CN107634450B - Spark plug - Google Patents

Abstract

The present invention provides a kind of spark plug, can be achieved at the same time heat resistance and insulating properties.The axial length L of the front end of insulator is 9mm hereinafter, heat dissipation path therefore can be shortened, and can be improved heat resistance.Front end is formed with the cricoid slot of end-side openings forward around axis.The radial width of slot is 0.2mm or more.In the section comprising axis, creepage distance D until the space length of the outer surface of front end and the inner peripheral surface of main metal fixture is position (P) to the link position of the outer surface of front end and axis hole near front end side in the position below 0.1mm is 1.1 or more divided by the value D/L of length L.As a result, it can be ensured that the insulating properties of front end.

Description

Spark plug

Technical field

The present invention relates to spark plug, the spark plug for ensuring insulating properties is related to.

Background technique

Via insulator and main metal fixture central electrode is carried out insulation holding spark plug in, because of imperfect combustion etc. Generated coke build-up the front end of insulator surface and insulation resistance decline, when apply voltage lower than require voltage (produce The voltage of raw spark discharge) when, spark discharge no longer generates.Long leg of the spark plug of heat resistance high (calorific value is high) due to insulator (front end) short and creepage distance from main metal fixture to the front end of central electrode is short, therefore caused by the accumulation there are carbon absolutely The worry of the decline of edge.Moreover, the spark plug of heat resistance low (calorific value is low) is since the long leg of insulator is long, insulating properties is mentioned Height, but there are the worries that poor thermal conductivity, heat resistance decline.

Such as patent document 1 discloses in a kind of spark plug low in heat resistance (the length 17mm of front end), it will be to diameter To outer openings slot insulator is set long leg (front end) in the thicker position of wall thickness technology.Such case Under, the carbon edge for being attached to front end can be made axial discontinuous by slot, therefore be able to suppress the insulation as caused by the accumulation of carbon The decline of property.

[existing technical literature]

[patent document]

[patent document 1] Japanese Unexamined Patent Publication 6-176848 bulletin

Summary of the invention

[summary of invention]

[subject to be solved by the invention]

However, in the above prior art, there is insulating properties to be ensured and improve the such requirement of heat resistance.Relative to heat Be worth high spark plug, with reference to technology, that is, patent document 1 of the low spark plug of calorific value technology and be arranged in front end to radial When the slot of outer openings, the intensity of insulator may decline, therefore be unable to ensure sufficient creepage distance.

The present invention makes to meet the requirement, and it is an object of the present invention to provide one kind can be achieved at the same time heat resistance and insulating properties Spark plug.

[solution for solving the problem and invention effect]

In order to realize the purpose, according to first scheme record spark plug, in central electrode, leg from front end side backward End side extends along axis, and the rear end of lip portions from leg is prominent to radial outside.Cylindric insulator is along axis shape At axis hole be formed with the support portion being supported to lip portions, and be formed in outer peripheral surface with from front end side towards rear end side And expanding stage portion.It is formed in inner peripheral surface via lining in the cylindric main metal fixture of the radial outside configuration of insulator It pads and the shelf portion in support level portion.Than existing with the front-end edge of the first contact surface of gasket contacts by front end side in stage portion The axial length L of front end of insulator be 9mm hereinafter, heat dissipation path therefore can be shortened.Thereby, it is possible to improve spark The heat resistance of plug.

Front end is formed with the cricoid slot of end-side openings forward around axis.The radial width of slot is 0.2mm or more. In the section comprising axis, the space length between the outer surface of front end and the inner peripheral surface of main metal fixture be 0.1mm with Under position in the position P to the link position that the outer surface of front end is connect with axis hole near front end side until climb electricity away from From D divided by the value D/L after length L be 1.1 or more.It, can be from insulator due to cricoid slot end-side openings forward The thicker position of wall thickness that front end has separated predetermined distance forms slot.Therefore, decline the intensity of insulator, and can increase Ratio of the creepage distance of big front end relative to length L.Since the insulation resistance for the front end for being attached with carbon can be made to be difficult to Decline, therefore have the effect of can be achieved at the same time heat resistance and insulating properties.

According to the spark plug that alternative plan is recorded, the front-end edge of the second contact surface contacted with lip portions in support portion Axial position with the front-end edge of the first contact surface it is identical or compared with the front-end edge of the first contact surface be located at front end side.It can make The heat of the central side of the front end of insulator is mainly diffused from central electrode, makes the heat in the outside of front end mainly from main body Accessory release.Heat can be swimmingly radiated from multiple heat dissipation paths, therefore other than the effect of first scheme, also there is energy Enough improve the effect of heat resistance.

According to the spark plug that third program is recorded, the ratio slot in front end leans on the axis of the front end face of the part in radial outside To position be present in from the range within position P forward end side 2mm.The ratio slot in front end can be shortened by radial outside The heat dissipation path of part also have the effect of can be improved heat resistance therefore other than the effect of first or second scheme.

