WO2012042852A1 - スパークプラグ - Google Patents
スパークプラグ Download PDFInfo
- Publication number
- WO2012042852A1 WO2012042852A1 PCT/JP2011/005431 JP2011005431W WO2012042852A1 WO 2012042852 A1 WO2012042852 A1 WO 2012042852A1 JP 2011005431 W JP2011005431 W JP 2011005431W WO 2012042852 A1 WO2012042852 A1 WO 2012042852A1
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- WIPO (PCT)
- Prior art keywords
- diameter
- spark plug
- component
- shaft hole
- tip
- Prior art date
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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
- H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
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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
- H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
- H01T13/34—Sparking plugs characterised by features of the electrodes or insulation characterised by the mounting of electrodes in insulation, e.g. by embedding
Definitions
- the present invention relates to a spark plug used for ignition of an internal combustion engine, and more particularly to a spark plug having a resistor inside.
- a spark plug used for ignition of an internal combustion engine such as an automobile engine generally includes a cylindrical metal shell, a cylindrical insulator disposed in an inner hole of the metal shell, and a tip side of the insulator.
- An electrode Furthermore, a spark plug is also known in which a resistor is provided between the center electrode and the terminal fitting in the shaft hole for the purpose of preventing the occurrence of radio noise.
- claim 1 of Patent Document 1 includes: “... the diameter D of the conductive glass seal layer is in a range of 3.3 mm or less and the conductive glass seal layer.
- the spark plug is characterized in that the joint surface between the resistor and the resistor is formed into a curved surface.
- a spark plug having improved vibration resistance and resistance load life characteristics and having a reduced diameter can be provided by enhancing the adhesion between the resistor and the conductive glass seal layer” ( Paragraph number 0012 column).
- This invention is excellent in load life performance and adhesion strength of terminal fittings to insulators, and has a reduced spark plug occurrence rate due to insulator breakdown when the terminal fittings are press-fitted into the shaft holes of the insulators. It is an issue to provide.
- an insulator having an axial hole extending in the axial direction; A center electrode held on one end side of the shaft hole; A terminal fitting held at the other end of the shaft hole; A connecting portion for electrically connecting the center electrode and the terminal fitting in the shaft hole;
- the terminal fitting has a first component exposed from the shaft hole and a second component accommodated in the shaft hole,
- the shaft hole has a medium diameter part in which a tip part of the second component part is disposed,
- the diameter of the tip of the second component is the tip diameter (A)
- the inner diameter of the medium diameter part is the medium diameter part diameter (B)
- the length from the rear end of the center electrode to the rear end of the connection member constituting the connection portion is a filling length (D)
- the connection length (C) When the length from the rear end of the center electrode to the tip of the second component is the connection length (C),
- a preferred embodiment of (1) is as follows: (2) The second component portion has a minimum outer diameter portion having a smallest outer diameter at a portion other than the tip portion in the second component portion, and the diameter of the minimum outer diameter portion is set to a minimum outer diameter portion diameter ( E)
- the ratio (E / A) of the minimum outer diameter (E) and the tip diameter (A) is 0.85 or more and 1.16 or less
- the ratio (E / A) is 1.00 or more and 1.16 or less
- (5) The medium diameter portion diameter (B) is 2.9 mm or less
- the distance ((BA) / 2), the shrinkage (DC), and the Vickers hardness of the second component at room temperature are within a predetermined range. It is possible to provide a spark plug that is excellent in performance and adhesion of the terminal fitting to the insulator, and has a reduced defective product rate due to the breakdown of the insulator when the terminal fitting is press-fitted into the shaft hole of the insulator. .
- the spark plug of the present invention is further excellent in load life performance because the ratio (E / A) is within a predetermined range.
- the distance ((BA) / 2) is X
- the ratio (E / A) is Y
- the axial length of the fixing portion is within a predetermined range, it is further excellent in fixing strength of the terminal fitting to the insulator.
- the medium diameter part diameter (B) of the spark plug of the present invention is 2.9 mm or less, the effect is further enhanced for improving the load life performance and the fixing force of the terminal fitting to the insulator.
- FIG. 1 is an entire cross-sectional explanatory view of a spark plug as an embodiment of the spark plug according to the present invention.
- 2 (a) and 2 (b) are cross-sectional explanatory views of a terminal fitting which is an embodiment of a spark plug terminal fitting according to the present invention.
- FIG. 3 is a cross-sectional explanatory view of a main part of a spark plug which is an embodiment of the spark plug according to the present invention.
- FIG. 4 is a diagram showing the relationship between the distance ((BA) / 2) and the ratio (E / A).
- FIG. 1 shows a spark plug as an embodiment of the spark plug according to the present invention.
- FIG. 1 is an entire cross-sectional explanatory view of a spark plug 1 which is an embodiment of a spark plug according to the present invention.
- the axis of the insulator is O
- the lower side of the paper is the tip direction of the axis O
- the upper side of the paper is the rear end direction of the axis O.
