WO2013065741A1 - 内燃機関用のスパークプラグ及びその取付構造 - Google Patents
内燃機関用のスパークプラグ及びその取付構造 Download PDFInfo
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- WO2013065741A1 WO2013065741A1 PCT/JP2012/078179 JP2012078179W WO2013065741A1 WO 2013065741 A1 WO2013065741 A1 WO 2013065741A1 JP 2012078179 W JP2012078179 W JP 2012078179W WO 2013065741 A1 WO2013065741 A1 WO 2013065741A1
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- Prior art keywords
- spark plug
- spark
- internal combustion
- combustion engine
- gap
- Prior art date
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
- F02P13/00—Sparking plugs structurally combined with other parts of internal-combustion engines
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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
-
- 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
- H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
-
- 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
- H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
- H01T13/32—Sparking plugs characterised by features of the electrodes or insulation characterised by features of the earthed electrode
-
- 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
- H01T1/00—Details of spark gaps
- H01T1/20—Means for starting arc or facilitating ignition of spark gap
- H01T1/22—Means for starting arc or facilitating ignition of spark gap by the shape or the composition of the electrodes
Definitions
- the present invention relates to a spark plug for an internal combustion engine used for an automobile, a motorcycle, a cogeneration, a gas pressure pump, and the like, and a mounting structure thereof.
- FIG. 1 there is a spark plug 9 for an internal combustion engine used as an ignition means for an air-fuel mixture introduced into a combustion chamber of an internal combustion engine such as an automobile.
- the spark plug 9 has a center electrode 94 and a ground electrode 95.
- One end of the ground electrode 95 is fixed to the housing 92 and bent, and the other end is disposed at a position facing the center electrode 94, thereby forming a spark discharge gap 911 with the center electrode 94.
- the ground electrode 95 is provided with a protrusion 96 protruding toward the spark discharge gap 911.
- the protrusion 96 has a facing surface 960 that faces the center electrode 94.
- discharge is made in the spark discharge gap 911 and an air-fuel mixture is ignited by this discharge.
- symbol E in a figure shows the discharge spark formed by discharge
- symbol F shows the airflow of air-fuel
- symbol I shows a flame (refer patent document 1).
- Patent Document 2 discloses a spark plug in which the shape of the ground electrode is devised in order to suppress wear of the ground electrode.
- the discharge spark E is continuously caused to flow in a certain direction, that is, the downstream side by the air flow, so that the re-discharge is repeated in the corner portion 966 on the downstream side of the projection portion 96, and this portion is biased and easily consumed (hereinafter referred to as “discharging”). This is called partial consumption). As a result, there has been a problem that the life of the spark plug is reduced.
- the facing surface 960 of the protrusion 96 may take heat from the flame F during the flame growth and may hinder the growth of the flame F (hereinafter referred to as this). Called anti-inflammatory action). As a result, the ignitability of the spark plug may be reduced.
- the ground electrode has a shape in which the volume on the downstream side is larger than the upstream side of the airflow of the air-fuel mixture. This is disadvantageous for improving ignitability.
- the spark plug described in Patent Document 2 does not have a protrusion on the ground electrode, and does not solve the above-described problem of wear of the protrusion.
- the present invention has been made in view of such a background, and intends to provide a spark plug for an internal combustion engine and its mounting structure that can improve the ignitability and life while suppressing the flame extinguishing action and the discharge voltage. It shall be.
- One embodiment of the present invention includes a cylindrical housing, a cylindrical insulator held inside the housing, a center electrode held inside the insulator so that a tip portion protrudes, and the housing
- a spark plug for an internal combustion engine comprising a grounding electrode that has a facing portion that is connected to the center electrode from the plug axis direction and forms a spark discharge gap with the center electrode, Both the tip portion of the center electrode and the opposing portion of the ground electrode are each provided with a protrusion protruding toward the spark discharge gap, and at least one of the protrusions is the spark discharge.
- the facing surface facing the gap is inclined with respect to a surface orthogonal to the plug axis direction, and the spark discharge gap is in one direction orthogonal to the plug axis direction of the spark plug, It is configured to gradually expand from a narrow gap having a gap length smaller than that of the other end side toward a wide gap having a gap length larger than that of the one end side.
- a spark plug for an internal combustion engine is inclined with respect to a surface orthogonal to the plug axis direction, and the spark discharge gap is in one direction orthogonal to the plug axis direction of the spark plug, It is configured to gradually expand from a narrow gap having a gap length smaller than that of the other end side toward a wide gap having a gap length larger than that of the one end side.
- spark plug attachment structure in which the spark plug is attached to an internal combustion engine, and the spark discharge gap is supplied to the combustion chamber on the narrow gap side than on the wide gap side.
- the spark plug mounting structure for an internal combustion engine is arranged to be upstream of the airflow of the air-fuel mixture.
- At least one of the projecting portions is inclined with respect to a surface orthogonal to the plug axis direction, the facing surface facing the spark discharge gap.
- the spark discharge gap extends from one end side to the other end side so that a narrow gap is formed on one end side and a wide gap is formed on the other end side in one direction perpendicular to the plug axis direction. It is configured to gradually expand. Accordingly, when the spark plug is attached to the combustion chamber of the internal combustion engine, if the narrow gap side of the protrusion is arranged to be upstream of the airflow of the air-fuel mixture in the combustion chamber than the wide gap side, It is possible to suppress the discharge voltage of the plug, improve wear resistance and ignitability.
- the narrow gap is arranged on the upstream side. In the vicinity of the narrow gap, the electric field is most easily concentrated, and one end side of the protrusion is likely to be a starting point of discharge. As a result, the discharge voltage can be suppressed. And by arranging one end side forming the narrow gap on the upstream side, it is possible to obtain an initial discharge spark on the upstream side of the protrusion, and the discharge spark is caused to flow downstream by the air-fuel mixture. You can earn time until blown out.
- the wide gap is arranged on the downstream side of the airflow in the protrusion. Therefore, as described above, when a discharge spark is caused to flow downstream of the protrusion, the distance of the discharge spark between the center electrode and the ground electrode (hereinafter referred to as the discharge distance) can be increased. Therefore, it is easy to ensure a long discharge distance of the discharge spark, and a sufficient opportunity for ignition of the air-fuel mixture can be obtained. As a result, the ignitability of the spark plug can be improved.
- At least one of the protrusions is inclined with respect to a surface orthogonal to the plug axis direction so that the opposed surface facing the spark discharge gap is perpendicular to the plug axis direction.
- it is realized by gradually expanding from a narrow gap on one end side toward a wide gap on the other end side.
- the wear resistance can be improved without particularly increasing the diameter of the protrusion itself. Therefore, it is possible to improve the life of the spark plug while suppressing the flame extinguishing action.
- a spark plug for an internal combustion engine and its mounting structure that can improve the ignitability and life while suppressing the flame extinguishing action and the discharge voltage.
