Patent Application
20070236125
The present invention will become more fully understood from the detailed description given here below, the appended claims, and the accompanying drawings in which:
The present invention as illustrated in the figures is directed to a spark plug 10 (
The spark portion 30 is formed from an alloy which is highly resistant spark erosion, and corrosion. The spark portion may also be formed from an Iridium alloy that is highly resistant to Calcium and Phosphorus corrosion mechanisms that typically corrode Iridium spark portions. This Iridium alloy includes Nickel (Ni) and Copper (Cu) which allows the spark portion 30 to be formed through a powdered metal sintering process which is not possible or very difficult to do with pure Iridium or common Iridium alloys. The addition of the Nickel and Copper to the Iridium allow the formation of the spark portion through the powdered metal sintering process while retaining or improving resistance to Calcium and Phosphorus corrosion and oxidation, durability against spark erosion, and sufficient longevity. Different embodiments may be seen in
The Iridium alloy is formed from 50% to 96% Iridium by weight, 0% to 30% Nickel by weight, and 0% to 20% Copper by weight. While an Iridium-Nickel-Copper alloy is a preferred embodiment, it has also been found that Iridium-Nickel and believed that Iridium-Copper alloys may also be formed through the powdered metal sintering process while still retaining sufficient durability to spark erosion and superior resistance to combustion corrosion and in particular corrosion from Calcium, Phosphorus, Sulfur, and Oxygen. The alloy may further include elements selected from the group consisting of Platinum (Pt), Palladium (Pd), Rhodium (Rh), Ruthenium (Ru), Rhenium (Re), Chromium (Cr), Vanadium (V), Zirconium (Zr), Tungsten (W), Gold (Au), Osmium (Os), Iron (Fe), and Aluminum (Al) to further refine or enhance the desired characteristics of the alloy.
It has been found or it is believed that the following elements or alloys provide sufficient protection against corrosion, sufficient durability, and sufficient work function when added to Iridium, Platinum, or an Iridium and Platinum alloy. When used with the following elements or alloys thereof, the Iridium, Platinum, or alloys thereof form at least 50% by weight of the spark portion and therefore form the primary material of the spark portion. These elements or alloys include (1) Nickel, (2) Copper, (3) Nickel and Copper, (4) Nickel and Chromium, (5) Nickel, Copper, and Chromium, (6) Copper and Chromium, (7) Nickel plus one of the elements selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Zirconium, Tungsten, Gold, Osmium, Iron, and Aluminum, (8) Copper plus one of the elements selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Zirconium, Tungsten, Gold, Osmium, Iron, and Aluminum, (9) Nickel, Copper, plus one of the elements selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Zirconium, Tungsten, Gold, Osmium, Iron, and Aluminum, (10) Nickel, Chromium, and an element selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Zirconium, Tungsten, Gold, Osmium, Iron, and Aluminum, (11) Copper, Chromium, and an element selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Zirconium, Tungsten, Gold, Osmium, Iron, and Aluminum, (12) Nickel, Copper, Chromium, and an element selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Zirconium, Tungsten, Gold, Osmium, Iron, and Aluminum, (13) Nickel, Copper, Tungsten, and an element selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Zirconium, Gold, Osmium, Iron, and Aluminum, (14) Nickel, Tungsten, and an element selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Zirconium, Gold, Osmium, Iron, and Aluminum, (15) Copper, Tungsten, and an element selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Zirconium, Gold, Osmium, Iron, and Aluminum, (16) Nickel, Chromium, Tungsten, and an element selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Zirconium, Gold, Osmium, Iron, and Aluminum, (17) Copper, Chromium, Tungsten, and an element selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Zirconium, Gold, Osmium, Iron, and Aluminum, (18) Nickel, Copper, Chromium, Zirconium, and an element selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Tungsten, Gold, Osmium, Iron, and Aluminum, (19) Copper, Chromium, Zirconium, and an element selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Tungsten, Gold, Osmium, Iron, and Aluminum, (20) Nickel, Chromium, Zirconium, and an element selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Tungsten, Gold, Osmium, Iron, and Aluminum, (21) Copper, Zirconium, Tungsten, and an element selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Gold, Osmium, Iron, and Aluminum, (22) Nickel, Zirconium, Tungsten, and an element selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Gold, Osmium, Iron, and Aluminum, (23) Copper, Nickel, Zirconium, Tungsten, and an element selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Gold, Osmium, Iron, and Aluminum, (24) Chromium and an element selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Zirconium, Tungsten, Gold, Osmium, Iron, and Aluminum, (25) Chromium, Zirconium, and an element selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Zirconium, Tungsten, Gold, Osmium, Iron, and Aluminum, (26) Chromium, Zirconium, Tungsten, and an element selected from the group consisting of Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Gold, Osmium, Iron, and Aluminum, (27) Nickel, Rhodium, plus one of the elements selected from the group consisting of Palladium, Ruthenium, Rhenium, Vanadium, Zirconium, Tungsten, Gold, Osmium, Iron, and Aluminum, (28) Copper, Rhodium, plus one of the elements selected from the group consisting of Palladium, Ruthenium, Rhenium, Vanadium, Zirconium, Tungsten, Gold, Osmium, Iron, and Aluminum, (29) Nickel, Copper, Rhodium, plus one of the elements selected from the group consisting of Palladium, Ruthenium, Rhenium, Vanadium, Zirconium, Tungsten, Gold, Osmium, Iron, and Aluminum, (30) Tungsten and Nickel, (31) Tungsten and Copper, and (32) Tungsten and Vanadium. Of course Palladium, Ruthenium, Tungsten, Rhodium, and Rhenium, or alloys thereof may be substituted for either the Iridium or Platinum, or alloys thereof as the primary material to which the above listed elements may be added.