- the spark plug 1 includes an insulator 3 having a shaft hole 2 extending in the direction of the axis O, a center electrode 4 held on the front end side of the shaft hole 2, and a terminal held on the rear end side of the shaft hole 2.
- a ground electrode 8 which is bonded to the surface and is disposed so that the other end faces the central electrode 4 with a gap.
- the metal shell 7 has a substantially cylindrical shape and is formed so as to accommodate and hold the insulator 3.
- a threaded portion 9 is formed on the outer peripheral surface in the front end direction of the metal shell 7, and the spark plug 1 is attached to a cylinder head of an internal combustion engine (not shown) using the threaded portion 9.
- the metal shell 7 can be formed of a conductive steel material, for example, low carbon steel.
- the threaded portion 9 is preferably M12 or less in order to reduce the diameter.
- the insulator 3 is held on the inner periphery of the metal shell 7 via a talc 10 or a packing 11.
- the shaft hole 2 of the insulator 3 accommodates the small-diameter portion 12 that holds the center electrode 4 on the distal end side of the axis O and the connection portion 6, and has an inner diameter larger than the inner diameter of the small-diameter portion 12 via the first step portion 13.
- a medium diameter portion 14 adjacent to the small diameter portion 12 and a large diameter portion 16 having an inner diameter larger than the inner diameter of the medium diameter portion 14 and adjacent to the medium diameter portion 14 via the second step portion 15.
- the insulator 3 is fixed to the metal shell 7 with the end of the insulator 3 in the distal direction protruding from the tip surface of the metal shell 7.
- the insulator 3 is desirably a material having mechanical strength, thermal strength, electrical strength, and the like. Examples of such a material include a ceramic sintered body mainly composed of alumina.
- the center electrode 4 is accommodated in the small diameter portion 12 of the shaft hole 2, and a large diameter flange portion 17 provided at the rear end of the center electrode 4 is engaged with the first step portion 13 of the shaft hole 2, and the tip is It is insulated and held with respect to the metal shell 7 in a state of protruding from the tip surface of the insulator 3.
- the center electrode 4 is desirably formed of a material having thermal conductivity, mechanical strength, and the like.
- the center electrode 4 is formed of a Ni-based alloy such as Inconel (trade name).
- the axial center portion of the center electrode 4 may be formed of a metal material having excellent thermal conductivity such as Cu or Ag.
- the ground electrode 8 is formed in, for example, a substantially prismatic body, one end is joined to the front end surface of the metal shell 7, and is bent into a substantially L shape in the middle, and the front end is connected to the front end of the center electrode 4. Its shape and structure are designed to face each other with a gap.
- the ground electrode 8 is formed of the same material as that for forming the center electrode 4.
- Precious metal tips 29 and 30 formed of platinum alloy, iridium alloy, or the like may be provided on the surface where the center electrode 4 and the ground electrode 8 face each other. A precious metal tip may be provided on only one of them.
- noble metal tips 29 and 30 are provided on both the center electrode 4 and the ground electrode 8, and a spark discharge gap g is formed between the noble metal tips 29 and 30. .
- the terminal fitting 5 is a terminal for applying a voltage for performing a spark discharge between the center electrode 4 and the ground electrode 8 to the center electrode 4 from the outside.
- the terminal metal fitting 5 has an outer diameter larger than the inner diameter of the shaft hole 2, is exposed from the shaft hole 2, and a first component 18 that a part thereof abuts on the rear end side end surface of the insulator 3 in the axis O direction;
- the first component 18 has a second component 19 that extends from the end surface on the tip end side in the axis O direction in the tip direction and is accommodated in the shaft hole 2.
- the terminal fitting 5 is made of, for example, low carbon steel or the like, and a Ni metal layer is formed on the surface thereof by plating or the like.
- the second component 19 in this aspect is located on the rear end side of the axis O from the front end 20 and the front end 20 that is a portion from the front end in the direction of the axis O to the rear end of the axis O about 1 mm. It has one component 18 and an adjacent barrel 22. As will be described later, the second component portion 19 has a fixing portion 25 having an uneven surface on the tip side in the direction of the axis O, and the outermost diameter of the body portion 22 on the rear end side of the fixing portion 25. The outer diameter minimum portion 21 is smaller, and the outer diameter larger portion 36 having a larger outer diameter than the outer diameter minimum portion 21 is located on the rear end side.
- the distal end portion 20 is accommodated in the medium diameter portion 14, and the outer diameter large portion 36 is accommodated in the large diameter portion 16.
- a second step portion 24 is formed between the one step portion 23, the minimum outer diameter portion 21, and the large outer diameter portion 36.
- the 2nd structure part 19 in the spark plug 1 of this aspect is a multistage cylindrical body which has three types of different outer diameters
- the cylindrical shape with which an outer diameter does not change may be sufficient, and two types of The shapes may have different outer diameters, or may have shapes having more than three different outer diameters.