- tip part of the spark plug in background art It is explanatory drawing of the front-end
- the spark plug for the internal combustion engine can be used as an ignition means for the internal combustion engine in, for example, an automobile, a motorcycle, a cogeneration, a gas pressure pump, and the like.
- the side inserted into the combustion chamber of the internal combustion engine will be described as the front end side, and the opposite side as the base end side.
- the spark plug 1 of this example includes a cylindrical housing 2, a cylindrical insulator 3 held inside the housing 2, and an inner side of the insulator 3 so that the tip portion protrudes. Between the held center electrode 4 and the center electrode 4 having a facing portion 52 that is connected to the housing 2 and faces the center electrode 4 from the plug axial direction (longitudinal direction of the spark plug 1: see FIG. 3). And a ground electrode 5 for forming a spark discharge gap 11.
- a projecting portion 41 and a projecting portion 6 projecting toward the spark discharge gap 11 are disposed on both the front end portion of the center electrode 4 and the facing portion 52 of the ground electrode 5. Further, as shown in FIG. 4, in the protrusion 6 disposed on the ground electrode 5, the facing surface 60 that faces the spark discharge gap 11 is inclined with respect to a surface that is orthogonal to the plug axis direction.
- the spark discharge gap 11 is directed from a narrow gap 111 formed on one end side thereof to a wide gap 112 formed on the other end side in one direction orthogonal to the plug axis direction. It is configured to gradually expand.
- the narrow gap 111 has a smaller gap length in the plug axis direction than the gap on the other end side (that is, the wide gap 112).
- the narrow gap 112 has a larger gap length in the plug axis direction than the gap on one end side (that is, the narrow gap 111). That is, the “narrow” of the narrow gap 111 and the “wide” of the wide gap 112 express a relative magnitude relationship with each other.
- the spark discharge gap 11 is configured to gradually expand along a direction orthogonal to the extending direction of the facing portion 52 of the ground electrode 5 (broken line L5 shown in FIG. 6). .
- the diameter of the housing 2 is 10 mm, for example.
- the tip of the center electrode 4 protrudes 1.5 mm from the tip of the insulator 3 in the axial direction.
- the protrusion 41 has a circular cross-sectional shape orthogonal to the plug axis direction, and has a substantially cylindrical shape as a whole.
- the height of the protrusion 41 in the plug axis direction is 0.6 mm.
- the ground electrode 5 has one end fixed to the distal end portion of the housing 2 and a standing portion 51 standing on the distal end side, and a central electrode bent from the other end of the standing portion 51. 4 has a facing portion 52 facing from the plug axis direction.
- the protrusion part 6 is comprised by noble metal tips, such as a platinum alloy, for example.
- a noble metal tip is joined to the facing portion 52 of the ground electrode 5 by welding, and the projection 6 is constituted by this noble metal tip.
- the protrusion 6 has a substantially cylindrical shape in which one end surface (opposing surface 60) is inclined with respect to the axial direction.
- the base material of the housing 2 and the ground electrode 5 (parts other than the protrusions 6) is made of a nickel alloy.
- tip part of the center electrode 4 is comprised by the projection part 41 which makes
- tip can be comprised from an iridium alloy, for example.
- the spark plug 1 of this example is used for internal combustion engines for vehicles such as automobiles.
- the spark plug 1 of this example is attached to the internal combustion engine 7, for example, the flow direction of the air flow F of the air-fuel mixture in the combustion chamber 70 using known techniques (Japanese Patent Laid-Open Nos. 11-324878 and 11-351115).
- the spark plug 1 is attached to the internal combustion engine 7 by adjusting the position of the ground electrode 5.
- the extending direction of the facing portion 52 of the ground electrode 5 (broken line L ⁇ b> 5 shown in FIG. 6) is adjusted to be orthogonal to the airflow direction of the airflow F.
- the spark plug 1 is attached to the internal combustion engine 7. That is, the spark plug 1 is attached to the internal combustion engine 7 so that the standing portion 51 of the ground electrode 5 does not shield the airflow F.
- the protrusion 6 disposed in the combustion chamber 70 is arranged such that the narrow gap 111 is located upstream of the airflow F of the air-fuel mixture supplied to the combustion chamber 70 rather than the wide gap 112. .
- spark E When the spark discharge gap 11 is discharged by applying a predetermined voltage between the center electrode 4 and the ground electrode 5, as shown in FIG. Spark E can be obtained. That is, the initial discharge spark E occurs in the narrow gap 111 where the electric field strength tends to be high. Then, as shown in FIG. 7B, the discharge spark E is caused to flow to the downstream side while expanding the discharge distance by the airflow F of the air-fuel mixture. As shown in FIG. 7C, the discharge spark E is greatly stretched at the corner 66 on the downstream side of the protrusion 6. During this time, the air-fuel mixture is ignited by the discharge spark E.
- the spark plug protrusion 6 has an opposing surface 60 that faces the spark discharge gap 11 inclined with respect to a plane orthogonal to the plug axis direction.
- the spark discharge gap 11 is in one direction orthogonal to the plug axis direction so that a narrow gap 111 is formed on one end side and a wide gap 112 is formed on the other end side, from one end side to the other end side. It is configured to gradually expand toward.
- the narrow gap 111 side of the protrusion 6 is arranged to be upstream of the airflow F of the air-fuel mixture in the combustion chamber 70 rather than the wide gap 112 side. For example, it is possible to suppress the discharge voltage of the spark plug 1 and to improve wear resistance and ignitability.
- the narrow gap 111 is arranged on the upstream side. In the vicinity of the narrow gap 111, the electric field is most easily concentrated, and one end side of the protrusion 6 is likely to be the starting point of discharge. As a result, the discharge voltage can be suppressed.
- an initial discharge spark E can be obtained on the upstream side of the protrusion 6, and the discharge spark E flows to the downstream side by the air-fuel mixture. You can earn time until it is blown out.
- a wide gap 112 is arranged on the downstream side of the airflow in the protrusion 6. Therefore, as described above, when the discharge spark E flows on the downstream side of the protrusion 6, the discharge distance of the discharge spark E between the center electrode 4 and the ground electrode 5 can be increased (see FIG. 5). Therefore, it is easy to ensure a long discharge distance of the discharge spark E, and a sufficient opportunity to ignite the air-fuel mixture can be obtained. As a result, the ignitability of the spark plug 1 can be improved.
- the protrusion 6 is inclined with respect to a surface in which the facing surface 60 facing the spark discharge gap 11 is orthogonal to the plug axis direction, and the spark discharge gap 11 is in one direction orthogonal to the plug axis direction.
- This is realized by gradually expanding from the narrow gap 111 on one end side toward the wide gap 112 on the other end side.
- the wear resistance can be improved without particularly increasing the diameter of the protrusion itself. Therefore, the life of the spark plug 1 can be improved while suppressing the flame-extinguishing action.
