SPARK PLUG

Abstract

A spark plug (10) comprising: a tubular metal casing (20) extending from a front end to a rear end along an axial line; a center electrode (13) being insulated and held on an inner circumferential side of the metal casing (25); a ground electrode (30) having one end section (31) connected to the metal casing (20) and having another end section (32) forming a spark gap (33) between the other end section (32) and a front end section of the center electrode (13), wherein the ground electrode (30) is a rod-shaped component; and a cap element (40) which is connected to a front end section of the metal shell (20) which covers the front end section of the middle electrode (13) and the other end section of the ground electrode (32) and forms a lower chamber (42), and in which a through-hole (43) is formed which connects the lower chamber (42) and a combustion chamber, wherein a first melting section (50),which connects the metal casing (20) and the cap element (40), is arranged on the front end side relative to the spark gap (33), wherein the spark plug (10) has a first opposing section (52) at which the metal casing (20) and the cap element (40) are opposite each other, wherein at least a part of the first opposing section (52) is arranged on the lower chamber side relative to the first melting section (50), and wherein the first melting section (50) is not formed in an inner circumferential surface of the metal casing (25) and an inner circumferential surface of the cap element (41).

Description

BACKGROUND OF THE INVENTION Area of ​​the invention

[0001] The present invention relates to a spark plug in which a cap element forming a sub-chamber is connected to a metal casing. Description of the state of the art

[0002] A spark plug is known in which a cap element forming a lower chamber is connected via a fused section to a metal casing intended for mounting on an engine (see, for example, PTL 1). A spark plug of this type generates a flame in the lower chamber by igniting a combustible air-fuel mixture that has flowed into the lower chamber from the through-holes in the cap element, expelling the gas stream, including the flame, from the through-holes into a combustion chamber, and causing the combustible air-fuel mixture in the combustion chamber to combust rapidly by means of the expelled gas stream. Citation list - Patent literature

[0003] PTL 1: Publication of Japanese unexamined patent application no. 2012-199236 SUMMARY OF THE INVENTION

[0004] However, the technology described in PTL 1 has the following problem: Since the melting section, which has a lower thermal conductivity than the cap element and the metal shell, is exposed in the lower chamber, the melting section overheats and causes pre-ignition of the combustible air-fuel mixture that has flowed into the lower chamber.

[0005] The present invention was made to solve the problem, and one objective of it is to provide a spark plug that can suppress the pre-ignition of a combustible air-fuel mixture that has flowed into the lower chamber.

[0006] To achieve this objective, a spark plug according to the present invention comprises: a tubular metal casing extending along an axial line from a front end to a rear end; a center electrode that is insulated and held on an inner circumferential side of the metal casing; a ground electrode, one end of which is connected to the metal casing and the other end of which forms a spark gap between the other end and a front end of the center electrode; and a cap element connected to a front end of the metal casing, which covers the front end of the center electrode and the other end of the ground electrode, forming a lower chamber, and in which a through-hole is formed connecting the lower chamber and a combustion chamber. A first melted section connecting the metal casing and the cap element is located on the front end relative to the spark gap.The spark plug comprises a first opposing section where the metal casing and the cap element are opposite each other. At least part of the first opposing section is located on the side of the lower chamber with respect to the first molten section. The first molten section does not form an inner circumferential surface of the metal casing or an inner circumferential surface of the cap element.

[0007] A spark plug according to the present invention comprises: a tubular metal casing extending along an axial line from a front end to a rear end; a center electrode, which is insulated and held on an inner circumferential side of the metal casing; a ground electrode, one end section of which is connected to the metal casing and the other end section of which forms a spark gap between the other end section and a front end section of the center electrode; and a cap element connected to a front end section of the metal casing, which covers the front end section of the center electrode and the other end section of the ground electrode and forms a lower chamber, and in which a through-hole is formed connecting the lower chamber and a combustion chamber. The ground electrode is connected to the metal casing via a second fused section.The spark plug contains a second, opposing section where the metal casing and the ground electrode are opposite each other. At least part of this second, opposing section is located on the side of the lower chamber with respect to the second molten section. The second molten section is not formed within an inner circumferential surface of the metal casing and a region of the ground electrode located in the lower chamber.

[0008] In a spark plug, the melting section connecting the metal casing and the cap element is located on the front side relative to the spark gap. At least part of the first opposing section, where the metal casing and the cap element meet, is located on the lower chamber side relative to the first melting section. Since the first melting section is not formed on the inner circumferential surface of the metal casing and the inner circumferential surface of the cap element, it is possible to suppress overheating of the first melting section. This, in turn, suppresses the pre-ignition of the combustible air-fuel mixture flowing into the lower chamber, which would otherwise occur due to overheating of the first melting section.

[0009] In a spark plug designed according to a second aspect, the first opposing section, which is curved, ensures sufficient distance between the lower chamber and the first melting section. Since it is possible to reduce the heat input of the first melting section to the lower chamber, it is also possible, in addition to the advantages of the first aspect, to further suppress the pre-ignition of the combustible air-fuel mixture flowing into the lower chamber.

[0010] In a spark plug designed according to a third aspect, the inner circumferential surface of the cap element corresponds to the inner circumferential surface of the metal casing, and a radially inward end of the first opposing section is located at the rear, axially relative to a radially outward end of the first opposing section. Thus, it is easy to position a step, formed by the first opposing section between the metal casing and the cap element, at the rear of the lower chamber. The velocity of the gas flow ejected from the passage into the combustion chamber is lower at the rear of the lower chamber than at the front.Therefore, by arranging the step on the back side of the lower chamber, in addition to the advantage of the second aspect, it is possible to reduce the effect of the turbulent flow created by the step on the expelled flow.

