CN104143766A - A spark plug - Google Patents
A spark plug Download PDFInfo
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- CN104143766A CN104143766A CN201410191258.4A CN201410191258A CN104143766A CN 104143766 A CN104143766 A CN 104143766A CN 201410191258 A CN201410191258 A CN 201410191258A CN 104143766 A CN104143766 A CN 104143766A
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- China
- Prior art keywords
- mentioned
- terminal electrode
- nickel dam
- spark plug
- rear end
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
- H01T13/00—Sparking plugs
- H01T13/02—Details
- H01T13/04—Means providing electrical connection to sparking plugs
Abstract
A spark plug is provided. A recess part is disposed at the rear end of a terminal electrode and a nickel layer is formed at the rear end of the terminal electrode. In the spark plug, the corrosion resistance of the terminal electrode is fully enhanced and inhibition for peeling of the nickel layer is more reliable. The spark plug (1) comprises: an insulation electrotechnical porcelain (2) provided with an axis hole (4) penetrating along the axis direction (CL1); and the terminal electrode (6), wherein the rear end of the terminal electrode is inserted into the axis hole (4) in a state that the rear end of the terminal electrode protrudes out from the rear end of the insulation electrotechnical porcelain (2). The rear end of the terminal electrode (6) is provided with the recess part adopting the axis direction (CL1) as the depth direction. The nickel layer (35) is disposed on the external surface of the rear end of the terminal electrode (6), and has a thickness of 3-25 [mu]m. In a cross section orthogonal to the external surface of the nickel layer (35), the average section area of crystal grains forming the nickel layer (35) is 50-500 [mu]m<2>.
Description
Technical field
The present invention relates to a kind of spark plug that is used in internal combustion engine etc.
Background technology
Spark plug is installed on internal combustion engine (engine) etc., for the igniting such as mist in combustion chamber.In general, spark plug comprises: insulator, and it has the axis hole extending along axis direction; Central electrode, its insertion is set to the tip side of this axis hole; Terminal electrode, its insertion is set to the rear end side of axis hole; Base metal shell, it is located at the periphery of insulator; And grounding electrode, it is fixed on the top ends of base metal shell.In addition, the rearward end of terminal electrode self is exposed from the rear end of insulator, and connects in this rearward end the terminal that electric power is supplied with use.In addition, expose the rear end of the rearward end autonomous agent metal shell of insulator self, and this insulator is between the rearward end of terminal electrode and the rear end of base metal shell.
In addition, in recent years, in order to prevent more reliably the surperficial electric discharge of the insulator between the rearward end at terminal electrode and the rear end of base metal shell, thereby known have by guaranteeing that significantly the rear end of autonomous agent metal shell for example, to the method for the distance of the rearward end of terminal electrode (, with reference to patent documentation 1 etc.) the distance of the rear end of autonomous agent metal shell to the rear end of terminal electrode being remained to the rearward end that further lengthens insulator in constant.And, proposed to take the technology (for example,, with reference to patent documentation 2 etc.) of the recess that axis direction is depth direction in the rearward end setting of terminal electrode.
In addition, in order to realize the raising of the corrosion resistance in terminal electrode, sometimes at least rearward end of terminal electrode, for example form, by take the nickel dam that metal that nickel is main component forms (, with reference to patent documentation 3 etc.).In addition, when forming nickel dam, conventionally by electroplanting device, terminal electrode is carried out to electroplating processes.
Prior art document
Patent documentation
Patent documentation 1:WO2011/33902 communique
Patent documentation 2: TOHKEMY 2012-128948 communique
Patent documentation 3: TOHKEMY 2005-285468 communique
Yet as described above in the situation that terminal electrode is provided with recess, it is inhomogeneous that the thickness of nickel dam easily becomes, easily cause the peeling off of reduction, nickel dam of corrosion resistance.Particularly, for the bottom surface of recess, because electric field strength is relatively low, therefore there is the easy attenuation of nickel dam, the inadequate hidden danger of corrosion resistance.On the other hand, position for the periphery that is positioned at recess in terminal electrode, because electric field strength becomes higher relatively, therefore exist the thermal expansion difference between the easy thickening of nickel dam, nickel dam and terminal electrode to become the hidden danger that the resistance to fissility in large (thermal stress that in other words, puts on nickel dam becomes large), nickel dam reduces.
Summary of the invention
The present invention In view of the foregoing completes, its object is, the rearward end that is terminal electrode arranges recess and is formed with in the spark plug of nickel dam at the rearward end outer surface of terminal electrode, improves fully the corrosion resistance of terminal electrode and suppresses more reliably peeling off of nickel dam.
Below, to being applicable to solve each structure subitem of above-mentioned purpose, describe.In addition, as required institute's counter structure is recorded to distinctive action effect.
The spark plug of 1. structures of structure is characterised in that, this spark plug comprises: insulator, and it has the axis hole running through along axis direction; And
Terminal electrode, the state that its rearward end with self is exposed from the rear end of above-mentioned insulator is inserted in above-mentioned axis hole;
In the rearward end of above-mentioned terminal electrode, be provided with and take the recess that above-mentioned axis direction is depth direction,
On the outer surface of the rearward end of above-mentioned terminal electrode, be provided with nickel dam,
The thickness of above-mentioned nickel dam is 3 μ m～25 μ m, and,
In the cross section of the outer surface quadrature with above-mentioned nickel dam, the average cross-section that forms the crystal grain of above-mentioned nickel dam is 50 μ m
2～500 μ m
2.
According to said structure 1, because the thickness of nickel dam is below 25 μ m, therefore can relatively reduce the thermal expansion difference producing between nickel dam and terminal electrode.Thereby, the thermal stress of nickel dam can be relatively reduced to put on, thereby the resistance to fissility of nickel dam can be improved.