According to the spark plug that fourth program is recorded, insulator has: being formed as cricoid first component；And cricoid second Component configures in the radial outside of first component.Support portion is formed in the inner peripheral surface of first component, and stage portion is formed in second The outer peripheral surface of component.The gap of the inner peripheral surface of the outer peripheral surface and second component of first component constitutes slot, therefore can be easy landform Grooving.As a result, in addition to first into third program other than the effect of either a program, also have that can be easily manufactured can The effect of the spark plug of heat resistance and insulating properties is realized simultaneously.

Detailed description of the invention

Fig. 1 is the cross-sectional view of the spark plug of first embodiment of the invention.

Fig. 2 is the cross-sectional view of the front end of spark plug.

Fig. 3 is the cross-sectional view of the spark plug of second embodiment.

Fig. 4 is the cross-sectional view of the spark plug of third embodiment.

Fig. 5 is the figure for indicating the relationship of length of time and slot until insulation resistance drops to 1000M Ω.

[label declaration]

10,90,130 spark plug

20 main metal fixtures

27 shelf portions

40,100,140 insulator

41,151,161 axis hole

45,101,141 front end

46 stage portions

47 liners

48 support portions

52 slots

55,115,157 front end face

57,124,167 front end face

58 link positions

59 first contact surfaces

60 front-end edges

61 second contact surfaces

62 front-end edges

70 central electrodes

72 legs

73 lip portions

110,150 first component

114,156 outer peripheral surface

120,160 second component

123,166 inner peripheral surface

125,168 gaps (slot)

O axis

Specific embodiment

Hereinafter, illustrating the preferred embodiment of the present invention referring to attached drawing.Fig. 1 is the fire of first embodiment of the invention The face by the inclusion of axes O of flower plug 10 has carried out the cross-sectional view of cutting, and Fig. 2 is at the face comprising axes O of spark plug 10 The cross-sectional view of front end 45.In fig. 1 and fig. 2, the front end side of spark plug 10 will be known as on the downside of paper, fire will be known as on the upside of paper The rear end side of flower plug 10.As shown in Figure 1, spark plug 10 has main metal fixture 20, insulator 40 and central electrode 70.

Main metal fixture 20 is affixed to the substantially cylindric component of the threaded hole (not shown) of internal combustion engine, is formed with along axis The through hole 21 at line O perforation center.Main metal fixture 20 is formed by conductive metal material (such as mild steel etc.), from rear End side forward end lateral edge axes O be configured with peening portion 22, tool engagement portion 23, base portion 24, main part 25.Main part 25 exists Outer peripheral surface is formed with the threaded portion 26 chimeric with the threaded hole of internal combustion engine.

Peening portion 22 is for by the position of 40 peening of insulator, tool engagement portion 23 to be by threaded portion 26 and internal combustion engine Threaded hole makes the position of the tool engagements such as spanner when (not shown) chimeric.Base portion 24 is to being embedded in the base portion 24 and main body The position that gasket 28 between portion 25 is pressed.Gasket 28 is clipped between base portion 24 and internal combustion engine and by threaded portion 26 and spiral shell The clearance seal of pit.Main part 25 is formed in inner peripheral surface to radial inside shelf portion 27 outstanding.Shelf portion 27 with From rear end side towards front end side and undergauge.

Grounding electrode 30 has: the made of metal that is engaged with the front end (end face of main part 25) of main metal fixture 20 (such as nickel Based alloy system) electrode base metal 31；And the end 32 engaged with the front end of electrode base metal 31.Electrode base metal 31 be with axes O The rodlike component that the mode of intersection is bent towards axes O.End 32 is by noble metals such as platinum, iridium, ruthenium, rhodiums or with them The component that the alloy of principal component is formed, and it is bonded on the position intersected with axes O.

Insulator 40 is by the substantially cylindric of the formation such as the excellent aluminium oxide of the insulating properties under mechanical property or high temperature Component.Insulator 40 is formed with the axis hole 41 along the perforation of axes O direction, and it is maximum to be formed with shape in the center in axes O direction Protruding portion 42.Insulator 40 than protruding portion 42 by rear end side be formed with after main part 43, than protruding portion 42 lean on front end side shape At having intermediate body portions 44 and front end 45.

Front end 45 is the position of the outer diameter tubular smaller than the outer diameter of intermediate body portions 44, in intermediate body portions 44 and front end The stage portion 46 towards front end side undergauge is formed between portion 45.Match between stage portion 46 and the shelf portion 27 of main metal fixture 20 It is equipped with liner 47.Liner 47 is by metal materials shapes such as soft mild steel plates compared with the metal material for constituting main metal fixture 20 At circular plate.

Insulator 40 forms oriented radial inside support portion 48 outstanding in the inner peripheral surface of intermediate body portions 44.Support portion 48 with from rear end side towards front end side and undergauge.Insulator 40 is inserted into the through hole 21 of main metal fixture 20, and solid in periphery Determine main metal fixture 20.The through hole 21 of the front end of the front end 45 of insulator 40 and the rear end of rear main part 43 from main metal fixture 20 Expose respectively.Insulator 40 is formed with slot 52 in front end 45.