- the second components 19a and 19b are composed of a plurality of columnar portions having different outer diameters from the first metal fittings 31a and 31b to the fifth metal fittings 35a and 35b in order from the tip side. May be.
- the outer diameter decreases from the front end side, the outer diameter of the third metal fitting 33a is the smallest, and the outer diameter increases toward the rear end.
- the outer diameter may increase in order from the front end side, the outer diameter of the third metal fitting may be the largest, and the outer diameter may further decrease toward the rear end ( Not shown).
- the shape where an outer diameter becomes large toward a rear end side in order from a front end side may be sufficient, and conversely to this, it is on a rear end side in order from a front end side.
- the shape may be such that the outer diameter becomes smaller (not shown).
- the fixed portion 25 in this aspect is knurled on the outer peripheral surface near the tip of the second component portion 19.
- the surface near the tip of the second component 19 has an uneven structure formed by, for example, knurling, so that the adhesion between the terminal fitting 5 and the connection portion 6 is improved.
- the body 3 is firmly fixed. Therefore, it is preferable that the second component 19 has the fixing portion 25 in the vicinity of the tip that contacts the connection portion 6 of the second component 19.
- the connecting portion 6 is disposed between the center electrode 4 and the terminal fitting 5 in the shaft hole 2 and electrically connects the center electrode 4 and the terminal fitting 5.
- the connection unit 6 includes a resistor 26, and the resistor 26 prevents generation of radio noise.
- the connecting portion 6 has a first seal layer 27 between the resistor 26 and the center electrode 4, and a second seal layer 28 between the resistor 26 and the terminal fitting 5. 27 and the second seal layer 28 seal and fix the insulator 3, the center electrode 4, and the terminal fitting 5.
- the resistor 26 is made of glass powder such as borosilicate soda glass, ceramic powder such as ZrO 2 , non-metallic conductive powder such as carbon black, and / or metal powder such as Zn, Sb, Sn, Ag, Ni, etc. It can be comprised by the resistance material formed by sintering the resistor composition to contain.
- the resistance value of the resistor 5 is usually 100 ⁇ or more.
- the first seal layer 27 and the second seal layer 28 can be configured by a seal material formed by sintering a glass powder such as sodium borosilicate glass and a metal powder such as Cu and Fe. .
- the resistance values of the first seal layer 27 and the second seal layer 28 are usually several hundred m ⁇ or less.
- the connecting portion 6 may be formed of only the resistor 26 without the first seal layer 27 and the second seal layer 28, and one of the first seal layer 27 or the second seal layer 28 and the resistor. 26 may be formed.
- connection member the resistor material and / or the seal material constituting the connection portion 6
- resistor composition and / or the seal powder forming the connection portion 6 may be collectively referred to as a connection powder.
- the spark plug according to the present invention has a tip portion 20 of the second component 19 having a tip diameter (A), an inner diameter of the middle portion 14 being a medium diameter (B), and a center electrode. 4 is the filling length (D), and the length from the rear end of the center electrode 4 to the tip of the second component 19 is the connection length (C). ),
- the following conditions (1) to (3) are satisfied.
- (1) The distance ((BA) / 2) between the distal end portion 20 and the medium diameter portion 14 of the second component portion 19 is 0.02 mm or more and 0.2 mm or less, preferably 0.19 mm or less. is there.
- Shrinkage (DC) is 6 mm or more and 27 mm or less.
- the Vickers hardness of the second component 19 at room temperature is 100 Hv or more and 430 Hv or less, preferably 150 Hv or more and 350 Hv or less.
- the second component 19 is bent and bent in a direction perpendicular to the axis O. Can be suppressed. If the terminal fitting 5 is not bent and bent more than necessary when pressing the terminal fitting 5 into the shaft hole 2, which will be described later, the pressure is applied to the resistor composition forming the connection portion 6. Since it can transmit effectively, the high-density resistor 26 can be formed, and as a result, a spark plug excellent in load life performance can be provided.
- the fixing force of the terminal fitting 5 to the insulator 3 decreases.
- the contraction amount (DC) of (2) is within the above range, the connection member and the inner peripheral surface of the insulator 3 and the vicinity of the connection member and the tip of the second component 19 are fixed, for example. Since the contact area of the outer peripheral surface of the part 25 is sufficiently obtained, the fixing force of the terminal fitting 5 to the insulator 3 becomes good. As a result, it is possible to suppress the terminal fitting 5 from rattling in the shaft hole 2 even when the spark plug is continuously vibrated.
- the distance ((BA) / 2) is smaller than 0.02 mm, it may be difficult to insert the terminal fitting 5 into the shaft hole 2, and the terminal fixing force may be reduced.