- the spark discharge gap 11 is configured to gradually expand along a direction orthogonal to the extending direction of the facing portion 52 of the ground electrode 5 (broken line L5 shown in FIG. 6). Accordingly, the wide gap 112 is disposed on the downstream side of the air flow F and the narrow gap 111 is disposed on the upstream side of the air flow F while more reliably preventing the ground electrode 5 from shielding the air flow F toward the spark discharge gap 11.
- the spark plug 1 can be arranged as described. Therefore, as described above, the wear resistance of the protrusion 6 can be improved, and a sufficient ignition opportunity can be secured. As a result, the ignitability can be improved more effectively while improving the life of the spark plug 1. In addition, the discharge voltage can be more effectively suppressed.
- the protrusion part 6 of this example may distribute
- the wide gap 112 is disposed on the downstream side of the air flow F and the narrow gap 111 is disposed on the upstream side of the air flow while preventing the ground electrode 5 from shielding the air flow F toward the spark discharge gap 11.
- the opposing surfaces 410 and 60 of the protrusions 41 and 6 of both the center electrode 4 and the ground electrode 5 are inclined.
- the opposing surfaces 410 and 60 in the protrusions 41 and 6 of both the center electrode 4 and the ground electrode 5 are in the same direction with respect to the surface orthogonal to the plug axis direction and from the narrow gap 111 side to the wide gap 112. As it goes to the side, it inclines toward the tip side of the spark plug 1.
- the arrangement of the spark plug 1 with respect to the internal combustion engine 7 is such that a narrow gap 111 is arranged on the upstream side of the airflow F of the air-fuel mixture and a wide gap 112 is arranged on the downstream side of the airflow F. .
- the opposing surfaces 410 and 60 of the protrusions 41 and 6 of both the center electrode 4 and the ground electrode 5 are in a state of moving toward the distal end side of the spark plug 1 from the upstream side to the downstream side of the airflow F. ing. Others are the same as in the first embodiment.
- the direction of the airflow F entering the spark discharge gap 11 can be changed, and the flame can be easily spread in the combustion chamber. Therefore, the ignitability of the spark plug 1 can be improved effectively. In addition, it has the same operational effects as the first embodiment.
- the ground electrode 5 of the spark plug 1 has a corner 66 facing the narrow gap 111 of the spark discharge gap 11 made of a noble metal and the other parts made of a nickel alloy. This is an example in which part 6 is arranged. Others are the same as in the first embodiment.
- the ground electrode 5 of the spark plug 1 has a corner 66 facing the wide gap 112 of the spark discharge gap 11 made of a noble metal and the other part made of a nickel alloy. This is an example in which part 6 is arranged. Others are the same as in the first embodiment.
- the wear resistance on the other end side of the protrusion 6 in the wide gap 112 through which the discharge spark E flows can be improved.
- the life of the spark plug 1 can be further extended.
- the manufacturing cost of the projection part 6 can also be reduced.
- it has the same operational effects as the first embodiment.
- the ground electrode 5 and the center electrode 4 of the spark plug 1 are formed on the projecting portion 6 and the projecting portion 41 whose cross-sectional shape perpendicular to the plug axis direction forms the specific shape shown in FIG. Is an example.
- the protrusion 6 and the protrusion 41 have the same cross-sectional shape orthogonal to the plug axis direction. Therefore, first, the shape of the protrusion 6 will be described. As shown in FIG. 11 and FIG. 12, the protrusion 6 has a cross-sectional shape orthogonal to the plug axis direction having a minimum curvature radius portion 62 having the smallest curvature radius in the contour 61 and a specific shape satisfying the following conditions: It is.
- the conditions are determined as follows. That is, as shown in FIG. 12, first, a first straight line L1 connecting the minimum curvature radius portion 62 and the geometric gravity center P1 in the cross-sectional shape is assumed. Next, a first line segment M connecting the two intersection points P2 where the first straight line L1 intersects the cross-sectional outline 61 is assumed. Next, a second straight line L2 orthogonal to the first line segment M at the midpoint P3 of the first line segment M is assumed. Next, the cross-sectional shape is divided into a first region B including the minimum curvature radius portion 62 and a second region C not including the minimum curvature radius portion 62 by the second straight line L2.
- the condition is that the area of the second region C is larger than the area of the first region B.
- a wide gap 112 is formed in the second region C, and a narrow gap 111 is formed in the minimum curvature radius portion 62 of the first region B.
- the protrusion 6 in this example is arranged so that the first straight line L1 is orthogonal to the extending direction of the facing portion 52 of the ground electrode 5 (broken line L5 shown in FIG. 13).
- the protrusion part 6 is formed so that the full length W1 of the same direction as the 1st straight line L1 may become smaller than the width W2 of the direction orthogonal to the extension direction of the opposing part 52.
- the protrusion 6 has a cross-sectional outline 61 that is line-symmetric with respect to the first straight line L1.
- the width of the contour 61 in the direction of the second straight line L2 gradually increases from the minimum curvature radius portion 62 (intersection P2 on the first region B side) of the first region B toward the second region C, and the second A maximum width portion 63 is formed in the region C, and the shape is constricted toward the intersection P2 on the second region C side with the maximum width portion 63 as a base point.
- the maximum width portion 63 is a portion having the smallest curvature radius in the contour 61 in the second region C.
- the total length W1 of the protrusion 6 along the first straight line L1 is 0.88 mm
- the width W3 in the direction orthogonal to both the same direction and the plug axis direction as the first straight line L1 is 0.88 mm.
- the present invention is not limited to this.
- the total length W1 of the protrusion 6 may be set to 0.83 mm
- the width W3 may be set to 0.96 mm.
- the curvature radius R of the minimum curvature radius portion 62 in the first region B of the protrusion 6 is 0.1
- the curvature radius R of the maximum width portion 63 in the second region C is 0.2
- the width W2 of the facing portion 52 of the ground electrode 5 is 2.4 mm.
- the projection part 6 is a substantially columnar body in which the said cross-sectional shape satisfy
- the protrusion 6 has a maximum height T1 in the plug axis direction on one end side in a direction orthogonal to the plug axis direction, and a minimum height T2 in the plug axis direction on the other end side.
- the facing surface 60 facing the spark discharge gap 11 is inclined with respect to the surface orthogonal to the plug axis direction.
- the protrusion 41 is also a columnar body whose cross-sectional shape perpendicular to the plug axis direction satisfies the specific shape.
- the protrusion 41 is formed with a constant height in the plug axis direction.
- the discharge spark E is flowed, expanding the discharge distance to the downstream side by the airflow F of air-fuel mixture. Then, the discharge spark E is stretched at the corner 66 on the downstream side of the protrusion 6. During this time, the air-fuel mixture is ignited by the discharge spark E. Further, the discharge spark E is stretched and disappears at the corner 66 on the downstream side of the protrusion 6, but the re-discharge is repeated at the same portion, that is, the corner 66 on the downstream side of the protrusion 6. Others are the same as in the first embodiment.