Ring element 49,50 is between the peening portion 22 of main metal fixture 20 and the rear main part of tool engagement portion 23 and insulator 40 Between 43.To being filled with the packing materials 51 such as talcum between ring element 49,50.When peening portion 22 is by peening, via ring element 49,50 and packing material 51 by insulator 40 along axes O direction press.As a result, shelf portion of the configuration in main metal fixture 20 Liner 47 between 27 and the stage portion 46 of insulator 40 deforms, and is tightly attached to shelf portion 27 and stage portion 46.

Central electrode 70 is to be embedded with heat conductivity in the inside for the electrode base metal for being formed as bottomed tube to compare electrode base metal The rodlike electrode of excellent core material 71.Core material 71 is formed by copper or by the alloy of principal component of copper.Central electrode 70 has: edge The leg 72 that axes O extends in axis hole 41 to front end side；And the lip portions 73 that the rear end side in leg 72 is arranged.Lip portions 73 Engaging in the support portion 48 formed in insulator 40 (intermediate body portions 44).The front end of leg 72 is prominent from axis hole 41, and preceding End engagement end 74.End 74 is by the noble metals such as platinum, iridium, ruthenium, rhodium or the column formed using them as the alloy of principal component Component.

Terminal fittings 80 are the rodlike components for connecting high voltage cable (not shown), by conductive metal material (such as mild steel etc.) is formed.The front end side of terminal fittings 80 configures in the axis hole 41 of insulator 40.Resistor body 81 is to be used for Inhibit the component of the electric wave noise generated in electric spark, configures the axis hole 41 between terminal fittings 80 and central electrode 70 It is interior.Resistor body 81 via the glass system for being mixed with metal powder electric conductivity seal 82,83 and with central electrode 70 and terminal fittings 80 are electrically connected.

Referring to Fig. 2, illustrate the front end 45 of insulator 40.Front end 45 is the lining in the stage portion 46 compared to insulator 40 The front-end edge 60 for the first contact surface 59 that pad 47 contacts is located at the part of front end side (on the downside of Fig. 2).Front-end edge 60 is the first contact Front end side in face 59 is the edge being present near axes O.Contacting with lip portions 73 in the support portion 48 of insulator 40 The axial position of the front-end edge 62 of second contact surface 61 and the axial position of front-end edge 60 are identical, or than front-end edge 60 Axial position is by front end side (on the downside of Fig. 2).It is attached that front-end edge 62 is that the front end side in the second contact surface 61 is present in axes O Close edge.

In front end 45, the inner peripheral surface 29 of the main part 25 of main metal fixture 20 is set with the gap (space length) of outer surface It is set to 0.1mm or less.This is to be easy heat dissipation from front end 45 to main part 25.Equally, in front end 45, central electrode 70 Leg 72 and the gap (space length) of axis hole 41 be set as 0.1 or less.This is in order to from front end 45 to central electrode 70 It is easy heat dissipation.The axial length L of the slave front-end edge 60 of front end 45 to front end face 55 is set as 9mm or less.This is to contract The heat dissipation path of short front end 45 and improve heat resistance.

Front end side of the main metal fixture 20 in the inner peripheral surface 29 of main part 25 be formed with towards front end side and it is expanding Inclined surface 29a.As inclined surface 29a is towards front end side, the space length of front end 45 and inclined surface 29a (main metal fixture 20) by Gradual change is wide.Position P is that the outer surface of front end 45 and the space length of the inner peripheral surface 29 of main part 25 become the position below 0.1mm The position of front end side in setting.

The circular slot 52 of end side forward (on the downside of Fig. 2) opening of front end 45 is formed around axes O.The radial direction of slot 52 Width W be 0.2mm or more.Width W is that the slot 52 of 0.2mm or more is able to suppress because carbon caused by imperfect combustion etc. is along slot The case where 52 width direction is built bridge.Due to forming slot 52 in front end 45, with no slot 52 the case where compared with, Neng Gouzeng The surface area of the outer surface of big front end 45.It should be noted that forming or processing before the firing that slot 52 passes through insulator 40, Or machining after the firing for passing through insulator 40 is formed.

The creepage distance D of the outer surface and link position 58 to the position P of axis hole 41 from front end 45 of front end 45 is removed With the value D/L of length L for 1.1 or more.D/L is the index for indicating the surface area of front end 45 relative to the ratio of length L.Pass through Meet D/L >=1.1, is capable of increasing the creepage distance D of the outer surface of front end 45 relative to end using the creepage distance of slot 52 The ratio of 45 length L.Due to being capable of increasing the surface area of front end 45, carbon can be made to be attached to the front end 45 on surface Insulation resistance be difficult to decline.As a result, can be achieved at the same time the heat resistance and insulating properties of spark plug 10.