[0011] In a spark plug of a fourth aspect, the first opposing section has a first part located on its innermost side in the radial direction; and on a second part, which is radially connected to an outer side of the first part, the metal casing and the cap element are oriented in a different direction than in the direction in which the metal casing and the cap element are oriented on the first part. Since the cap element on the second part is in contact with the metal casing along its entire circumference, it is possible, in addition to the advantages of the second or third aspect, to further reduce the effect of the first melting section on pre-ignition.

[0012] In the case of a spark plug with a fifth aspect, since the first melted section is in contact with the second part, it is possible, in addition to the advantage of any second to fourth aspect, to increase the strength of the connection compared to a case where the first melted section is not in contact with the second part.

[0013] In a spark plug according to a sixth aspect, in a cross-section that includes the axial line, the shortest distance of the first melted section from an outer circumferential surface of the first melted section, where the outer circumferential surface is exposed at an outer circumferential surface of the cap element, to the first opposite section is greater than or equal to the shortest distance of the first opposite section along the first opposite section. Thus, in addition to the advantage of any of the first to fifth aspects, it is possible to increase the strength of the connection.

[0014] In a spark plug of the seventh aspect, the ground electrode is connected to the metal casing via the second molten section, and at least part of the second, opposing section, where the metal casing and the ground electrode meet, is located on the lower chamber side with respect to the second molten section. Since the second molten section is not formed on the inner circumferential surface of the metal casing and is not located in a region of the ground electrode situated in the lower chamber, it is possible to suppress overheating of the second molten section. Thus, pre-ignition of the combustible air-fuel mixture that has flowed into the lower chamber can be suppressed due to overheating of the second molten section.

[0015] In a spark plug designed according to the eighth aspect, the bending of the second, opposite section ensures sufficient distance between the lower chamber and the second melting section, as this second, opposite section is curved. Thus, in addition to the advantage of the seventh aspect, it is possible to further suppress the pre-ignition of the combustible air-fuel mixture flowing into the lower chamber.

[0016] In a spark plug according to a ninth aspect, a third part is located on the radially innermost side of the second, opposing section; and on a fourth part, which is radially connected to an outer side of the third part, the metal casing and the ground electrode face each other in a different direction than the direction in which the metal casing and the ground electrode face each other on the third part. Since the second molten section is in contact with the fourth part, it is possible, in addition to the advantage of the eighth aspect, to increase the bond strength compared to a case where the second molten section is not in contact with the fourth part. List of characters Fig. 1 is a partial cross-section of a spark plug according to a first embodiment. Fig. Figure 2 is a cross-section through the spark plug, showing an enlarged view of part II in Fig. 1 shows. Fig. Figure 3 is a cross-section of a spark plug according to a second embodiment. Fig. Figure 4 is a cross-section of a spark plug according to a third embodiment. Fig. Figure 5 is a cross-section of a spark plug according to a fourth embodiment. DESCRIPTION OF PREFERRED EXECUTION FORMS

[0017] In the following, embodiments of the present invention are described with reference to the drawings. Fig. 1 is a partial cross-section of a spark plug 10 according to a first embodiment. The lower side in Fig. 1 is referred to as the "front end" of the spark plug 10 and the upper side in Fig. 1 as the "back side" of the spark plug 10 designated (the same applies to the Fig. 2 to Fig. 5). Fig. Figure 1 shows a cross-section, including an axial line O, of part of the spark plug 10on the front end. As in Fig. 1 shown contains the spark plug 10 an insulator 11 , a central electrode 13 , a metal casing 20 , a ground electrode 30 and a cap element 40 .

[0018] The insulator 11 is an essentially cylindrical element in which an axial bore is located 12 is formed, extending along the axial line O. The insulator 11 It is made of ceramic, such as aluminum oxide, with desired mechanical properties and high insulating capacity at high temperatures. The center electrode 13 is located at the front end of the axial bore 12 of the insulator 11 arranged. The center electrode 13 is electrically connected to a metal terminal 14 in the axial bore 12 connected. The metal connection 14is a rod-shaped element to which a high-voltage cable (not shown) is to be connected. The metal clamp 14 It consists of an electrically conductive metal material (e.g., low-carbon steel). The metal connection 14 is at the rear end of the insulator 11 attached.

[0019] The metal casing 20 is an essentially cylindrical element made of an electrically conductive metal material (e.g., low-carbon steel). The metal casing 20 surrounds the front end of the insulator 11 and holds the insulator 11 fixed within it. An external thread 22 is located on an outer circumferential surface of a fuselage section 21 on the front of the metal casing 20 trained. The external thread 22 is a section that fits into a threaded hole 2 of an engine 1 is screwed in. The ground electrode 30 is with the fuselage part 21the metal sleeve 20 tied together.

[0020] The ground electrode 30 is a rod-shaped element made primarily of nickel and similar materials. In the present embodiment, the ground electrode is 30 at the location of the external thread 22 arranged, runs through the fuselage section 21 and is the center electrode 13 Facing the cap element. 40 is with a front-end section of the metal casing 20 connected. The cap element 40 is an element made primarily of Ni and similar materials and has a subchamber 42 forms. In the present embodiment, the cap element 40 hemispherical. In a state where the spark plug 10 via the external thread 22 at the threaded hole 2 of the engine 1 The cap element is attached. 40 in a combustion chamber 3of the engine 1 free. In the cap element 40 are several through-openings 43 trained, which the combustion chamber 3 and the lower chamber 42 connect.