And according to said structure 1, the average cross-section that forms the crystal grain of nickel dam is 50 μ m
2above, suppressed crystal grain and become excessively tiny.Therefore, can improve fully Grain-boundary Junctions and make a concerted effort, when nickel dam has been applied in thermal stress, can prevent from more reliably cracking at crystal boundary.In addition, according to said structure 1, the average cross-section of crystal grain is 500 μ m
2below, the particle diameter of crystal grain is relatively little.Thereby, in nickel dam, can improve fully the endurance to thermal stress resistance.These action effects and the above-mentioned thickness that makes nickel dam become the action effect that 25 μ m bring when following and interact, and can prevent more reliably peeling off of nickel dam.
In addition, according to said structure 1, the thickness of nickel dam is more than 3 μ m.Thereby, can reduce fully the pinhole number in each per surface area in nickel dam, thus can suppress more reliably to become corrosion reason, the contact to terminal electrode such as oxygen.
And, according to said structure 1, owing to making the average cross-section of crystal grain become 50 μ m
2therefore above, be difficult for cracking at crystal boundary, therefore can further suppress reliably the contact to terminal electrode such as oxygen.And although nickel dam forms in the stacked mode of crystalline phase, according to said structure 1, the average cross-section of crystal grain is 500 μ m
2below, the particle diameter of crystal grain is relatively little.Thereby, the concavo-convex of crystal boundary can be further reduced, thereby the local attenuation of crystallizing layer can be prevented more reliably.These action effects and the above-mentioned thickness that makes nickel dam become the action effect that 3 μ m bring when above and interact, and can realize good corrosion resistance.
As described above, according to said structure 1, can improve fully resistance to fissility and corrosion resistance the two.As a result, even if be the rearward end of terminal electrode to form recess, more worry the reduction of the corrosion resistance in terminal electrode, in the situation about peeling off of nickel dam, also can optimize resistance to fissility and corrosion resistance the two.
The spark plug of 2. structures of structure is, the spark plug according to described in said structure 1, is characterized in that, the thickness of above-mentioned nickel dam is 10 μ m～20 μ m, and,
In above-mentioned cross section, the average cross-section of above-mentioned crystal grain is 200 μ m
2～400 μ m
2.
According to said structure 2, because the thickness of nickel dam is below 20 μ m, therefore can further reduce to put on the thermal stress of nickel dam.And, because the average cross-section of crystal grain is 200 μ m
2above, therefore can further improve Grain-boundary Junctions and make a concerted effort, thereby can further prevent from reliably cracking at crystal boundary.In addition, the average cross-section due to crystal grain is 400 μ m
2below, therefore can further improve the endurance to thermal stress resistance of nickel dam.Above result, can further improve the resistance to fissility of nickel dam.
And, according to said structure 2, because the thickness of nickel dam is more than 10 μ m, therefore can further reduce the pinhole number in each per surface area in nickel dam.And, owing to making the average cross-section of crystal grain become 200 μ m
2therefore above, can further suppress the generation of the crackle of grain boundaries, in addition, because the average cross-section of crystal grain is 400 μ m
2below, therefore can further prevent reliably the local attenuation of crystallizing layer.Above result, can increase substantially corrosion resistance.
As described above, according to said structure 2, can obviously improve resistance to fissility and corrosion resistance the two.As a result, even if be that the rearward end of terminal electrode is formed with in the situation of recess, also can realize very excellent resistance to fissility and corrosion resistance.
The spark plug of 3. structures of structure is, the spark plug according to described in said structure 1 or 2, is characterized in that, the thickness of the oxide-film on the outer surface of above-mentioned nickel dam is below 1.0 μ m.
According to said structure 3, the thickness of the oxide-film on the outer surface of nickel dam is below 1.0 μ m.Thereby, the flexibility of nickel dam can be guaranteed fully, thereby the endurance to thermal stress resistance in nickel dam can be further improved.As a result, can realize better resistance to fissility.In addition, aspect resistance to fissility, oxide-film is more thin more preferred.
The spark plug of 4. structures of structure is, the spark plug according to described in any one in said structure 1 to 3, is characterized in that, the hardness at the rearward end place of above-mentioned terminal electrode is Vickers hardness 140Hv～180Hv.According to said structure 4, the hardness of the rearward end of terminal electrode is 140Hv～180Hv.Thereby, the thermal expansion difference between terminal electrode and nickel dam can be further reduced, thereby the thermal stress of nickel dam can be obviously reduced to put on.As a result, can increase substantially resistance to fissility.
The spark plug of 5. structures of structure is, according to the spark plug described in any one in said structure 1 to 4, it is characterized in that, above-mentioned terminal electrode possesses the outside wall portions of the ring-type of the surrounding that surrounds above-mentioned recess, above-mentioned recess is at least formed with the bottom surface of the plane of above-mentioned axis direction quadrature by inner peripheral surface and the conduct of above-mentioned outside wall portions, and, thickness in the inner peripheral surface of above-mentioned outside wall portions, be at least greater than the nickel dam at place, above-mentioned bottom surface than half thickness by the above-mentioned nickel dam at the position of rear end side on above-mentioned axis direction.In the terminal arrangement of electric power being supplied with to use during in recess, half on the ratio axis direction in the inner peripheral surface of outside wall portions plays the effect of guiding of supplying with the terminal of use for correctly configure electric power in recess by the position of rear end side.Now, while that the terminal of supplying with use due to electric power is wiped the inner peripheral surface rubbing in outside wall portions is directed, so the hidden danger that exists nickel dam to be pruned.According to said structure 5, due in the inner peripheral surface of above-mentioned outside wall portions, at least larger by the thickness of the above-mentioned nickel dam at the position of rear end side than half on above-mentioned axis direction, even if therefore nickel dam is pruned and also can be suppressed terminal electrode mother metal and expose.