Slot 52 forms one or more in front end 45.In the present embodiment, the situation that slot 52 is 1 is illustrated.In slot In the case where 1, slot 52 is preferably provided at the periphery from 1/2 position of the radial thickness of front end 45 to front end 45 Between.This is because the middle electrocardio that by the part of radial inside mainly to make heat than slot 52 lower than main metal fixture 20 from thermal resistance Pole 70 is diffused, the reason for diffusing heat from main metal fixture 20 by the part in radial outside than slot 52.

In the case where slot is multiple, slot is configured to the concentric circles centered on axes O under end on observation.Slot is more The depth (axial length) of each slot when a can arbitrarily be set.

The axial position of the front-end edge 62 of second contact surface 61 is identical as the front-end edge 60 of the first contact surface 59, Huo Zhewei In the front-end edge 60 than the first contact surface 59 by front end side (on the downside of Fig. 2), therefore, the heat of the central side of front end 45 can be made It is mainly diffused from central electrode 70, diffuses the heat in the outside of front end 45 mainly from main metal fixture 20.Since heat can be made Amount is swimmingly diffused from multiple heat dissipation paths, therefore can be improved thermal diffusivity.As a result, can be improved the heat-resisting of spark plug 10 Property.

Front end 45 is divided into than slot 52 by first 54 of radial inside and than slot 52 by slot 52 by radial outside Second 56.The width W of slot 52 is with first 54 and second 56 (rest part of the slot 52 of front end 45) radial direction Thickness is able to ensure that the mode of 0.7mm or more sets the upper limit.This is in order to ensure the machinery of first 54 and second 56 Intensity.

It should be noted that the axial length L of the front end 45 of the high spark plug 10 of calorific value is short, therefore from front end 45 The front end thicker position of wall thickness that has been axially separated predetermined distance length it is also short.Therefore, though as patent document 1 that The sample position that the wall thickness being arranged in front end 45 to the slot of radial outer openings is thicker, can not also increase of slot Number, therefore creepage distance D is less long.If the relatively thin portion of wall ratio in order to ensure creepage distance D in front end 45 Position is also provided with the slot to radial outer openings, then the intensity of insulator 40 may decline.

In contrast, the slot 52 of end-side openings forward is arranged in front end 45 in spark plug 10, therefore it is arranged in insulator Patent document 1 to the slot of radial outer openings is different, and the intensity of insulator 40 will not be made to decline, be capable of increasing front end 45 Creepage distance relative to front end 45 length L ratio.Spark plug 10 can ensure the intensity of insulator 40 as a result, and It can be achieved at the same time heat resistance and insulating properties.

First 54 front end face 55 compares second 56 front end face 57 and is located at axial front end side (on the downside of Fig. 2), It is the range within axial 2mm that front end face 57, which is present in away from position P,.There are slot 52 between second 56 and first 54, Therefore second 56 heat effectively can be diffused mainly to main metal fixture 20.Therefore, by making second 56 front end face 57 Axial direction distance S with position P is 2mm hereinafter, can shorten the heat dissipation path from second 56 to main part 25, therefore can Improve heat resistance.

The axial bottom 53 of slot 52 is located at the front end side of front end 45 compared to front-end edge 60 (on the downside of Fig. 2).Here, In In the case that the bottom 53 of slot 52 is located at rear end side (on the upside of Fig. 2) compared to front-end edge 60, the bottom 53 of slot 52 nearby becomes resistance Barrier, therefore, it is difficult to diffuse first 54 heat from liner 47 to main metal fixture 20.Equally, it is difficult to make second 56 heat It measures and is diffused to central electrode 70.As a result, thermal diffusivity may deteriorate.

In contrast, being configured and front-end edge 60 are compared in the bottom 53 of slot 52 at front end side (on the downside of Fig. 2), can make First 54 and second 56 heat is easy to diffuse to main metal fixture 20 and central electrode 70.Due to that can ensure front end 45 Thermal diffusivity, therefore can ensure the heat resistance of spark plug 10.

Next, illustrating second embodiment referring to Fig. 3.In the first embodiment, the axis in insulator 40 is illustrated To end face on formed slot 52 the case where.In contrast, in this second embodiment, illustrating insulator 100 by first component 110 and second component 120 constitute, the gap 125 of the inner peripheral surface 123 of the outer peripheral surface 114 and second component 120 of first component 110 The case where constituting slot.It should be noted that marking same label about part identical with the part that first embodiment illustrates And omit the following description.

Fig. 3 is the cross-sectional view of the front end 101 at the face comprising axes O of spark plug 90.Spark plug 90 passes through the first structure Part 110 and second component 120 constitute insulator 100.Second component 120 is configured in the radial outside of first component 110 Component.First component 110 and a part of second component 120 constitute front end 101.First component 110 and second component 120 by The formation such as aluminium oxide, aluminium nitride.First component 110 and the material of second component 120 can be the same or different.

First component 110 is in the axial front end side of protruding portion 42 (referring to Fig.1) along axes O connection main part 111, company Knot 112 and first 113.Linking part 112 is will to be formed with first 113 of support portion 48 and main part 111 in inner circumferential The cylindric part of radial inside connection, outer diameter forms smaller than the outer diameter of main part 111.First 113 is at center The cylindric part of the radial outside configuration of the leg 72 of electrode 70.The space in leg 72 and first 113 gap away from From being set as 0.1mm or less.

