SPARK PLUG

Abstract

A spark plug (10) comprising: a center electrode (13); a metal casing (20) which insulates the center electrode (13) at an outer circumference of the center electrode (13); a ground electrode (30) which is arranged such that a spark gap (33) is formed between the center electrode (13) and an end section of the ground electrode (31); and a spark plug cap (40) which is connected to the metal casing (20), wherein the spark plug cap (40) covers the center electrode (13) and the end section of the ground electrode (31) from the front and has a through-hole (41) in a region in front of the ground electrode (30), wherein an inner surface of the spark plug cap (44) has at least one burr (52) in a first region (45) which is located in front of an inner open end of the through-hole (48).

Description

Description BACKGROUND OF THE INVENTION Field of invention

[0001] The present invention relates to a spark plug with a pre-chamber for the combustion chamber of an engine. Description of the technical background

[0002] A spark plug with a pre-chamber for the combustion chamber of an engine is known. This type of spark plug contains A candle cap connected to a metal casing and featuring a through-hole. The candle cap is in the The combustion chamber is exposed, so the pre-chamber is located within the combustion chamber. The spark plug ignites combustible air. Fuel mixture that has flowed from the combustion chamber through the through-hole into the spark plug cap. The combustible An air-fuel mixture is burned to create an expansion pressure that produces a gas stream including a flame. The fuel is injected through the through-hole into the combustion chamber. The combustible air-fuel mixture in the combustion chamber is then... burned by the injected flame stream. Patent document 1 (especially Fig. 26) discloses a spark plug. This text has been copied by the DPMA from the original sources. It does not contain any drawings. The tables and formulas may be of unsatisfactory quality. with a candle cap that has an inner surface on which burrs are present in an area behind the through holes. are formed so that the cross-sectional area of ​​the antechamber gradually increases towards the rear. Citation list Patent literature

[0003] PTL 1: Publication of the Japanese unexamined patent application No. 2006-144648

[0004] However, according to the technology disclosed in patent document 1, when the flammable air-fuel mixture The mixture flows from the combustion chamber through the through-holes into the spark plug cap, the spark plug cap which is in the The combustion chamber is exposed and cooled by the combustible air-fuel mixture. In particular, the temperature of a The temperature of the front part of the spark plug cap is lower than the temperature of the rear part of the spark plug cap. This results in the The temperature of the combustible air-fuel mixture is reduced in a front area of ​​the spark plug cap. Accordingly, the flame propagation speed is reduced in the area around the front end of the candle cap. corresponding to the reduction in the temperature of the combustible air-fuel mixture. If the The flame propagation speed from the inside of the candle cap towards the through holes is reduced, The combustion rate in the combustion chamber is adversely affected. SUMMARY OF THE INVENTION

[0005] The present invention was made to solve the problem described above, and is an object of the The present invention is to provide a spark plug capable of increasing the speed of the To increase flame spread from the inside of a candle cap to a through-hole.

[0006] To achieve the above-described goal, a spark plug according to the present invention contains a central electrode; a metal casing that insulates the central electrode against an outer circumference of the central electrode; a ground electrode arranged such that a connection exists between the center electrode and an end section of the ground electrode A spark gap is formed; and a candle cap connected to the metal casing, the candle cap being the The center electrode and the end section of the ground electrode are covered from the front and in an area in front of the ground electrode It has a through-hole. An inner surface of the candle cap has at least one burr in a first region, which located in front of an inner open end of the through-hole.

[0007] In a spark plug of a first aspect, the inner surface of the spark plug cap comprises the first region in which At least one ridge is formed in front of the inner open end of the through-hole. Therefore, the flow of flammable air-fuel mixtures near the first region will be more severely disrupted than if the first region has no ribs. The influence of the degree of interruption in the flow of the combustible air-fuel mixture on An increase in the flame propagation speed is greater than the influence of the temperature of the combustible air. Fuel mixtures affect the flame propagation speed. Therefore, the flame propagation speed can Despite the reduction in the temperature of the combustible air-fuel mixture, it can be increased. This allows the The flame propagation speed from the inside of the candle cap towards the through-hole is increased.