- the distance ((BA) / 2) is greater than 0.2 mm, particularly greater than 0.19 mm, the pressure applied to the resistor composition when the terminal fitting 5 is press-fitted into the shaft hole 2 of the insulator 3. Cannot be sufficiently transmitted, and the high-density resistor 26 may not be obtained.
- the shrinkage (DC) is less than 6 mm, the terminal fixing force may be insufficient. Further, when the terminal fitting 5 is press-fitted into the shaft hole 2 of the insulator 3, the pressure cannot be sufficiently transmitted to the resistor composition, and the high-density resistor 26 cannot be obtained, and the load life performance There is a risk of a spark plug inferior to. If the shrinkage (DC) is larger than 27 mm, a high pressure is transmitted to the resistor composition when the terminal fitting 5 is press-fitted into the shaft hole 2 of the insulator 3, so that the medium diameter portion 14 and the small diameter are reduced. The vicinity of the boundary with the portion 12 is easily broken, and the defective product occurrence rate is increased.
- the Vickers hardness is less than 100 Hv, when the terminal fitting 5 is press-fitted into the shaft hole 2 of the insulator 3, the pressure cannot be sufficiently transmitted to the resistor composition, and the high-density resistor 26. May not be obtained.
- the Vickers hardness is larger than 430 Hv, a high pressure is transmitted to the resistor composition when the terminal fitting 5 is press-fitted into the shaft hole 2 of the insulator 3, so that the medium diameter portion 14 and the small diameter portion 12 The vicinity of the boundary is easily broken, and the defective product occurrence rate is increased.
- the spark plug of the present invention further satisfies the following condition (4) when the diameter of the smallest outer diameter portion 21 having the smallest outer diameter in the second component portion 19 is defined as the smallest outer diameter portion diameter (E). It is good.
- the ratio (E / A) between the minimum outer diameter (E) and the tip diameter (A) is 0.85 or more and 1.16 or less, preferably 1.00 or more and 1.16 or less. It is.
- the minimum outer diameter portion 21 is a portion having the smallest outer diameter in the body portion 22 and a length in the axis O direction of 1 mm or more.
- the smallest outer diameter portion is the third fitting 33a
- the smallest outer diameter portion is the first fitting 31b. is there.
- the ratio (E / A) of (4) is within the above range, the bending and bending of the second component 19 in the direction perpendicular to the axis O can be further suppressed, and the load life performance can be further improved. Excellent. Further, when the outer diameter minimum part diameter (E) is larger than the tip part diameter (A), that is, the ratio (E / A) is larger than 1, the strength of the second component part 19 is increased, curving and bending are suppressed, Furthermore, it is possible to reduce the breakage of the insulator 3 when the insulator 3 is inserted into the shaft hole 2. When the terminal fitting 5 has an outer diameter having a proper gap with the shaft hole 2, the terminal fitting 5 is not cracked when the terminal fitting 5 is press-fitted into the shaft hole 2 of the insulator 3. Can be inserted into the shaft hole 2.
- the distance ((BA) / 2) is X
- the ratio (E / A) is Y
- FIG. 4 shows a straight line corresponding to an equation in which the equal signs of the equations (i) to (iv) are established with the distance ((BA) / 2) as the X axis and the ratio (E / A) as the Y axis.
- FIG. 4 When the expressions (i) to (iv) are satisfied, X and Y in FIG. 4 are in a region surrounded by the straight lines (1) to (5).
- the strength of the second component portion 19 increases and curving and bending can be suppressed.
- the bending and bending of the second component 19 are suppressed, but as Y increases beyond 1.0, the barrel 22 becomes thicker than the distal end 20, and the distal end 20 and the shaft Even if X indicating the gap with the hole 2 can be maintained within a predetermined range, the insulator 22 may be broken when the terminal fitting 5 is inserted into the shaft hole 2 because the body portion 22 is thick. . Therefore, the formula (iv) Y ⁇ 1.06X + 0.96 is satisfied, that is, Y in FIG. 4 is preferably in a region smaller than the straight line (5).
- the spark plug according to the present invention preferably further satisfies the following condition (5) when the length in the axis O direction of the fixing portion 25 is the fixing portion length (F).
- the fixing portion length (F) is 3 mm or more and 25 mm or less.
- the spark plug of the present invention is more effective for improving the load life performance and the terminal fixing force when the medium diameter portion (B) is 2.9 mm or less.
- the dimensions (A) to (F) can be obtained by photographing the spark plug with a X-ray transmission device from a direction orthogonal to the axis O and measuring the corresponding part.
- the tip end diameter (A) is measured by measuring the distance in the direction perpendicular to the axis O at a portion of 1 mm from the tip of the second component 19 toward the rear end of the axis O.
- the medium diameter part diameter (B) measures the distance in the direction perpendicular to the axis O of the medium diameter part 14 in the above-mentioned part.
- the connection length (C) is a length in the direction of the axis O from the rear end of the center electrode 4 to the tip of the second component 19.
- the filling length (D) measures the length in the axis O direction from the rear end of the center electrode 4 to the rear end of the connecting member.