Second component 120 is in the front end side of main part 111 and the radial outside of linking part 112 and first 113 are matched The cylindric component set, and it is 122 axially connecting with annulus 121 and second.Annulus 121 is in linking part 112 The circular part of radial outside configuration.The rear end face 121a of annulus 121 is supported with the front end face 111a of main part 111 It connects, and is formed with stage portion 46 in the front end of annulus 121.Second 122 is that outer diameter forms smaller than the outer diameter of annulus 121 Cylindric part, the radial inside for the main part 25 configured in main metal fixture 20.Main part 25 inner peripheral surface 29 (in addition to Except the 29a of inclined surface) with the space length in second 122 gap it is set as 0.1mm or less.

Second 122 inner peripheral surface 123 and the space length in the gap 125 of first 113 outer peripheral surface 114 are set as 0.2mm or more, gap 125 constitute slot.The bottom 126 in gap 125 (slot) is configured in front end side compared to front-end edge 60 (under Fig. 3 Side).As a result, first 113 and second 122 heat can be made to be easy to put to main metal fixture 20 and central electrode 70 It dissipates, it can be ensured that the thermal diffusivity of front end 101.

It should be noted that can certainly inorganic binder (so-called cement) or with electric conductivity seal 82 same materials (such as include B₂O₃-SiO₂System etc. the metallic particles such as glass particles and Cu or Fe constituent) etc. heat transfer layer between the first structure Between part 110 and second component 120 (other than gap 125).It can be improved first component 110 and the second structure by heat transfer layer Pyroconductivity between part 120.Can also there is no heat transfer layer.

The interval (space length) of the part opposite with second component 120 of first component 110 (other than gap 125) is 0.1mm or less.In the case where heat transfer layer is between first component 110 and second component 120, first component 110 and second Any of component 120 and the interval (space length) of heat transfer layer are set as 0.1mm or less.As a result, other than gap 125 Heat transfer is easy between first component 110 and second component 120.

The axial length L of the slave front-end edge 60 of front end 101 to front end face 115 is set as 9mm or less.Position P is The space length of the inner peripheral surface 29 of two 122 outer surfaces and main part 25 become in the position below 0.1mm near front end The position of side.Electricity is climbed to position P from the link position 58 of the axis hole 41 of first component 110 and first 113 front end face 115 Distance D is set as 1.1 or more divided by the value D/L of length L.It can be achieved at the same time spark in the same manner as first embodiment as a result, The heat resistance and insulating properties of plug 90.

First 113 first component 110 is configured around central electrode 70 mainly to radiate from central electrode 70.In master The second component 120 that the inside in body portion 25 configures second 122 mainly radiates from main part 25.Second 122 front end face 124 Front end face 115 compared to first 113 and be located at axial rear end side (on the upside of Fig. 3), front end face 124 is present in is away from position P Range within axial direction 2mm.Thereby, it is possible to improve the heat resistance of second component 120.

Second component 120 is configured in the radial outside of first component 110, utilizes first component 110 and second component 120 Between gap 125 make grooving, therefore be able to easily form the elongated slot for being difficult to be formed in single component.According to Present embodiment, other than the function and effect that first embodiment obtains, additionally it is possible to be easily manufactured can be achieved at the same time it is resistance to Hot and insulating properties spark plug 90.In addition, can be improved the freedom degree of the design in gap 125 (slot) according to spark plug 90.

Next, illustrating third embodiment referring to Fig. 4.In this second embodiment, it illustrates in first component 110 The case where being formed with protruding portion 42 (referring to Fig.1).In contrast, in the third embodiment, illustrating in second component 160 The case where being formed with protruding portion 42.It should be noted that about part identical with the part that first embodiment illustrates, It marks same label and omits the following description.

Fig. 4 is the cross-sectional view of the front end 141 at the face comprising axes O of spark plug 130.Spark plug 130 passes through first Component 150 and second component 160 constitute insulator 140.Second component 160 is configured in the radial outside of first component 150 Component.First component 150 and second component 160 are formed by aluminium oxide, aluminium nitride etc..First component 150 and second component 160 Material can be the same or different.

First component 150 and a part of second component 160 constitute front end 141.First component 150 is to be formed with perforation The cylindric component of the axis hole 151 at center, and axially connecting annulus 152, linking part 154 and first 155.

Second component 160 is the cylindric component for being formed with the axis hole 161 at perforation center, in protruding portion 42 (referring to figure 1) axial front end side is along axes O connection main part 162, linking part 163 and second 165.Main part 162 is in ring-type The part of the radial outside configuration in portion 152.