[0008] According to a spark plug of a second aspect, the size of the burr is such that the length of the burr in The circumferential length of the inner surface is greater than the axial length of the ridge. Therefore, it can easily A turbulent flow is generated when the combustible air-fuel mixture exiting the combustion chamber is forced through The liquid flowing through the through-hole into the candle cap flows along the first region in the axial direction. Therefore Not only can the effects of the first aspect be achieved, but also the flame propagation speed can be further increased.This text has been copied by the DPMA from the original sources. It does not contain any drawings. The tables and formulas may be of unsatisfactory quality.

[0009] In a spark plug of a third aspect, the burr extends over the entire circumference of the inner surface of the spark plug core. throughout. Therefore, turbulent flow can be generated more easily than if only part of the total circumference of the The inner surface of the spark plug cap is provided with a burr. Accordingly, not only the effects of the first and second aspect, but the flame propagation speed can also be further increased.

[0010] In a spark plug of a fourth aspect, the inner surface of the spark plug cap additionally has the burr in a second Region located in front of the ground electrode and behind the inner open end. Therefore, turbulent flow can easily occur. are generated when the combustible air-fuel mixture, which flows from the combustion chamber through the through-hole into the The candle cap has flowed, flowing backwards along the second region. Furthermore, the turbulent flow can They can also be easily generated if the gas flow, including the flame, flows forward along the second region. Therefore, not only the effects of the first to third aspects can be achieved, but also the Flame propagation speed can be increased further. List of characters Fig. 1 is a partial sectional view of a spark plug according to one embodiment; Fig. 2 is an enlarged section of part II of the spark plug shown in Fig. 1; Fig. 3 is an enlarged section of part III of the spark plug shown in Fig. 2; Fig. 4 is a schematic top view of a first region in the direction of arrow IV in Fig. 2; and Fig. 5 is an enlarged section of part V of the spark plug, which is shown in Fig. 2. DESCRIPTION OF PREFERRED EXECUTION FORMS

[0011] Preferred embodiments of the present invention are now described with reference to the accompanying The drawings are described. Fig. 1 is a partial sectional view of a spark plug 10 according to one embodiment. The underside The front of Fig. 1 is defined as the front of the spark plug 10 and the top of Fig. 1 as the back of the spark plug 10. This also applies to Fig. 2. Fig. 1 shows a cross-section of a front end part of the spark plug 10 including an axial Line O. As shown in Fig. 1, the spark plug 10 contains an insulator 11, a center electrode 13, a metal casing 20, a ground electrode 30 and a spark plug cap 40.

[0012] The insulator 11 is a substantially cylindrical element with an axial bore 12 extending along the axial line O extends, and is made of a ceramic, such as aluminum oxide, which has good mechanical properties and high exhibiting insulating properties at high temperatures, the central electrode 13 is located in a front region of the axial bore 12 in the insulator 11. The central electrode 13 is electrically connected to a metal terminal 14 in the axial bore 12 connected. The metal connection 14 is a rod-shaped element to which a high-voltage cable (not (as shown) is connected and is made of a conductive metal material (e.g., low-carbon steel). Metal connector 14 is attached to the rear end of the insulator 11.

[0013] The metal casing 20 is a substantially cylindrical element made of a conductive metal material (e.g. low-carbon steel). The metal casing 20 includes a front end section 22 with an external thread 21 that is threaded onto an outer circumferential surface thereof is formed, a seat section 23 which is located next to and behind the front End section 22 is located, and a tool engagement section 24 is provided behind the seat section 23. External thread 21 is screwed into a threaded bore 2 in a motor 1. The seat section 23 is a section which This text has been copied by the DPMA from the original sources. It does not contain any drawings. The tables and formulas may be of unsatisfactory quality. seals a gap between the threaded bore 2 in the motor 1 and the external thread 21 and a has an outer diameter that is larger than the outer diameter of the external thread 21. The tool engagement part 24 engages a tool, such as a wrench, which is used to screw the external thread 21 into the Threaded hole 2 in motor 1 is used.

[0014] The ground electrode 30 is a rod-shaped element made of a metal material, which e.g. Ni as the main component contains. In the present embodiment, the ground electrode 30 is arranged at a location where the An external thread 21 is provided, and extends through the front end section 22 to enter the interior of the front End section 22 protrudes. An end section 31 of the ground electrode 30 is opposite the center electrode 13. The candle cap 40 is connected to the front end section 22 of the metal casing 20.