[0021] Fig. Figure 2 is a cross-sectional view of the spark plug. 10 , which shows an enlarged view of Section II in Fig. 1 shows and includes the axial line O. A recessed section 23 , which is offset radially inwards, is located in part of the fuselage section 21 the metal casing 20 with the external thread 22 trained. A hole 24 , which is thinner than the recessed section 23 is, is in the hull section 21 at a point within the recessed section 23 formed in a radial direction. The hole 24 extends through the hull section 21 and each forms an opening in an inner circumferential surface25 the metal sleeve 20 and the omitted section 23 .

[0022] A final section 31 the ground electrode 30 will go into the hole 24 introduced, and the other end section 32 the ground electrode 30 forms a spark gap 33 between the other end section 32 and a front-end section of the center electrode 13 Since one end section 31 the ground electrode 30 via a second melting section 60 with part of the metal casing 20 with the external thread 22 is connected, the heat of the ground electrode 30 from the external thread 22 via the threaded hole 2 on the engine 1 transferred. The other end section 32 the ground electrode 30 is on the axial line O at the front end of the center electrode 13provided. The ground electrode 30 will go into the hole 24 pressed in, and the ground electrode 30 stands with the entire circumference of the hole 24 in contact.

[0023] The cap element 40 covers the front end section of the center electrode 13 and the other final section 32 the ground electrode 30 and forms the lower chamber 42 To prevent [something] from happening at the boundary between a spherical cap-shaped inner circumferential surface 41 of the cap element 40 and the cylindrical inner circumferential surface 25 the metal casing 20 The cap element is designed so that a step can easily be formed. 40 arranged so that the inner circumferential surface 41 of the cap element 40 with the inner circumferential surface 25 the metal bowl 20 agrees. The through holes 43 of the cap element 40 , which is the lower chamber42 and the combustion chamber 3 connecting are directed downwards towards an outer circumferential surface. 44 of the cap element 40 inclined.

[0024] A first melting section 50 , the metal casing 20 and the cap element 40 The connection is located on the front end side relative to the spark gap. 33 and is along the entire periphery of the metal shell 20 and the cap element 40 formed around the axial line O. The first melting section 50 is a section where the basic materials of the metal casing 20 and the cap element 40 have fused together. The thermal conductivity of the first molten section 50 is lower than the thermal conductivity of the base material of the metal casing 20 and the thermal conductivity of the base material of the cap element 40 .

[0025] A first opposite section 52 , on which the metal casing 20 and the cap element 40 facing each other, comprises a first part 53 , which extends radially on the innermost side of the cap element 40 is located, and a second part 54 , which in a radial direction with the outside of the first part 53 is connected. The first part 53 is a ring-shaped section, and the second part 54 is a cylindrical section. The second part 54 is in relation to the first part 53 bent axially towards the front end. The second part 54 This is a so-called press fit. In the second part... 54 is the cap element 40 along the entire circumference with the metal casing 20 in contact.

[0026] The first melting section 50 is in contact with the second part 54Part of the first part 53 of the first opposite section 52 (part of the first part) 53 (in a radial direction inwards) is located on the side of the lower chamber 42 with regard to the first melting section 50 The first melting stage 50 is not in the inner circumferential area 25 the metal casing 20 and the inner circumferential surface 41 of the cap element 40 trained.

[0027] The cap element 40 is over the first melting section 50 with the metal casing 20 connected, so that the inner circumferential surface 41 of the cap element 40 with the inner circumferential surface 25 the metal casing 20 agrees. An end located radially inwards. 55 of the first opposite section 52is located axially on the rear end relative to an end located radially outside 56 of the first opposite section 52 The end 55 of the first opposite section 52 is located on the back side in relation to the passage openings 43 .

[0028] A distance D1 (shortest distance) is the length of a line segment that is the shortest among the line segments that define an outer circumferential surface 51 of the first melting section 50 , which is located on the outer circumferential surface 44 of the cap element 40 and an outer circumferential surface 29 the metal casing 20 is exposed, and the intersection of the first melt section 50 and the first opposite section 52 (the end) 56 ) connect. A distance of the first opposite section 52(Crawl distance), which is the sum of a distance D2 and a distance D3 is, is the shortest distance from the end 55 to the end 56 of the first opposite section 52 along the first opposite section 52 . Regarding the spark plug 10 is the distance D1 greater than or equal to the sum of the distances D2 and the distance D3 .

[0029] The ground electrode 30 The second melting stage is described below. 60 , the metal casing 20 and the ground electrode 30 connecting is along the entire perimeter of one end section. 31 the ground electrode 30 formed. The second melting stage 60 is a section where the base materials of the metal casing 20 and the ground electrode 30have fused together. The thermal conductivity of the second molten section 60 is lower than the thermal conductivity of the base material of the metal casing 20 and the thermal conductivity of the base material of the ground electrode 30 .

[0030] The entirety of a second, opposing section 62 , on which the metal casing 20 and the ground electrode 30 facing each other, is located on the side of the lower chamber 42 with regard to the second melting section 60 The second melting stage 60 is not in the inner circumferential area 25 the metal casing 20 and in part of the lower chamber 42 arranged ground electrode 30 trained.

