Spark plug electrode and method of manufacturing the same

Abstract

A spark plug electrode formed using an additive manufacturing process, such as a powder bed fusion technique, on an electrode base. The spark plug electrode includes an electrode base at least partially surrounding a heat sink core, an electrode tip formed on the electrode base and comprising a noble metal-based material, and a thermal coupling region directly thermally coupling the electrode tip to the heat sink core. In some examples, the electrode tip is formed on an electrode base that has been cut or severed to expose a portion of the heat sink core, such that the electrode tip is formed directly on the heat sink core using additive manufacturing.

Description

[0001] This application is a divisional application of Chinese invention patent application No. 202310071774.2, filed on January 13, 2023, entitled "Spark Plug Electrode and Manufacturing Method Thereof". Technical Field

[0002] This invention relates generally to spark plugs and other ignition devices, and more particularly to spark plug electrodes and other components manufactured using additive manufacturing processes. Background Technology

[0003] Spark plugs are used to ignite combustion in internal combustion engines. Typically, a spark plug ignites the air / fuel mixture in the combustion chamber, generating a spark across the spark gap between two or more electrodes. This spark ignites the air / fuel mixture, triggering the combustion reaction in the combustion chamber responsible for the engine's power stroke. High temperatures, high voltage, the rapid repetition of the combustion reaction, and the presence of corrosive substances in the combustion gases create a harsh environment in which spark plugs must operate. This harsh environment leads to electrode erosion and / or corrosion, which negatively impacts spark plug performance over time.

[0004] To reduce electrode erosion and / or corrosion, various precious metals and alloys, such as those containing platinum and iridium, have been used. However, these materials are expensive, especially iridium. Therefore, spark plug manufacturers attempt to minimize the amount of precious metal used in the electrodes. One approach involves using precious metals only at the electrode tips or the ignition section of the electrode (i.e., where sparks ignite at both ends of the spark gap), rather than using precious metals on the entire electrode body.

[0005] Various bonding techniques, such as circumferential laser welding, have been used to attach precious metal electrode tips to electrode bodies. However, when precious metal electrode tips are circumferentially laser welded to an electrode body (e.g., a body made of a nickel alloy), significant thermal and / or other stresses may exist on the weld seam during spark plug operation due to the different properties of the materials (e.g., different coefficients of thermal expansion, different melting points, etc.). In circumferential laser welding processes where the workpiece rotates and the laser remains fixed in a generally radial orientation, factors such as the concentricity of the workpiece support and uneven wear can lead to uneven circumferential weld seams (e.g., the weld geometry and / or alloy composition may vary around the circumference of the workpiece), which further exacerbates the aforementioned stresses. These stresses can then undesirably cause cracking or other damage to the electrode body, electrode tips, joints connecting the two components, or combinations thereof.

[0006] Another challenge relates to cooling the precious metal electrode tip. If the precious metal electrode tip is not adequately cooled and allows significant heat to accumulate, the aforementioned stresses become even greater. This is especially true in applications with frequent load changes and high engine combustion temperatures (e.g., engine start-stop). One approach to this challenge is simply to move the heat-conducting core closer to the precious metal electrode tip and attach the tip to the electrode body using ring laser welding, but this itself presents challenges. One challenge involves variations in the spark point or ignition location of the electrode. The spark point is preferably located on the precious metal electrode tip because precious metals typically have the highest resistance to erosion and / or corrosion. However, when using a heat-conducting core located near the electrode tip to circumferentially laser weld the electrode tip to the electrode base, the welding process can pull or drag the heat-conducting core material to the outside of the electrode base in the weld area. This can undesirably change the spark point from its proper location on the surface of the precious metal electrode tip or move it to a weld surface less resistant to erosion and / or corrosion. Such variations in spark point negatively impact spark plug life.

[0007] The spark plug electrodes described in this article are designed to address one or more of the aforementioned drawbacks and challenges. Summary of the Invention

[0008] According to one embodiment, a spark plug electrode is provided, the spark plug electrode comprising: an electrode base; a heat sink at least partially surrounded by the electrode base; an electrode tip formed on the electrode base and including a plurality of laser-deposited layers; and a thermal coupling region at least partially located between the electrode tip and the heat sink, wherein the thermal coupling region thermally couples the electrode tip directly to the heat sink.

[0009] According to various embodiments, the spark plug electrode may have any one or more of the following features, individually or in any technically feasible combination:

[0010] - Wherein, the heat dissipation core extends along the central axis of the spark plug electrode and terminates at an axial end that does not reach the axial end of the electrode base, and the axial distance Z between the axial end of the heat dissipation core and the axial end of the electrode base is less than or equal to 1.3 mm;

[0011] - The heat sink extends along the central axis of the spark plug electrode and terminates at an axial end that reaches the axial end of the electrode base, and the axial distance Z between the axial end of the heat sink and the axial end of the electrode base is approximately 0.0 mm;

[0012] - The heat sink extends along the central axis of the spark plug electrode and terminates at an imaginary axial end. If the imaginary axial end is not truncated, the imaginary axial end will extend beyond the axial end of the electrode base. The axial distance Z between the imaginary axial end of the heat sink and the axial end of the electrode base is less than 0.0 mm.

[0013] - The spark plug electrode is a center electrode, and the electrode tip is a cylindrical component formed on the axial end of the electrode base. The electrode tip is oriented such that the plurality of laser-deposited layers are perpendicular to the central axis of the spark plug electrode, and the electrode tip is fixed to the electrode base by a seamless joint.

[0014] - The spark plug electrode is a ground electrode, and the electrode tip is a flat component formed on the side surface of the electrode base. The electrode tip is oriented such that the plurality of laser-deposited layers are parallel to the central axis of the ground electrode in the region of the electrode tip, and the electrode tip is fixed to the electrode base using a seamless joint.

[0015] - The plurality of laser-deposited layers are formed on the electrode substrate by an additive manufacturing process. The additive manufacturing process uses powder bed melting technology to melt or sinter noble metal-based powder onto the electrode substrate using a laser beam or electron beam, and then allows the molten or sintered powder to solidify into a laser-deposited layer at the electrode tip. The average layer thickness T of the plurality of laser-deposited layers is between 5 μm and 60 μm (inclusive), and the total thickness of the plurality of laser-deposited layers is between 0.05 mm and 3.0 mm (inclusive) at the electrode tip height H.

[0016] - The electrode tip comprises a noble metal-based material having at least one noble metal selected from the group consisting of iridium, platinum, ruthenium, palladium, or rhodium;

[0017] - The precious metal-based material is a platinum-based material, a ruthenium-based material, or an iridium-based material containing no more than 60 wt% iridium;

[0018] - The electrode base comprises a nickel-based material, the heat dissipation core comprises a copper-based material, and the thermal coupling region comprises nickel in the nickel-based material, copper in the copper-based material, and a noble metal in the noble metal-based material;

[0019] - The thermal coupling region forms a heat conduit from the electrode tip to the heat dissipation core located inside the spark plug electrode, so that the thermal coupling region is not exposed on the outer surface of the spark plug electrode;

[0020] -The average thermal conductivity of the thermal coupling region at the location between the electrode tip and the heat dissipation core is higher than that of the electrode base;

[0021] - The thermal coupling region comprises a thermal coupling region alloy, which includes at least one of copper in the heat dissipation core, nickel in the electrode base, and iridium, ruthenium, or platinum in the electrode tip;

[0022] - The thermal coupling region includes a first portion located near the heat sink core and a second portion located near the electrode tip, the first portion comprising a thermal coupling region alloy having 2-45 wt% noble metal from the electrode tip, and the second portion comprising a thermal coupling region alloy having 2-45 wt% copper from the heat sink core;

[0023] - The proportion of noble metals in the thermally coupled region alloy decreases from the second part to the first part along the central axis, and the proportion of copper in the thermally coupled region alloy decreases from the first part to the second part along the central axis to form a compositional gradient structure;

[0024] The thermal coupling region includes a first portion located adjacent to the heat sink core and a second portion located adjacent to the electrode tip. The first portion is bulbous and absorbs the axial end of the heat sink core, while the second portion has a wide and shallow shape and fills the area below the electrode tip.