[0015] The spark plug cap 40 is a part that separates the center electrode 13 and the end section 31 of the ground electrode 30 from The front is covered. The spark plug cap 40 is made of a metal material that contains, for example, nickel as its main component. The candle cap 40 has at least one through hole 41 in one Area in front of the ground electrode 30. In the present embodiment, a plurality of Through holes 41 are formed. When installing the spark plug 10, the external thread 21 is screwed into the Threaded bore 2 in engine 1 exposes the spark plug cap 40 to a combustion chamber 3 of engine 1. The through-holes 41 connect a pre-chamber 42, which is surrounded by the metal shell 20 and the candle cap 40, to the combustion chamber 3.

[0016] Fig. 2 is an enlarged sectional view of part II of the spark plug 10 shown in Fig. 1, including the Axial line O. The front end section 22 of the metal shell 20 has a recess 25 located in an area where the The external thread 21 is provided, offset radially inwards. The front end section 22 also has a hole 26, which thinner than the recess 25, in an area radially within the recess 25. The hole 26 extends in radial direction through the front end section 22. The other end section 32 of the ground electrode 30 is inserted into the hole. 26 inserted and connected to the front end section 22 by a welded section 27. A spark gap 33 is formed between the end section 31 of the ground electrode 30 and the center electrode 13. Since the The ground electrode 30 is connected to the metal casing 20 in the area where the external thread 21 is provided. The heat is transferred from the ground electrode 30 to the motor 1 via the external thread 21.

[0017] Each through-hole 41 has an outer open end 47 in an outer surface 43 of the candle cap 40 and a inner open end 48 in an inner surface 44 of the candle cap 40. The inner open end 48 of each through-hole 41 is positioned in front of the end section 31 of the ground electrode 30. Each through-hole 41 faces forward in the direction of the The inner open end 48 is inclined towards the outer open end 47. In the present embodiment, the rear ends 49 of the inner open ends 48 of the through holes 41 all on one plane 50 perpendicular to the axial Line O is positioned. The spark plug cap 40 is welded to the front end section 22 of the metal casing 20. Section 51 connected.

[0018] The inner surface 44 of the candle cap 40 is divided into a first region 45, which is located in front of the inner open ends 48 of the The first region is divided into two parts: one with through holes 41, and a second region 46, which is located behind the first region 45. The first region 45 is a part of the inner surface 44 of the candle cap 40, which is located in front of a cross-section of the candle cap 40 along level 50. The second region 46 is part of the inner surface 44 of the candle cap 40, which is located behind the Cross-section of the candle cap 40 along the plane 50. The first region 45 is spherical, and the second Region 46 is cylindrical or spherical. The first region 45 comprises a front end surface 45a, which is circular. and is flat.This text has been copied by the DPMA from the original sources. It does not contain any drawings. The tables and formulas may be of unsatisfactory quality.

[0019] Fig. 3 is an enlarged section of part III of the spark plug 10, which is shown in Fig. 2. As shown in Fig. 3, The candle cap 40 contains at least one ridge 52 in the first region 45. In the present embodiment, Several ridges 52 are planned in the first region 45.

[0020] Fig. 4 is a schematic top view of the first region 45 in the direction of arrow IV in Fig. 2. Fig. 4 shows a Part of the first region 45 around the front face 45a in the middle, and a region around this part is not shown. As shown in Fig. 4, the ridges 52 formed in the first region 45 are in the part of the first region 45 around the front end surface 45a arranged around and extend circumferentially along the circular front End surface 45a. The size of each ridge 52 is such that the length of the ridge 52 in the circumferential direction of the first region 45 is greater than the length of the ridge 52 in the axial direction of the first region 45. The first region 45 spreads both in the radial and axial directions. Therefore, the length of each ridge can be 52 in the axial direction. the first region 45 can also be referred to as the length of each ridge 52 in the radial direction of the first region 45.

[0021] In the present embodiment, each ridge 52 has the shape of an arc with the axial line O in the middle, and The ridges 52 are connected to each other in the circumferential direction in such a way that the ridges 52 extend over the entire circumference of the first Region 45 are continuously interconnected. However, Fig. 4 is a schematic diagram and therefore does not show it. the parts of the arc-shaped ridges 52 that are connected to each other circumferentially. The ridges 52 that extend over the The entire perimeter of the first region 45 are continuously connected to each other and are concentric around the axial line O. arranged. The concentrically arranged ridges 52 lie next to each other in the radial direction of the first region 45. The ridges 52 extend over the entire area of ​​part of the first region 45, with the exception of the front end surface. 45a formed.