Linking part 163 is by the circular part of main part 162 and second 165 connection, and the front end shape in periphery At there is stage portion 46.Linking part 163 is formed in inner circumferential towards radial inside holding section 164 outstanding.Holding section 164 is from rear End side is towards front end side (Fig. 4 on the downside of) undergauge.Second 165 is cylindrical shape that outer diameter forms smaller than the outer diameter of linking part 163 Part, the radial inside for the main part 25 configured in main metal fixture 20.The inner peripheral surface 29 of main part 25 is (in addition to inclined surface Except 29a) with the space length in second 165 gap it is set as 0.1mm or less.

First component 150 be to the axis hole 161 of second component 160 be inserted into component, and the axis hole of itself 151 inserted with Central electrode 70.Annulus 152 is formed with holding section 153 in the front end of periphery.Holding section 153 is the card with second component 160 Conjunction portion 164 is along the part axially engaged, from rear end side towards front end side undergauge.Linking part 154 is will to be formed with support in inner circumferential The cylindric part of first 155 of portion 48 and the radial inside connection of annulus 152, and outer diameter forms to compare annulus 152 outer diameter is small.First 155 is in the cylindric part of the radial outside configuration of the leg of central electrode 70 72.Leg The space length in portion 72 and the gap of axis hole 151 is set as 0.1mm or less.

The gap 168 of first 155 outer peripheral surface 156 and second 165 inner peripheral surface 166 constitutes slot.The sky in gap 168 Between distance be set as 0.2mm or more.Between first component 150 and the opposite part (other than gap 168) of second component 160 It is 0.1mm or less every (space length).The bottom 169 in gap 168 (slot) is configured in front end side compared to front-end edge 60 (under Fig. 4 Side).As a result, first 155 and second 165 heat can be made to be easy to put to main metal fixture 20 and central electrode 70 It dissipates, it can be ensured that the thermal diffusivity of front end 141.

It should be noted that the heat transfer layer for having inorganic binder etc. that is situated between first component 150 and second component 160 In the case of, any of first component 150 and second component 160 and the interval (space length) of heat transfer layer are set as 0.1mm Below.It can be easy heat transfer between first component 150 and second component 160 other than gap 168 as a result,.

The axial length L of slave front-end edge 60 to the first 155 front end faces 157 of front end 141 be set as 9mm with Under.Position P is that second 165 outer surface and the space length of the inner peripheral surface 29 of main part 25 become the position below 0.1mm In the position near front end side.From the link position 58 of the axis hole 151 of first component 150 and first 155 front end face 157 Creepage distance D to position P is set as 1.1 or more divided by the value D/L of length L.It as a result, can be same in the same manner as first embodiment The heat resistance and insulating properties of Shi Shixian spark plug 130.

Second 165 front end face 167 compares first 155 front end face 157 and is located at axial rear end side (on Fig. 4 Side), it is the range within axial 2mm that front end face 167, which is present in away from position P,.Thereby, it is possible to improve the resistance to of second component 160 It is hot.Moreover, the radial outside in first component 150 configures second component 160, first component 150 and second component are utilized Grooving is made in gap 168 between 160, therefore can obtain function and effect same as second embodiment.

[embodiment]

The present invention is described in more detail by embodiment, but the present invention is not limited to the embodiment.

(embodiment 1)

Experimenter has prepared will be from the link position of the outer surface of the front end of insulator 101 (referring to Fig. 3) and axis hole 41 58 are fixed as 4mm to the creepage distance (creepage distance of the inside not comprising slot 123) of slot 123, and the axial length of slot and The radial various samples of different size of slot.Sample is other than the different point of the size in each portion, with second embodiment Spark plug 90 is identical (insulator is divided into first component and second component).

Experimenter starts to install each sample in machine in 1.6 liters of capacity of 4 cylinder DOHC, in the state of engine operating Under, measure the insulation resistance between the main metal fixture of each sample and terminal fittings, and determine from the operation start of engine to Insulation resistance drops to the time until 1000M Ω.The operating condition of engine is revolving speed 2000rpm, air-fuel ratio 10.

Fig. 5 is the figure for indicating the relationship of length of time and slot until insulation resistance drops to 1000M Ω.Solid line is slot Radial width be 0.2mm sample as a result, the result for the sample that the radial width that dotted line is slot is 0.1mm.

As shown in figure 5, the time that the insulation resistance of the sample of the width 0.1mm of slot declines is about 200 seconds.This and width The length of the slot of 0.2mm is that the result of the sample (not having slotted sample) of 0mm is roughly the same.In the radial width 0.2mm of slot Sample in, with the length of slot, insulation resistance decline time it is progressively longer, be saturated in the length 5mm or more of slot.Root According to the embodiment it is found that in order to improve insulating properties, the radial width of slot needs for 0.2mm or more, and the axial length of slot As long as being 5mm.

(embodiment 2)

Experimenter has prepared to have slotted sample 1~4 in the front end of insulator and has not had slotted sample 5~10.Have The radial width 0.2mm of the slot of the sample 1~4 of slot and the length L of front end and creepage distance D difference.Sample 1~3 in addition to It is identical as the spark plug 10 of first embodiment except the different point of the size in each portion.Sample 4 is different in addition to the size in each portion Except point, (insulator is divided into first component and second component) identical as the spark plug 90 of second embodiment.Sample 5~10 removes It is identical as the spark plug 10 of first embodiment except the point that does not have slotted point different with the size in each portion.