- the minimum outer diameter part diameter (E) measures the distance in the direction perpendicular to the axis O at the part having the smallest outer diameter in the second component part 19 and the length in the axis O direction of 1 mm or more.
- the fixing portion length (F) is a length of the concavo-convex portion provided on the surface of the second component 19 in the direction of the axis O.
- the sealing material adhering to the inner peripheral surface of the shaft hole 2 is recognized on the rear end side of the second seal layer 28.
- a portion of the sealing material located closest to the rear end side in the direction of the axis O is the rear end of the sealing material.
- the seal powder filled in the shaft hole 2 before the press step described later is applied with a load and heat, and is compressed to become a seal material constituting the second seal layer 28.
- a part of the sealing powder remains as a sealing material while adhering to the inner peripheral surface of the shaft hole 2. Therefore, it is estimated that the position of the sealing material at the rearmost end of the axis O is the same as the position of the rear end of the sealing powder filled in the shaft hole 2 before the pressing step. Therefore, the difference (D ⁇ C) between the filling length (D) and the connecting portion length (C) indicates the contraction length in the axis O direction of the connecting portion 6 before and after the pressing process.
- the connecting portion 6 includes a first seal layer 27, a resistor 26, and a second seal layer 28, and the first seal layer 27, resistor 26, Although the seal layer 28 is disposed in this order, the first seal layer 27 and the second seal layer 28 are not provided, and the connection portion 6 is formed only by the resistor 26, the resistor 26 and the first seal layer 27.
- the connection part 6 may be formed with the resistor 26 and the second seal layer 28. Therefore, in this embodiment, the component that remains attached to the inner peripheral surface of the shaft hole 2 is the sealing material that constitutes the second seal layer 28.
- the connecting portion 6 is formed by the resistor 27 and the resistor 26
- a resistor material constituting the resistor 26 is recognized as a component that remains attached to the inner peripheral surface of the shaft hole 2.
- the length in the axis O direction from the rear end of the center electrode 4 to the position of the resistance material located closest to the rear end side in the axis O direction is the filling length (D).
- the Vickers hardness of the second component 19 at normal temperature is obtained by polishing a cross section obtained by cutting a surface perpendicular to the axis O at a position 2 mm from the tip of the second component 19.
- the five points can be obtained by measuring the hardness in accordance with JISZ2244 and calculating the average value thereof.
- the Vickers hardness of the second component 19 at room temperature can be adjusted by selecting the material of the terminal fitting, changing the carbon content, or changing the heat treatment conditions.
- the spark plug 1 is manufactured, for example, as follows. First, the center electrode 4, the ground electrode 8, the metal shell 7, the terminal metal fitting 5, and the insulator 3 are prepared in a predetermined shape by a known method (preparation process), and grounded to the front end surface of the metal shell 7 by laser welding or the like. One end of the electrode 8 is joined (ground electrode joining step).
- center electrode 4 is inserted into the shaft hole 2 of the insulator 3, the flange portion 17 of the center electrode 4 is locked to the first step portion 13 of the shaft hole 2, and the center electrode 4 is disposed in the small diameter portion 12. (Center electrode placement step).
- the seal powder forming the first seal layer 27, the resistor composition forming the resistor 26, and the seal powder forming the second seal layer 28 are put in this order from the rear end side in the shaft hole 2. Then, a press pin is inserted into the shaft hole 2 and pre-compressed with a pressure of 60 N / mm 2 or more, and the medium diameter portion 14 is filled with the seal powder and the resistor composition (filling step).
- the distal end portion 20 of the terminal fitting 5 is inserted from the rear end side in the shaft hole 2, and the terminal fitting 5 is disposed so that the distal end portion 20 contacts the sealing powder (arrangement step).
- connection powder is heated at a temperature equal to or higher than the glass softening point of the glass powder contained in the seal powder, for example, at a temperature of 800 to 1000 ° C. for 3 to 30 minutes
- the tip surface of the first component 18 of the terminal fitting 5 is It press-fits until it contacts the rear end surface of the insulator 3 and compresses and heats the sealing powder and the resistor composition (pressing process).
- the seal powder and the resistor composition are sintered to form the resistor 26, the first seal layer, and the second seal layer.
- the spark plug satisfying the above conditions (1) to (3) effectively transmits the pressure from the terminal fitting 5 to the resistor composition, so that a high-density resistor 26 can be obtained. it can.
- the gap between the flange portion 17 and the shaft hole 2 and the gap between the tip portion 20 and the shaft hole 2 are filled with a sealing material, and the center electrode 4 and the terminal fitting 5 are sealed and fixed in the shaft hole 2. .
- the spark plug 1 that satisfies the condition (2) is appropriately filled with the sealing material in the gap between the distal end portion 20 and the shaft hole 2, the terminal metal 5 has excellent adhesion to the insulator 3. .