[0022] Again with reference to Fig. 3, a profile curve 53 of the surface of the first region 45 extends radially inwards (to the right in Fig. 3) with increasing distance forwards (downwards in Fig. 3). Profile curve 53 is a The line of intersection between a plane containing the axial line O (plane of Figure 3) and the first region 45. It is not It is necessary that the entire profile curve 53 is inclined radially inwards with increasing distance to the front. However, at least part of the profile curve 53 is inclined in this way. The profile curve 53 is determined, for example, by the fact that the Surface properties of the first region 45 according to JIS B0601:2013 using an optical non-contact A surface roughness measuring device detects and extracts short- and long-wave components from the resulting curve using a Filters will be removed.

[0023] A height H and a length T of each ridge 52 can be determined from the profile curve 53. The height H of each ridge 52 is the distance between a vertex 56 of the ridge 52 and a line segment 55, which is adjacent roots. 54 of ridge 52 connects to profile curve 53. The length T of ridge 52 is the length of line segment 55. The heights H and the lengths T of the ridges 52 are adjusted accordingly. For example, the ridges 52 are shaped so that their Heights H are in the range of 2 to 10 µm and their lengths T are in the range of 10 to 50 µm. The heights H and the lengths T The ridges 52 are preferably located in these areas because a gas flow in the radial direction (axial line direction) The first region 45 may be more severely disrupted.

[0024] Fig. 5 is an enlarged section of part V of the spark plug 10, which is shown in Fig. 2. As shown in Fig. 5, The spark plug cap 40 also contains at least one ridge 57 which extends circumferentially in the second region 46. extends. In the present embodiment, a plurality of ridges 57 are provided in the second region 46. The size of each ridge 57 is such that the length of the ridge 57 in the circumferential direction of the second region 46 is greater than the length of the ridge 57 in the axial line direction of the second region 46.This text has been copied by the DPMA from the original sources. It does not contain any drawings. The tables and formulas may be of unsatisfactory quality.

[0025] In the present embodiment, each ridge 57 has the shape of an arc with the axial line O in the middle, and The ridges 57 are connected to each other in the circumferential direction in such a way that the ridges 57 extend over the entire circumference of the second Region 46 are continuously interconnected. Ridges 57, which extend across the entire perimeter of the second Region 46 They are continuously connected to each other and are arranged concentrically around the axial line O. The arranged ridges 57 are arranged side by side in the axial direction of the second region 46. The ridges 57 are formed across the entire area of ​​the second region 46.

[0026] A profile curve 58 of the surface of the second region 46 extends radially inwards (right in Fig. 5) with increasing distance forward (below in Fig. 5). The profile curve 58 is an intersection line between a plane that the axial line O (plane of Fig. 5) and the second region 46. It is not necessary that the entire Profile curve 58 is inclined radially inwards with increasing distance to the front. However, at least part of the Profile curve 58 is inclined in this way. Profile curve 58 can be determined using a method similar to the method for Determination of the profile curve 53 of the first region 45 is similar.

[0027] Similar to the ridges 52 in the first region 45, the heights H and lengths T (not shown) of the Ridges 57, which are determined from the profile curve 58, are adjusted accordingly. The ridges 57 are, for example, set as follows: shaped such that their heights H are in the range of 2 to 10 µm and their lengths T are in the range of 10 to 50 µm. The heights H and the lengths T of the ridges 57 are preferably located in these areas, since a gas flow in the axial direction of the second Region 46 may be more severely disrupted.

[0028] The burrs 52 and 57 can be formed, for example, when a workpiece from which the candle cap 40 is formed is rotated together with a main shaft of a lathe or similar machine, and when a [device] is arranged on a pendulum table Cutting tool brought into contact with the workpiece and moved in left-right and forward-backward directions. is formed to create the inner surface 44 of the candle cap 40 by a cutting process. The ridges 52 and 57 are thus shaped so that its center lies on the axis of rotation of the main shaft. On the front end face 45a, which is the axis of rotation of the If the main shaft cuts perpendicularly, no burrs 52 are formed. The lengths of the burrs 52 and 57 in the direction of the axial line and in the circumferential direction, based on the speed at which the cutting tool is moved, to be adjusted. After the ridges 52 and 57 have been formed on the inner surface 44 of the candle cap 40, the Through holes 41 in the candle cap 40 are formed, for example, by a cutting process.

