JP2005268222A - Ignition plug - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a defect of a conventional technique in an ignition plug for an internal combustion engine having a center electrode and at least one grounding electrode connected to a plug housing, which is made to cooperate with the center electrode so as to form a spark distance. <P>SOLUTION: The ignition plug is configured so that a grounding electrode (18) has a supporting part (20) connected to a plug housing (12), the axial line of the supporting part (20) are arrayed almost in parallel with the center electrode and has a function part (22) connected to the supporting part (20) in a material connection manner to form the spark distance. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is a spark plug for an internal combustion engine, the spark plug having a center electrode and at least one ground electrode, the ground electrode being coupled to the plug housing, and It relates to a type adapted to cooperate with the central electrode to form a spark distance.

  A spark plug of this type is known, for example, from German Offenlegungsschrift 10201697 and is designed for use in an internal combustion engine of a motor vehicle operating on the so-called Otto principle.

  This known spark plug has a metal, generally tubular plug housing. The plug housing is formed with a screw for fixing to the cylinder head of the internal combustion engine and a wrench hexagonal portion as means for incorporation into the internal combustion engine. The housing is through-engaged by a substantially rotationally symmetric electrical insulator, and a so-called center electrode is fixed to the electrical insulator, and this center electrode is formed at the end of the plug housing on the combustion chamber side. Cooperate with the ground electrode. The center electrode and the ground electrode define the spark distance. This spark distance can be used to ignite the fuel mixture supplied into the combustion chamber. The ground electrode disposed laterally with respect to the center electrode is formed in a curved shape and has a small bending radius based on a slight configuration size. The bending process required to form the electrode can form a crack or the like. The bending process can also result in changes in the cross-section of the ground electrode. That is, material damage or material changes may be formed that adversely affect the mechanical stiffness of the material. Therefore, there is an increased risk of “vibration breakage” of the ground electrode when the spark plug is operated. The bending process also leads to detachment of the core that improves the thermal conductivity of the ground electrode from the electrode matrix, thereby degrading the overall thermal conductivity of the ground electrode.

  A spark plug provided with a ground electrode substantially corresponding to the spark plug, in which the ground electrode is formed in a roof shape, and the center electrode is covered with an end face, is, for example, European Patent No. 1244189. Known per specification. A spark plug with a ground electrode installed at an inclination with respect to the center electrode is known, for example, from German Offenlegungsschrift 10 20 5078.

In particular, in an internal combustion engine operating on the basis of the Otto principle, which is directly injected, the gas flow formed in the combustion chamber is almost independent of the orientation of the ground electrode by installing the ground electrode laterally or inclined. However, it is only slightly prevented. A ground electrode installed laterally or inclined has a relatively small length, which creates a slight peak temperature on the ground electrode during operation of the spark plug, and thus wear due to electrode corrosion. Is limited. Furthermore, a small electrode length leads to a high natural frequency.
German Patent Publication No. 10201697 European Patent No. 1244189 German Patent Publication No. 102050878

  The object of the present invention is therefore to improve the drawbacks of the prior art.

  According to the means of the present invention for solving this problem, there is provided a spark plug for an internal combustion engine, wherein the spark plug has a center electrode and at least one ground electrode, and the ground electrode is a plug. A spark plug for an internal combustion engine of the type coupled to the housing and adapted to cooperate with the center electrode to form a spark distance is aligned with the axis substantially parallel to the center electrode. And a ground electrode having a support portion coupled to the plug housing and a function portion coupled to the support portion in a material connection manner for forming a spark distance.

  Such a spark plug has the following advantages. In other words, the structure of the ground electrode obtained in this way can achieve an arrangement suitable for the function of the ground electrode with respect to the center electrode without causing the ground electrode to bend during a bending process that may cause damage. can do. Rather, the functional part only needs to be welded to a predetermined position of the support part. This reduces the risk of vibration breakage during operation of the spark plug compared to the prior art described above.

  The material connection of the ground electrode can be effected in particular by the use of welding or hard brazing.

  In a special configuration of the spark plug according to the invention, the functional part and the support of the ground electrode are aligned with each other at an angle of 45 ° to 135 °, preferably at an angle of about 90 °.

  The functional part and the support part can already be connected to each other before the support part and the plug housing are connected or welded together.

  In order to improve the wear resistance of the ground electrode, a special steel element may be integrally formed in the functional part. This special steel element is formed in a pin shape in particular, and reduces the spark corrosion of the functional part. The special steel is advantageously formed from an alloy containing platinum, iridium, rhodium and / or palladium.

  The support part and the functional part are each advantageously made of an alloy, in particular a nickel alloy. The alloy used for the support part may correspond to or different from the alloy used for the functional part.