Accompanying drawing explanation
Fig. 1 means the biopsy cavity marker devices front view of the structure of spark plug.
Fig. 2 means the amplification stereogram of structure of the rearward end of terminal electrode.
Fig. 3 is the cutaway view of terminal electrode etc.
(a) of Fig. 4, (b) are for the key diagram of computational methods of the average cross-section of crystal grain is described.
Fig. 5 means the amplification schematic cross-section of oxide-film of the outer surface that is formed at nickel dam etc.
Fig. 6 is the amplification view of the terminal electrode for the measuring position of the hardness of terminal electrode is described.
Fig. 7 is for to being formed at the amplification view of the terminal electrode that the relation of thickness of the nickel dam of terminal electrode describes.
description of reference numerals
1 ... spark plug; 2 ... insulation electroceramics (insulator); 4 ... axis hole; 6 ... terminal electrode; 6A ... outside wall portions; 6B ... recess; 6C ... bottom surface; 6D ... inner peripheral surface; 35 ... nickel dam; 36 ... oxide-film; CL1 ... axis.
Embodiment
Below, with reference to the accompanying drawings of an execution mode.Fig. 1 means the biopsy cavity marker devices front view of spark plug 1.In addition, in Fig. 1, the axis CL1 direction of spark plug 1 is made as to the above-below direction of accompanying drawing, downside is made as to the tip side of spark plug 1, upside is made as to rear end side and describes.
Spark plug 1 is by forming the insulation electroceramics 2 as insulator of tubular and keeping base metal shell 3 grades of the tubular of this insulation electroceramics 2 to form.
Insulation electroceramics 2 is by sintered alumina etc., to form as well-known, in its profile portion, comprises: rear end side main part 10, and it is formed at rear end side; Large-diameter portion 11, it is being given prominence to and is forming to radial outside by the position of tip side than this rear end side main part 10; Intermediate host portion 12, it is leaning on the position of tip side to form with the diameter thinner than this large-diameter portion 11 than this large-diameter portion 11; And foot 13, it is forming with the diameter thinner than this intermediate host portion 12 by the position of tip side than this intermediate host portion 12.In addition, large-diameter portion 11, intermediate host portion 12 and the most foot 13 in insulation electroceramics 2 is contained in the inside of base metal shell 3, and expose the rear end of rear end side main part 10 autonomous agent metal shells 3.And the connecting portion between intermediate host Bu12He foot 13 is formed with the stage portion 14 of taper, utilize this stage portion 14 will insulate electroceramics 2 engagings in base metal shell 3.
And, in insulation electroceramics 2, run through and be formed with the axis hole 4 extending along axis CL1, in the tip side of this axis hole 4, insert and be provided with central electrode 5.This central electrode 5 comprises internal layer 5A and outer 5B, and this internal layer 5A consists of the metal (such as copper, copper alloy etc.) of excellent thermal conductivity, and this skin 5B is by take the alloy formation that nickel (Ni) be main component.And, in the top ends of central electrode 5, be provided with the columned electrode tip 31 for example, being formed by the metal of resistance to expendable excellence (, containing more than one the metal etc. in Pt, Ir, Pd, Rh, Ru and Re etc.).In addition, central electrode 5 integral body form bar-shaped (cylindric), and the top of the electroceramics 2 that certainly insulate is outstanding.
In addition, in the rear end side of axis hole 4, be provided with the bar-shaped terminal electrode 6 for example, being formed by the metal of being scheduled to (, mild steel etc.).The rearward end of terminal electrode 6 is exposed from the rear end of the electroceramics 2 that insulate, and connects the terminal (not shown) of electric power supply use in the rearward end of terminal electrode 6.
And, between the central electrode 5 of axis hole 4 and terminal electrode 6, dispose columned resistive element 7.The both ends of this resistive element 7 are electrically connected to central electrode 5 and terminal electrode 6 respectively across the glass seal layer 8,9 of conductivity.
In addition, aforementioned body metal shell 3 forms tubular by metals such as mild steel, and is formed with threaded portion (external thread part) 15 at its outer peripheral face, and this threaded portion 15 is for being installed on spark plug 1 installing hole of internal combustion engine, fuel cell modification device etc.In addition, leaning on the position of rear end side to be formed with to the outstanding seat portion 16 of radial outside than threaded portion 15, in threaded portion, the screw neck 17 of 15 rear ends embeds the packing ring 18 that has ring-type.And, in the rear end side of base metal shell 3, be provided with the instrument holding section 19 of cross section hexagon shape, this instrument holding section 19 for when base metal shell 3 being installed on to internal combustion engine etc. and the instrument such as spanner fasten, and be provided with the fastening part 20 for the electroceramics 2 that keeps insulating in the rearward end of base metal shell 3.
In addition, the inner peripheral surface at base metal shell 3 is provided with the stage portion 21 for the taper of engaging insulation electroceramics 2.And, insulation electroceramics 2 inserts from its rear end side direction tip side with respect to base metal shell 3, under the state of stage portion 14 and the stage portion 21 phase engagings of base metal shell 3 of self, make the peristome of rear end side of base metal shell 3 fastening to radially inner side, form above-mentioned fastening part 20, thereby be fixed on base metal shell 3.In addition, between above-mentioned stage portion 14,21, be folded with circular liner plate 22.Thus, keep the air-tightness in combustion chamber, the gaseous fuel of avoiding entering the gap between the foot 13 of the insulation electroceramics 2 being exposed in combustion chamber and the inner peripheral surface of base metal shell 3 leaks to outside.