[0025] - The electrode tip is constructed on the cut-off end of the electrode body, which has an exposed surface of the heat sink core, such that the cut-off axial end of the heat sink core is absorbed into the thermal coupling region.

[0026] According to another embodiment, a spark plug electrode is provided, comprising: an electrode base comprising a nickel-based material; a heat sink comprising a copper-based material, the heat sink being at least partially surrounded by the electrode base; an electrode tip comprising a noble metal-based material, the electrode tip being formed on the electrode base by an additive manufacturing process and comprising a plurality of laser-deposited layers perpendicular to the central axis of the spark plug electrode; and a thermal coupling region at least partially located between the electrode tip and the heat sink, the thermal coupling region forming a heat conduit from the electrode tip to the spark plug electrode such that the thermal coupling region is not exposed to the outer surface of the spark plug electrode, and the thermal coupling region comprising nickel in the nickel-based material, copper in the copper-based material, and a noble metal in the noble metal-based material, wherein the thermal coupling region directly thermally couples the electrode tip to the heat sink.

[0027] According to yet another embodiment, an additive manufacturing process for manufacturing spark plug electrodes is provided, comprising the steps of: providing an electrode body including an electrode base and a heat sink core at least partially surrounded by the electrode base; covering the ignition end of the electrode body with a thin powder bed comprising a noble metal-based material; guiding a laser beam or electron beam to the ignition end of the electrode body, such that it melts or sinterstals at least some of the thin powder bed; repeating multiple cycles of covering and guiding steps such that an electrode tip having multiple laser-deposited layers is formed on the electrode base, and such that a thermal coupling region is at least partially formed between the electrode tip and the heat sink core, wherein the thermal coupling region directly thermally couples the electrode tip to the heat sink core.

[0028] According to various embodiments, the additive manufacturing process may have any one or more of the following features individually or in any technically feasible combination:

[0029] -The providing step further includes providing an electrode body, the electrode base being cut or sliced ​​through the heat sink core, such that a portion of the heat sink core is exposed at an axial end;

[0030] - The guiding step further includes guiding the laser beam or electron beam to the ignition end of the electrode body and driving the laser beam or electron beam according to a non-uniform energy profile, the energy profile concentrating more energy toward the center of the ignition end and less energy toward the radially outer section of the ignition end;

[0031] - When the laser beam or electron beam melts or sinters a thin powder bed in a circular region oriented towards the center of the ignition end, the non-uniform energy profile drives the laser beam or electron beam at a higher energy level; conversely, when the laser beam or electron beam melts or sinterstalls a thin powder bed in an annular region concentric with the circular region and oriented towards the radially outer segment of the ignition end, the non-uniform energy profile drives the laser beam or electron beam at a lower energy level.

[0032] - The non-uniform energy profile helps to create a customized thermal coupling region, which includes a first portion located deeper in the electrode body and concentrated toward the center of the electrode body, and a second portion located closer to the electrode tip and extending further outward so that it is mainly located below the electrode tip. Attached Figure Description

[0033] Preferred embodiments will now be described in conjunction with the accompanying drawings, in which the same reference numerals denote the same elements, and wherein:

[0034] Figure 1 This is a side view of the spark plug;

[0035] Figure 2 yes Figure 1 A cross-sectional view of the ignition end of a spark plug, wherein the ignition end has an electrode tip, which is constructed on the electrode base via an additive manufacturing process, so that it is directly thermally coupled to the heat sink.

[0036] Figure 3-4 The following is a cross-sectional view of another example of the ignition end of a spark plug, wherein the ignition end has electrode tips built on the electrode base via an additive manufacturing process, so that they are directly thermally coupled to the heat sink.

[0037] Figure 5-7 Is it possible to... Figure 1-4 The cross-sectional view of the electrodes used together in the various spark plug examples shown, where each electrode has a precious metal-based electrode tip that is formed by additive manufacturing and directly thermally coupled to the heat sink core.

[0038] Figure 8 It is possible to be with Figure 1-4 Examples of various spark plugs shown or Figure 5-7 The illustrated electrode examples are used together to form an additive manufacturing process for a noble metal-based electrode tip that is directly thermally coupled to a heat sink core; and

[0039] Figure 9-12 (B) is with Figure 8 Cross-sectional and end views of electrodes at different manufacturing stages corresponding to the additive manufacturing process. Detailed Implementation

[0040] The spark plug electrode disclosed herein includes an electrode tip formed on an electrode base using an additive manufacturing process (e.g., powder bed melting technology), such that the electrode tip is directly thermally coupled to a heat sink. Some non-limiting examples of potential powder bed melting technologies that can be used include selective laser melting (SLM), selective laser sintering (SLS), direct metal laser sintering (DMLS), and electron beam melting (EBM).

[0041] For example, the electrode base can be made of a nickel-based material and can surround a heat sink made of a copper-based material, while the electrode tip is made of a precious metal-based material, such as one containing iridium, platinum, palladium, ruthenium, rhodium, etc. The choice of a precious metal-based material improves the spark plug electrode's resistance to corrosion and / or galvanic erosion. By using additive manufacturing processes to directly construct the electrode tip on the electrode base, a spark plug electrode with ideal cooling performance can be formed, where the electrode tip is directly thermally coupled to the heat sink. Those skilled in the art will understand that when a precious metal-based electrode tip is joined to a nickel-based electrode base, for example by circumferential laser welding, a significant amount of thermal stress and / or other stresses are typically present on the weld joint during spark plug operation due to various factors (e.g., different coefficients of thermal expansion, different melting points, non-uniform or inconsistent circumferential weld seams, etc.). These stresses can then undesirably lead to cracking or other damage to the electrode base, electrode tip, the joint connecting the two components, or their combination. Another possibility is that when using circumferential laser welding to attach a precious metal-based electrode tip to the electrode base, the laser welding process may pull or draw the copper-based material of the heat sink core to the circumferential sides of the electrode. This can have undesirable consequences, creating spark points on the circumferential sides of the electrode away from the intended ignition surface, thus shortening spark plug life. These and other challenges are exacerbated in internal combustion engines, such as start-stop engines, where spark plug electrodes are subjected to harsh conditions and extreme temperature and / or load variations. The spark plug electrode described in this paper—featuring an electrode tip formed through additive manufacturing that allows it to be directly thermally coupled to the heat sink core—is designed to address these challenges in an economical manner.

[0042] The spark plug electrode disclosed herein can be used in a variety of spark plugs and other ignition devices, including industrial spark plugs, automotive spark plugs, aviation igniters, glow plugs, pre-combustion chamber spark plugs, or any other device for igniting an air / fuel mixture in an engine or other machinery. This includes, but is not limited to, the exemplary industrial spark plugs shown in the accompanying drawings and described below. Furthermore, it should be noted that this spark plug electrode can be used as a center electrode and / or a ground electrode. Other embodiments and applications of this spark plug electrode are also possible. Unless otherwise stated, all percentages provided herein are expressed as weight percentages (wt%), and all references to axial, radial, and circumferential directions are based on the central axis A of the spark plug or spark plug electrode.