(evaluation method of heat resistance)

Experimenter starts to install each sample in machine in 1.6 liters of capacity of 4 cylinder DOHC, operates engine, has detected The presence or absence of pre-ignition (prematur ignition).The operating condition of engine is set as revolving speed 6000rpm, air-fuel in the state of full throttle Than 12, ignition timing is 40 ° before top dead centre.Using a series of stroke of engine as 1 circulation, engine is operated to the circulation Until being repeated 1000 times.

During the operating of 1000 circulations, also undetected sample is evaluated as " excellent (◎) " for pre-ignition 1 time, in 1000 circulations Operating during, preignition detecting to 1 time sample is evaluated as " good (zero) ", 1000 circulation operating during, preignition detecting to 2 The secondary above sample is evaluated as " poor (×) ".

(evaluation method of insulating properties)

Experimenter starts to install each sample in machine in 1.6 liters of capacity of 4 cylinder DOHC, in the state of engine operating Under, the insulation resistance between the main metal fixture of each sample and terminal fittings is determined, and determine the operation start from engine Time until insulation resistance drops to 1000M Ω.The operating condition of engine is set as turning in the state of full throttle Fast 6000rpm, air-fuel ratio 10.

The sample that time until operation start to insulation resistance drops to 1000M Ω is 250 seconds or more is evaluated as " excellent (◎) ", 200 seconds samples more than and less than 250 seconds are evaluated as " good (zero) ", the sample evaluation more than and less than 200 seconds in 100 seconds For " common (△) ".The results are shown in Table 1.

[table 1]

As shown in table 1, do not have in slotted sample 5~10, there is no heat resistance and insulating properties this two side be all evaluated as it is " good (zero) " sample.The especially length L of front end is that the insulating properties of 9mm sample 8~10 below is evaluated as common (△).

On the other hand, heat-resisting other than the length L of front end is the sample 1 of 11mm in having slotted sample 1~4 Property is evaluated as " good (zero) ".The length L of especially front end is that the heat resistance of 9mm sample 3,4 below is that excellent and D/L value is 1.1 or more, therefore insulating properties is evaluated as " good (zero) " or " excellent (◎) ".By the embodiment it is found that can obtain can be real simultaneously The spark plug of existing heat resistance and insulating properties.

(embodiment 3)

Experimenter has prepared the front-end edge 62 of the second contact surface 61 (support portion 48) relative to 59 (reference figure of the first contact surface 2) the different sample 11~16 in the position in the axes O direction of front-end edge 60 (stage portion 46).The radial direction of the slot of sample 11~16 Width 0.2mm, the length L of front end is 9mm or 10mm, and creepage distance D is 12mm.(the ginseng of front end 45 of sample 11~16 According to Fig. 2) in ratio slot 52 by the position (distance S) of the front end face 57 of the part in radial outside be S=3mm.Sample 11~16 It is identical as the spark plug 10 of first embodiment other than the different point of the size in each portion.

The front-end edge 62 (support portion 48) and the position phase in the axes O direction of front-end edge 60 (stage portion 46) of sample 13,14 Together.Compare the axis of front-end edge 60 (stage portion 46) in the position in the axes O direction of the front-end edge 62 (support portion 48) of sample 11,12 The position in the direction O and rear end side (Fig. 2 on the upside of) in 1mm.The axes O side of the front-end edge 62 (support portion 48) of sample 15,16 To position compared to front-end edge 60 (stage portion 46) axes O direction position and front end side (Fig. 2 on the downside of) in 1mm.

Experimenter has rated heat resistance and insulating properties about sample 11~16.The evaluation method and reality of heat resistance and insulating properties It is identical to apply example 2.The results are shown in Table 2.

[table 2]

As shown in table 2, when the sample 12,14,16 that the length L of front end is 10mm being compared, (the support of front-end edge 62 Portion 48) sample 16 compared to front-end edge 60 (stage portion 46) and along axes O direction end side 1mm forward is more heat-resisting than sample 12,14 Property is excellent.Moreover, when the sample 11,13,15 that the length L of front end is 9mm is compared, front-end edge 62 (support portion 48) phase Than front-end edge 60 (stage portion 46) along axes O direction forward the sample 15 of end side 1mm and front-end edge 62 (support portion 48) with before Excellent heat resistance of the identical sample 13 in the position in the axes O direction of ora terminalis 60 (stage portion 46) than sample 11.Pass through the implementation Example is it is found that can obtain the position of the position of the front-end edge of setting support portion and the front-end edge of stage portion and can be improved heat resistance Spark plug.