And, in order to make airtight more complete under fastening effect, at ring element 23,24 rear end side of base metal shell 3, that be folded with ring-type between base metal shell 3 and insulation electroceramics 2, between ring element 23,24, be filled with the powder of talcum (talc) 25.That is, base metal shell 3 keeps insulation electroceramics 2 by liner plate 22, ring element 23,24 and talcum 25.
In addition, the top ends 26 at base metal shell 3 is fixed with the grounding electrode 27 that is bar-shaped.Grounding electrode 27 forms by take alloy that Ni is main component etc., and is folded back in the roughly pars intermedia office of self.In addition, in the top ends of grounding electrode 27, be provided with the columned electrode tip 32 for example, being formed by the metal of resistance to expendable excellence (, containing more than one the metal etc. in Pt, Ir, Pd, Rh, Ru and Re etc.).And, between the top ends (electrode tip 31) of central electrode 5 and the top ends (electrode tip 32) of grounding electrode 27, form spark-discharge gap 33, in this spark-discharge gap 33, roughly along producing sparkover in the direction of axis CL1.
And, in the present embodiment, in order to suppress the generation of the surperficial electric discharge (so-called arcing) along rear end side main part 10, make the length along axis CL1 of rear end side main part 10 larger.On the other hand, in order to make the distance of rear end to the rear end of terminal electrode 6 of autonomous agent metal shell 3, be in predetermined value, make the length along axis CL1 of rearward end (position that expose the rear end of the electroceramics 2 that certainly insulate) of terminal electrode 6 relatively little.In addition, as shown in Fig. 2 (rearward end of terminal electrode 6 is only shown in Fig. 2), in the rearward end periphery of terminal electrode 6, be provided with the outside wall portions 6A of the ring-type of extending to axis CL1 direction rear end side, utilize outside wall portions 6A to form and take the recess 6B that axis CL1 direction is depth direction in the rearward end central authorities of terminal electrode 6.So, the rearward end at terminal electrode 6 is provided with the outside wall portions 6A of ring-type to surround the mode of the surrounding of recess 6B.And the terminal (not shown) that electric power is supplied with use is disposed at recess 6B.
In addition, as shown in Figure 3, at the outer surface of the rearward end of terminal electrode 6, be provided with by take the nickel dam 35 that metal that Ni is main component forms (in addition, " main component " refer to material in the highest composition of mass ratio).Nickel dam 35 is configured to, although thickness T 1 has some differences at each several part, this thickness T 1 is 3 μ m～25 μ m.In addition, on the cross section of the outer surface quadrature with nickel dam 35, the average cross-section that makes to form the crystal grain of nickel dam 35 is 50 μ m
2～500 μ m
2(200 μ m more preferably
2～400 μ m
2).In addition, in the present embodiment, the average perimeter of above-mentioned crystal grain is 60 μ m～200 μ m (more preferably 80 μ m～150 μ m).In addition, in the inner peripheral surface 6D of outside wall portions 6A, be at least positioned at the thickness that is greater than the nickel dam 35 at 6C place, bottom surface than half thickness by the nickel dam 35 at the position of rear end side in axis CL1 direction.In the present embodiment, with the tip side of the inner peripheral surface from outside wall portions 6A distolateral going and mode that thickness increases is gradually formed with nickel dam 35 backward.
In addition, can obtain by following method average cross-section, the average perimeter of crystal grain.That is, by predetermined focused ion beam processing unit (plant) (FIB), along the direction of the outer surface quadrature with nickel dam 35, cut off nickel dam 35, obtain the thin slice that comprises nickel dam 35.Then, the thin slice that utilizes predetermined sweep electron microscope (SIM) observation post to obtain, and take and comprise nickel dam 35 in the scope of interior vertical 20 μ m * horizontal 30 μ m with the multiplying power of 6500 times, obtain gray level image.Afterwards, as Fig. 4 (a) (only shows a crystal grain 35A in Fig. 4, but in actual gray level image, there are a plurality of crystal grain 35A) shown in, in above-mentioned gray level image, appointment is positioned at the lateral center of this image and is positioned at the crystal grain 35A of the nickel dam 35 on the line extending longitudinally, and, the object line of the crystal grain 35A of appointment is transferred on predetermined thin paper.Then, on predetermined computer, obtain the data of above-mentioned thin paper, use afterwards predetermined image software (for example, paint), as shown in Fig. 4 (b), to fill the region of the inner side that is positioned at above-mentioned object line.Then, utilize predetermined parsing software (for example, imageJ: U.S.'s National Institutes of Health system) measure area, the girth in each region after filling.Finally, the mean value of the area going out by computation and measurement, can obtain the average cross-section of crystal grain, and the mean value of the girth going out by computation and measurement can obtain the average perimeter of crystal grain.In addition, as FIB, for example, can enumerate the focused ion beam processing unit (plant) (model FB-2000, SIM " sweep electron microscope " is one-piece type) of society of Hitachi system etc.
And, by by nickel dam 35 oxidation, thereby at the outer surface of nickel dam 35, form oxide-film 36 as shown in Figure 5.But in the present embodiment, the wall thickness of oxide-film 36 is very thin, its thickness T 2 is below 1.0 μ m.In addition, for the face of the resistance to fissility of nickel dam 35, consider, the wall thickness of oxide-film 36 is more thin more preferred, does not more preferably have oxide-film 36.Yet, in the present embodiment, due to fire end sub-electrode 6 in heated sealant operation described later, on the outer surface of nickel dam 35, forming oxide-film 36, the thickness T 2 of oxide-film 36 is more than 0.01 μ m.