- the cross-sectional shape orthogonal to the plug axis direction of the protrusion 6 is formed in the specific shape. That is, as shown in FIG. 12, the area of the second region C in the cross-sectional shape is formed to be larger than the area of the first region B.
- the first region B (narrow gap 111 side) of the protrusion 6 is the second region C (wide gap side 112 side). If it arrange
- the electric field is most easily concentrated in the vicinity of the minimum curvature radius portion 62, and the minimum curvature radius portion 62 is likely to be the starting point of discharge. Therefore, by disposing the minimum radius of curvature 62 on the upstream side, as shown in FIG. 15A, an initial discharge spark E can be obtained on the upstream side of the protrusion 6 as shown in FIG. Then, as shown in FIG. 15B, it is possible to earn time until the discharge spark E is caused to flow downstream by the air-fuel mixture and blown off. Therefore, it is possible to ensure a sufficient ignition opportunity by the flame. As a result, the ignitability of the spark plug 1 can be improved effectively.
- the above configuration is realized by setting the cross-sectional shape of the protrusion 6 to the specific shape. Thereby, the flame-extinguishing action can be suppressed without particularly increasing the diameter of the protrusion 6 itself. As a result, a reduction in ignitability of the spark plug 1 can be effectively prevented.
- the protruding portion 6 is arranged so that the first straight line L ⁇ b> 1 is orthogonal to the extending direction of the facing portion 52 of the ground electrode 5.
- the second region C is disposed on the downstream side of the air flow F while the air flow F toward the discharge spark gap 11 is more reliably prevented from being shielded by the ground electrode 5, and the first region B is disposed on the upstream side of the air flow F.
- the ground electrode 5 of the spark plug 1 is provided with a protruding portion 6 whose cross-sectional shape perpendicular to the plug axis direction forms the specific shape shown in FIG.
- the region C is arranged on the upstream side of the airflow F of the air-fuel mixture in the combustion chamber 70 with respect to the first region B.
- the projecting portion 6 has the minimum curvature radius portion 62 having the smallest curvature radius in the contour 61 in the cross-sectional shape orthogonal to the plug axis direction, and satisfies the conditions described in the fifth embodiment. It is a specific shape (see FIG. 12).
- a wide gap 112 is formed in the minimum curvature radius portion 62 of the first region B, and a narrow gap 111 is formed in the second region C.
- the spark plug 1 when the spark plug 1 is attached to the combustion chamber 70 of the internal combustion engine 7, the second region C (narrow gap 111 side) of the protrusion 6 burns more than the first region B (wide gap 112 side). It arrange
- FIG. Others are the same as in the fifth embodiment.
- the cross-sectional shape orthogonal to the plug axis direction of the protrusion 6 is formed in the specific shape. That is, the area of the second region C in the cross-sectional shape is formed to be larger than the area of the first region B (see FIG. 12). Accordingly, as shown in FIG. 16, when the spark plug 1 is attached to the combustion chamber 70 of the internal combustion engine 7, the second region C of the projection 6 is more upstream of the air-fuel mixture F in the combustion chamber 70 than the first region B. If it arrange
- the second area C having a large area is arranged on the upstream side (the narrow gap 111 side) of the airflow F in the protrusion 6 where the initial discharge is performed. Therefore, even if the initial discharge is repeated at the corner 66 on the upstream side of the protrusion 6, as shown in FIG. 16A, the expansion of the consumption range of the protrusion 6 due to the discharge is suppressed due to the large area. it can. Therefore, the consumption of the protrusion 6 can be suppressed, and the wear resistance can be further improved. That is, expansion of the narrow gap 111 can be suppressed and the discharge voltage can be suppressed. As a result, the life of the spark plug 1 can be effectively improved.
- region B will be arrange
- the protrusion 6 having the specific shape is formed by increasing the area difference between the first region B and the second region C.
- the contour 61 having a cross-sectional shape orthogonal to the plug axis direction is a part of the contour 61 extending from the minimum curvature radius portion 62 of the first region B to a part of the second region C in the cross-sectional shape. 2, a hollow portion 64 that is depressed toward the middle point P3 side of the first line segment M is formed.
- the cross-sectional shape of the protrusion 6 perpendicular to the plug axis direction is such that the area of the first region B is particularly smaller than the area of the second region C, and the area difference is large. It is formed as follows.
- the protrusion 41 may have the same cross-sectional shape as the protrusion 6 in this example.
- the spark plug 1 of this example is configured such that a narrow gap 111 is formed in the minimum curvature radius portion 62 of the first region B, and a wide gap 112 is formed in the second region C. Others are the same as in the fifth embodiment.
- the electric field is easily concentrated on the first region B side including the minimum curvature radius portion 62 in the protrusion 6, and the minimum curvature radius portion 62 is easily set as the starting point of discharge. Therefore, it is easy to secure an ignition opportunity.
- the wear resistance on the second region C side can be further improved. As a result, the ignitability and life of the spark plug 1 can be effectively improved. In addition, it has the same effects as the fifth embodiment.
- a recess 64 is provided in the contour 61 of the protrusion 6 having the specific shape to increase the area difference between the first region B and the second region C. It is an example formed. Moreover, in this example, the straight part 65 orthogonal to the said 1st straight line L1 is formed in a part of the outline 61 of the 2nd area
- the spark plug 1 of this example is configured such that a narrow gap 111 is formed in the minimum curvature radius portion 62 of the first region B, and a wide gap 112 is formed in the second region C. In addition, it has the same effects as the fifth embodiment.
- the narrow gap 111 is formed in the minimum radius of curvature portion 62 of the first region B, and the wide gap 112 is formed in the second region C.
- the wide gap 112 may be formed in the minimum curvature radius portion 62 of the first region B, and the narrow gap 111 may be formed in the second region C.
- the operational effects shown in the sixth embodiment can be exhibited more.
- the spark plug 9 of this example is formed by providing protrusions 941 and 96 on both the front end portion of the center electrode 94 and the facing portion 952 of the ground electrode 95.
- Each of the protrusions 941 and 96 protrudes toward the spark discharge gap 911 and has a substantially cylindrical shape (see FIG. 1). Others are the same as in the first embodiment.
- the discharge spark E is first generated at any part of the corner portion 966 of the projection 96.
- the position is not particularly specified, and is not necessarily the upstream position in the airflow direction of the airflow F. Therefore, depending on the position where the initial discharge occurs, the time until the discharge spark E is caused to flow downstream by the air-fuel mixture and blown off tends to be shortened, and the opportunity for ignition is reduced. Then, as shown in FIG. 19B, the discharge spark E is caused to flow downstream of the protrusion 96 by the airflow F. Then, as shown in FIG.
- Example 1 In this example, as shown in FIG. 20, the wear resistance of the protrusion of the spark plug was examined by measuring the amount of expansion of the spark discharge gap (hereinafter referred to as “gap expansion amount” as appropriate).