[0043] Reference Figure 1 and 2An exemplary spark plug 10 is shown, comprising a center electrode 12, an insulator 14, a metal housing 16, and a ground electrode 18. The center electrode 12 is disposed within an axial bore of the insulator 14 and includes an ignition end 20 protruding beyond a free end 22 of the insulator 14. As explained in more detail below, the ignition end 20 may include an electrode base 30 made of a nickel-based material, a heat sink 32 contained within the electrode base and made of a copper-based material, and an electrode tip 34 made of a noble metal-based material, wherein the electrode tip is formed on the electrode base using an additive manufacturing process such that the electrode tip is directly thermally coupled to the heat sink. The insulator 14 is disposed within an axial bore of the metal housing 16 and is made of a material (e.g., a ceramic material) sufficient to electrically insulate the center electrode 12 from the metal housing 16. The free end 22 of the insulator 14 may be retracted within the free end 24 of the metal housing 16 as shown, or it may protrude beyond the metal housing 16. The ground electrode 18 may be constructed according to a conventional J-gap configuration as shown in some of the figures or according to some other arrangement, and is attached to the free end 24 of the metal housing 16. According to this particular embodiment, the ground electrode 18 includes a side surface 26 facing the ignition end 20 of the center electrode, and has an electrode tip or electrode sheet 40 that may or may not be formed according to the additive manufacturing process described herein, as well as its own heat sink 42. The electrode tip 40 is in the form of a flat pad and, together with the electrode tip 34 of the center electrode, defines a spark gap G such that they provide ignition surfaces for electron emission, reception, and exchange across the spark gap G. The electrode tips 34 and 40 may be formed of the same noble metal-based material, or they may be formed of different noble metal-based materials.

[0044] exist Figure 1 and 2In the example shown, the electrode base 30 is an extension of the main electrode body 36 and is made of the same nickel-based material as the main electrode body 36. The electrode base 30 is part of the electrode body 36 and may have the same diameter (as shown), or it may be machined, reduced in diameter, or otherwise manufactured such that it has a smaller diameter than the adjacent electrode body 36, thus providing a base or surface on which the electrode tip 34 can be constructed. As will be explained more thoroughly, the electrode tip 34 can be formed directly on the electrode base 30 using an additive manufacturing process by selectively directing a laser beam or electron beam into contact with a bed of noble metal-based powder that is in axial contact with the electrode base. This causes the noble metal-based powder, along with a portion of the electrode base 30 and / or the heat sink 32, to melt or mix together and solidify at the ignition end 20. The additive manufacturing process is then repeated such that the noble metal-based electrode tip 34 is constructed layer by layer on the electrode base 30 until it reaches its desired height. By controlling various parameters such as laser energy distribution and the axial distance between the axial ends of the heat sink and the axial ends of the electrode base, additive manufacturing can establish a direct thermal coupling or connection between the electrode tip and the heat sink, which can have a significant impact on the thermal management of the electrode.

[0045] As described above, this spark plug electrode is not limited to Figure 1 and 2 The exemplary configuration is shown below. Figure 1 and 2 As shown, this spark plug electrode can be used in any number of different applications, including various industrial spark plugs, automotive spark plugs, aviation igniters, glow plugs, pre-combustion chamber spark plugs, or other devices. This spark plug electrode is also not limited to a center electrode, as it can be some type of ground electrode or grounding electrode. Some non-limiting examples of other potential applications for this spark plug electrode are shown below. Figure 3 and 4 As shown in the figure, where with Figure 1 and 2 Similar reference numerals denote similar features. Many other embodiments and examples are possible, such as various types of spark plugs with different axial, radial, and / or semi-surface spark gaps; pre-combustion chambers, non-pre-combustion chambers, shielded and / or unshielded configurations; multiple center and / or ground electrodes; and spark plugs that burn or ignite gasoline, diesel, natural gas, hydrogen, propane, butane, etc. The spark plug electrodes and methods of this application are by no means limited to the illustrative examples shown and described herein.

[0046] exist Figure 3In this spark plug, a ground electrode 18' with a bridge design, the opposite of a J-gap design, is connected at multiple locations to the free end 24' of a metal housing 16'. A center electrode 12' is at least partially surrounded by an insulator 14' and includes an electrode base 30' facing its ignition end 20', which has the same diameter as the adjacent electrode body 36' (this is not required, as the electrode base 30' can have different diameters; several possibilities are listed, it can be tapered, it can be stepped, etc.). As in the previous example, an electrode tip 34' is constructed or formed on the electrode base 30' using additive manufacturing processes and a precious metal-based powder bed. This process forms a thermally coupled region 38', which may be at least partially located between the heat sink 32' and the electrode tip 34' and thermally connects or links the two components in a more substantial way than if the electrode tip were simply circumferentially laser-welded to the electrode base. The accompanying diagram shows that the end shape of the heat sink 32' is more rounded or blunter, and the thermal coupling region 38' is larger than... Figure 2 The corresponding portion is flatter. It should be understood that the size, shape, location, orientation, and / or composition of the heat sink, thermal coupling region, and / or electrode tip may vary depending on the specific application in which they are used, and such components are not limited to the illustrative examples shown herein. The electrode tip or electrode sheet 40'—which is optionally and preferably made of a noble metal-based material—can be formed by this additive manufacturing process, or it can be soldered to the side surface 26' of the bridge ground electrode 18' to define the spark gap G together with the electrode tip 34'. Electrode tips 34' and 40' may be formed of the same noble metal-based material, or they may be formed of different noble metal-based materials. Other embodiments are also possible.

[0047] Go to Figure 4The spark plug is a pre-combustion chamber spark plug having a center electrode 12'', an insulator 14'', a metal housing 16'', and a ground electrode 18''. The center electrode 12'' includes an electrode base 30'' with a noble metal-based electrode tip 34'' formed thereon, a heat sink 32'', and an electrode body 36'', and the center electrode extends into the pre-combustion chamber space or volume 46''. A radial spark gap G is formed between the outer peripheral surface of the center electrode tip 34'' and the inner circular surface of the annular electrode plate 40'', which is fixed in place by a plurality of ground electrodes or ground electrode supports 18''. The additive manufacturing process described herein can be used to form the noble metal-based electrode tip 34'' one layer at a time on the axial end of the electrode base 30'', such that the electrode tip 34'' is directly thermally coupled to the heat sink 32'' via a thermal coupling region 38''. In this example, the annular electrode 40'' is made of a precious metal-based material and is attached to the ground electrode 18'' via welding or this additive manufacturing process. The electrode tip and electrode sheets 34'' and 40'' can be formed of the same precious metal-based material, or they can be formed of different precious metal-based materials.

[0048] Now go to Figure 5-7 Several center electrode ignition terminals are shown (e.g., those that can be connected to...). Figure 1-4An enlarged schematic diagram of those used with spark plugs. In any case, the center electrodes 12, 12', 12'' have ignition ends 20, 20', 20'', which include electrode bases 30, 30', 30'', heat sinks 32, 32', 32'', electrode tips 34, 34', 34'', and thermal coupling regions 38, 38', 38'', which act as heat conduits between the electrode tips and the heat sinks, allowing the two components to be directly thermally coupled to each other. Increasing the thermal connectivity between the electrode tips 34, 34', 34'' and the heat sinks 32, 32, 32'' allows for more efficient cooling of the electrode tips during operation, thereby allowing for the use of a wider range of precious metal-based materials in the electrode tips, including more cost-effective materials. It should be noted that the electro-corrosion rate of the electrode tips and therefore their effective service life are affected by a variety of factors, including the melting point of the precious metal-based materials. Iridium, with a melting point of approximately 2450°C, is more resistant to electro-corrosion than platinum, with a melting point of approximately 1750°C. Electrode tips made of iridium-based materials generally exhibit stronger resistance to electro-corrosion than those made of platinum-based materials, and are therefore sometimes more desirable. However, iridium can be more expensive, and in some cases significantly more expensive than platinum, so it may be desirable to minimize the use of iridium and / or other high-cost materials in the production of the electrode tips. This spark plug electrode achieves this by forming electrode tips 34, 34', 34'' on the electrode bases 30, 30'' using additive manufacturing technology, such that the electrode tips are directly thermally coupled to the heat sink 32, 32', 32'' via thermal coupling regions 38, 38', 38''. This keeps the electrode tips cool and allows for the use of a wider range of precious metal-based materials, including cheaper materials with lower melting points. It should be understood that the following description of the electrode base, electrode tip, heat sink, and thermal coupling regions is not limited to the center electrode shown in the figures, and also applies to other center electrode and / or ground electrode embodiments. For example, according to this application, a ground electrode may be provided having an electrode base made of a nickel-based material, an electrode tip made of a noble metal-based material, and a heat sink core (whether a single-material core or a multi-material core) made of one or more thermally conductive materials. In such an arrangement, the electrode tip can be formed on the side surface or axial end surface of the electrode base using this additive manufacturing technique, such that the electrode tip is directly thermally coupled to the heat sink core, as explained. Such and other center and / or ground electrode embodiments are, of course, within the scope of this application.