In addition, in the present embodiment, the hardness that makes the rearward end place of terminal electrode 6 is Vickers hardness 140Hv～180Hv.In addition, the hardness at the rearward end place of terminal electrode 6 can be measured by the following method.That is, as shown in Figure 6, in the cross section that comprises axis CL1, choose line segment SL, this line segment SL is located at the outer peripheral face from terminal electrode 6 in the direction with axis CL1 quadrature and to axis CL1 side, leaves the position of 0.5mm, and extends along axis CL1 direction, and is present on terminal electrode 6.Then, according to the regulation of JIS Z2244, the diamond penetrator that utilizes positive quadrangular pyramid shape applies predetermined (for example, load 20kgf) to the position of the mid point CP that is positioned at above-mentioned line segment SL in terminal electrode 6.Then, the hardness at rearward end place of catercorner length measurement terminal electrode 6 that can be based on being formed at the impression of terminal electrode 6.
Next, illustrate that the manufacture method of the spark plug 1 of formation describes as described above.First, manufacture in advance base metal shell 3.That is, for example, by columned metal material (, this iron type materials of S17C, S25C, stainless steel material) being implemented to Cold Forging etc., form through hole, manufacture general shape.Afterwards, by cut, adjust profile, obtain base metal shell intermediate.
Then the straight bar-shaped grounding electrode 27 that, resistance welded consists of Ni alloy etc. on the top end face of base metal shell intermediate.Owing to producing so-called " limit of collapsing " when carrying out this welding, therefore remove should " limit of collapsing " afterwards, at the predetermined position of base metal shell intermediate, by rolling, form threaded portion 15.Thus, obtain being welded with the base metal shell 3 of grounding electrode 27.
Then, for example,, by processing predetermined metal material (, mild steel), obtain bar-shaped terminal electrode 6.On this basis, by tumble-plating process, terminal electrode 6 is implemented to electroplating processes, on the outer surface of terminal electrode 6, form nickel dam 35.When carrying out electroplating processes, use Tumble-plating device (not shown) as follows, this Tumble-plating device comprises: electroplating bath, it stores the nickelous sulfate (NiSO of predetermined concentration (for example, 250 ± 20g/L)
4), the nickel chloride (NiCl of predetermined concentration (for example, 50 ± 10g/L)
2), the boric acid (H of predetermined concentration (for example, 40 ± 10g/L)
3bO
3) and the electroplating water solution of the acidity (pH is 4.0 ± 0.5 left and right) that comprises polishing material; And maintenance container, its wall by net, offer porose plate etc. and form, and be immersed in the liquid of above-mentioned electroplating water solution.Particularly, terminal electrode 6 is contained in to above-mentioned maintenance container, terminal electrode 6 is immersed in electroplating water solution.Then, make electroplating water solution become predetermined temperature (for example, 55 ± 5 ℃) afterwards, Yi Bian utilize predetermined motor to make above-mentioned maintenance container rotation, for example, Yi Bian make predetermined current density (, 0.13A/dm
2～1.33A/dm
2) direct current flow into terminal electrode 6 predetermined conduction time (for example, 9 seconds～1500 seconds).Thus, in the region of the whole outer surface of terminal electrode 6, form nickel dam 35.Conduction time, current density (A/dm during in the present embodiment, by adjusting electroplating processes
2), make the thickness T 1 of nickel dam 35 become 3 μ m～25 μ m, and the average cross-section that makes to form the crystal grain of nickel dam 35 become 50 μ m
2～500 μ m
2.In addition, by regulating conduction time, the thickness T 1 of nickel dam 35 can be changed, by regulating current density, the average cross-section of crystal grain can be changed.
In addition, be independent of aforementioned body metal shell 3 ground shaping processing insulation electroceramics 2.For example, use and take aluminium oxide and use blank granules as main body the material powder preparation that comprises adhesive etc. are shaped, use this shaping to carry out rubber with blank granules compressing, thus the formed body of acquisition tubular.The formed body obtaining is implemented attrition process and adjusted its shape, and sintering is adjusted the formed body after shape in sintering furnace, thereby obtain insulation electroceramics 2.
In addition, be independent of aforementioned body metal shell 3, insulation electroceramics 2 ground manufacturing center electrodes 5.That is, to having configured at central portion for seeking to improve the Ni alloy of the copper alloy etc. of thermal diffusivity, implement to forge processing, thereby make central electrode 5.In addition, by laser welding etc., electrode tip 31 is engaged in to the top ends of central electrode 5.
Then, utilize 8,9 pairs of insulation electroceramics that obtain as described above of glass seal layer, 2 sealing fixed center electrode 5, terminal electrode 6 and resistive elements 7.As glass seal layer 8,9, normally pyrex is mixed and prepared with metal dust, and by the raw material after this preparation across resistive element 7 be injected into insulation electroceramics 2 axis hole 4 in, afterwards utilizing terminal electrode 6 to press from rear when, in sintering furnace, heat, thus sealing fixed center electrode 5 etc.In addition, now, both can, at the 10 surface while of rear end side main part of insulation electroceramics 2 sintering glaze layer, also can be pre-formed glaze layer.In addition, in the present embodiment, by regulating heating time, the thickness T 2 of oxide-film 36 is become below 1.0 μ m.
Afterwards, with respect to base metal shell 3, after its rear end side opening inserts insulation electroceramics 2, the rearward end of pressing base metal shell 3 along axis CL1 direction, make above-mentioned rearward end crooked (towards radially inner side, form fastening part 20), thus the electroceramics 2 that will insulate is fixing with base metal shell 3.
Then,, after electrode tip 32 being engaged in to the top ends of grounding electrode 27 by resistance welded etc., make grounding electrode 27 to central electrode 5 lateral bends.And, finally, by adjustment, be formed at the size of the spark-discharge gap 33 between central electrode 5 (electrode tip 31) and grounding electrode 27 (electrode tip 32), obtain above-mentioned spark plug 1.