- the insulator 3 to which the center electrode 4 and the terminal fitting 5 are fixed is assembled to the metal shell 7 to which the ground electrode 8 is joined (assembly process).
- spark plug 1 is manufactured such that the tip of the ground electrode 8 is bent toward the center electrode 4 so that one end of the ground electrode 8 faces the tip of the center electrode 4.
- the spark plug according to the present invention is used as an ignition plug for an internal combustion engine for automobiles such as a gasoline engine, and the screw portion 10 is formed in a screw hole provided in a head (not shown) that defines a combustion chamber of the internal combustion engine. Are screwed together and fixed in place.
- the spark plug according to the present invention can be used for any internal combustion engine, it is particularly effective for a spark plug with a reduced diameter, and is therefore preferably used for an internal combustion engine that requires space saving of the spark plug. Can be done.
- the spark plug 1 has a fixing portion 25 that is knurled in the vicinity of the tip of the terminal fitting 5, and the surface of the fixing portion has a shape that provides good adhesion to the sealing material, such as unevenness. If it is a shape, it will not specifically limit, The shape formed by threading etc. may be sufficient. Moreover, the whole outer peripheral surface of the adhering portion 25 may be uneven, or a part of the surface may be uneven.
- the spark plug according to the present invention satisfies the requirements (1) to (3), particularly (1) to (5), irrespective of the axial length and diameter of the first component, and thereby provides load life performance and It is possible to provide a spark plug that is excellent in fixing strength of the terminal fitting to the insulator and that has a reduced defective product rate due to breakdown of the insulator when the terminal fitting is pressed into the shaft hole of the insulator.
- the spark plug shown in FIG. 1 was produced according to the manufacturing process described above.
- the tip diameter (A), the minimum outer diameter (E), the fixed length (F), the medium diameter (B), the connection length (C), and the filling length (D) are changed and shown in Table 1. Spark plugs of various dimensions were made. The various dimensions were measured using an X-ray transmission device.
- the terminal metal fitting was manufactured with the low carbon steel, and the Vickers hardness was changed by adjusting the component. As described above, the Vickers hardness of the second component at room temperature was measured according to JISZ2244.
- Terminal adhesion test The first component part of the metal terminal was sandwiched with a jig, the jig was pulled with an autograph, and the strength when the metal terminal was pulled out of the insulator was measured.
- the terminal fixing force was evaluated according to the following criteria. The evaluation results are shown in Table 2. 1: Less than 2500N 5: 2500N or more and less than 3500N 10: 3500N or more, or the terminal fitting is broken
- Table 2 The comprehensive judgment in Table 2 was performed according to the following criteria. ⁇ : When there is an evaluation of less than 5 points among the above 3 evaluation items ⁇ : When there are 5 evaluation results among the above 3 evaluation items, and others are 5 points or more ⁇ : Above 3 evaluations When all of the items are higher than 5 points and all are not 10 points ⁇ : When the results of the above three evaluation items are all 10 points
- the spark plug included in the scope of the present invention was excellent in load life performance and terminal fixing force, and had a low incidence of defective products due to breakdown of the insulator. On the other hand, at least one of the above spark plugs outside the scope of the present invention was inferior.
- Test No. with a distance ((BA) / 2) smaller than 0.02 mm The spark plug No. 1 was inferior in terminal fixing force as compared with the spark plug included in the scope of the present invention. In addition, the test No. in which the distance ((BA) / 2) is larger than 0.2 mm.
- the spark plugs 6, 30, and 32 were inferior in load life performance compared to the spark plugs included in the scope of the present invention.
- the 27 spark plugs were inferior in both the load life performance and the terminal fixing force as compared with the spark plugs included in the scope of the present invention. Test No. with shrinkage (DC) larger than 27 mm.
- the 29 spark plugs had a high rate of defective products due to the breakdown of the insulator.
- the 16 spark plugs had a higher incidence of defective products due to the breakdown of the insulator than the spark plugs included in the scope of the present invention.
- the spark plug No. 21 had a higher incidence of defective products due to the breakdown of the insulator than the spark plug included in the scope of the present invention.
- FIG. 4 shows the relationship between ((BA) / 2) and the ratio (E / A).
