di side) of the part towards formation the 1st demarcation line L10 in outer layer 35c for the ground Extend.Additionally, the 2nd boundary end P21c of in figure is the 2nd demarcation line L20c by base metal housing 50 The end of side.Sloping portion L21c is from the 2nd boundary central axis with respect to ground electrode 30c for the end P21c Obliquely towards the outer circumferential side of the part of formation the 2nd demarcation line L20c in outer layer 35c, (here is outer to CLx Direction Do side) extend.Part in the outer direction Do side of ground electrode 30c and the part of interior direction Di side In both, outer layer 35c extends along the top end face 57 of base metal housing 50 towards central axis CLx. So, because both two demarcation line L10, L20c comprise sloping portion L11, L21c, therefore, with It is only that the situation that two demarcation line one of L10, L20c comprise sloping portion is compared, can increase outer Bonding area between layer 35c and base metal housing 50.As a result, can be lifted ground electrode 30c and Bond strength between base metal housing 50.

Method as forming bonding part as Fig. 6, can adopt arbitrary method.For example, may be used To adopt with the following method, that is,：Prepare Fig. 4 such 1st cutting off tool of cutting off tool 920 of (A) and 2nd cutting off tool, is clamped ground electrode and is cut off using two cutting off tools.1st cutting off tool from The interior direction Di side of ground electrode is moved towards central axis CLx, and the 2nd cutting off tool is from ground electrode Direction Do side is moved towards central axis CLx.Thus, with (B) of Fig. 4 towards base metal shell The 1st demarcation line L10u that body 50 extends tilts in the way of in the close central axis CLx in the vicinity of end face 37 Form same, two demarcation line corresponding with demarcation line L10, L20c of Fig. 6 are with ground electrode 30c The vicinity of cardinal extremity face 37c tilt near the mode of central axis CLx.Thus, it is possible to using with Fig. 4's (D) same welding, forms sloping portion L11, L21c of Fig. 6.

In the variation of Fig. 6, it is also preferred that surface oxygen amount is on the surface being illustrated with reference to table 1 In the preferred scope of oxygen amount.May infer that as good bond strength is capable of using this structure.Example As surface oxygen amount is preferably below 8wt%, particularly preferably below 5wt%.Additionally, in Fig. 6 the 2nd It is through the 2nd boundary end P21c apart from W12 and the straight line LP2c parallel with central axis CLx and through the The distance between 2 outer circumference end P42 and the straight line LP4 parallel with central axis CLx.Engage and adopt apart from W1 Between 1st boundary end P11 and the 1st outer circumference end P32 the 1st is apart from W11 (identical apart from W1 with Fig. 3) And the 2nd boundary end P21c and the 2nd outer circumference end P42 between the 2nd is apart from the aggregate value of W12.Preferably, Ratio t (=W1/W2) being calculated apart from W1 (=W11+W12) according to this joint is in reference In the preferred scope of ratio t that table 1 is illustrated.May infer that as being capable of more using this structure Good bond strength.For example, it is preferable that, ratio t is more than 0% and is less than 80%.

Fig. 7 is the profile of an example of the spark plug of another variation.The spark plug of this variation 100d is that two demarcation line both of which are comprised the embodiment party that the such structure of sloping portion is applied to Fig. 5 The example of spark plug obtained from formula.The base end part of ground electrode 30d is shown in figure in the same manner as Fig. 5 The profile of the bonding part between top ends 50x of 30dx and base metal housing 50.With shown in Fig. 5 The discrepancy of the 2nd embodiment is only that, two between the outer layer 35d and core 36d of ground electrode 30d 2nd demarcation line L20d of the outer direction Do side in demarcation line L10b, L20d comprises sloping portion L21d.? In the variation of Fig. 7, in the bonding part of ground electrode 30d than central axis CLx inner direction Di side The structure of part and the bonding part of Fig. 5 in the part than central axis CLx inner direction Di side Structure is identical.Additionally, the ratio central shaft in the variation of Fig. 7, in the bonding part of ground electrode 30d The structure of part of line CLx outer direction Do side and the part contrasting central axis CLx inner direction Di side The structure obtained from mirror transformation that carries out with central axis CLx as axis of symmetry of structure be substantially the same.

The structure of the other parts of ground electrode 30d and the big body phase of structure of the ground electrode 30b shown in Fig. 5 With.For example, the structure of the 1st layer of 34c and the 2nd layer of 34d of outer layer 35d and core 36d is except base end part Outside the shape of the 2nd demarcation line L20d at 30dx, respectively with the outer layer 35 of Fig. 5 and core 36b The structure of the 1st layer of 34a and the 2nd layer of 34b is substantially the same.Additionally, in the structure of spark plug 100d of variation The structure in addition to ground electrode 30d identical with the structure of the spark plug 100 shown in Fig. 1.Hereinafter, right In the key element of spark plug 100d of variation and Fig. 1, Fig. 5 spark plug 100 and ground electrode 30b's Key element identical key element marks identical reference, and omits the description.