[0031] A distance D4(shortest distance) is the length of a line segment that is the shortest among the line segments that define an outer circumferential surface 61 of the second melting section 60 , which is in the omitted section 23 the metal casing 20 is exposed, and the intersection of the second melt section 60 and the second opposite section 62 connect. A distance D5 is the shortest distance from the second melting section 60 to the inner circumferential surface 25 the metal casing 20 along the second opposite section 62 . Regarding the spark plug 10 is the distance D4 greater than or equal to the distance D5 .

[0032] The spark plug 10 creates a flame core in the spark gap 33 , by generating a spark discharge between the center electrode 13 and the ground electrode 30caused and ignites a flammable air-fuel mixture that escapes from the through-holes 43 of the cap element 40 into the lower chamber 42 has flowed. The one in the lower chamber 42 The generated gas flow and the flame are expelled from the through holes. 43 of the cap element 40 into the combustion chamber 3 expelled, and the gas stream quickly burns a flammable air-fuel mixture in the combustion chamber. 3 .

[0033] Since the spark plug 10 the first melting section 50 , which has a lower thermal conductivity than the metal casing 20 and the cap element 40 has, not in the inner circumferential area 25 the metal casing 20 and the inner circumferential surface 41 of the cap element 40 If it is formed, it is possible to prevent overheating of the first melting section. 50to suppress it. This makes it possible to prevent the pre-ignition of the combustible air-fuel mixture entering the lower chamber. 42 has flowed, to suppress, since the first melting section 50 acts as an ignition source.

[0034] Since the first opposite section 52 If it is curved, it is possible to maintain a sufficient distance from the inner circumferential surfaces. 25 and 41 to the first melting section 50 to provide for this. This makes it possible to control the heat impact of the first melting stage. 50 on the inner circumferential surfaces 25 and 41 to reduce, and thus it is possible to reduce the pre-ignition of the combustible air-fuel mixture in the lower chamber 42 to suppress further.

[0035] In the second part 54 of the first opposite section 52 The cap element is 40 along the entire circumference with the metal casing20 in contact, so that between the cap element 40 and the metal casing 20 It cannot form a gap. Therefore, it is possible to detect the radiation from the first melting section. 50 into the lower chamber 42 to prevent this. Accordingly, it is possible to limit the effect of the first melting stage. 50 to further suppress pre-ignition. It should be noted that the heat transfer in the first part 53 This occurs through heat conduction when the metal casing 20 and the cap element 40 be in contact with each other, and through radiation when the metal casing 20 and the cap element 40 are separate.

[0036] The inner circumference 41 of the cap element 40 corresponds to the inner circumference area 25 the metal casing 20 , and the radially inner end 55 of the first opposite section 52is located on the rear end side in relation to the radially outer end 56 of the first opposite section 52 Therefore, it is easy to define a step that lies between the inner circumferential surfaces. 25 and 41 the metal casing 20 and the cap element 40 due to the first opposite section 52 is formed on the rear end of the lower chamber 42 to arrange. The speed of the gas flow exiting the through-holes 43 into the combustion chamber 3 The ejected fluid is located on the back side of the lower chamber. 42 less than at the front end of the lower chamber 42 Therefore, it is possible to achieve this by arranging the step on the rear side of the lower chamber. 42 the effect of the turbulent flow created by the step in the lower chamber 42 on the expelled gas flow in the combustion chamber3 to reduce.

[0037] The shortest distance D1 of the first melting section 50 from the outer circumferential surface 51 of the first melting section 50 to the first opposite section 52 is greater than or equal to the shortest distance ( D2 + D3) of the first opposite section 52 along the first opposite section 52 Thus, it is possible to increase the bond strength by the penetration of the first molten section. 50 to increase. Since the first melting section 50 in contact with the second part 54 Furthermore, it is possible to increase the bond strength compared to a case where the first melting section 50 not in contact with the second part 54 stands.

[0038] Since the second melting section 60 not in the inner circumferential area 25the metal casing 20 and an area located in the lower chamber 42 arranged ground electrode 30 Once formed, it is possible to prevent overheating of the second melting section. 60 to suppress low thermal conductivity. This can prevent pre-ignition of the combustion in the lower chamber. 42 The inflowing flammable air-fuel mixture is suppressed, as the second melting section 60 acts as an ignition source. Furthermore, the shortest distance D4 of the second melting section 60 from the outer circumferential surface 61 of the second melting section 60 to the second opposite section 62 greater than or equal to the shortest distance D5 of the second opposite section 62 along the second opposite section 62 In this way, it is possible to increase the strength of the connection.

[0039] With reference to Fig. Section 3 describes a second embodiment. The second embodiment differs from the first embodiment in the shape of a part on the front end with respect to the spark gap. 33 However, it is identical to the first embodiment in other respects. Therefore, parts of the second embodiment that are identical to those described in the first embodiment are designated with the same numbers, and the description of such parts is omitted. Fig. Figure 3 is a cross-sectional view of a spark plug. 70 according to the second embodiment, including the axial line O. Fig. 3 is an enlarged view showing part 11 (see Fig. 1) the spark plug 70 in the same way as in the first embodiment (the same applies to the Fig. 4 and Fig. 5).