- the spark plug 1 shown in the first example in which the opposing surface 60 of the protrusion 6 provided on the ground electrode 5 is inclined with respect to the surface orthogonal to the plug axis direction, is “sample 1”. Prepared as “Sample 2”. Further, the spark plug 9 shown in Comparative Example 1 in which the opposing surface 960 of the protrusion 96 provided on the ground electrode 95 was orthogonal to the plug axial direction was prepared as “Sample 3” and “Sample 4”. In the spark plugs of Sample 1 to Sample 4, the facing surfaces of the protrusions provided on the center electrode are orthogonal to the plug axis direction.
- the protrusion of the center electrode has a cylindrical shape with a diameter of 0.7 mm and a length in the plug axis direction of 0.6 mm.
- the protrusion of the ground electrode has a diameter of 0.7 mm, and the length in the plug axis direction is 0.5 mm at the shortest portion and 0.7 mm at the longest portion.
- the dimensions of the spark discharge gap are 0.7 mm for the narrow gap and 0.9 mm for the wide gap.
- the central electrode protrusion and the ground electrode protrusion have a diameter of 1.0 mm. Furthermore, the dimensions of the spark discharge gap are 0.5 mm in the narrow gap and 0.7 mm in the wide gap. Others are the same as those of Sample 1.
- the central electrode protrusion and the ground electrode protrusion have a cylindrical shape with a diameter of 0.7 mm and a length in the plug axis direction of 0.6 mm.
- the dimension of the spark discharge gap is 0.8 mm.
- the protrusion of the center electrode and the protrusion of the ground electrode have a cylindrical shape with a diameter of 1.0 mm and a length in the plug axis direction of 0.6 mm.
- the dimension of the spark discharge gap is 0.6 mm.
- the center electrode protrusion is formed of a noble metal tip made of an iridium alloy
- the ground electrode protrusion is formed of a noble metal tip made of a platinum alloy.
- Samples 1 and 3 and Samples 2 and 4 have the same volume of the protrusions and the same amount of material used. Sample 3 and sample 4 are set so that the initial required voltage is equivalent. Three spark plugs of Sample 1 to Sample 4 were prepared as samples. The following durability tests were conducted using these samples.
- the spark plug of each sample was attached to a test apparatus simulating a combustion chamber, the inside of the apparatus was set to a nitrogen atmosphere, and the pressure was set to 0.6 MPa. Further, an air-fuel mixture was fed into the apparatus so that an air flow having a flow rate of 30 m / sec was formed near the tip of the spark plug, and a voltage was applied to the spark plug at a discharge period of 30 Hz. The ignition energy at this time was 70 mJ.
- the spark plug was attached to the apparatus in such an attitude that the standing portion of the ground electrode (see reference numeral 51 in FIG. 3) was disposed at a position orthogonal to the direction of the airflow.
- the line graph connecting the diamond-shaped plots labeled D1 is the measurement result of the sample 1
- the line graph connecting the cross-plots labeled D2 is the measurement result of the sample 2.
- a line graph connecting rectangular plots denoted by reference sign D3 is the measurement result of the sample 3.
- a line graph obtained by connecting triangular plots denoted by reference sign D4 is the measurement result of the sample 4.
- the measured value is an average value of actually measured values for three samples in each sample.
- the vertical axis of the graph shown in the figure represents the gap (mm) in the spark discharge gap, and the horizontal axis represents the endurance time (time).
- the gap of each sample gradually increases as the durability time elapses.
- a gap is hard to become large with respect to sample 3 (D3). That is, in the sample 1, the spark discharge gap is rapidly expanded at the initial stage of the durability test because the narrow gap is enlarged rapidly, but the subsequent gap expansion is suppressed.
- size of the spark discharge gap of the sample 1 is a value smaller than the magnitude
- sample 2 (D2) similarly to sample 4 (D4) having the same volume and material usage, the spark discharge gap is unlikely to increase.
- the spark plug of the first example can suppress the expansion of the spark discharge gap more than the spark plug of the comparative example 1.
- Example 2 In this example, as shown in FIG. 21, the wear resistance of the projections of the spark plug was examined by measuring the discharge voltage. Generally, the discharge voltage increases as the spark discharge gap increases. Therefore, in this example, in the durability test, the spark discharge voltage was measured, and it was confirmed whether the discharge voltage of the spark plug of the first example was suppressed as compared with that of Comparative Example 1.
- Example 1 to sample 4 The conditions of the durability test method and the evaluation target (sample 1 to sample 4) in this example are the same as in Experimental Example 1 above. And about each sample, the discharge voltage of 1000 times of spark discharge was measured for every division
- the line graph connecting the diamond-shaped plots labeled D1 is the measurement result of the sample 1
- the line graph connecting the cross-plots labeled D2 is the measurement result of the sample 2.
- a line graph connecting rectangular plots denoted by reference sign D3 is the measurement result of the sample 3.
- a line graph obtained by connecting triangular plots denoted by reference sign D4 is the measurement result of the sample 4.
- the measured value is an average value of actually measured values for three samples in each sample.
- the vertical axis of the graph shown in the figure represents the discharge voltage (kV), and the horizontal axis represents the endurance time (time).
- the discharge voltage of each sample gradually increased with the passage of the endurance time. And about the sample 1 (D1), a discharge voltage does not become high easily with respect to the sample 3 (D3). That is, in Sample 1, the discharge voltage rises relatively quickly as the narrow gap increases in the initial stage of the durability test, but the subsequent increase in the discharge voltage is suppressed. And the discharge voltage of the spark discharge gap of the sample 1 is a value smaller than the discharge voltage of the sample 3 and rises at the same gentle rising speed. Thereby, finally, an increase in the discharge voltage of the sample 1 can be suppressed as compared with the sample 3 having the same volume and material usage. Similarly, the discharge voltage of sample 2 (D2) is unlikely to increase similarly to sample 4 (D4) having the same volume and material usage.
- the spark plug of the first example can suppress the increase of the discharge voltage more than the spark plug of Comparative Example 1.
- Example 3 In this example, as shown in FIG. 22, the ignitability of the spark plug was examined by measuring the value of the A / F limit. In this example, in the durability test, it was confirmed whether the ignitability of the spark plug of the first example was improved as compared with that of the comparative example by measuring the value of the A / F limit.
- Example 1 to sample 4 The conditions of the durability test method and the evaluation target (sample 1 to sample 4) in this example are the same as in Experimental Example 1 above. And about each sample, the value of the A / F limit was measured for every break of the endurance time of 100 hours. The A / F limit value was measured using an in-line four-cylinder engine. In this measurement, the A / F limit values of three samples in each sample are measured, and the averages of the three actually measured values are plotted in FIG.
- the line graph connecting the diamond-shaped plots labeled D1 is the measurement result of the sample 1
- the line graph connecting the cross-plots labeled D2 is the measurement result of the sample 2.
- a line graph connecting rectangular plots denoted by reference sign D3 is the measurement result of the sample 3.
- a line graph obtained by connecting triangular plots denoted by reference sign D4 is the measurement result of the sample 4.