The sloping portion L11b of the 1st demarcation line L10b is from the 1st boundary end P11b with respect to central axis CLx Obliquely towards the outer circumferential side of part of formation the 1st demarcation line L10b in outer layer 35d, (here is interior direction Di side) extend.Additionally, the 2nd boundary end P21d of in figure is the 2nd demarcation line L20d by base metal shell The end of body 50 side.Sloping portion L21d is from the 2nd boundary central shaft with respect to ground electrode 30d for the end P21d Obliquely towards the outer circumferential side of the part of formation the 2nd demarcation line L20d in outer layer 35d, (here is line CLx Outer direction Do side) extend.Part in the outer direction Do side of ground electrode 30d and the portion of interior direction Di side In both point, outer layer 35d expands along the top end face 57 of base metal housing 50 towards central axis CLx Exhibition.So, because both two demarcation line L10b, L20d comprise sloping portion L11b, L21d, Therefore, be only energy compared with two demarcation line one of L10b, L20d comprise the situation of sloping portion Enough increase the bonding area between outer layer 35d and base metal housing 50.As a result, ground connection can be lifted Bond strength between electrode 30d and base metal housing 50.

Method as forming bonding part as Fig. 7, can adopt arbitrary method.For example, may be used Method so that two cutting off tools are equally used using the method with explanation in the variation of Fig. 6.

In the variation of Fig. 7, it is also preferred that surface oxygen amount is in above-mentioned preferred scope.Permissible It is inferred as, good bond strength is capable of using this structure.For example, surface oxygen amount is preferably 8wt% Hereinafter, particularly preferably below 5wt%.Additionally, the in Fig. 7 the 2nd is through the 2nd boundary end apart from W12d P21d and the straight line LP2d parallel with central axis CLx and through the 2nd outer circumference end P42 and and central axis The distance between parallel straight line LP4 of CLx.Engage and adopt the 1st boundary end P11b and the 1st periphery apart from W1 Between the P32 of end the 1st is apart from W11d (identical apart from W1 with Fig. 5) and the 2nd boundary end P21d and the 2nd Between outer circumference end P42 the 2nd is apart from the aggregate value of W12d.Preferably, according to this joint apart from W1 (= W11d+W12d ratio t (=W1/W2)) calculating is in ratio t being illustrated with reference to table 2 Preferred scope in.May infer that as better bond strength is capable of using this structure.For example, Preferably, ratio t be more than 0%, its be less than 20%.

(2) when using two components of solder joints, form melting sometimes between this two components Portion.Fusing department is the part being formed by the component of the coalesced object melting in welding.In this case, Two components also can engage.For example, it is also possible in ground electrode 30,30b, 30c, 30d and main body Form fusing department between metal shell 50.Here, in outer layer 35,35c, 35d and base metal housing 50 In the case of being joined together by fusing department, outer layer 35,35c, 35d can be connect with base metal housing 50 It is combined.In the case of separating between 34a, 34c and fusing department at the 1st layer, base metal housing 50 can and the 1st layer separate between 34a, 34c.Borrow in the 1st layer of 34a, 34c and base metal housing 50 In the case of helping fusing department to be joined together, base metal housing 50 can be bonded on the 1st layer of 34a, 34c Together, do not separate between 34a, 34c with the 1st layer.

(3) it is formed with melting between ground electrode 30,30b, 30c, 30d and base metal housing 50 In the case of portion, boundary end adopt outer layer 35 in baseline cross-section, 35c, 35d and core 36,36b, The marginal end by base metal housing 50 side between 36c, 36d.In this case, Boundary end can be only fitted on the profile of fusing department.Outer circumference end similarly adopts outside the expression in baseline cross-section Layer 35, the end by base metal housing 50 side of the outer peripheral lines of the outer peripheral face of 35c, 35d.At this In the case of kind, outer circumference end can be only fitted on the profile of fusing department.In either case, at two points Position on each leisure in this 4 ends of the boundary end and two outer circumference end direction parallel with central axis CLx can With different.

(4) it is believed that being ratio t by the parameter related to ground electrode and surface oxygen amount causes enforcement The raising of the bond strength between the ground electrode of spark plug 100 of mode and base metal housing.Thus, Key element in addition to these parameters can carry out various changes.

For example, as the material of outer layer 35,35c, 35d, it is preferred to use containing nickel as main component, But also the material containing chromium and aluminum.I.e., it is preferred to use at least with the addition of the nichrome of aluminum.In addition, The containing ratio of aluminum is not limited to 1.4wt%, can adopt various values, for example can using more than 0wt%, And be 2.5wt% value below.Using the value in the range of this, the oxidative resistance of outer layer 35 can be lifted.Chromium Containing ratio can also adopt various values, for example can be using more than 10wt% and below 30wt% The value of scope.