[0040] A section recessed inwards in a radial direction 71 is in part of the hull section 21 the metal casing 20 with the external thread 22 trained. A hole 72 , which is thinner than the recessed section 71 is, is in the hull section 21 at a point within the recessed section 71 formed in a radial direction. The hole 72 extends through the hull section 21 and each forms an opening in the inner circumferential surface 25 the metal sleeve 20 and the omitted section 71 The hole 72 is near the recessed section 71 wide (on the outer circumferential surface) 29 the metal casing 20 ) and near the inner circumferential surface 25 narrow. An end section 73 the ground electrode 30 , who went into the hole 72The inserted section has a flange-like shape that is thicker than the other end section. 32 the ground electrode 30 .

[0041] A first melting section 74 , the metal casing 20 and the cap element 40 The connection is located on the front end side in relation to the spark gap. 33 and is along the entire periphery of the metal shell 20 and the cap element 40 formed around the axial line O. The thermal conductivity of the first melting section 74 is lower than the thermal conductivity of the base material of the metal casing 20 and the thermal conductivity of the base material of the cap element 40 .

[0042] A first opposite section 76 , on which the metal casing 20 and the cap element 40 facing each other, comprises a first part 77, which extends radially on the innermost side of the cap element 40 is located, a second part 78 , which in a radial direction with the outside of the first part 77 is connected, and an outer edge part 79 , which in a radial direction with the outside of the second part 78 is connected. The first part 77 and the outer edge part 79 are each in relation to the second part 78 bent in a direction that intersects the axial line O. The second part 78 This is a so-called press fit. On the second part... 78 is the cap element 40 along the entire circumference with the metal casing 20 in contact. The first part 77 is located on the front end relative to the outer edge 79 The entire first part 76 is located on the side of the lower chamber 42 with regard to the first v melting section74 The first melting stage 74 is not in the inner circumferential area 25 the metal casing 20 and the inner circumferential surface 41 of the cap element 40 trained.

[0043] A second melting section 80 , the metal casing 20 and the ground electrode 30 connecting is along the entire perimeter of one end section. 73 the ground electrode 30 formed. The second melting stage 80 is a section where the base materials of the metal casing 20 and the ground electrode 30 have fused together. The thermal conductivity of the second molten section 80 is lower than the thermal conductivity of the base material of the metal casing 20 and the thermal conductivity of the base material of the ground electrode 30 .

[0044] A second opposite section 82, on which the metal casing 20 and the ground electrode 30 facing each other, comprises a third part 83 , which extends radially on the innermost side of the metal shell 20 is located, and a fourth part 84 , which in a radial direction with the outside of the third part 83 is connected. The fourth part 84 is compared to the third part 83 bent. In the third part 83 is the ground electrode 30 a so-called press fit, and the outer circumferential surface of the ground electrode 30 The entire circumference is covered by the metal casing. 20 in contact.

[0045] The second melting section 80 is in contact with the fourth part 84 Part of the third part 83 of the second opposite section 82 (part of the third part) 83(inside in the radial direction) is located on the side of the lower chamber 42 relative to the second melting section 80 The second melting stage 80 is not in the inner circumferential area 25 the metal casing 20 and an area located in the lower chamber 42 arranged ground electrode 30 trained.

[0046] at the spark plug 70 is, since the first melting section 74 not in the inner circumferential area 25 the metal casing 20 and the inner circumferential surface 41 of the cap element 40 If it is formed, it is possible to overheat the first melting section. 74 to suppress and prevent the pre-ignition of a flammable air-fuel mixture entering the lower chamber 42 has flowed, to suppress.

[0047] Since the first opposite section 76If it is curved, it is possible to maintain a sufficient distance from the inner circumferential surfaces. 25 and 41 up to the first melting section 74 to provide for and pre-ignition of the flammable air-fuel mixture in the lower chamber 42 through the first melting section 74 to suppress further. Since the cap element 40 in the second part 78 along the entire circumference with the metal casing 20 In contact, it is also possible to influence the effect of the first melting section 74 to further reduce the pre-ignition.

[0048] Since the second melting section 80 not on the inner circumferential surface 25 the metal casing 20 and an area located in the lower chamber 42 arranged ground electrode 30 When formed, it is possible to pre-ignite the gas flowing into the lower chamber. 42Flowing flammable air-fuel mixture due to the overheating of the second melting section 80 to suppress. Since the second opposite section 82 If it is curved, it is also possible to maintain a sufficient distance from the inner circumferential surface. 25 the metal casing 20 until the second melting stage 80 to provide for and pre-ignition of the flammable air-fuel mixture in the lower chamber 42 to suppress further.

[0049] Since the ground electrode 30 along the entire circumference of the third part 83 of the second opposite section 82 with the metal casing 20 When in contact, it is possible to observe the effect of the second melting section. 80 to further reduce the pre-ignition. Since the second melting phase 80 in contact with the fourth part 84Furthermore, it is possible to determine the bond strength of the second melt section. 80 to increase.

[0050] With reference to Fig. Section 4 describes a third embodiment. This third embodiment differs from the first embodiment in the shape of a section on the front end with respect to the spark gap. 33 However, it is identical to the first embodiment in other respects. Therefore, parts of the third embodiment that are identical to those of the first embodiment are designated with the same reference numerals, and the description of such parts is omitted. Fig. Figure 4 is a cross-sectional view of a spark plug. 90 according to the third embodiment, containing the axial line O.