- the vertical axis of the graph shown in the figure shows the value of the A / F limit, and the horizontal axis shows the endurance time (time).
- sample 1 has a higher A / F limit than sample 3 (D3). That is, the sample 1 is more excellent in ignitability than the sample 3 having an equivalent volume and material usage.
- sample 2 also has a higher A / F limit than sample 4 (D4), and sample 2 has better ignitability than sample 4 having the same volume and material usage.
- the spark plug of the first example is superior to the spark plug of Comparative Example 1 in terms of ignitability.
- the configuration in which the facing surface facing the spark discharge gap is inclined with respect to the plug axis direction is formed on the protruding portion of either the center electrode or the ground electrode. You may comprise, or you may comprise in the said projection part of both the said center electrode and the said ground electrode.
Abstract
Description
上記スパークプラグ9は、中心電極94と接地電極95とを有する。該接地電極95はその一端がハウジング92に固定されると共に屈曲して、他端を中心電極94に対向する位置に配置されることで、中心電極94との間に火花放電ギャップ911を形成している。
なお、特許文献2には、接地電極の磨耗を抑制すべく、接地電極の形状を工夫したスパークプラグが開示されている。
しかし、この場合、突起部96の上記対向面960が拡大するため、火炎成長時において対向面960が火炎Fから熱を奪い、火炎Fの成長を阻害してしまうおそれがある(以下、これを消炎作用という)。その結果、スパークプラグの着火性の低下を招くおそれがある。
内燃機関に対するスパークプラグの配置を上記のような配置とすれば、上記狭いギャップが上流側に配置される。上記狭いギャップの付近は最も電界集中させやすく、上記突起部における一端側が放電の起点となりやすい。その結果、放電電圧を抑制することもできる。そして、上記狭いギャップを形成する一端側を上流側に配置することにより、上記突起部の中でもその上流側において初期の放電火花を得ることができ、放電火花が混合気によって下流側まで流されて吹き消されるまでの時間を稼ぐことができる。そのため、火炎による着火機会を充分確保することができると共に、これによって、再放電発生回数を抑制して、突起部の消耗の促進も抑制しやすくすることができる。その結果、スパークプラグの耐消耗性及び着火性を向上させることができる。
なお、内燃機関用のスパークプラグは、例えば、自動車、自動二輪、コージェネレーション、ガス圧送用ポンプ等における内燃機関の着火手段として用いることができる。
このスパークプラグにおいて、内燃機関の燃焼室内に挿入される側を先端側、その反対側を基端側として説明する。
実施例にかかるスパークプラグにつき、図3~図7を用いて説明する。
本例のスパークプラグ1は、図3に示すごとく、筒状のハウジング2と、ハウジング2の内側に保持された筒状の絶縁碍子3と、先端部が突出するように絶縁碍子3の内側に保持された中心電極4と、ハウジング2に接続されると共に中心電極4にプラグ軸方向(スパークプラグ1の長手方向:図3参照)から対向する対向部52を有して中心電極4との間に火花放電ギャップ11を形成する接地電極5とを備えている。
また、図4に示すごとく、接地電極5に配された突起部6は、火花放電ギャップ11に対向する対向面60がプラグ軸方向に直交する面に対して傾斜している。
また、本例では、火花放電ギャップ11は、接地電極5の対向部52の延設方向(図6に示す破線L5)に対して直交する方向に沿って徐々に拡大するように構成されている。
また、突起部41は、プラグ軸方向に直交する断面形状が円形であり、全体を略円柱形状をなしている。また、突起部41のプラグ軸方向高さは0.6mmである。
また、突起部6は、一方の端面(対向面60)が軸方向に対して傾斜した略円柱形状を有する。
また、本例においては、中心電極4の先端部は、貴金属チップからなる略円柱状をなす突起部41によって構成されている。また、この貴金属チップは、例えば、イリジウム合金から構成することができる。
なお、本例のスパークプラグ1は、自動車等の車両用の内燃機関に用いられる。
スパークプラグ1の内燃機関7への取付に際して、例えば、周知技術(特開平11-324878号公報、特開平11-351115号公報等)を用いて、燃焼室70における混合気の気流Fの気流方向に対して接地電極5の位置を調節して、スパークプラグ1を内燃機関7へ取付ける。
中心電極4と接地電極5との間に所定の電圧を印加することにより、火花放電ギャップ11に放電させる際には、図7(A)に示すごとく、突起部6の上流側において初期の放電火花Eを得ることができる。つまり、電界強度が高くなりやすい狭いギャップ111において、初期の放電火花Eが生じる。そして、図7(B)に示すごとく、放電火花Eは、混合気の気流Fによって下流側まで、その放電距離を拡大しながら流される。そして、図7(C)に示すごとく、突起部6の下流側の角部66において放電火花Eが大きく引き伸ばされる。この間に放電火花Eによって混合気に着火する。
上記スパークプラグの突起部6は、図3、図4に示すごとく、火花放電ギャップ11に対向する対向面60がプラグ軸方向に直交する面に対して傾斜している。そして、火花放電ギャップ11が、プラグ軸方向に直交する一つの方向において、一端側に狭いギャップ111が形成され、かつ他端側に広いギャップ112が形成されるように、一端側から他端側に向かって徐々に拡大して構成されている。これによって、スパークプラグ1を内燃機関7の燃焼室70に取付ける際、突起部6の狭いギャップ111側が広いギャップ112側よりも燃焼室70における混合気の気流Fの上流側となるように配置すれば、スパークプラグ1の放電電圧の抑制、耐消耗性及び着火性の向上を図ることができる。
内燃機関7に対するスパークプラグ1の配置を上記のような配置とすれば、狭いギャップ111が上流側に配置される。狭いギャップ111の付近は、最も電界集中させやすく突起部6における一端側が放電の起点となりやすい。その結果、放電電圧を抑制することもできる。そして、狭いギャップ111を形成する一端側を上流側に配置することにより、突起部6の中でもその上流側において初期の放電火花Eを得ることができ、放電火花Eが混合気によって下流側まで流されて吹き消されるまでの時間を稼ぐことができる。そのため、火炎による着火機会を充分確保することができると共に、これによって、再放電発生回数を抑制して、突起部6の消耗の促進も抑制しやすくすることができる。その結果、スパークプラグ1の耐消耗性及び着火性を向上させることができる。