[0049] Electrode bases 30, 30', 30'' are typically electrode segments or portions on which electrode tips are formed through additive manufacturing, thus serving as carrier material for the electrode tips. As described above, electrode bases 30, 30', 30'' can be integral extensions of electrode bodies 36, 36', 36'', or they can be separate parts or components welded, additively manufactured, or otherwise attached to the electrode body. Electrode bases 30, 30', 30'' can be manufactured by stretching, extrusion, machining, and / or using certain other conventional processes and can be made of nickel-based materials. As used herein, the term "nickel-based material" refers to a material in which nickel is the single component by weight, and it may or may not contain other components (e.g., nickel-based material can be pure nickel, nickel containing some impurities, or a nickel-based alloy). According to one example, electrode bases 30, 30', 30'' are made of nickel-based materials with a relatively high weight percentage of nickel, such as nickel-based materials containing 98 wt% or more of nickel. In one different example, the electrode bases 30, 30', 30'' are made of a nickel-based material with a low nickel weight percentage, such as a nickel-based material containing 50-90 wt% nickel (e.g., INCONEL). TM (600 or 601). A particularly suitable nickel-based material contains approximately 70-80 wt% nickel, 10-20 wt% chromium, 5-10 wt% iron, and trace amounts of other elements. For nickel-based materials, the coefficient of thermal expansion of the electrode bases 30, 30', and 30'' may be around 10 × 10⁻⁶. -6 m / mK and 15×10 -6 The thermal conductivity is between 10 W / m·K and 20 W / m·K (measured at 100°C), with a melting point between 1,200°C and 1,600°C, and a thermal conductivity between 10 W / m·K and 20 W / m·K (measured at 100°C). The diameter or size of the electrode bases 30, 30', and 30'' can vary significantly depending on the specific application and embodiment (e.g., the size of the electrode base 30, which is part of the center electrode, may be smaller than the size of the electrode base of the electrode tip 40, which is part of the ground electrode; furthermore, the size of the electrode base of an industrial spark plug may be larger than that of an automotive spark plug). According to Figure 2-4The non-limiting examples shown (which are industrial spark plugs) have electrode base diameters that can be between 1.4 mm and 4.2 mm (inclusive), more preferably between 1.8 mm and 3.8 mm (inclusive). For automotive spark plugs and other spark plugs, these dimensions may be smaller and electrode base diameters may be between 0.7 mm and 3.0 mm (inclusive), more preferably between 1.0 mm and 2.5 mm (inclusive). Electrode bases 30, 30', 30'' can be made of other materials (including non-nickel-based materials) and other sizes and shapes (e.g., the electrode base does not necessarily include a circular cross-section with a "diameter," but may include an elliptical, square, rectangular, or other cross-section with a "dimension").

[0050] The heat sink 32, 32', 32'' is a segment or portion of the electrode, typically an elongated section extending along the central axis, at least partially surrounded or enclosed by the electrode base, and designed to transfer heat or thermal energy away from the ignition end. The exact dimensions, shape, and location of the heat sink 32, 32', 32'' may vary depending on the application, but it is generally an elongated internal portion extending along the central axis of the electrode and circumferentially surrounded by the nickel-based material of the electrode base, so that it is not exposed on either side of the electrode. Figure 5 In the example, the heat sink 32 has elongated sides 50, 52 extending in the longitudinal direction of the core, tapered sides 54, 56 converging toward one end of the core, and an axial end 58 terminating at the core. The heat sink 32 is made of one or more thermally conductive materials (e.g., copper-based or silver-based materials) with a thermal conductivity greater than that of the surrounding electrode base 30. The thermal conductivity of the thermally conductive material can be greater than 70 W / m·K (measured at 100°C), and more preferably, the thermal conductivity can be greater than 200 W / m·K (measured at 100°C). As used herein, the term "copper-based material" refers to a material in which copper is the single component with the largest weight percentage in the material, and it may or may not contain other components (e.g., a copper-based material can be pure copper, copper containing some impurities, or a copper-based alloy). According to one example, the heat sinks 32, 32', 32'' are made of a thermally conductive material that is a copper-based material with a high weight percentage of copper, such as a copper-based material containing 90 wt% or more copper. For copper-based materials, the coefficient of thermal expansion of heat sinks 32", 32'", and 32'' may be around 14 × 10⁻⁶. -6 m / mK and 19×10 -6 It has a temperature between m / mK (measured at 100°C), a melting point between 950°C and 1,200°C, and a thermal conductivity greater than 275 W / m·K (measured at 100°C).

[0051] The elongated sides 50 and 52 are generally parallel to each other and parallel to the central axis A, and contribute to forming the outer boundary of the heat sink 32. As mentioned above, it is generally undesirable for the heat sink material, which has much lower corrosion and / or erosion resistance than materials based on precious metals and has high electrical conductivity, to be exposed on the outer surface of the electrodes, which could become accidental spark points. Therefore, it is preferable that the heat sink 32 is covered in the region of the elongated sides 50 and 52 by such a sheath or shell of the electrode base 30—whose radial thickness X on both sides is greater than or equal to 0.2 mm.

[0052] The heat sink 32 typically does not terminate in a perfectly square shape, but rather tapers or narrows towards the axial end 58. This may be due to design factors or manufacturing processes, such as when the heat sink is initially inserted into the electrode base cup and then co-extruded or co-stretched with the electrode base. In some examples, the tapered sides 54, 56 are generally straight, angled sections that gradually converge toward each other (e.g., as shown). Figure 2 (as shown), but the conical side surface can also be rounded (e.g., as shown). Figure 3 (as shown) or even more square (e.g., as shown) Figure 4 (As shown). Although not required, it is preferred that the radial thickness Y of the electrode base 30 in the region of the tapered sides 54, 56 (measured at approximately halfway between the axial start and axial end points of the tapered side) is greater than or equal to 0.3 mm, but this dimension depends largely on the shape of the heat sink 32 in this region.

[0053] The axial end 58 of the core can have many different shapes and configurations, including pointed, rounded, blunt, square, etc. The position of the axial end 58 determines the axial distance Z, which is the axial distance between the axial end 58 of the core and the axial end 60 of the electrode base, excluding the electrode tip 34. The axial distance Z can significantly affect the thermal coupling between the electrode tip 34 and the heat sink 32, and can affect the operation and manufacturing of the spark plug. In a non-limiting example, the axial distance Z is less than or equal to 1.3 mm, more preferably less than or equal to 1.05 mm, more preferably less than or equal to 0.8 mm, and more preferably less than or equal to 0.55 mm. In some examples, the axial end 58 of the heat sink 32 can even be in the same axial position as the axial end 60 of the electrode base 30 (e.g., see...). Figure 6 This makes the axial spacing Z essentially 0 mm, or the axial end 58 of the heat sink core can be cut off (e.g., see...). Figure 7This results in a negative axial spacing Z. However, testing has shown that simply reducing and / or increasing the axial spacing Z can be challenging without adequate countermeasures. For example, if the axial spacing Z in some conventional spark plugs is too small, reliable circumferential laser welding may be difficult to achieve because the heat sink is very close, causing it to absorb a significant amount of heat from the welding area, which in turn affects weld quality. On the other hand, if the axial spacing Z is too large in some conventional spark plugs, the thermal coupling between the electrode tip and the heat sink is insufficient because the interposed nickel-based material with low thermal conductivity can act as a thermal barrier between the components. This spark plug electrode overcomes these and other challenges by forming the electrode tip 34 on the electrode base 30 using an additive manufacturing process so that they are directly thermally coupled to each other via the thermal coupling region 38.