- the evaluation results of the load life performance shown in Table 2 are classified according to the following criteria, and are displayed with different types of symbols. ⁇ : When load life performance is 10 points ⁇ : When load life performance is 8 points *: When load life performance is 7 points ⁇ : When load life performance is 6 points ⁇ : When load life performance is 5 points
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Abstract
Description
(1) 軸線方向に延びる軸孔を有する絶縁体と、
前記軸孔の一端側で保持される中心電極と、
前記軸孔の他端側で保持される端子金具と、
前記軸孔内で前記中心電極と前記端子金具とを電気的に接続する接続部と、
を備えたスパークプラグにおいて、
前記端子金具は、前記軸孔から露出する第一構成部と前記軸孔に収容される第二構成部とを有し、
前記端子金具における前記第一構成部側を前記軸線方向の後端側としたとき、
前記軸孔は、前記第二構成部の先端部が配置される中径部を有し、
前記第二構成部の先端部の直径を先端部径(A)、
前記中径部の内径を中径部径(B)、
前記中心電極の後端から前記接続部を構成する接続部材の後端までの長さを充填長(D)、
前記中心電極の後端から前記第二構成部の先端までの長さを接続部長(C)とすると、
前記第二構成部の先端部と前記中径部との間の距離((B-A)/2)が0.02mm以上0.2mm以下であり、
収縮量(D-C)が6mm以上27mm以下であり、かつ、
前記第二構成部の常温におけるビッカース硬さが100Hv以上430Hv以下
であることを特徴とするスパークプラグであり、
(2) 前記第二構成部は、前記第二構成部における前記先端部以外の部位で最も外径の小さい外径最小部を有し、前記外径最小部の直径を外径最小部径(E)とすると、
前記外径最小部径(E)と前記先端部径(A)との比(E/A)が0.85以上1.16以下であり、
(3) 前記中径部径(B)が3.2mm以下であり、前記距離((B-A)/2)をX、前記比(E/A)をYとしたときに、次の式(i)~(iv)を満たし、
(i) X≦0.19
(ii)Y≧X+0.8、
(iii)Y≧0.85、
(iv)Y≦1.06X+0.96
(4) 前記比(E/A)が1.00以上1.16以下であり、
(5) 前記中径部径(B)が2.9mm以下であり、
(6) 前記第二構成部の常温におけるビッカース硬さが150Hv以上350Hv以下であり、
(7) 前記第二構成部は凹凸状の表面を備える固着部を有し、前記固着部の前記軸線方向長さが3mm以上25mm以下であることを特徴とする。
(1)第二構成部19の先端部20と中径部14との間の距離((B-A)/2)が0.02mm以上0.2mm以下であり、好ましくは0.19mm以下である。
(2)収縮量(D-C)が6mm以上27mm以下である。
(3)第二構成部19の常温におけるビッカース硬さが100Hv以上430Hv以下であり、好ましくは150Hv以上350Hv以下である。
(4)前記外径最小部径(E)と前記先端部径(A)との比(E/A)が0.85以上1.16以下であり、好ましくは1.00以上1.16以下である。
(i) 0.02≦X≦0.19
(ii)Y≧X+0.8
(iii)Y≧0.85
(iv)Y≦1.06X+0.96
(5)固着部長(F)が3mm以上25mm以下である。
まず、公知の方法により所定の形状に中心電極4、接地電極8、主体金具7、端子金具5及び絶縁体3を作製し(準備工程)、主体金具7の先端面に、レーザ溶接等により接地電極8の一端部を接合する(接地電極接合工程)。
図1に示すスパークプラグを、前述した製造工程にしたがって作製した。先端部径(A)、外径最小部径(E)、固着部長(F)、中径部径(B)、接続部長(C)及び充填長(D)を変化させて、表1に示す種々の寸法のスパークプラグを作製した。
前記各種寸法は、X線透過装置を用いて測定した。
なお、端子金具は低炭素鋼により製造され、その成分を調整することによりビッカース硬さを変化させた。第二構成部の常温におけるビッカース硬さは、前述したように、JISZ2244に準拠して測定した。
(負荷寿命性能試験)
製造したスパークプラグを350℃の環境下に置き、20kVの放電電圧を印加して、1分間に3600回放電させ、この試験前後のスパークプラグの抵抗体の抵抗値(R0、R1)を測定した。上記試験を10回行い、初期抵抗値R0に対する試験後の抵抗値R1の平均値(R1/R0)が1.5倍以上になった時間を測定し、この時間が長いほど負荷寿命性能が良好であるとして、次の基準にしたがって評価した。評価結果を表2に示す。
1:150時間未満
2:150時間以上200時間未満
3~9:200時間以上のときは、50時間毎に1点加算
10:550時間以上
金属端子の第一構成部を治具にて挟み、この治具をオートグラフで引張り、金属端子が絶縁体から引き抜けたときの強さを測定した。端子固着力は次の基準にしたがって評価した。評価結果を表2に示す。
1:2500N未満
5:2500N以上3500N未満
10:3500N以上、又は端子金具が破壊
スパークプラグを20本作製したときに、製造工程中に絶縁体が破壊することにより不良品と判定された個数の割合を次の基準にしたがって評価した。評価結果を表2に示す。
1:30%以上
5:5%以上30%未満
10:5%未満