本例は、図8に示すごとく、中心電極4及び接地電極5の双方の突起部41、6の対向面410、60を傾斜させた例である。
本例では、中心電極4及び接地電極5の双方の突起部41、6における対向面410、60は、プラグ軸方向に直交する面に対して同一方向に、かつ狭いギャップ111側から広いギャップ112側へ行くほどスパークプラグ1の先端側へ向かうように傾斜している。
その他は、第1の実施例と同様である。
その他、第1の実施例と同様の作用効果を有する。
本例は、図9に示すごとく、スパークプラグ1の接地電極5に、火花放電ギャップ11の狭いギャップ111に面する角部66が貴金属によって構成され、その他の部位がニッケル合金によって構成された突起部6を配した例である。
その他は、第1の実施例と同様である。
その他、第1の実施例と同様の作用効果を有する。
本例は、図10に示すごとく、スパークプラグ1の接地電極5に、火花放電ギャップ11の広いギャップ112に面する角部66が貴金属によって構成され、その他の部位がニッケル合金によって構成された突起部6を配した例である。
その他は、第1の実施例と同様である。
その他、第1の実施例と同様の作用効果を有する。
本例は、図11~図15に示すごとく、スパークプラグ1の接地電極5及び中心電極4に、プラグ軸方向に直交する断面形状が図12に示す特定形状をなす突起部6、突起部41を配した例である。
突起部6は、図11、図12に示すごとく、プラグ軸方向に直交する断面形状が、その輪郭61のうち最も曲率半径の小さい最小曲率半径部62を有すると共に、以下の条件を満たす特定形状である。
そして、本例では、第2領域Cに広いギャップ112が形成され、第1領域Bの最小曲率半径部62において狭いギャップ111が形成されている。
お、突起部6は、第一直線L1と同一方向の全長W1が、対向部52の延設方向に直交する方向の幅W2よりも小さくなるように形成されている。
また、突起部6の第1領域Bにおける最小曲率半径部62の曲率半径Rは0.1であり、第2領域Cにおける最大幅部63の曲率半径Rは0.2である。また、接地電極5の対向部52の幅W2は2.4mmである。
突起部41も、プラグ軸方向に直交する断面形状が上記特定形状を満たす柱状体である。そして、突起部41は、プラグ軸方向の高さが一定に形成されている。
中心電極4と接地電極5との間に所定の電圧を印加することにより、火花放電ギャップ11に放電させる際には、図15(A)に示すごとく、突起部6の上流側において初期の放電火花Eを得ることができる。つまり、電界強度が高くなりやすい最小曲率半径部62(図12参照)において、初期の放電火花Eが生じる。
その他は、第1の実施例と同様である。
その他、第1の実施例と同様の作用効果を有する。
本例は、図16に示すごとく、スパークプラグ1の接地電極5に、プラグ軸方向に直交する断面形状が図12に示す特定形状をなす突起部6を配すると共に、突起部6の第2領域Cが第1領域Bよりも燃焼室70における混合気の気流Fの上流側となるように配置した例である。
そして、本例では、図16に示すごとく、第1領域Bの最小曲率半径部62において広いギャップ112が形成され、第2領域Cに狭いギャップ111が形成されている。
その他は、第5の実施例と同様である。
その他、第5の実施例と同様の作用効果を有する。
本例は、図17(A)、(B)に示すごとく、上記特定形状をなす突起部6を、第1領域Bと第2領域Cの面積差を大きくして形成した例である。
本例における突起部6は、プラグ軸方向に直交する断面形状の輪郭61が、上記断面形状における第1領域Bの最小曲率半径部62から第2領域Cの一部に亘る輪郭61の一部において、第1線分Mの中点P3側に向って窪んだ窪み部64を形成してなる。これによって、図17(A)に示すごとく、突起部6のプラグ軸方向に直交する断面形状が、第1領域Bの面積が第2領域Cの面積よりも特に小さく、その面積差が大きくなるように形成されている。
また、本例のスパークプラグ1は、第1領域Bの最小曲率半径部62において狭いギャップ111が形成され、第2領域Cに広いギャップ112が形成されるように構成される。
その他は、第5の実施例と同様である。
その他、第5の実施例と同様の作用効果を有する。
本例も、図18(A)、(B)に示すごとく、上記特定形状をなす突起部6の輪郭61に窪み部64を設けて第1領域Bと第2領域Cの面積差を大きくして形成した例である。
また、本例においては、突起部6の上記断面形状における第2領域Cの輪郭61の一部に、上記第一直線L1と直交するストレート部65を形成している。
その他は、第5の実施例と同様である。
その他、第5の実施例と同様の作用効果を有する。
本例は、図19に示すごとく、通常のスパークプラグ9の放電時の突起部96における放電火花Eの移動と突起部96の消耗との関係を示した例である。
その他は、第1の実施例と同様である。
本例は、図20に示すごとく、スパークプラグの突起部の耐消耗性について、火花放電ギャップの拡大量(以下、これを適宜、ギャップ拡大量という。)の測定によって調べた例である。
試料1~試料4のスパークプラグにおいて、中心電極に設けた突起部の対向面は、プラグ軸方向に対して直交している。
また、試料4において、中心電極の突起部および接地電極の突起部は、直径1.0mm、プラグ軸方向の長さが0.6mmの円柱形状である。また、火花放電ギャップの寸法は、0.6mmである。
また、試料1~試料4のスパークプラグは、それぞれ3個ずつサンプルとして用意した。
これらの試料を用いて以下の耐久試験を行った。
また、スパークプラグの先端部分付近に流速30m/秒の気流が形成されるように、装置内に混合気を送りこみ、放電周期30Hzにて、スパークプラグに電圧を印加した。このときの点火エネルギは70mJとした。
また、装置に対するスパークプラグの取付姿勢は、気流の方向に対して直交する位置に、接地電極の立設部(図3における符号51参照)が配置されるような姿勢とした。
同図に示すグラフの縦軸は、火花放電ギャップにおけるギャップ(mm)を示し、横軸は、耐久時間(時間)を示す。
また、試料2(D2)についても、同等の体積および材料使用量である試料4(D4)に対して、同様に火花放電ギャップが大きくなり難い。
本例は、図21に示すごとく、スパークプラグの突起部の耐消耗性を、放電電圧の測定によって調べた例である。
一般に、火花放電ギャップが拡大するに伴い放電電圧も増加する。そこで、本例では、耐久試験において、火花放電の電圧をそれぞれ計測し、第1の実施例のスパークプラグの放電電圧が、比較例1のそれに比べて抑制されているか確認を行った。
同図に示すグラフの縦軸は、放電電圧(kV)を示し、横軸は耐久時間(時間)を示す。
また、試料2(D2)についても、同等の体積および材料使用量である試料4(D4)に対して、同様に放電電圧が大きくなり難い。
本例は、図22に示すごとく、スパークプラグの着火性を、A/F限界の値の測定によって調べた例である。
本例では、耐久試験において、A/F限界の値をそれぞれ計測することにより、第1の実施例のスパークプラグの着火性が、比較例のそれに比べて向上しているか確認を行った。
同図に示すグラフの縦軸は、A/F限界の値を示し、横軸は耐久時間(時間)を示す。
同様に、試料2(D2)についても、試料4(D4)に対してA/F限界が高く、試料2は、同等の体積および材料使用量である試料4よりも着火性に優れている。
なお、前述した各種の実施例において、前記火花放電ギャップに対向する対向面がプラグ軸方向に直交するに対して傾斜した構成は、上記中心電極または上記接地電極のいずれか一方の上記突起部に構成してもよいし、或いは上記中心電極及び上記接地電極の双方の上記突起部に構成してもよい。
2 ハウジング
3 絶縁碍子
4 中心電極
41 突起部