[0054] Although the heat dissipation cores 32, 32', and 32'' are shown in the figures as single-material cores (i.e., cores formed from a single thermally conductive material, which may or may not contain multiple components), they can also be multi-material cores. According to a first example of a multi-material core, an inner heat dissipation core component (e.g., a heat dissipation core component made of a nickel-based material) extends along a portion of the electrode, and an outer heat dissipation core component (e.g., a heat dissipation core component made of a copper-based material) extends along the same portion of the electrode, such that it at least partially surrounds and is concentric with the inner heat dissipation core component. In such a concentric or layered arrangement, the inner heat dissipation core component may extend or protrude beyond the end of the outer heat dissipation core component. According to a second example of a multi-material core, a forward heat dissipation core component extends along a portion of the electrode closer to the ignition end, while a backward heat dissipation core component extends along a portion of the electrode further away from the ignition end. In such an end-to-end or series arrangement, one of the heat dissipation core components may be longer than the other. The first and / or second multi-material core examples can be used with a center electrode and / or a ground electrode. If a multi-material core is used, the axial distance Z (i.e., the shortest axial distance Z) is measured from the axial end of the nearest heat sink core component to the electrode tip. Of course, many other heat sink arrangements and configurations are also possible and are certainly within the scope of this application.

[0055] Electrode tips 34, 34', and 34'' are sections or portions of the electrode typically formed on the electrode base via additive manufacturing, and are usually ignition portions. Therefore, electrode tips 34, 34', and 34'' can be made from a bed of noble metal-based powder near the electrode base, such that upon irradiation by a laser or electron beam, the noble metal-based powder melts and solidifies with a portion of the solid material of the electrode base 30 and / or the heat sink 32 to form a laser-deposited layer. This process of producing the individual layers is repeated to produce multiple laser-deposited layers 70 sequentially constructed or stacked on top of each other, such that these layers are perpendicular to the central axis A of the electrode (in this context, "perpendicular" does not require perfect perpendicularity, as long as the layer 70 is perpendicular to the central axis A within a tolerable error range when viewed in cross-section). Some laser-deposited layers 70 may contain material from the heat sink 32, the electrode base 30, and the electrode tips 34; some layers 70 may contain only material from the electrode base 30 and the electrode tips 34; while other layers 70 may contain only material from the electrode tips 34. The average layer thickness T of each laser-deposited layer can be between 5 μm and 60 μm, and the sum or total of all layer thicknesses is the electrode tip height H, which can be between 0.05 mm and 3.0 mm, or more preferably between 0.1 mm and 1.5 mm. The electrode tips 34, 34', 34'' can be manufactured according to the following embodiments: several possibilities are listed, including radially narrowed relative to the electrode base and not radially narrowed relative to the electrode base; shapes such as rivets, cylinders, rods, columns, lines, spheres, blocks, cones, plates, disks, sheets, rings, sleeves, etc.; in terms of cross-section, circular, elliptical, square, rectangular, and / or other shapes; located at the axial end of the electrode base, and located on the side or other part of the electrode base; and being part of the center electrode or ground electrode.

[0056] Electrode tips 34, 34', 34'' can be made of precious metal-based materials to provide improved resistance to corrosion and / or erosion. As used herein, the term "precious metal-based material" refers to a material in which the precious metal is the single largest component by weight, and it may or may not contain other components (e.g., a precious metal-based material can be a pure precious metal, a precious metal containing some impurities, or a precious metal-based alloy). Several possibilities include iridium-based, platinum-based, ruthenium-based, palladium-based, and / or rhodium-based materials. As an example, electrode tips 34, 34', 34'' are made of iridium, platinum, or ruthenium-based materials, wherein the material has been processed into powder form, making it suitable for additive manufacturing processes. For iridium-based materials, the coefficient of thermal expansion of the electrode tip may be 6 × 10⁻⁶. -6 m / mK and 7×10 -6The coefficient of thermal expansion is between m / mK (measured at 100℃), melting point is between 2,300℃ and 2,500℃, and thermal conductivity is between 120 W / m·K and 180 W / m·K (measured at 100℃); for platinum-based materials, the coefficient of thermal expansion at the electrode tip may be 8 × 10⁻⁶. -6 m / mK and 10×10 -6 The melting point is between 1,650°C and 1,850°C, and the thermal conductivity is between 50 W / m·K and 90 W / m·K (measured at 100°C). As mentioned above, certain precious metals, such as iridium, can be very expensive. Therefore, it is generally desirable to reduce the content of such materials in the electrode tip, as long as doing so does not unacceptably degrade the performance of the electrode tip. Precious metal-based powders with an iridium content not exceeding 60 wt% (e.g., Pt-Ir40, Pt-Ir50, Ir-Pt40, Ru-Rh5, etc.), preferably not exceeding 50 wt% (e.g., Pt-Ir40, Pt-Ir50, Ru-Rh5, etc.), can be used to fabricate electrode tips 34, 34', 34'' when the electrode tip is directly thermally coupled to the heat sink cores 32, 32', 32'', because such materials achieve an ideal balance between cost and performance. However, other precious metal-based powders can also be used, such as powders with up to about 98 wt% iridium (e.g., Ir-Rh2.5, Ir-Rh5, Ir-Rh10, Ir-Pt5, Ir-Pt5-Rh5, etc.), especially if the price of these materials decreases in the future. The diameter or size of the electrode tips 34, 34', 34'' varies depending on the specific application and embodiment. For example, in Figure 2-4 In the non-limiting example of the industrial spark plug shown, the diameter of each electrode tip can be between 1.0 mm and 4.2 mm (inclusive), more preferably between 1.2 mm and 3.0 mm (inclusive). For automotive and other spark plugs, these dimensions may be smaller, and the diameter of the electrode tip may be between 0.4 mm and 3.0 mm (inclusive), more preferably between 0.6 mm and 2.0 mm (inclusive). The electrode tip does not necessarily include a circular cross-section with a "diameter," but may include an oval, square, rectangular, or other cross-section with a "size."

[0057] Thermal coupling regions 38, 38', 38'' are at least partially located between the heat sink and the electrode tip and include material from the heat sink, the electrode base, and / or the electrode tip. Thermal coupling regions 38, 38', 38'' are designed to act as heat conduits or channels, allowing heat accumulated during spark plug operation to be effectively transferred from the electrode tips 34, 34', 34'' to the heat sink 32, 32', 32'', from which it can be further dissipated to the insulator 14, the housing 16, and ultimately the cylinder head of the engine. As mentioned above, enhanced cooling of the electrode tips 34, 34', 34'' is necessary for several reasons: it reduces thermal stress at the junction between the electrode tip and the electrode base; it reduces the erosion and / or corrosion rate of the electrode tip; and it allows for the use of a wider variety of precious metal-based materials, including inexpensive materials with lower melting points, and fewer precious metal materials, to name a few. The thermal coupling regions 38, 38', and 38'' are located inside the electrode, concentrating towards the center or middle of the electrode, and may contain material from the heat sink 32, 32', 32'', the electrode base 30, 30', 30'', and / or the electrode tip 34, 34', 34'' (when all are present in the thermal coupling region, these materials together constitute the thermal coupling region alloy). By including the thermal coupling regions 38, 38', and 38'' in the middle of the electrode, the thermal coupling regions 38, 38', and 38'' are prevented from being exposed to the outside and becoming undesirable spark points. Furthermore, the average thermal conductivity of the thermal coupling region alloy is higher than the average thermal conductivity of the electrode base 30, 30', and 30'' themselves, which can sometimes act as a thermal barrier or obstacle in spark plugs—a significant amount of electrode base material in a spark plug lies between the tip and the core. The alloy of the thermal coupling region (e.g., Ni-Ir-Cu, Ni-Pt-Cu, Ni-Ir-Pt-Cu, etc.), the close spacing between the electrode tip and the heat sink (e.g., less than 2.0 mm), and the concentrated shape of the thermal coupling region (e.g., a shape slightly elongated along the central axis A of the electrode) facilitate the formation of a direct thermal coupling or connection between the electrode tip and the heat sink without undesirably creating unwanted spark points on the electrode side. The thermal coupling regions 38, 38', and 38'' also help reduce stress at the junction between the electrode tip and the base, such as stress caused by different coefficients of thermal expansion. The following paragraphs describe different examples of thermal coupling regions and combine them with… Figure 5-7 Provided. It should be understood that these figures are for illustrative purposes only, as the heat sink, thermal coupling area, electrode base, electrode tip, etc., may differ from those shown in the figures.