  The ground electrode may be configured as follows, that is, the functional portion is welded to the side surface of the support portion that does not face the ground electrode.

  The function part can be engaged with the notch of the support part for the connection with the support part so that the position part with high positional accuracy is guaranteed.

  The notch may be formed by, for example, a hole provided in a side surface of the support portion that does not face the center electrode, or may be disposed on an end surface of the support portion that does not face the plug housing. .

  In order to ensure good thermal conductivity in the ground electrode, at least the support may be provided with a nucleus, for example, a copper nucleus. The thermal conductivity of the copper core is higher than the thermal conductivity of the base material of the support portion. It is also possible to provide the functional part with an excellent nucleus due to its special high thermal conductivity. However, this sometimes leads to high manufacturing labor when the functional part and the support part are coupled. This is because it is inconvenient for the nucleus to be exposed to a reactive atmosphere formed in the combustion chamber of the internal combustion engine.

  The functional part and the support part are each manufactured by a coating molding method, and can have a shape suitable for each application. Thus, the support can also be formed by a rectangular, trapezoidal, conical, cylindrical, or stepped shape, for example. The support part is provided with a substantially S-shaped bent part, and a nucleus for improving thermal conductivity, which is provided in some cases, can follow the bent part.

  The functional part connected to the support part by welding connection may have a rectangular, trapezoidal, cylindrical or conical shape.

  In order to connect the functional part of the ground electrode and the support part, resistance welding, laser welding, or soldering can also be used.

  Further advantages and advantageous configurations of the object according to the invention are apparent from the drawings, the description and the claims.

  A spark plug 10 is shown in FIG. This spark plug 10 is designed for incorporation into an internal combustion engine (not shown) of an automobile. The spark plug 10 has a metal, generally tubular housing 12. The housing 12 has a tool shoulder in the form of a double hexagon 13 and a threaded shaft for mounting on a cylinder head of an internal combustion engine.

  The plug housing 12 is through-engaged by an electrical insulator 15, and a so-called center electrode 16 is fixed to an end surface side end portion of the electrical insulator 15. The center electrode 16 cooperates with a ground electrode 18 that similarly enters the combustion chamber of the internal combustion engine. The ground electrode 18 is coupled to the plug housing 12.

  The spark plug 10 has a connection contact 20 for connecting to the ignition coil at the end portion not facing the center electrode 16.

  The ground electrode 18 shown in detail in FIG. 2, FIG. 3 and FIG. 4 is disposed laterally with respect to the center electrode 16, and has a support portion 20 formed in a substantially tongue shape. The support 20 is aligned substantially parallel to the center electrode 18 and is welded to the plug housing 12. A functional part 22 is applied to the side of the support part 20 facing the center electrode 16 by laser welding. The function unit 22 defines a spark distance between the ground electrode 18 and the center electrode 16. The axis of the function part 22 and the axis of the support part 20 form an angle α of approximately 90 °.

  A special steel pin 24 (enlarged in FIG. 4) made of a platinum-containing alloy is welded to the tip of the functional part 22. In this case, in the present embodiment of the special steel pin 24, the welding process is applied to the functional layer 22 made of a nickel alloy by means of a continuously radiated disk type laser. In the welding process, a weld seam 26 is formed between the special steel alloy of the special steel pin and the nickel alloy of the functional part 22. The weld seam 26 is formed to be substantially homogeneous and substantially free of an interface. The outer circumference of the weld seam 26 has a height H from 0.35 mm to 0.8 mm, preferably 0.5 mm. The weld seam 26 tapers in a substantially conical shape over the entire circumference of the special steel pin 24 toward the symmetry axis of the special steel pin 24. The weld seam 26 has a height h of 0.03 mm to 0.3 mm, preferably 0.15 mm, in the region of the symmetry axis of the special steel pin 24.

  The support part 20 manufactured from the same nickel alloy as the functional part 22 has a copper core 28 in order to improve thermal conductivity.

  The support part 20 has a substantially rectangular outline. The functional part 22 provided with the special steel pin 24 has a substantially cylindrical shape or a stepped cylindrical shape.

  5 and 6 show an alternative configuration of the ground electrode 18 of the spark plug. This spark plug substantially corresponds to the spark plug shown in detail in FIG. The ground electrode 18 has a support portion 20, which is welded to the spark plug housing 12 and made of a nickel alloy, and a copper core 28 is embedded in the nickel alloy. Yes.