410 対向面
5 接地電極
52 対向部
6 突起部
60 対向面
11 火花放電ギャップ
111 狭いギャップ
112 広いギャップ
Claims (9)
- 筒状のハウジングと、該ハウジングの内側に保持された筒状の絶縁碍子と、先端部が突出するように上記絶縁碍子の内側に保持された中心電極と、上記ハウジングに接続されると共に上記中心電極にプラグ軸方向から対向する対向部を有して上記中心電極との間に火花放電ギャップを形成する接地電極とを備えた内燃機関用のスパークプラグにおいて、
上記中心電極の上記先端部及び上記接地電極の上記対向部の双方は、上記火花放電ギャップに向かって突出した突起部を各々有し、
該突起部のうち少なくとも一方は、上記火花放電ギャップに対向する対向面がプラグ軸方向に直交する面に対して傾斜しており、
上記火花放電ギャップは、上記スパークプラグのプラグ軸方向に直交する一つの方向において、その方向における一端側の、他端側よりも小さいギャップ長の狭いギャップから上記他端側の、上記一端側よりも大きいギャップ長の広いギャップに向かって徐々に拡大するように構成されていることを特徴とする内燃機関用のスパークプラグ。 - 請求項1に記載の内燃機関用のスパークプラグにおいて、
上記中心電極及び上記接地電極の双方の上記突起部における上記対向面は、プラグ軸方向に直交する面に対して同一方向に、かつ狭いギャップ側から広いギャップ側へ行くほど上記スパークプラグの先端側へ向かうように傾斜していることを特徴とする内燃機関用のスパークプラグ。 - 請求項1又は2に記載の内燃機関用のスパークプラグにおいて、
上記火花放電ギャップは、上記接地電極の上記対向部の延設方向に対して交差する方向に沿って徐々に拡大するように構成されていることを特徴とする内燃機関用のスパークプラグ。 - 請求項1~3のいずれか一項に記載の内燃機関用のスパークプラグにおいて、
上記火花放電ギャップは、上記接地電極の上記対向部の延設方向に対して直交する方向に沿って徐々に拡大するように構成されていることを特徴とする内燃機関用のスパークプラグ。 - 請求項1~4のいずれか一項に記載の内燃機関用のスパークプラグにおいて、
上記突起部のうち少なくとも一方は、
i)上記プラグ軸方向に直交する断面形状が、その輪郭のうち最も曲率半径の小さい最小曲率半径部を有すると共に、
ii)上記断面形状における上記最小曲率半径部と幾何学的重心とを結ぶ第一直線を想定し、次いで、該第一直線が上記断面形状の輪郭と交差する2つの交点間を結ぶ第一線分を想定し、次いで、上記第一線分の中点において該第一線分と直交する第二直線を想定し、上記断面形状を上記第二直線によって、上記最小曲率半径部を含む第1領域と上記最小曲率半径部を含まない第2領域とに分割したとき、上記第2領域の面積が上記第1領域の面積よりも大きいという条件を満たす特定形状を有し、
上記第2領域において上記広いギャップが形成され、上記第1領域の上記最小曲率半径部において上記狭いギャップが形成されていることを特徴とする内燃機関用のスパークプラグ。 - 請求項1~4のいずれか一項に記載の内燃機関用のスパークプラグにおいて、
上記突起部のうち少なくとも一方は、
i)上記プラグ軸方向に直交する断面形状が、その輪郭のうち最も曲率半径の小さい最小曲率半径部を有すると共に、
ii)上記断面形状における上記最小曲率半径部と幾何学的重心とを結ぶ第一直線を想定し、次いで、該第一直線が上記断面形状の輪郭と交差する2つの交点間を結ぶ第一線分を想定し、次いで、上記第一線分の中点において該第一線分と直交する第二直線を想定し、上記断面形状を上記第二直線によって、上記最小曲率半径部を含む第1領域と上記最小曲率半径部を含まない第2領域とに分割したとき、上記第2領域の面積が上記第1領域の面積よりも大きいという特定を満たす特定形状を有し、
上記第1領域の上記最小曲率半径部において上記広いギャップが形成され、上記第2領域に上記狭いギャップが形成されていることを特徴とする内燃機関用のスパークプラグ。 - 請求項5又は6に記載の内燃機関用のスパークプラグにおいて、上記中心電極と上記接地電極との双方の上記突起部の上記断面形状が、上記特定形状であることを特徴とする内燃機関用のスパークプラグ。
- 請求項1~7のいずれか一項に記載の内燃機関用のスパークプラグにおいて、少なくとも一方の上記突起部は、貴金属チップから構成されていることを特徴とする内燃機関用のスパークプラグ。
- 請求項1~8のいずれか一項に記載の内燃機関用のスパークプラグを内燃機関に取り付けてなるスパークプラグの取付構造であって、
上記火花放電ギャップは、上記狭いギャップ側が上記広いギャップ側よりも、上記燃焼室に供給される混合気の気流の上流側となるように配置されていることを特徴とする内燃機関用のスパークプラグの取付構造。
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US14/355,708 US9343875B2 (en) | 2011-11-01 | 2012-10-31 | Spark plug for internal combustion engines and mounting structure for the spark plug |
CN201280053723.7A CN103907252B (zh) | 2011-11-01 | 2012-10-31 | 内燃机用的火花塞及其安装构造 |
DE112012004594.7T DE112012004594B4 (de) | 2011-11-01 | 2012-10-31 | Zündkerze für eine Brennkraftmaschine und Montagestruktur für die Zündkerze |
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JP2015124674A (ja) | 2013-12-26 | 2015-07-06 | トヨタ自動車株式会社 | 内燃機関 |
JP6206270B2 (ja) | 2014-03-17 | 2017-10-04 | トヨタ自動車株式会社 | 火花点火式内燃機関 |
JP6390636B2 (ja) * | 2016-02-16 | 2018-09-19 | 株式会社豊田中央研究所 | 内燃機関 |
JP6400049B2 (ja) * | 2016-06-30 | 2018-10-03 | 日本特殊陶業株式会社 | 点火プラグ |
JP6948904B2 (ja) | 2017-09-29 | 2021-10-13 | 株式会社Soken | 内燃機関用のスパークプラグ |
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- 2012-10-31 DE DE112012004594.7T patent/DE112012004594B4/de active Active
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US20140318490A1 (en) | 2014-10-30 |
US9343875B2 (en) | 2016-05-17 |
CN103907252B (zh) | 2016-11-09 |
JP5906670B2 (ja) | 2016-04-20 |
DE112012004594T5 (de) | 2014-08-21 |
CN103907252A (zh) | 2014-07-02 |
DE112012004594B4 (de) | 2023-03-23 |
JP2013098042A (ja) | 2013-05-20 |
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