[0058] In 5, it is shown that it can be used with Figure 2An example of a thermal coupling region 38 used with spark plugs. Since the axial end 58 of the heat sink 32 does not reach the axial end 60 of the electrode base 30, the axial spacing Z of the electrodes 12 is approximately 0.5 mm. The material distribution or concentration in the thermal coupling region 38 may vary along the central axis A, but the elements of the heat sink 32, electrode base 30, and electrode tip 34 are all present in the thermal coupling region 38. Preliminary tests indicate that in the first portion 80 of the thermal coupling region 38—which is adjacent to the heat sink 32 and furthest from the electrode tip 34—the thermal coupling region may contain a thermal coupling region alloy having approximately: 2-45 wt% noble metals (e.g., Ir, Pt, Pd, Ru, Rh, etc.), 2-50 wt% copper, 20-75 wt% nickel, and the remainder being other elements from the electrode components. In the second portion 82 of the thermal coupling region—which is adjacent to the electrode tip 34 and furthest from the heat sink 32—the thermal coupling region may comprise a thermal coupling region alloy having approximately: 10-65 wt% noble metals (e.g., Ir, Pt, Pd, Ru, Rh, etc.), 2-45 wt% copper, 10-65 wt% nickel, and the remainder being other elements from the electrode components. Although the exact composition of the thermal coupling region 38 may differ from the example provided above, preferably, the thermal coupling region alloy comprises thermally conductive material from the heat sink 32, nickel from the electrode base 30, and noble metals from the electrode tip 34, and the thermal coupling region is configured according to a gradient structure such that the first portion 80 contains more copper than the second portion 82, and the second portion 82 contains more noble metals than the first portion 80.

[0059] Figure 6 It shows that it can be used with Figure 3Another possible example of a thermally coupled region 38' used in conjunction with a spark plug. In this example, the axial end 58' of the heat sink 32' reaches the axial end 60' of the electrode base 30', such that the axial spacing Z of the electrodes 12' is approximately 0.0 mm. As shown, the electrode body 36' has been cut or severed such that the axial end 58' of the heat sink 32' is located at or near the axial end 60' of the electrode base 30' (therefore, the axial spacing Z is approximately 0.0 mm). When the additive manufacturing process begins to build the initial layer of the electrode tip 34', a laser beam or electron beam is guided in the axial direction such that it melts the thin, noble metal-based powder coating covering the axial end 60', and partially melts the lower electrode base 30' and the heat sink 32'. Due to the precision of the additive manufacturing process (e.g., a process using powder bed fusion technology), disproportionate energy can be concentrated or directed toward the center of the electrode, which in turn can begin to create a deeper thermally coupled region 38' in that area. This process can continue layer by layer, with its energy concentrated towards the center or middle of the axial end 60', causing the thermal coupling region 38' to become deeper towards the center of the electrode. Although not necessary, the thermal coupling region 38' can become slightly spherical or bulbous towards the center; Figure 6 This is illustrated in the diagram, where the axial end 58' of the heat sink 32' has been at least partially absorbed into the bulbous first portion 80' of the thermal coupling region 38'. The second portion 82' of the thermal coupling region 38' can be wider and shallower, filling most of the area below the electrode tip 34', but not extending as deep into the electrode as the first portion 80'. The thermal coupling region 38' can have a similar composition and / or gradient structure as described above in conjunction with the previous example.

[0060] exist Figure 7 The text shows that it can be used with... Figure 4Another example of a thermal coupling region 38'' used with spark plugs. In this example, the electrode body 36'' is cut off at the location where it cuts through the heat sink 32'' before the electrode tip 34'' is added (i.e., the axial end of the heat sink is cut off to expose the surface of the core). Therefore, the axial distance Z between the imaginary axial end 58'' of the electrode base 30'' (which would otherwise be here if it were not cut off, as shown by the dashed line) and the axial end 60'' is a negative dimension, for example, between 0.0 mm and -0.5 mm. Due to the axial proximity between the body of the heat sink 32'' and the electrode tip 34'', this example will likely exhibit high thermal conductivity, allowing the electrode tip to be effectively cooled during operation. As mentioned earlier, special care must be taken to ensure that the copper-based material in the heat sink 32'' is not drawn or pulled to the outer surface of the electrode, as this could create an undesirable ignition point at that location. In the first portion 80'' of the thermal coupling region, the truncated axial end 84'' of the heat sink 32'' has been absorbed into the thermal coupling region. The truncated axial end portion 84'' can also be absorbed and mixed with other materials in the second portion 82''. In this example, the electrode tip 34'' is constructed on the truncated end of the electrode body 36'', allowing the noble metal-based powder to be directly melted into the exposed portions of the electrode base 30'' and the heat sink 32''. This can be achieved using the additive manufacturing process described herein, which forms a weld-free joint between the electrode tip 34'' and the electrode body 36'', but without forming a circumferential laser weld.

[0061] Now go to Figure 8 The flowchart illustrates the steps of an additive manufacturing process 100 (sometimes referred to as a 3D printing process) that can be used to manufacture the spark plug electrode described herein. According to this example, additive manufacturing process 100 uses powder bed melting technology to form an electrode tip 134 on the electrode base 130, as shown in... Figure 9-12 The progressive steps shown are illustrated. However, it should be understood that additive manufacturing process 100 can be used with any electrode taught herein, as well as other electrodes, and is certainly not limited to the examples shown.

[0062] Starting from step 102, the electrode body 136 is provided with a heat dissipation core 132, which is at least partially surrounded by or encapsulated within the electrode base 130. (As in combination...) Figure 5-7 As explained, the electrode body can be configured in one of several different ways, including, for example, a configuration in which the heat sink is retracted into the electrode base so that it does not reach the axial end of the electrode base (see, for example, [reference]). Figure 5 The heat sink terminates at or near the axial end of the electrode base (e.g., see...). Figure 6); or a configuration in which the electrode body has been cut or pierced through the electrode base and the heat sink core so that the imaginary axial end of the core extends beyond the axial end of the electrode base and exposes a portion of the core (e.g., see Figure 7 This last possibility is... Figure 9 As further shown, the truncated axial end 154 of the heat sink 132 is exposed and is generally flush with the axial end 160 of the electrode base 130. It should be understood that any suitable method for cutting, severing, or terminating the electrode body can be used, including mechanical cutting or shearing, grinding cutting, water jetting or laser cutting, or some other suitable method for removing the end of the electrode body.

[0063] Next, the electrode body 136 is secured within a tool or fixture, such that the electrode base 130 and / or the heat sink 132 are exposed at the ignition end 120, step 104. Preferably, the electrode body 136 is vertically secured or mounted within the tool such that the ignition end 120 faces upward. Many different tool and fixture arrangements can be used for this purpose, including horizontal build plates having a flush or nearly flush design with the axial end 160 and designed to receive a thin powder bed.

[0064] Once secured within the tool, the ignition end 120 with its exposed electrode base and / or heat sink portion is covered by a thin powder bed 128 comprising a first mixture of noble metal-based materials, step 106. The first mixture may contain no more than 60 wt% iridium (e.g., Pt-Ir40, Pt-Ir50, Ir-Pt40, Ru-Rh5, etc.) and preferably no more than 50 wt% iridium (e.g., Pt-Ir40, Pt-Ir50, Ru-Rh5, etc.) of a noble metal-based material, although this is not mandatory. In one example, the thickness of the powder bed 128 is between 5 μm and 60 μm (inclusive), more preferably between 10 μm and 20 μm (inclusive).