The firing tip 30 includes at least 40% and more particularly at least 50% by weight Iridium, Platinum, Palladium, Rhodium, Ruthenium, Rhenium, Tungsten or combination thereof. Furthermore, the firing tip 30 includes less than 99%, more particularly less than approximately 98%, and typically less than approximately 95% of Iridium, Platinum, Palladium, Rhodium, Ruthenium, Rhenium, Tungsten or combination thereof. The inventors have found that a firing tip having about 80% to 98% and more particularly 85% to 98% and yet more particularly 88% to 93% by weight of Iridium, Platinum, Palladium, Rhodium, Ruthenium, Rhenium, Tungsten or combination thereof provides a firing tip with desirable characteristics.
As stated above, the firing tip includes Nickel, Copper, or Nickel and Copper. More preferably, the firing tip also includes at least one element selected from the group consisting of Chromium, Tungsten, Vanadium, or Zirconium. The addition of Copper or Chromium, at least to Iridium or Platinum, provides an alloy with substantial desirable characteristics for a firing tip, such as enhanced corrosion protection, enhanced spark erosion resistance, and enhanced sparking as compared with firing tips formed solely from either Nickel or Iridium. Exemplary alloy firing tips may include 88% to 95% Iridium, and 2% to 12% Copper; 88% to 95% Iridium and 5% to 12% Nickel; 85% to 95% Iridium, 2% to 6% Copper, and 5% to 10% Nickel; 85% to 95% Iridium, 3% to 10% Nickel, and 1% to 6% Chromium; 85% to 95% Iridium, 2% to 6% Copper, and 2% to 6% Chromium; or 85% to 95% Iridium and 2% to 10% Nickel, 2% to 6% Copper, and 1% to 6% Chromium. Other elements such as Nickel, Vanadium, Zirconium, Tungsten, Platinum, Palladium, Rhodium, Ruthenium, Rhenium, Gold (Au), Osmium (Os), Iron (Fe), and Aluminum (Al) may be added to the above Iridium-Copper, Iridium-Nickel, Iridium-Nickel-Copper, or Iridium-Nickel-Chromium, Iridium-Copper-Chromium, Iridium-Nickel-Copper-Chromium, Iridium-Tungsten, Iridium-Tungsten-Nickel, or alloys thereof to provide improved or enhanced protection to corrosion and oxidation. Of the above additional elements, it has been found that Platinum, Vanadium, Zirconium, and Tungsten, or combination thereof, are particularly advantageous to add to an lridium-Copper, Iridium-Nickel, Iridium-Copper-Nickel, Iridium-Copper-Chromium, Iridium-Nickel-Chromium, or Iridium-Nickel-Copper-Chromium alloy firing tip. In particular, up to 3% Vanadium, 3% Platinum, 3% Zirconium, and 7% Tungsten, or in some combination up to 10% by weight may be added to enhance the desirable characteristics of the alloy firing tip for the above exemplary embodiments. However, for a spark portion having at least 50% of a primarily material of Iridium, Platinum, Palladium, Rhodium, Ruthenium, Rhenium, Tungsten or combination thereof may include up to 15% Vanadium, 50% Platinum (when the primary material is not Platinum), 10% Zirconium, and 50% Tungsten, or in some combination up to 50% by weight of the spark portion.