[0029] The cutting process with a cutting tool is an example of a method for forming the burrs 52 and 57, And ridges 52 and 57 can of course also be formed by a different method. An example of another method... The process is laser processing, in which the inner surface 44 of the candle cap 40 is irradiated with a laser beam, while auxiliary gas is blown against it to remove the molten part. Alternatively, the spark plug cap 40 can be used on The ridges 52 and 57, which are formed, are produced using powder metallurgy.

[0030] In response to a valve actuation of the engine 1 (see Fig. 1), the combustible air-fuel mixture flows from the combustion chamber 3 through the through holes 41 into the spark plug cap 40 of the spark plug 10, which is attached to the engine 1. The flow of the combustible air-fuel mixture that has entered the spark plug cap 40 is a Turbulent flow. The spark plug 10 causes a discharge between the center electrode 13 and the ground electrode. 30, to generate a flame core in the spark gap 33. As the flame core grows, the combustible air- The fuel mixture in spark plug cap 40 is ignited and burned. The combustion creates an expansion pressure, so that the spark plug 10 directs a gas flow, including flame, through each through-hole 41 into the combustion chamber 3 The combustible air-fuel mixture in combustion chamber 3 is ignited by the injected flame stream. burned.This text has been copied by the DPMA from the original sources. It does not contain any drawings. The tables and formulas may be of unsatisfactory quality.

[0031] When the combustible air-fuel mixture flows from the combustion chamber 3 through the through-holes 41 into the The spark plug cap 40, which is exposed in combustion chamber 3, is exposed to the combustible air-fuel mixture. The mixture is cooled. Accordingly, the temperature of a front part of the spark plug cap will be 40 degrees lower than the Temperature of a rear part of the candle cap 40, located near the insulator 11 serving as a heat source is arranged. This reduces the temperature of the combustible air-fuel mixture in a front area in the Spark plug cap 40 reduced. Accordingly, in the area of ​​spark plug cap 40 around the front end, the Flame propagation speed corresponds to the reduction in the temperature of the combustible air-fuel mixture. The mixture will be reduced.

[0032] However, since the inner surface 44 of the candle cap 40 is the first region 45 in which at least one ridge 52 is formed, the inner open ends 48 of the through holes 41, the flow of flammable air-fuel- The mixture is more severely disturbed when the combustible air-fuel mixture flows along the first region 45 than if the first region 45 has no ridges. The flow of the combustible air-fuel mixture is affected by the first region 45 both when the combustible air-fuel mixture flows into the spark plug cap 40 and when The outflow of the combustible air-fuel mixture from the spark plug cap 40 is disrupted. The influence of the degree of interruption of the flow of the combustible air-fuel mixture to an increase in the The flame propagation speed is greater than the influence of the temperature of the combustible air-fuel mixture. on the flame propagation speed. Therefore, the flame propagation speed can still increase despite the reduction. the temperature of the combustible air-fuel mixture is increased. This allows the The flame propagation speed from the inside of the candle cap 40 to the through holes 41 is increased. This allows the flammable air-fuel mixture to be burned quickly in combustion chamber 3.

[0033] The size of each burr 52 of the spark plug 10 is dimensioned such that the length of the burr 52 in the circumferential direction of the The inner surface 44 is larger than the length of the ridge 52 in the direction of the axial line of the inner surface 44. Therefore, it more likely that the combustible air-fuel mixture, which is drawn from combustion chamber 3 through the through-holes 41 has flowed into the candle cap 40, comes into contact with the ridges 52 when the flammable air-fuel mixture along the first region 45 in the axial line direction (radial direction), and the turbulent flow can easily can be generated. Accordingly, the flame propagation speed can be further increased.

[0034] The ridges 52 extend continuously over the entire circumference of the inner surface 44 of the candle cap 40. Therefore, it more likely that the flammable air-fuel mixture will come into contact with the ridges 52 if the flammable The air-fuel mixture flows along the first region 45 in an axial direction (radial direction), as if the ribs were in a part of the total circumference of the inner surface 44 of the candle cap 40 are provided, and the turbulent flow It can be generated more easily. Accordingly, the flame propagation speed can be further increased.