[0051] In part of the hull section 21 the metal casing 20 with the external thread 22is a section recessed inwards in a radial direction 91 formed a hole 92 , which is thinner than the recessed section 91 is, is in the hull section 21 at a point within the recessed section 91 formed in a radial direction. The hole 92 extends through the hull section 21 and each forms an opening in the inner circumferential surface 25 the metal casing 20 and the omitted section 91 The hole 92 is near the recessed section 91 (the outer circumferential surface 29 the side of the metal casing 20 ) narrow and near the inner circumferential surface 25 wide. An end section 93 the ground electrode 30 , who went into the hole 92 The one that is inserted is thinner than the other end section. 32 the ground electrode 30 .

[0052] A first melting section 94 , the metal casing 20 and the cap element 40 The connection is located on the front end side relative to the spark gap. 33 and is along the entire periphery of the metal shell 20 and the cap element 40 formed around the axial line O.

[0053] The first melting section 94 is a part where the base materials of the metal casing 20 and the cap element 40 have merged together. The thermal conductivity of the first melting section 94 is lower than the thermal conductivity of the base material of the metal shell 20 and the thermal conductivity of the base material of the cap element 40 .

[0054] The entirety of a first opposing section 96 , on which the metal casing 20 and the ground electrode 30facing each other, is located on the side of the lower chamber 42 with regard to the first melting section 94 . On the first opposite section 96 The cap element is located 40 in contact with the metal casing 20 The first melting stage 94 is not in the inner circumferential area 25 the metal casing 20 and the inner circumferential surface 41 of the cap element 40 trained.

[0055] A distance D1 (shortest distance) is the length of a line segment that is the shortest among the line segments that define an outer circumferential surface 95 of the first melting section 94 , which is located on the outer circumferential surface 44 of the cap element 40 and the outer circumferential surface 29 the metal casing 20 is exposed, and the intersection of the first melt section 94and the first opposite section 96 connect. A distance D2 is the length of the first opposite section 96 along the first opposite section 96 . Regarding the spark plug 90 is the distance D1 greater than or equal to the distance D2 .

[0056] A second melting section 100 , the metal casing 20 and the ground electrode 30 connecting is along the entire perimeter of one end section. 93 the ground electrode 30 formed. The second melting stage 100 is a section where the base materials of the metal casing 20 and the ground electrode 30 have fused together. The thermal conductivity of the second molten section 100 is lower than the thermal conductivity of the base material of the metal casing 20and the thermal conductivity of the base material of the ground electrode 30 .

[0057] A second opposite section 102 , on which the metal casing 20 and the ground electrode 30 facing each other, comprises a third part 103 , which is located radially on the innermost side, and a fourth part 104 , which in a radial direction with the outside of the third part 103 is connected. The fourth part 104 is in relation to the third part 103 bent. In the third part 103 is the ground electrode 30 a so-called press fit, and the outer circumferential surface of the ground electrode 30 The metal shell runs along the entire circumference 20 in contact.

[0058] The second melting section 100 is in contact with the fourth part 104 Part of the third part 103of the second opposite section 102 (part of the third part) 103 (inside in the radial direction) is located on the side of the lower chamber 42 with regard to the second melting section 100 The second melting stage 100 is not in the inner circumferential area 25 the metal casing 20 and an area located in the lower chamber 42 arranged ground electrode 30 trained.

[0059] A distance D4 (shortest distance) is the length of a line segment that is the shortest among the line segments that define an outer circumferential surface 101 of the second melting section 100 , which are in the omitted section 91 the metal casing 20 is exposed, and the intersection of the second melt section 100 and the second opposite section 102 connect. A distance D5is the length of the fourth part 104 and a distance D6 is the length of the third part 103 . Regarding the spark plug 90 is the distance D4 greater than or equal to the sum of the distances D5 and the distance D6 .

[0060] Since the spark plug 90 the first melting section 94 not on the inner circumferential surface 25 the metal casing 20 and the inner circumferential surface 41 of the cap element 40 is trained, it is at the spark plug 90 possible, the overheating of the first melting section 94 to suppress and prevent the pre-ignition of a flammable air-fuel mixture entering the lower chamber 42 has flowed, to suppress it. Since the distance D1 of the first melting section 94 greater than or equal to the distance D2 of the first opposite section 96Furthermore, it is possible to increase the strength of the bond through the first melting stage. 94 to increase.

[0061] Since the second melting section 100 not on the inner circumferential surface 25 the metal casing 20 and an area located in the lower chamber 42 arranged ground electrode 30 When formed, it is possible to pre-ignite the gas flowing into the lower chamber. 42 Flowing flammable air-fuel mixture due to the overheating of the second melting section 100 to suppress. Since the second opposite section 102 If it is curved, it is also possible to maintain a sufficient distance from the inner circumferential surface. 25 the metal casing 20 until the second melting stage 100 to provide for this. This makes it possible to pre-ignite the combustible air-fuel mixture in the lower chamber. 42 to suppress further. Since the ground electrode30 in the third part 103 along the entire circumference with the metal casing 20 Furthermore, it is possible to determine the influence of the second melting section when in contact with the melting section. 100 to further reduce the pre-ignition.

[0062] Since the second melting section 100 in contact with the fourth part 104 If this is the case, it is possible to determine the connection strength of the ground electrode. 30 to increase. Since the distance D4 greater than or equal to the sum of the distances D5 and the distance D6 is, it is also possible to determine the bond strength of the ground electrode 30 to increase.

[0063] With reference to Fig. Section 5 describes a fourth embodiment. This fourth embodiment differs from the first embodiment in the form of a section on the front end relative to the spark gap. 33However, it is identical to the first embodiment in other respects. Therefore, parts of the fourth embodiment that are identical to those of the first embodiment are designated with the same reference numerals, and the description of such parts is omitted. Fig. Figure 5 is a cross-sectional view of a spark plug 110 according to the fourth embodiment, including the axial line O.