(embodiment 4)

The ratio slot 52 that experimenter has prepared in front end 45 (referring to Fig. 2) leans on the front end face 57 of the part in radial outside The different sample 17~22 in position (distance S).The radial width 0.2mm of the slot of sample 17~22, the length L of front end are 9mm or 10mm, creepage distance D are 12mm.It compares the position in the axes O direction of the front-end edge 62 (support portion 48) of sample 17~22 The position in the axes O direction of front-end edge 60 (stage portion 46) and position in end side backward (on the upside of Fig. 2) 1mm.Sample 17~ 22 other than the different point of the size in each portion, identical as the spark plug 10 of first embodiment.

Experimenter has rated heat resistance and insulating properties about sample 17~22.The evaluation method of heat resistance and insulating properties with Embodiment 2 is identical.The results are shown in Table 3.

[table 3]

As shown in table 3, distance S is that 2mm sample 19~22 below is more excellent than the heat resistance of the distance S sample 17,18 for being 3mm It is different.By the embodiment it is found that can obtain distance S being set as the spark plug that 2mm or less can be improved heat resistance.

More than, illustrate the present invention based on embodiment, but the present invention is by any restriction of above embodiment, It can easily speculate the case where being able to carry out various improvement deformation without departing from the spirit and scope of the invention.For example, Insulator 40,100,140, slot 52, gap 125,168 (slot) shape, size etc. as an example of, can suitably set.

In the respective embodiments described above, illustrate in the section comprising axes O, slot 52 or gap 125,168 (slot) with The case where axes O is formed parallel to, but it is not necessarily limited to this.It can certainly be formed as making slot 52 or gap 125,168 (slot) is relative to the inclined state of axes O (not parallel relative to axes O).Moreover, can certainly by slot 52 or gap 125, 168 (slots) are formed as narrowing with towards the width of bottom and slot.

In the respective embodiments described above, the grounding electrode 30 engaged with the front end of the main part 25 of main metal fixture 20 is illustrated Along axes O direction spark plug 10,90,130 outstanding, but it is not necessarily limited to this.It can certainly be for example by grounding electrode Be formed as the spark plug (so-called creeping discharge spark plug) of the shape of winding center electrode 70, grounding electrode is configured with multiple fire The respective embodiments described above are applicable in Hua Sai (so-called multi-gap spark plug) etc..

In the respective embodiments described above, illustrate that grounding electrode 30 and central electrode 70 have the feelings of end 32,74 respectively Condition, but it is not necessarily limited to this.End 32,74 can certainly be omitted.

In the above-described embodiment, it illustrates the spark plug 10,90,130 of in-built electrical resistance body 81, but is not necessarily limited to This.Certainly the respective embodiments described above can also be applied in the spark plug of non-in-built electrical resistance body 81.In this case, resistance is omitted Body 81 and electric conductivity sealing 83, as long as being engaged central electrode 70 with terminal fittings 80 by electric conductivity sealing 82.

Claims (5)

1. a kind of spark plug, has:

Central electrode has the rear end from the leg that front end side rear end lateral edge axis extends and from the leg to outside radial direction Side lip portions outstanding；

Cylindric insulator, is formed with the support being supported to the lip portions in the axis hole formed along the axis Portion, and be formed in the outer peripheral surface of the insulator with the stage portion expanding towards rear end side from front end side；And

Cylindric main metal fixture, the shelf portion for via liner and supporting the stage portion, and the master are formed in inner peripheral surface Body accessory configures in the radial outside of the insulator, and the spark plug is characterized in that,

Than in the stage portion with the insulation existing for the front end side of the front-end edge of the first contact surface of the gasket contacts The axial length L of the front end of body be 9mm hereinafter,

The cricoid slot that the front end has end-side openings forward and formed around the axis,

The radial width of the slot is 0.2mm or more,

In the section comprising the axis, between the outer surface of the front end and the inner peripheral surface of the main metal fixture The outer surface and institute of the space length for the position P near front end side in the position below 0.1mm to the front end State axis hole connection link position until creepage distance D divided by the value D/L after the length L be 1.1 or more.

2. spark plug according to claim 1, which is characterized in that

The axial position and described first of the front-end edge of the second contact surface contacted with the lip portions in the support portion The identical or front-end edge compared to first contact surface of the front-end edge of contact surface is located at front end side.

3. spark plug according to claim 1 or 2, which is characterized in that

Slot described in ratio in the front end is present in by the axial position of the front end face of the part in radial outside from described The position P range within the 2mm of end side forward.

4. spark plug according to claim 1 or 2, which is characterized in that

The insulator has: being formed as cricoid first component；And cricoid second component, second component configuration this The radial outside of one component and the gap composition slot between the inner peripheral surface of itself and the outer peripheral surface of the first component,

The support portion is formed in the inner peripheral surface of the first component, and the stage portion is formed in the periphery of the second component Face.

5. spark plug according to claim 3, which is characterized in that

The insulator has: being formed as cricoid first component；And cricoid second component, second component configuration this The radial outside and the gap of the inner peripheral surface of itself and the outer peripheral surface of the first component of one component constitute the slot,

The support portion is formed in the inner peripheral surface of the first component, and the stage portion is formed in the periphery of the second component Face.