As described in detail above, according to present embodiment, make the thickness T 1 of nickel dam 35 become 3 μ m～25 μ m, and make the average cross-section of crystal grain become 50 μ m
2～500 μ m
2.Thereby, can improve fully resistance to fissility and corrosion resistance the two.As a result, even if be that the rearward end of terminal electrode 6 forms recess 6B and more worries the reduction of the corrosion resistance in terminal electrode 6, in the situation about peeling off of nickel dam, also can optimize resistance to fissility and corrosion resistance the two.
And, in the thickness T 1 that makes nickel dam 35, become 10 μ m～20 μ m and make the average cross-section of crystal grain become 200 μ m
2～400 μ m
2situation under, can further improve resistance to fissility and corrosion resistance the two.
In addition, in the present embodiment, the thickness T 2 of oxide-film 36 is become below 1.0 μ m.Thereby, can guarantee fully the flexibility of nickel dam 35, thus can further improve in nickel dam 35, the endurance to thermal stress resistance.As a result, can realize better resistance to fissility.
And, make the hardness of the rearward end of terminal electrode 6 become 140Hv～180Hv.Thereby, the thermal expansion difference between terminal electrode 6 and nickel dam 35 can be further reduced, thereby the thermal stress of nickel dam 35 can be obviously reduced to put on.As a result, can obviously improve resistance to fissility.
Then,, for the action effect of confirming to bring into play by above-mentioned execution mode, current density, conduction time when reconciling electroplating processes, make thickness T 1 (μ m) in a plurality of nickel dams and average cross-section (the μ m of crystal grain
2) sample of different terminal electrode, and each sample is carried out to resistance to fissility evaluation test and corrosion resistance evaluation test.In addition, terminal electrode has recess in rearward end.
The summary of resistance to fissility evaluation test is as following.That is, utilize tube furnace that each sample is heated 8 minutes with 1000 ℃, slowly cool to afterwards room temperature.Then, by visual or predetermined magnifying glass, be confirmed whether peel off (the breaking etc.) that the outer surface in the rearward end of terminal electrode has produced nickel dam.At this, for the sample of peeling off that does not produce nickel dam, make as the evaluation with " ☆ " of extremely excellent resistance to fissility.In addition, though for produced nickel dam peel off the area (peeling off area) that produces the position of peeling off is less than 5% the sample of surface area of the rearward end of terminal electrode makes as the evaluation with " ◎ " of excellent resistance to fissility, although be that 5%～10% the sample of surface area of the rearward end of terminal electrode is made as the evaluation with " zero " of good resistance to fissility for the area of peeling off that has produced nickel dam.On the other hand, for 10% the sample of surface area that area is greater than the rearward end of terminal electrode of peeling off and peel off that has produced nickel dam, make the evaluation as resistance to fissility poor " * ".
In addition, the summary of corrosion resistance evaluation test is as following.That is, each sample is placed on to lower 48 hours of the environment of ejection salt solution, is confirmed whether to have produced iron rust on the rearward end surface of terminal electrode.At this, for unconfirmed, to the sample that produces iron rust, make as the extremely evaluation of excellent " ☆ " of corrosion resistance.And, although for produced iron rust, but the area (iron rust generation area) that produces the position of iron rust is less than 5% the sample of surface area of the rearward end of terminal electrode makes the evaluation as " ◎ " of excellent corrosion resistance, although to produce area be that 5%～30% the sample of surface area of the rearward end of terminal electrode is made as the evaluation with " zero " of good corrosion resistance for having produced iron rust iron rust.On the other hand, iron rust is produced to 30% the sample of surface area that area surpasses the rearward end of terminal electrode and make the evaluation as corrosion resistance poor " * ".
In the result of resistance to fissility evaluation test shown in table 1, in the result of the evaluation test of corrosion resistance shown in table 2.
[table 1]
[table 2]
As shown in table 1, obviously make the thickness T 1 of nickel dam become below 25 μ m and make the average cross-section of crystal grain become 50 μ m
2～500 μ m
2sample there is good resistance to fissility.Consider that this strengthens ground effect mutually because of following (1)～(3).
(1) by the thickness T 1 of nickel dam is become below 25 μ m, be accompanied by heating cooling, the thermal expansion difference producing between nickel dam and terminal electrode becomes relatively little, and then the thermal stress that puts on nickel dam becomes relatively little.
(2) by making the average cross-section of crystal grain become 50 μ m
2above, suppressed crystal grain and become excessively tiny, further improved Grain-boundary Junctions and made a concerted effort, result, when nickel dam has been applied to thermal stress, crystal boundary is difficult to crack.
(3) by making the average cross-section of crystal grain become 500 μ m
2below, make the particle diameter of crystal grain become relatively little, thus fully improved in nickel dam, the endurance to thermal stress resistance.
And, as shown in table 2, obviously by making the thickness T 1 of nickel dam become 3 μ m above and make the average cross-section of crystal grain become 50 μ m
2～500 μ m
2sample there is good corrosion resistance.Consider that this is because ensuing (4)～(6) strengthen the cause of ground effect mutually.
(4) by making more than the thickness T 1 of nickel dam becomes 3 μ m, the pinhole number in each per surface area in nickel dam tails off, and has suppressed salt solution and has been attached to terminal electrode.
(5) by making the average cross-section of crystal grain become 50 μ m
2above, improved Grain-boundary Junctions and made a concerted effort, thereby crystal boundary is difficult to crack, and then suppressed salt solution and be attached to terminal electrode.
(6) although nickel dam in the stacked mode of crystalline phase, form, by making the average cross-section of crystal grain become 500 μ m
2below, make the particle diameter of crystal grain become relatively little, can make the concavo-convex of crystal boundary become less, can prevent more reliably the local attenuation of crystallizing layer.