[0035] The inner surface 44 of the candle cap 40 additionally contains the ridges 57 in the second region 46, which is located in front of the The ground electrode 30 and the inner open ends 48 are located there. Therefore, turbulent flow can easily occur even then. are generated when the combustible air-fuel mixture, which comes out of the combustion chamber 3 through the through holes 41 has flowed into the candle cap 40 and flows backwards along the second region 46. Furthermore, the turbulent Flow can also be easily generated if the gas flow, including the flame, runs along the second region 46 flowing forwards. Therefore, the flame propagation speed through the ridges 57 behind the inner open Ends 48 will be increased further.

[0036] Although the present invention has been described on the basis of one embodiment, the present The invention is in no way limited to the embodiment described above, and it is easily understood that in Various improvements and modifications are possible within the meaning of the present invention. For example, the shape of the Candle cap 40, the number, shapes, sizes, etc. of the through holes 41, as well as the heights H and lengths T of the ridges 52 These are only examples and can be adjusted accordingly. This text has been copied by the DPMA from the original sources. It does not contain any drawings. The tables and formulas may be of unsatisfactory quality.

[0037] Although the spark plug cap 40 is welded to the metal casing 20 in the embodiment, the spark plug cap is not absolutely limited to that. For example, the candle cap can be a front one. End section of a tubular element with a closed front end, which is connected to the front End section 22 of the metal casing 20 is connected. The tubular element is arranged such that it forms the outer circumference. surrounding the front end section 22 of the metal casing 20. A [feature] on the outer circumferential surface of the tubular element. The formed external thread is screwed into the threaded hole 2 in the motor 1.

[0038] The tubular element (candle cap) can be connected to the front end section 22 of the metal casing 20. this can be achieved, for example, by forming an internal thread on an inner circumferential surface of the tubular element and The internal thread is screwed onto the external thread 21 formed on the front end section 22. Alternatively, a rear end section of the tubular element and the seat section 23 of the metal shell 20 e.g. by welding They can be connected to each other. Alternatively, a flange can be formed at the rear end section of the tubular element. The seat section 23 of the metal shell 20 and the flange can be joined together, for example, by welding. The tubular element can be made, for example, from a metal material such as a nickel-based alloy, or be made from a ceramic, such as silicon nitride.

[0039] Although the ground electrode 30, which extends through the front end section 22 of the metal shell 20, is attached to a The position at which the external thread 21 is provided in the embodiment is the position of the The ground electrode is not necessarily limited to that. The spark plug cap can, for example, be positioned so that the front one The end surface of the front end section 22 of the metal shell 20 is exposed, and the ground electrode can of course be connected to the The front end face of the front end section 22 is connected. The ground electrode can be either straight or They have a curved shape. The ground electrode can be connected to the spark plug cap.

[0040] Although the inner open ends 48 of the through holes 41 in a cross-section of the candle cap 40 along The through holes do not necessarily appear in a plane that includes the axial line O in the execution. limited to that. The through holes in the candle cap 40 can of course be designed such that the positions their inner open ends are shifted relative to the axial line O such that the inner open ends are not in a Cross-section along a plane enclosing the axial line O. In such a case, the positions of the The inner open ends of the through holes are determined based on the inner open ends that are in a Cross-section of the candle cap 40 along a plane parallel to the axial line O appear. The first region 45 and the second Region 46 is determined based on the identified positions of the inner open ends of the through holes.

[0041] In this embodiment, an end section 31 of the ground electrode 30 is arranged in front of the center electrode 13, so that that the spark gap 33 is formed in front of the central electrode 13. However, the spark gap 33 is not necessarily located there. limited. For example, an end section 31 of the ground electrode 30 can of course be arranged such that it is protected by a The side surface of the central electrode 13 is spaced apart, so that the spark gap 33 is between the side surface of the The middle electrode 13 and the end section 31 of the ground electrode 30 are formed. Additionally, a variety of other components can be used. ground electrodes 30 are provided to form a multitude of spark gaps 33.

[0042] In the embodiment, the rear ends 49 of the inner open ends 48 of the through holes 41 are all on the plane 50 is positioned perpendicular to the axial line O. In other words, the rear ends 49 of the inner The open ends 48 are in the same position along the axial line. However, the arrangement of the rear ends 49 is not absolutely limited to this. The rear ends 49 of the inner open ends 48 can of course be attached to various Positions are located in the axial line direction. When the rear ends 49 of the inner open ends 48 are at The first region45, located in different positions in the axial line direction, is part of the inner surface 44 of the Candle cap 40, which is located in front of a cross-section of the candle cap 40, which is located along a plane perpendicular to the axial line O is taken and passes through one of the rear ends 49 of the inner open ends 48, which corresponds to the This text has been copied by the DPMA from the original sources. It does not contain any drawings. The tables and formulas may be of unsatisfactory quality. The rear end of the spark plug is closest to 10. The second region 46 is part of the inner surface 44 of the spark plug cap. 40, which is located behind the first region 45.