[0065] Next, a thin powder bed 128 covering the ignition end 120 is melted or at least sintered using a laser beam or electron beam, step 108. Any reference to “laser” herein should be understood to broadly include any suitable light or energy source, including but not limited to electron beams and lasers; the same applies to “laser-deposited layer,” which broadly includes deposited layers produced by any suitable light or energy source, including but not limited to deposited layers produced by electron beams and lasers. Figure 10As shown in Figure A, the laser L is generally aligned with the central axis A of the electrode and points towards the ignition end 120 (in this example, including the exposed portion 160 of the electrode base 130 and the exposed portion 154 of the heat sink 132), such that it melts or sintersects the thin powder bed 128 as the laser passes through or moves across the axial end surface of the ignition end; this is part of the powder bed fusion process. This forms the initial laser deposition layer 162 and begins to form different portions of the thermally coupled region 138, which, when the additive manufacturing process is complete, will establish a direct thermal connection between the electrode tip 134 and the heat sink 132.

[0066] According to one example, step 108 does not use a constant or uniform laser energy level when melting the thin powder bed. Instead, it selectively controls the energy level based on the non-uniform energy distribution, so that more energy is concentrated toward the center of the ignition end 120. Figure 10 B is an end view or top view of the ignition end 120, where different circular or annular regions represent different laser energy levels in a non-uniform energy distribution. For example, region 140 is a circular region surrounding the central axis A and located in the middle of the ignition end. In region 140, the laser energy is the highest level used during the non-uniform energy distribution and can be between 90% and 100% of the maximum or predetermined energy level. Region 142 is an annular region concentrically surrounding region 140, and according to this example, the applied laser energy level is slightly lower than the laser energy level applied in region 140, for example, between 75% and 90% of the maximum or predetermined energy level. Region 144 is also an annular region and it concentrically surrounds regions 140 and 142, such that it is positioned toward the radially outer segment of the ignition end 120. For region 144, a laser energy level less than 75% of the maximum or predetermined energy can be used; the lower energy level reduces the possibility of pulling excessive copper-based and / or nickel-based material to both sides of the electrode. Furthermore, by concentrating more laser energy toward the center of the ignition end 120, the non-uniform energy distribution allows for the melting of more material in the middle of the electrode body, including copper-based material from the heat sink 132, nickel-based material from the electrode base 130, and noble metal-based material from the thin powder bed 128. This deeper penetration into the middle of the electrode body helps to shape the thermal coupling region 138 without pulling the copper-based material to the sides of the electrode (where it could become an undesirable flash point), as is the case with circumferential laser welding.

[0067] This method has the potential to alter the laser energy distribution during each pass or at each of multiple passes in order to control or at least influence the size, shape, and / or composition of the thermally coupled region 138. (Reference) Figure 11A-11B shows a cross-sectional view of the electrode body 136 and a top view of the ignition end 120 having different circular or annular regions representing different laser energy levels. Similarly, a non-uniform energy distribution can concentrate laser energy towards the center of the ignition end 120, such that the thermally coupled region 138 extends deeper into the heat sink core 132 with each addition of a new laser deposition layer 164. For example, the non-uniform energy distribution may include region 150, which is a circular region surrounding the central axis A in the middle of the ignition end 120, and may have a laser energy level between 80% and 90% of the maximum or predetermined level. Region 152—which is a concentric annular region surrounding the remainder of the axial end 160—may have a laser energy level of approximately 80% of the maximum or predetermined level. During the repeated cycles of steps 106-108, the method not only constructs the electrode tip 134 with multiple stacked laser deposition layers, but it can also vary or modulate the laser energy across the ignition end 120 according to the non-uniform energy distribution to produce a customized thermally coupled region 138 with a first portion 180 and a second portion 182. The first portion 180 is located deeper within the electrode body 136 (i.e., further from the axial end 160) and more centrally focused towards the electrode body, while the second portion 182 is located closer to the ignition end 120 and extends further outward, thus primarily situated below the electrode tip 134. The first portion 180 helps form the main heat channel or conduit between the electrode tip 134 and the heat sink 132. It should be understood that the first portion 180 and the second portion 182 are depicted for illustrative purposes, and the actual portions may have different shapes and dimensions than those shown.

[0068] On the final pass, the method forms a final laser-deposited layer 166, which constitutes at least a portion of the ignition surface of the electrode tip 134. When forming the final laser-deposited layer 166, the method may use a uniform energy profile or distribution, rather than a non-uniform energy profile, to help smooth the ignition surface or provide a more uniform ignition surface, such as... Figure 12 As shown in AB. In this example, a single circular region 156 can be used across the entire ignition end 120, allowing the final laser-deposited layer 166 to be formed at a constant laser energy level (e.g., approximately 80% of the maximum energy). By using a constant laser energy level in the last cycle or several cycles of this method, an electrode tip 134 with a flatter ignition surface 168 can be formed. Of course, the foregoing description is merely one example of an additive manufacturing process that can be used, as other such processes are certainly possible. Specific parameters, such as the size, shape, number, and energy level of different laser energy regions, may differ from the non-limiting examples provided herein.

[0069] Repeat steps 106-108 in a loop or sequence until the method determines that no laser-deposited layer is needed (i.e., the electrode tip 134 has reached the desired height). If step 110 determines that more laser-deposited layers are needed, the method loops back and repeats steps 106 and 108, allowing a new laser-deposited layer to be built on top of the previous layer. It should be understood that during the initial pass or loop through steps 106-108, step 106 may cover the axial end 160 and the truncated axial end 154 with a thin powder bed 128 (i.e., the precious metal-based material of the thin powder bed may be in direct contact with the nickel-based material of the axial end 160 and the copper-based material of the truncated axial end 154), and step 108 may directly melt or sinter the thin powder bed into the ends 160 and / or 154. In subsequent passes through or cycles through steps 106-108, after the initial laser-deposited layer 162 has been formed, step 106 may apply a thin powder bed 128 such that it covers one or more previously formed laser-deposited layers 162, rather than covering the actual surfaces of ends 160 and / or 154. In this example, step 108 melts or sintersects the thin powder bed material into the previously formed laser-deposited layer, and possibly into the electrode itself (depending on the thickness of the previously formed laser-deposited layer and the depth of the melting or sintering step). In both cases (i.e., during the initial and subsequent passes through steps 106-108), step 106 covers the ignition end 120 with a thin powder bed, and step 108 melts or sintersects the thin powder bed into the ignition end 120.

[0070] Since each laser-deposited layer is formed by first melting or sintering powder from a thin powder bed and then solidifying the material, the composition of different laser-deposited layers can be tuned or modified by changing the composition of the powder bed along this route. This allows the electrode to have a customized compositional gradient over the thermal coupling region 138 and / or the electrode tip 134, thereby dispersing differences in the coefficients of thermal expansion rather than experiencing all of these differences at a single interlayer boundary. For example, in a second or subsequent pass through the method, step 106 could cover the ignition end 120 with a second mixture of a noble metal-based material having a different composition than the first mixture (e.g., the second mixture could have a larger proportion of noble metal-based material), although this is not required.

[0071] Once step 110 determines that no additional laser deposition layer is needed (i.e., the electrode tip 134 is entirely formed by additive manufacturing), the method proceeds to step 112, where the spark plug electrode or workpiece is removed from the tool. Those skilled in the art will understand that the additive manufacturing process just described can be used to manufacture a large number of electrodes at once (i.e., batch processing), and various types of electrodes different from those shown here. One difference in spark plug electrodes produced according to the above process is that the electrode tip is securely fixed to the electrode base without the use of circumferential laser welding (i.e., the electrode has a weld-free joint between the electrode tip and the base), which is advantageous for a variety of reasons, including those described above.