In addition, particularly, learn and make the thickness T 1 of nickel dam become 10 μ m～20 μ m and make the average cross-section of crystal grain become 200 μ m
2～400 μ m
2sample in resistance to fissility and corrosion resistance, the two is extremely excellent.
According to the result of above-mentioned two tests, can say for optimize resistance to fissility and corrosion resistance the two, preferably make the thickness T 1 of nickel dam become 3 μ m～25 μ m, and make the average cross-section of crystal grain become 50 μ m
2～500 μ m
2.
In addition, can say in order to seek the further raising of resistance to fissility and corrosion resistance, preferably make the thickness T 1 of nickel dam become 10 μ m～20 μ m, and make the average cross-section of crystal grain become 200 μ m
2～400 μ m
2.
Next, for the thickness T 1 that makes nickel dam, become 3 μ m～25 μ m and make the average cross-section of crystal grain become approximately 300 μ m
2the sample of terminal electrode, carried out above-mentioned resistance to fissility evaluation test heating-up temperature being changed over to (in other words, after making the condition of peeling off that more easily produces nickel dam) after 1200 ℃.In addition, in this test, by changing heating time, the thickness T 2 (μ m) of oxide-film of outer surface that makes to be formed at nickel dam after heating is different.Result in this test shown in table 3.In addition, in table 3, as a reference, be shown in the lump heating time.
[table 3]
As shown in table 3, confirmed to make the sample that the thickness T 2 of oxide-film becomes below 1.0 μ m to there is excellent resistance to fissility.Consider that this is because fully guaranteed the flexibility of nickel dam, and the endurance to thermal stress resistance further improves in nickel dam.
According to the result of above-mentioned test, can say in order further to improve resistance to fissility, preferably make the thickness T 2 of the oxide-film on the outer surface of nickel dam become below 1.0 μ m.
Then, in the thickness T 1 that makes nickel dam, become 3 μ m～25 μ m and make the average cross-section of crystal grain become 300 μ m
2basis on, regulate the amount (quality %) of carbon (C), thereby the sample of the terminal electrode that the hardness of making the rearward end place of sening as an envoy to is different, for each sample, after making heating-up temperature become 1200 ℃, making to become 8 minutes heating time, carried out above-mentioned resistance to fissility evaluation test.Result in this test shown in table 4.In addition, in table 4, as a reference, show in the lump the C content in each sample.
[table 4]
As shown in table 4, the sample that obviously makes the hardness of rearward end become 140Hv～180Hv has excellent resistance to fissility.Consider this be because, can reduce the thermal expansion difference producing between terminal electrode and nickel dam, the thermal stress that puts on nickel dam further diminishes.
According to the result of above-mentioned test, for further improving this viewpoint of resistance to fissility, can say that the hardness of the rearward end that preferably makes terminal electrode becomes Vickers hardness 140Hv～180Hv.
In addition, be not limited to the record content of above-mentioned execution mode, for example, also can implement as described below.Certainly, also can adopt following not illustrative other application examples, modification.
(a) in the above-described embodiment, in the whole outer surface region of terminal electrode 6, be provided with nickel dam 35, but as long as at least at the outer surface of the rearward end of terminal electrode 6, be provided with nickel dam 35.
(b) also can for arrange above-mentioned nickel dam 35 electroplating processes before the stage terminal electrode 6 implemented to impactive nickel platings process, and the impactive nickel plating of film is set on the surface of terminal electrode 6.Impactive nickel plating processing example comprises NiSO as used
4, NiCl
2, H
3bO
3, HCl the electroplating water solution of highly acid (pH is below 1) implement barrel plating and process, by implementing impactive nickel plating, process and remove the lip-deep impurity that is attached to terminal electrode 6.As a result, the close property of 35 pairs of terminal electrodes 6 of nickel dam can be further improved, thereby resistance to fissility and corrosion resistance can be further improved.
(c) in the above-described embodiment, on the surface of terminal electrode 6, be only provided with nickel dam 35, but trivalent chromium layer (more than 95 quality % in contained chromium component consisting of trivalent chromium) also can be set on the surface of nickel dam 35.Now, can seek the further raising of corrosion resistance.
(d) in the above-described embodiment, spark plug 1 is for making spark-discharge gap 33 produce sparkover, and the structure that still can apply the spark plug of technological thought of the present invention is not limited thereto.Thereby, for example, for dropping into alternating current to spark-discharge gap and produce the spark plug (AC plasma spark plug) of AC plasma, the isoionic spark plug (plasma jet spark plug) generating etc. in spark-discharge gap in the top ends of insulation electroceramics having cavity portion (space) and is ejected in cavity portion, also can apply technological thought of the present invention.
(e) in the above-described embodiment, the situation that top ends at base metal shell 3 is engaged to grounding electrode 27 is specialized, but a part for the base metal shell that also can be applied to prune (or be welded in advance the top metal shell of base metal shell a part) and the situation (for example, TOHKEMY 2006-236906 communique etc.) of grounding electrode of forming.
(f) in the above-described embodiment, instrument holding section 19 adopts cross section hexagon shape, but is not limited to such shape about the shape of instrument holding section 19.For example, also can adopt Bi-HEX (distortion 12 limits) shape (ISO22977:2005 (E)) etc.
Claims (5)
1. a spark plug, is characterized in that, this spark plug comprises:
Insulator, it has the axis hole running through along axis direction; And
Terminal electrode, the state that its rearward end with self is exposed from the rear end of above-mentioned insulator is inserted in above-mentioned axis hole;
In the rearward end of above-mentioned terminal electrode, be provided with and take the recess that above-mentioned axis direction is depth direction,
On the outer surface of the rearward end of above-mentioned terminal electrode, be provided with nickel dam,
The thickness of above-mentioned nickel dam is 3 μ m～25 μ m, and,
In the cross section of the outer surface quadrature with above-mentioned nickel dam, the average cross-section that forms the crystal grain of above-mentioned nickel dam is 50 μ m
2～500 μ m
2.