[0064] A cap element 111 , the lower chamber 42 It forms a spherical cap-shaped inner circumferential surface 112 To prevent this from happening at the boundary between the inner circumferential surface 112 of the cap element 111 and the cylindrical inner circumferential surface 25 the metal casing 20 The cap element is designed so that a step can easily be formed. 111 arranged so that the inner circumferential surface 112 of the cap element 111 with the inner circumferential surface 25the metal casing 20 matches. The cap element 111 is with the metal casing 20 connected in such a way that an outer circumferential surface 113 of the cap element 111 in a radial direction relative to an outer circumferential surface 114 the metal casing 20 is located inside.

[0065] A first melting section 120 , the metal casing 20 and the cap element 111 The connection is located on the front end side in relation to the spark gap. 33 and is along the entire periphery of the metal shell 20 and the cap element 111 formed around the axial line O.

[0066] The first melting section 120 is a part where the base materials of the metal casing 20 and the cap element 111 have merged together.

[0067] The thermal conductivity of the first melting section120 is lower than the thermal conductivity of the base material of the metal casing 20 and the thermal conductivity of the base material of the cap element 111 .

[0068] A first opposite section 122 , on which the metal casing 20 and the cap element 111 facing each other, comprises a first part 123 , which extends radially on the innermost side of the cap element 111 is located, and a second part 124 , which in a radial direction with the outside of the first part 123 is connected. The second part 124 is in relation to the first part 123 bent. The second part 124 This is a so-called press fit. In the second part... 124 is the cap element 111 along the entire circumference with the metal casing 20 in contact. The first melting section 120 is in contact with the second part124 .

[0069] An end 125 of the first opposite section 122 The inner side, in the radial direction, is located on the back side in the axial direction relative to one end. 126 of the first opposite section 122 outside in a radial direction. The end 125 of the first opposite section 122 is located on the back side in relation to the passage openings 43 Part of the first part 123 of the first opposite section 122 (part of the first part) 123 (inside in the radial direction) is located on the side of the lower chamber 42 relative to the first melting section 120 The first melting stage 120 is not in the inner circumferential area 25 the metal casing 20 and the inner circumferential surface 112 of the cap element 111 trained.

[0070] A distance D1 (shortest distance) is the length of a line segment that is the shortest among the line segments that define an outer circumferential surface 121 of the first melting section 120 , which are located on the outer circumferential surface 114 the metal casing 20 be exposed, and the intersection of the first melt section 120 and the first opposite section 122 (the end) 126 ) connect. A distance that is the sum of a distance D2 and a distance D3 is the shortest distance of the first opposite segment 122 along the first opposite section 122 . Regarding the spark plug 110 is the distance D1 greater than or equal to the sum of the distances D2 and the distance D3 .

[0071] at the spark plug 110 is, since the first melting section 120not in the inner circumferential area 25 the metal casing 20 and the inner circumferential surface 112 of the cap element 111 If it is formed, it is possible to overheat the first melting section. 120 to suppress and prevent the pre-ignition of a flammable air-fuel mixture entering the lower chamber 42 has flowed, to suppress it. Since the first opposite section 122 If it is curved, it is also possible to maintain a sufficient distance from the inner circumferential surface. 25 the metal casing 20 and the inner circumferential surface 112 of the cap element 111 to the first melting section 120 to ensure this. This makes it possible to pre-ignite the combustible air-fuel mixture in the lower chamber. 42 to suppress further. Since the cap element 111 along the entire circumference of the second part 124 with the metal casing 20Furthermore, when in contact, it is possible to observe the effect of the first melting section. 120 to further reduce the pre-ignition. Since the distance D1 of the first melting section 120 greater than or equal to the sum of the distances D2 and the distance D3 Furthermore, it is possible to increase the strength of the connection.

[0072] Up to this point, the present invention has been described with reference to embodiments. However, the present invention is not limited to the embodiments described above, and it is readily apparent that various improvements and modifications can be made within the spirit and scope of the present invention.

[0073] In the embodiments, the cap parts 40 and 111 with the spherical inner circumferential surfaces 41 and 112 with the metal casing 20connected. However, this does not represent a limitation. The cap element can have any suitable shape. For example, a cap element with a bottom-cylindrical shape or a disc-like shape can be used.

[0074] In the embodiments, the second parts 54 , 78 and 124 the first opposing sections 52 , 76 and 122 Each has a so-called press fit. However, this is not a limitation. The second parts 54 , 78 and 124 Each can be either a game pass or a transition pass.

[0075] In the first version, the distance D1 of the first melting section 50 greater than or equal to the distance ( D2 + D3) of the first opposite section 52 However, this is not a limitation. The distance D1 can be smaller than the distance ( D2+ D3). In this case too, it is possible to increase the strength of the joint, as long as the first melting section 50 with the second part 54 is in contact.

[0076] In the second version, the first melting section 74 and the second part 78 separated. The first melting section 74 However, it can be used with the second part. 78 be in contact to increase the strength of the bond. Even in the case that the first melting section 74 and the second part 78 If the joints are separated, it is possible to increase the strength of the connection by increasing the shortest distance between the first melted section. 74 from an outer circumferential surface 75 of the first melting section 74 to the first opposite section 76 greater than or equal to the shortest distance of the first opposite segment 76along the first opposite section 76 is done.