[0043] In the embodiment, the ridges 52 extend over the entire region of a part of the first region 45 with the exception of the front end face 45a and the ridges 57 over the entire second region 46. However, ridges 52 and 57 are not necessarily limited to that. Ridge 52 can of course be found in part of the first region 45, including the Front surface 45a can be formed, and the ridges 57 can of course be formed in part of the second region 46.

[0044] In the embodiment, the ridges 52 and 57 each have the shape of an arc with the axial line O in the middle, and the ridges 52 and 57 are connected to each other in the circumferential direction in such a way that the ridges 52 extend over the entire circumference the first region 45 and the ridges 57 over the entire perimeter of the second region 46 continuously are connected to each other. However, ridges 52 and 57 are not necessarily limited to this. For example, ridges 52 and 57 naturally be provided in parts of the circumference of the inner surface 44 of the candle cap 40 or in a It may be formed in a helical (spiral) shape.

[0045] If the burrs 52 and 57 are formed by a cutting process, the burrs 52 and 57 can be in a A helical shape can be formed by slowly rotating the workpiece together with the main shaft and the The cutting tool is moved slowly in left-right and forward-backward directions while the cutting tool is pressed against the workpiece. A single burr 52 can be provided if the burr 52 has a helical shape. has a shape and extends continuously in the first region 45. A single ridge 57 can be provided if the Ridge 57 has a spiral shape and extends continuously into the second region 46. Of course, several are possible. helical ridges 52 in the first region 45 and several helical ridges 57 in the second region 46 are provided. If several helical ridges 52 and several helical ridges 57 are provided, The helical ridges 52 and 57 can be arranged in several helix patterns or in the axial line direction. be arranged side by side.

[0046] Although the ridges 57 are formed in the second region 46 in the embodiment, the second region 46 not necessarily limited to that. The second region 46 cannot, of course, have ridges 57. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was generated automatically and is solely for the purpose of Included for the better information of the reader. 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 2006144648

[0003] ClaimsThis text has been copied by the DPMA from the original sources. It does not contain any drawings. The tables and formulas may be of unsatisfactory quality. 1. Containing a spark plug: a central electrode; a metal casing that holds the center electrode insulatorily against an outer circumference of the center electrode; a ground electrode which is arranged such that between the center electrode and an end section of the ground electrode a spark gap is formed; and a spark plug cap connected to the metal casing, wherein the spark plug cap contains the center electrode and the end section the ground electrode is covered from the front and has a through-hole in an area in front of the ground electrode, wherein an inner surface of the candle cap has at least one burr in a first area which is located in front of a is located at the inner open end of the through-hole. 2. The spark plug according to claim 1, wherein the size of the burr is such that a length of the burr in a circumferential direction the inner surface is greater than the length of the ridge in an axial line direction of the inner surface. 3. The spark plug according to claim 1 or 2, wherein the burr extends over the entire circumference of the inner surface. 4. The spark plug according to one of claims 1 to 3, wherein the inner surface of the spark plug cap additionally has the burr in a It has a second area that lies in front of the ground electrode and behind the inner open end.

Claims

[1] Containing a spark plug: a central electrode; a metal casing that holds the center electrode insulatorily against an outer circumference of the center electrode; a ground electrode arranged in such a way that a spark gap is formed between the center electrode and an end section of the ground electrode will; and a spark plug cap connected to the metal casing, the spark plug cap containing the center electrode and the end section of the ground electrode of The front is covered and it has a through hole in an area in front of the ground electrode. wherein an inner surface of the candle cap has at least one ridge in a first area which extends in front of an inner open end of the is located in the through-hole. [2] The spark plug according to claim 1, wherein the size of the burr is such that a length of the burr in a circumferential direction of the inner surface is greater than the length of the ridge in an axial line direction of the inner surface. [3] The spark plug according to claim 1 or 2, wherein the burr extends over the entire circumference of the inner surface. [4] The spark plug according to one of claims 1 to 3, wherein the inner surface of the spark plug cap additionally has the burr in a second area, which lies in front of the ground electrode and behind the inner open end.

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