The material of the 2nd layer of 34b, 35d (Fig. 5, Fig. 7) is not limited to pure nickel, can adopt and outer layer 35th, 35d compares the various materials containing more nickel.The nickel alloys such as nichrome for example can be adopted.

The core 36 of Fig. 3, the material of the 1st layer of 34c of core 36c and Fig. 7 of the 1st layer of 34a, Fig. 6 of Fig. 5 Material is not limited to fine copper, can be using the high various materials of thermal conductivity ratio outer layer 35,35c, 35d. The material as main component for example can be adopted containing copper.Containing copper as main component material for example The copper alloys such as corronil can be adopted.The containing ratio of copper can adopt less than 100% various values. Here, in order to realize good heat conductivity, the containing ratio of copper is preferably more than 80wt%, especially excellent Elect more than 95wt% as.

The material of base metal housing 50 is not limited to low-carbon (LC) steel, and can adopt can be with ground electrode The various conductive materials of 30 welding.Nichrome for example can also be adopted.

Width Wa, Wb of ground electrode 30 is not limited to width Wa, Wb of above-mentioned sample, permissible Using various values.

(5) structure of spark plug is not limited to the structure illustrating using Fig. 1, can adopt various structures. For example can also formation gap g in ground electrode 30,30b, 30c, 30d part setting noble metal Electrode tip.The material of noble metal electrode head can adopt the material containing the various noble metal such as iridium, platinum.With Sample is it is also possible to the part setting noble metal electrode head of formation gap g in central electrode 20.

More than, the present invention is illustrated according to embodiment, variation, the embodiment of foregoing invention is used for So that the present invention is understood by, do not limit the present invention.The present invention can be without departing from its purport and right Carry out in the case of claimed range changing, improve, and comprise its equivalent invention in the present invention.

Industrial applicability

The present invention can suitably be applied to the spark plug that internal combustion engine etc. is used.

Description of reference numerals

5th, packing ring；6th, the 1st rear end side seal；7th, the 2nd rear end side seal；8th, front end side seal Part；9th, Talcum；10th, insulator (insulation electroceramics)；11st, the 2nd contracting outer diameter part；12nd, through hole； 12nd, axis hole；13rd, leg；15th, the 1st contracting outer diameter part；16th, contracting inside diameter；17th, front main body Portion；18th, rear end side main part；19th, flange part；20th, central electrode；21st, outer layer；22nd, core； 23rd, head；24th, flange part；25th, leg；29th, top end face；30th, 30b, 30c, 30d, connect Ground electrode；30s, maintenance part；30x, 30bx, 30cx, 30dx, base end part；31st, top ends； 34a, 34c, the 1st layer；34b, 34d, the 2nd layer；35th, 35c, 35d, outer layer；36、36b、36c、 36d, core；37th, 37b, 37c, cardinal extremity face；38th, sweep；40th, terminal metal piece；50、 Base metal housing；50x, top ends；51st, tool engagement portion；52nd, threaded portion；53rd, crimp portion； 54th, portions；55th, main part；56th, contracting inside diameter；57th, top end face；58th, variant part；59th, pass through Through hole；60th, the 1st sealing；70th, resistive element；80th, the 2nd sealing；100、100b、100c、 100d, spark plug；350th, wide width part；910th, support tool；920th, cutting off tool；L10、L10u、 L10b, the 1st demarcation line；L20, L20u, L20b, L20c, L20d, the 2nd demarcation line；L30、L30u、 1st outer peripheral lines；L40, L40u, the 2nd outer peripheral lines；P11, P11b, the 1st boundary end；P21、P21b、 P21c, P21d, the 2nd boundary end；P32, the 1st outer circumference end；P42, the 2nd outer circumference end；L11、L11b、 L21c, L21d, sloping portion；CL, CLx, central axis (axis)；P1, plane；D1, front Extreme direction；D1r, rear extreme direction；Do, outer direction；Di, interior direction；LP1、LP1b、LP2、 LP2b, LP2c, LP2d, LP3, LP4, straight line；W1, joint distance；W2, total distance；W11、 W11d, the 1st distance；W12, W12d, the 2nd distance；AR, angular range；Wa, the 1st width； Wb, the 2nd width；Sa, the 1st side；Sb, the 2nd side；G, gap；Si, the 1st datum level；So, 2 datum levels.

Claims

1. a kind of spark plug, this spark plug includes：

Central electrode；

Insulator, it keeps described central electrode；

Described ground electrode comprises：

Core, it configures in the inner circumferential side of described outer layer,

2. spark plug according to claim 1, wherein,

Now, described ratio t is more than 0% and is less than 80%.

3. spark plug according to claim 1, wherein,

Now, described ratio t is more than 0% and is less than 20%.

4. spark plug according to claim 3, wherein,

In described section, separate between described base metal housing and described 1st layer, and with institute State outer layer and described 2nd layer engage.

5. the spark plug according to any one of Claims 1 to 4, wherein,