[0077] In the fourth embodiment, the second part 124 on the back side of the first enamel section 120 formed. However, this is not a limitation. The second part 124 can be omitted by considering the penetration of the first melt section 120 is set and by the first melting section 120 with the first part 123 is brought into contact.

[0078] In the embodiments, the first parts 53 , 77 and 123 the first opposing sections 52 , 76 and 122 as well as the first opposite section 96 perpendicular to the axial line O. However, this is not a limitation. These can intersect the axial line O. In the embodiments, the second parts have 54 , 78 and 124the first opposing sections 52 , 76 and 122 Each a cylindrical shape centered on the axial line O. The second parts 54 , 78 and 124 They can each have a frustoconical or spherical shape centered on the axial line O.

[0079] In the embodiments, the first parts 53 , 77 and 123 and the second parts 54 , 78 and 124 in the first opposing sections 52 , 76 and 122 directly connected. However, this is not a limitation. The first parts 53 , 77 and 123 and the second parts 54 , 78 and 124 can be connected via a frustoconical section or a spherical zone-shaped section. Likewise, the second parts can be 82 and 102, the third parts 83 and 103 and the fourth parts 84 and 104 are connected via a frustoconical or spherical zone-shaped section.

[0080] Each embodiment can be modified by adding one or more parts of another embodiment or by replacing one or more parts of the embodiment with one or more parts of another embodiment.

[0081] For example, instead of the configuration with which the ground electrode 30 with the metal casing 20 in the first embodiment, the configuration with which the ground electrode is connected 30 with the metal bowl 20 in the second embodiment, or the configuration with which the ground electrode 30 with the metal casing 20The third embodiment is connected, while the first embodiment uses a different configuration. Furthermore, in the first embodiment, the cap element can be used instead of the configuration with which it is connected. 40 with the metal casing 20 In the second version, the configuration used with which the cap element is connected is employed. 40 with the metal casing 20 is connected, or the configuration with which the cap element 40 with the metal casing 20 in the third version it is connected, in the first version it can be used. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2012199236

[0003]

Claims

[1] A spark plug containing: a tubular metal shell extending from a front end side to a rear end side along an axial line; a center electrode which is insulated and held on an inner peripheral side of the metal shell; a ground electrode, one end portion of which is connected to the metal shell and the other end portion of which forms a spark gap between the other end portion and a front end portion of the center electrode; and a cap member connected to a front end portion of the metal shell, covering the front end portion of the center electrode and the other end portion of the ground electrode and forming a sub-chamber, and in which a through hole is formed connecting the sub-chamber and a combustion chamber, wherein a first melting portion connecting the metal shell and the cap member is arranged on the front end side relative to the spark gap, wherein the spark plug has a first opposing portion at which the metal shell and the cap member are opposed to each other, wherein at least a part of the first opposing section is arranged on the sub-chamber side relative to the first melting section, and wherein the first melting portion is not formed in an inner peripheral surface of the metal shell and an inner peripheral surface of the cap member. [2] The spark plug according to claim 1, wherein the first opposing portion is bent. [3] The spark plug according to claim 2, wherein the inner peripheral surface of the cap member coincides with the inner peripheral surface of the metal shell, and wherein a radially inner end of the first opposing portion is arranged on the rear side in the axial direction relative to a radially outer end of the first opposing portion. [4] The spark plug according to claim 2, wherein the first opposing portion includes a first part arranged on an innermost side in the radial direction, and a second part connected to an outer side of the first part in the radial direction and at which the metal shell and the cap member face each other in a direction different from a direction in which the metal shell and the cap member face each other at the first part, and wherein in the second part the cap element is in contact with the metal shell along its entire circumference. [5] The spark plug according to claim 2, wherein the first melting portion is in contact with the second part. [6] The spark plug according to claim 1, wherein, in a cross section including the axial line, a shortest distance of the first fusion portion from an outer peripheral surface of the first fusion portion, the outer peripheral surface being exposed on an outer peripheral surface of the cap member, to the first opposing portion is equal to or greater than a shortest distance of the first opposing portion along the first opposing portion. [7] A spark plug comprising: a tubular metal shell extending along an axial line from a front end side to a rear end side; a center electrode which is insulated and held on an inner peripheral side of the metal shell; a ground electrode having one end portion connected to the metal shell and the other end portion forming a spark gap between the other end portion and a front end portion of the center electrode; and a cap member connected to a front end portion of the metal shell, covering the front end portion of the center electrode and the other end portion of the ground electrode and forming a sub-chamber, and in which a through hole is formed connecting the sub-chamber and a combustion chamber, wherein the ground electrode is connected to the metal shell via a second melting section, wherein the spark plug has a second opposing portion at which the metal shell and the ground electrode are opposed to each other, wherein at least a part of the second opposing section is located on the sub-chamber side relative to the second melting section, and wherein the second melting portion is not formed in an inner peripheral surface of the metal shell and a portion of the ground electrode disposed in the sub-chamber. [8] The spark plug according to claim 7, wherein the second opposing portion is bent. [9] The spark plug according to claim 8, wherein the second opposing portion has a third part arranged on an innermost side in a radial direction, and a fourth part connected to an outer side of the third part in the radial direction and at which the metal shell and the ground electrode face each other in a direction different from a direction in which the metal shell and the ground electrode face each other at the third part, and wherein the second melt portion is in contact with the fourth part.

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