  In order to fix the functional part 22 to the support part 20, the support part 20 has a hole 30 on the side facing the central electrode. The diameter of the hole 30 substantially corresponds to the diameter of the functional part 22, and the functional part 22 is inserted into the diameter of the hole 30. For mechanical fixation, the support part 20 is embossed laterally after insertion of the function part 22, whereby the wall of the hole 30 is pressed against the function part 22. Subsequently, the support part 20 and the function part 22 are mutually couple | bonded by the laser welding method. In this case, the laser radiation can be directed to the side of the support 20 that is coupled to the plug housing 12 or to the end of the support 20 that is not directed to the plug housing 12, so that welding A seam 32 is formed between the support portion 20 and the functional portion 22.

  7 and 8 show another alternative configuration for the ground electrode 18 of the spark plug. Again, this spark plug substantially corresponds to the spark plug shown in FIG. The ground electrode 18 has a support portion 20, which has a copper core 28 and is welded to the plug housing 12. On the end surface not facing the plug housing 12, the support portion 20 has a substantially semicircular cutout 36 before being coupled to the functional portion 22. The functional portion 20 is inserted into the notch 36 when coupled to the support portion 20. Subsequently, the support part 20 is embossed laterally for mechanical fixation of the functional part 20. Next, the functional portion 22 is welded to the support portion 20 by forming a weld seam 32 by laser welding. In this case, laser radiation is applied to the end of the pre-assembled ground electrode 18 that is not facing the plug housing 12.

  In the said Example, the function part 22 and the support part 20 are welded by the largest possible surface, and, thereby, it is good from the spark surface of the ground electrode 18 formed by the function part 22 or the special steel pin 24 to the plug housing 12. Heat flow is guaranteed.

  In order to adjust the distance between the ground electrode 18 and the center electrode 16, the ground electrode 18 can be bent in the direction of the center electrode 16, respectively. In this case, the bending angle may be from 0 ° to 20 °, preferably about 10 °. In this case, the inclination of the ground electrode 18 is performed with respect to the pivot axis formed between the support portion 20 and the plug housing 12.

It is a schematic partial cross-sectional view of a spark plug.

It is a side view which shows the ground electrode of the ignition plug by FIG.

FIG. 3 is a second side view showing the ground electrode according to FIG. 2.

FIG. 3 is an enlarged view showing a region defining a spark distance of the ground electrode according to FIG. 2.

It is a figure which shows the support part of a ground electrode with the plug housing of the alternative structure of the ignition plug by this invention.

It is a figure which shows the support part shown in FIG. 5 regarding the functional part of a ground electrode.

It is a figure which shows the plug housing of the 3rd structure of the ignition plug by this invention with the support part of a ground electrode.

It is a figure which shows the support part shown in FIG. 7 provided with the function part integrally molded.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Spark plug, 12 Housing, 13 Double hexagon part, 14 Screw shaft, 15 Electrical insulator, 16 Center electrode, 18 Ground electrode, 20 Support part, 22 Function part, 24 Special steel pin, 26 Weld seam, 28 Copper core , 30 holes, 32 weld seams, 36 notches,

Claims (9)

  A spark plug for an internal combustion engine, the spark plug having a center electrode (16) and at least one ground electrode (18), the ground electrode (18) being plug housing (12). ) And is adapted to cooperate with the central electrode (16) to form a spark distance, a ground electrode (18) is coupled to the plug housing (12). A support part (20), the axis of the support part (20) being aligned substantially parallel to the central electrode (16) and coupled to the support part (20) in material connection A spark plug for an internal combustion engine, characterized in that it has a function part (22) for forming a spark distance.   Spark plug according to claim 1, characterized in that the functional part (22) and the support part (20) are aligned with each other at an angle between 45 ° and 135 °, preferably at an angle of about 90 °.   The spark plug according to claim 1 or 2, wherein the special steel element (24) is integrally formed in the functional part (22).   The spark plug according to any one of claims 1 to 3, wherein the functional part (22) is welded to a side surface of the support part (20) facing the center electrode (16).   The function part (22) according to any one of claims 1 to 4, wherein the functional part (22) engages the notch (30, 36) of the support part (20) for coupling with the support part (20). Spark plug.   6. The spark plug according to claim 5, wherein the notch (30) is formed by a hole provided in a side surface of the support portion (20) facing the center electrode (16).   6. The spark plug according to claim 5, wherein the notch (36) is arranged on the end face of the support part (20) not facing the plug housing (12).   The support (20) comprises a nucleus (28), the thermal conductivity of which is greater than the thermal conductivity of the base material of the support (20). The spark plug according to the item.   The spark plug according to any one of claims 1 to 8, wherein the support portion (20) and the functional portion (22) are formed of a base material made of the same alloy.

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