[0072] It should be understood that one or more preferred exemplary embodiments of the invention have been described above. The invention is not limited to the specific embodiments disclosed herein, but is defined only by the appended claims. Furthermore, the statements contained in the foregoing description relate to specific embodiments and should not be construed as limiting the scope of the invention or the definition of terms used in the claims, unless the term or phrase is explicitly defined above. Various other embodiments, as well as various changes and modifications to the disclosed embodiments, will become apparent to those skilled in the art. For example, the exact dimensions, shape, composition, etc., of the thermal coupling regions covered may differ from the disclosed examples, but are still covered by this application (e.g., a micrograph of an actual part may look significantly different from the illustrated figures, but is still covered). All such other embodiments, changes, and modifications are intended to fall within the scope of the appended claims.

[0073] As used in this specification and claims, the terms “for example,” “such as,” “for instance,” “like,” and “e.g.,” as well as the verbs “comprising,” “having,” “including,” and other verbal forms thereof, when used with a list of one or more parts or other articles, shall each be interpreted as open-ended, meaning that the list shall not be construed as excluding other, additional parts or articles. Other terms shall be interpreted in their broadest reasonable sense unless they are used in a context that requires a different interpretation.

Claims

1. An additive manufacturing process for manufacturing spark plug electrodes, comprising the following steps: An electrode body is provided, comprising an electrode base and a heat dissipation core at least partially surrounded by the electrode base; The ignition end of the electrode body is covered with a thin powder bed containing a precious metal-based material; A laser beam or electron beam is directed to the ignition end of the electrode body, causing it to melt or sinter at least some of the thin powder bed; as well as The covering and guiding steps are repeated multiple times to form an electrode tip with multiple laser deposition layers and an ignition surface on the electrode base, and to form at least partially a thermal coupling region between the electrode tip and the heat sink core, wherein the thermal coupling region directly thermally couples the electrode tip to the heat sink core.

2. The additive manufacturing process according to claim 1, wherein, The step further includes providing an electrode body comprising an electrode base having a nickel-based material and a heat sink having a copper-based or silver-based material.

3. The additive manufacturing process according to claim 1, wherein, The provision step further includes providing an electrode body that is part of the center electrode for an industrial plug, and whose ignition end has a diameter between 1.4 mm and 4.2 mm, including the end value.

4. The additive manufacturing process according to claim 1, wherein, The provision further includes providing an electrode body that is part of the center electrode for an automotive plug and whose ignition end has a diameter between 0.7 mm and 3.0 mm, including the end value.

5. The additive manufacturing process according to claim 1, wherein, The step further includes providing an electrode body that includes a heat dissipation core having a single material core containing a thermally conductive material.

6. The additive manufacturing process according to claim 1, wherein, The step further includes providing an electrode body comprising a heat dissipation core having a multi-material core, the multi-material core including an inner heat dissipation core component and an outer heat dissipation core component, the outer heat dissipation core component at least partially surrounding the inner heat dissipation core component and comprising a thermally conductive material.

7. The additive manufacturing process according to claim 1, wherein, The step further includes providing an electrode body comprising an electrode base and a heat sink, the heat sink being recessed into the electrode base such that the axial end of the heat sink does not reach the axial end of the electrode base. and The covering step further includes covering the ignition end of the electrode body with a thin powder bed such that, during the initial cycle, the thin powder bed only contacts the axial end of the electrode base.

8. The additive manufacturing process according to claim 1, wherein, The step further includes providing an electrode body comprising an electrode base and a heat sink, wherein an axial end of the heat sink terminates at or near an axial end of the electrode base. and The covering step further includes: covering the ignition end of the electrode body with a thin powder bed such that, during the initial cycle, the thin powder bed contacts the axial end of the electrode base and / or the axial end of the heat sink.

9. The additive manufacturing process according to claim 1, wherein, The step further includes providing an electrode body comprising an electrode base and a heat sink, wherein the electrode body has been cut off or pierced through the heat sink such that an imaginary axial end of the heat sink extends beyond the axial end of the electrode base. and The covering step further includes covering the ignition end of the electrode body with a thin powder bed such that, during the first cycle, the thin powder bed contacts the axial end of the electrode base and the truncated axial end of the heat sink core.

10. The additive manufacturing process according to claim 9, wherein, In the initial cycle, after the provision step and before the coverage step, the truncated axial end of the heat sink is exposed and is generally flush with the axial end of the electrode base.

11. The additive manufacturing process according to claim 1, wherein, The guiding step further includes guiding a laser beam or electron beam to the ignition end of the electrode body as part of a powder bed fusion process, such that an initial laser deposition layer is formed during the initial cycle and the thermally coupled region is formed during subsequent cycles.

12. The additive manufacturing process according to claim 1, wherein, The guiding step further includes guiding a laser beam or electron beam to the ignition end of the electrode body as part of a powder bed fusion process, so that a final laser-deposited layer is formed with a uniform energy profile during the final cycle.

13. The additive manufacturing process according to claim 1, wherein, The guiding step further includes: guiding the laser beam or electron beam to the ignition end of the electrode body, and driving the laser beam or electron beam according to the non-uniform energy profile.

14. The additive manufacturing process according to claim 13, wherein, The non-uniform energy profile generates a first region located at the center of the ignition end and a second region surrounding the first region, wherein the laser energy level in the first region is higher than that in the second region, causing more energy to concentrate toward the center of the ignition end.

15. The additive manufacturing process according to claim 14, wherein, The non-uniform energy profile also generates a third region, which is positioned toward the radially outer segment of the ignition end such that the third region surrounds the second region.

16. The additive manufacturing process according to claim 13, wherein, The non-uniform energy profile helps to create a customized thermal coupling region comprising a first portion and a second portion, the first portion being located deeper within the electrode body and concentrated toward the center of the electrode body, and the second portion being located closer to the ignition end and extending further outward, such that it is primarily located below the electrode tip.

17. The additive manufacturing process according to claim 1, wherein, The guiding step further includes guiding a laser beam or electron beam to the ignition end of the electrode body, such that it melts at least some of the material from the thin powder bed, the electrode base, and the heat sink core to produce a thermally coupled region alloy.

18. The additive manufacturing process according to claim 1, wherein, The repeating step further includes repeating the covering step and the guiding step multiple times, such that the thermally coupled region reaches deeper into the electrode body each time a new laser deposition layer is formed.

19. An additive manufacturing process for manufacturing spark plug electrodes, comprising the following steps: An electrode body is provided, comprising an electrode base and a heat dissipation core at least partially surrounded by the electrode base, wherein the electrode body is cut off or cut through the heat dissipation core such that the axial end of the electrode base and the truncated axial end of the heat dissipation core are exposed. During the initial cycle, the ignition end of the electrode body is covered with an initial thin powder bed containing a precious metal-based material, the initial thin powder bed contacting the axial end of the electrode base and the truncated axial end of the heat sink core; During the initial cycle, a laser beam or electron beam is directed to the ignition end of the electrode body, causing it to melt or sinter at least some of the initial thin powder bed and a portion of the electrode base and heat sink core, and causing the melted or sintered material to solidify at least partially into the initial laser deposition layer. During subsequent cycles, the ignition end of the electrode body is covered with a thin powder bed containing a precious metal-based material, the thin powder bed contacting the previously formed laser-deposited layer; During the subsequent cycle, a laser beam or electron beam is directed to the ignition end of the electrode body, causing it to melt or sinter at least some of the thin powder bed and a portion of the previously formed laser-deposited layer, and causing the melted or sintered material to solidify at least partially into a newly formed laser-deposited layer. as well as The covering and guiding steps of the subsequent cycle are repeated to form an electrode tip having multiple laser deposition layers and an ignition surface on the electrode base, wherein the electrode tip is directly thermally coupled to the heat sink.

20. The additive manufacturing process according to claim 19, wherein, The electrode tip is directly thermally coupled to the heat sink core through a thermal coupling region, the thermal coupling region comprising a thermal coupling region alloy, the thermal coupling region alloy comprising: copper or silver from the heat sink core, nickel from the electrode base, and at least one of iridium, ruthenium, or platinum from the electrode tip.

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