As stated above, the firing tip 30 may include Nickel, Copper, or Nickel and Copper. It has been found that adding Nickel up to 50% by weight may add desirable characteristics, before the susceptibility of Nickel to electrical spark erosion overcomes the benefits of Nickel against corrosion. It has been found that the addition of Nickel to the firing tip 30 to form an alloy containing at least 50% by weight of Iridium and 0.5% to 50% Nickel with the addition of an element selected from the group consisting of Copper, Chromium, Vanadium, Zirconium, and Tungsten provides excellent wear resistance, longevity, and resistance to erosion and corrosion. It has been further found that the addition of Nickel to Iridium in an amount of 4% to 40% by weight provides excellent resistance to erosion and corrosion and increases the longevity and wear resistance of the firing tip. Another addition to the above Iridium Nickel spark portion is Platinum.
When Nickel is added in an amount of 0.5% to 40% by weight to an Iridium-Copper firing tip, which includes at least one element selected from the group consisting of Chromium, Vanadium, Zirconium, and Tungsten, the alloy forming the firing tip 30 has increased longevity and wear resistance as well as resistance to erosion and corrosion. More specifically it has been found that a firing tip having at least 50% Iridium, up to 20% by weight Chromium, and a substantial portion of the balance being Nickel provides an excellent balance of desirable characteristics. It has also been found that a firing tip having up to 20% by weight Copper, at least 50% by weight Iridium and a substantial portion of the balance being Nickel provides an excellent balance of desirable characteristics. Another alloy with an excellent balance of desirable characteristics includes at least 50% Iridium, either Copper, Chromium or combination of at Copper and Chromium up to 40% by weight and the substantial portion of the balance being Nickel. In all of the above alloys, the alloy contains at least 0.5% and more particularly at least 1% of either Copper, Chromium, or the combination of Copper and Chromium. Of course, the alloy may be further improved by the addition of Platinum, Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Zirconium, and Tungsten individually or combinations thereof to improve the longevity and improve the wear resistance as well as stop erosion and corrosion that happens to pure Iridium or pure Nickel firing tips when used in spark plugs.
In particular it has been found that spark plugs containing 40% to 95% Iridium by weight, 4% to 40% Nickel by weight, 0% to 20% Copper by weight, and 0% to 20% Chromium by weight wherein either said Copper or Chromium or Copper and Chromium combined form 0.5% to 40% by weight, provides excellent wear resistance, increased longevity and excellent resistance to erosion and corrosion. While the reason is unknown, the addition of either Copper or Chromium or the combination of Copper and Chromium with Nickel and Iridium provides the desired benefits and improves the desired characteristics, compared to a firing tip for a spark plug that includes only Iridium or only Nickel. The addition of the other elements such as Platinum, Palladium, Rhodium, Ruthenium, Rhenium, Vanadium, Zirconium, and Tungsten also can help improve the alloy characteristics.
While the Iridium Nickel Copper alloy can contain 50% to 93% Iridium, 0% to 30% Nickel, and 0% to 20% Copper by weight, and still provide the desired characteristics it has been found that a composition formed from approximately 88% to 91% Iridium, 6% to 7.5% Nickel, and 2.5% to 4.5% Copper by weight provides the best overall combination of desired characteristics, including (1) the good durability to spark erosion, (2) good resistance to, Phosphorus, Oxygen, Sulfur, and Calcium corrosion, and (3) easy formation through a powdered metal sintering process.
The spark plug and particularly the spark portion of the spark plug is formed through a powdered metal sintering process which allows powdered metal of each element of the alloy to be mixed thoroughly and then formed to net shape by sintering the powdered metal in molds at high temperature and pressure. The addition of the Nickel or Copper or combination thereof allows the formation at lower temperatures and pressures than previously possible with Iridium or common Iridium alloys. The powdered metal sintering process is similar to those commonly used for manufacturing many other items with powdered metal. Previously, due to the extreme pressure and temperature required to form powdered Iridium metal to the final net shape, it was impractical or impossible to use this process to manufacture the spark portion 30 of the spark plug. However, the addition of Nickel or Copper or in particular the combination of Nickel and Copper thereof to Iridium to form an alloy with the given percent ranges described above allows for easy powdered metal sintering process and removes the need for additional steps to form the spark portion 30 to net shape such as grinding, diamond cutting, or hot heading. Furthermore, the addition of Nickel or Copper or both Nickel and Copper provides increased resistance to in particular Calcium and Phosphorus corrosion to prevent the spark portion looking like the picture in
The foregoing discussion discloses and describes an exemplary embodiment of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the true spirit and fair scope of the invention as defined by the following claims.
This application claims priority to U.S. Provisional Application Ser. No. 60/790,216, filed Apr. 7, 2006 which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60790216 | Apr 2006 | US |