×:上記3つの評価項目の中で5点未満の評価がある場合
○:上記3つの評価項目の中で5点の評価結果があり、その他は5点以上である場合
◎:上記3つの評価項目の中で全てが5点よりも高く全てが10点ではないとき
◎◎:上記3つの評価項目の結果が全て10点であるとき
○:負荷寿命性能が10点のとき
◇:負荷寿命性能が8点のとき
*:負荷寿命性能が7点のとき
▲:負荷寿命性能が6点のとき
■:負荷寿命性能が5点のとき
X≧0.02・・・(1)
X≦0.19・・・(2)
Y≧X+0.8・・・(3)
Y≧0.85・・・(4)
Y≦1.06X+0.96・・・(5)
2 軸孔
3 絶縁体
4 中心電極
5 端子金具
6 接続部
7 主体金具
8 接地電極
9 ネジ部
10 タルク
11 パッキン
12 小径部
13 第一段部
14 中径部
15 第二段部
16 大径部
17 フランジ部
18 第一構成部
19 第二構成部
20 先端部
21 外径最小部
22 胴部
23 第一段差部
24 第二段差部
25 固着部
26 抵抗体
27 第一シール層
28 第二シール層
29,30 貴金属チップ
31a~35a、31b~35b 第一金具、第二金具、第三金具、第四金具、第五金具
36 外径大部
Claims (7)
- 軸線方向に延びる軸孔を有する絶縁体と、
前記軸孔の一端側で保持される中心電極と、
前記軸孔の他端側で保持される端子金具と、
前記軸孔内で前記中心電極と前記端子金具とを電気的に接続する接続部と、
を備えたスパークプラグにおいて、
前記端子金具は、前記軸孔から露出する第一構成部と前記軸孔に収容される第二構成部とを有し、
前記端子金具における前記第一構成部側を前記軸線方向の後端側としたとき、
前記軸孔は、前記第二構成部の先端部が配置される中径部を有し、
前記第二構成部の先端部の直径を先端部径(A)、
前記中径部の内径を中径部径(B)、
前記中心電極の後端から前記接続部を構成する接続部材の後端までの長さを充填長(D)、
前記中心電極の後端から前記第二構成部の先端までの長さを接続部長(C)とすると、
前記第二構成部の先端部と前記中径部との間の距離((B-A)/2)が0.02mm以上0.2mm以下であり、
収縮量(D-C)が6mm以上27mm以下であり、かつ、
前記第二構成部の常温におけるビッカース硬さが100Hv以上430Hv以下
であることを特徴とするスパークプラグ。 - 前記第二構成部は、前記第二構成部における前記先端部以外の部位で最も外径の小さい外径最小部を有し、前記外径最小部の直径を外径最小部径(E)とすると、
前記外径最小部径(E)と前記先端部径(A)との比(E/A)が0.85以上1.16以下であることを特徴とする請求項1に記載のスパークプラグ。 - 前記中径部径(B)が3.2mm以下であり、前記距離((B-A)/2)をX、前記比(E/A)をYとしたときに、次の式(i)~(iv)を満たすことを特徴とする請求項1又は2に記載のスパークプラグ。
(i) X≦0.19
(ii)Y≧X+0.8
(iii)Y≧0.85
(iv)Y≦1.06X+0.96 - 前記比(E/A)が1.00以上1.16以下であることを特徴とする請求項2に記載のスパークプラグ。
- 前記中径部径(B)が2.9mm以下であることを特徴とする請求項1~3のいずれか一項に記載のスパークプラグ。
- 前記第二構成部の常温におけるビッカース硬さが150Hv以上350Hv以下であることを特徴とする請求項1~4のいずれか一項に記載のスパークプラグ。
- 前記第二構成部は凹凸状の表面を備える固着部を有し、前記固着部の前記軸線方向長さが3mm以上25mm以下であることを特徴とする請求項2又は3に記載のスパークプラグ。
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JPS58111286A (ja) * | 1981-12-25 | 1983-07-02 | 日本特殊陶業株式会社 | 抵抗体入り点火栓 |
JP2003142224A (ja) * | 2001-10-31 | 2003-05-16 | Ngk Spark Plug Co Ltd | スパークプラグ |
JP2009245816A (ja) | 2008-03-31 | 2009-10-22 | Panasonic Corp | 有機elインク組成物およびその製造方法 |
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JP2000048931A (ja) * | 1998-05-22 | 2000-02-18 | Ngk Spark Plug Co Ltd | スパ―クプラグ及びその製造方法 |
JP2000215963A (ja) * | 1999-01-25 | 2000-08-04 | Ngk Spark Plug Co Ltd | スパ―クプラグの製造設備及びスパ―クプラグの製造方法 |
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JPS58111286A (ja) * | 1981-12-25 | 1983-07-02 | 日本特殊陶業株式会社 | 抵抗体入り点火栓 |
JP2003142224A (ja) * | 2001-10-31 | 2003-05-16 | Ngk Spark Plug Co Ltd | スパークプラグ |
JP2009245816A (ja) | 2008-03-31 | 2009-10-22 | Panasonic Corp | 有機elインク組成物およびその製造方法 |
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CN103140998B (zh) | 2014-09-17 |
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