2. spark plug according to claim 1, is characterized in that,
The thickness of above-mentioned nickel dam is 10 μ m～20 μ m, and,
In above-mentioned cross section, the average cross-section of above-mentioned crystal grain is 200 μ m
2～400 μ m
2.
3. spark plug according to claim 1 and 2, is characterized in that,
The thickness of the oxide-film on the outer surface of above-mentioned nickel dam is below 1.0 μ m.
4. spark plug according to claim 1 and 2, is characterized in that,
The hardness at the rearward end place of above-mentioned terminal electrode is Vickers hardness 140Hv～180Hv.
5. spark plug according to claim 1 and 2, is characterized in that,
Above-mentioned terminal electrode possesses the outside wall portions of the ring-type of the surrounding that surrounds above-mentioned recess,
Above-mentioned recess is at least formed with the bottom surface of the plane of above-mentioned axis direction quadrature by inner peripheral surface and the conduct of above-mentioned outside wall portions, and,
Thickness in the inner peripheral surface of above-mentioned outside wall portions, be at least greater than the nickel dam at place, above-mentioned bottom surface than half thickness by the above-mentioned nickel dam at the position of rear end side on above-mentioned axis direction.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2013-099069 | 2013-05-09 | ||
| JP2013099069 | 2013-05-09 | ||
| JP2014-077465 | 2014-04-04 | ||
| JP2014077465A JP5778819B2 (en) | 2013-05-09 | 2014-04-04 | Spark plug |
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|---|---|
| CN104143766A true CN104143766A (en) | 2014-11-12 |
| CN104143766B CN104143766B (en) | 2016-09-28 |
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| CN201410191258.4A Active CN104143766B (en) | 2013-05-09 | 2014-05-07 | Spark plug |
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| JP (1) | JP5778819B2 (en) |
| CN (1) | CN104143766B (en) |
| DE (1) | DE102014106221B4 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108346975A (en) * | 2017-01-23 | 2018-07-31 | 日本特殊陶业株式会社 | Spark plug |
| CN110994361A (en) * | 2018-10-03 | 2020-04-10 | 日本特殊陶业株式会社 | Spark plug |
| CN113491046A (en) * | 2019-02-18 | 2021-10-08 | 株式会社电装 | Spark plug and method of manufacturing the same |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6878359B2 (en) * | 2018-07-05 | 2021-05-26 | 日本特殊陶業株式会社 | Spark plug |
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| JP2005285486A (en) * | 2004-03-29 | 2005-10-13 | Ngk Spark Plug Co Ltd | Spark plug |
| JP2010197163A (en) * | 2009-02-24 | 2010-09-09 | Mitsubishi Materials Corp | Thin-film temperature sensor and method for manufacturing the same |
| CN102484006A (en) * | 2009-09-18 | 2012-05-30 | 日本特殊陶业株式会社 | Spark plug |
| JP2012128948A (en) * | 2010-12-13 | 2012-07-05 | Ngk Spark Plug Co Ltd | Spark plug |
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| JPS6264084A (en) * | 1985-09-13 | 1987-03-20 | 日本特殊陶業株式会社 | Ignition plug |
| JPH11339925A (en) * | 1998-05-26 | 1999-12-10 | Ngk Spark Plug Co Ltd | Spark plug |
| JP4536006B2 (en) * | 2003-05-20 | 2010-09-01 | 日本特殊陶業株式会社 | Spark plug and manufacturing method thereof |
| JP2006236906A (en) * | 2005-02-28 | 2006-09-07 | Ngk Spark Plug Co Ltd | Manufacturing method of spark plug |
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2014
- 2014-04-04 JP JP2014077465A patent/JP5778819B2/en active Active
- 2014-05-05 DE DE102014106221.3A patent/DE102014106221B4/en active Active
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005285486A (en) * | 2004-03-29 | 2005-10-13 | Ngk Spark Plug Co Ltd | Spark plug |
| JP2010197163A (en) * | 2009-02-24 | 2010-09-09 | Mitsubishi Materials Corp | Thin-film temperature sensor and method for manufacturing the same |
| CN102484006A (en) * | 2009-09-18 | 2012-05-30 | 日本特殊陶业株式会社 | Spark plug |
| CN103109425A (en) * | 2010-09-15 | 2013-05-15 | 日本特殊陶业株式会社 | Spark plug and main fitting for spark plug |
| JP2012128948A (en) * | 2010-12-13 | 2012-07-05 | Ngk Spark Plug Co Ltd | Spark plug |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108346975A (en) * | 2017-01-23 | 2018-07-31 | 日本特殊陶业株式会社 | Spark plug |
| CN110994361A (en) * | 2018-10-03 | 2020-04-10 | 日本特殊陶业株式会社 | Spark plug |
| CN113491046A (en) * | 2019-02-18 | 2021-10-08 | 株式会社电装 | Spark plug and method of manufacturing the same |
| CN113491046B (en) * | 2019-02-18 | 2022-10-04 | 株式会社电装 | Spark plug and method for manufacturing the same |
Also Published As
| Publication number | Publication date |
|---|---|
| CN104143766B (en) | 2016-09-28 |
| JP5778819B2 (en) | 2015-09-16 |
| DE102014106221A1 (en) | 2014-11-13 |
| DE102014106221B4 (en) | 2021-01-28 |
| JP2014239026A (en) | 2014-12-18 |
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