EP0749365B1 - Procede de fabrication d'un ajutage pour clapet d'admission de carburant et cet ajutage - Google Patents

Procede de fabrication d'un ajutage pour clapet d'admission de carburant et cet ajutage Download PDF

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Publication number
EP0749365B1
EP0749365B1 EP95911230A EP95911230A EP0749365B1 EP 0749365 B1 EP0749365 B1 EP 0749365B1 EP 95911230 A EP95911230 A EP 95911230A EP 95911230 A EP95911230 A EP 95911230A EP 0749365 B1 EP0749365 B1 EP 0749365B1
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Prior art keywords
nozzle
maximum
fuel
hip
alloy
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EP95911230A
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German (de)
English (en)
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EP0749365A1 (fr
Inventor
Harro Andreas Hoeg
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MAN B&W Diesel GmbH
MAN B&W Diesel AS
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MAN B&W Diesel GmbH
MAN B&W Diesel AS
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Priority claimed from DK28294A external-priority patent/DK174073B1/da
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B22F5/10—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of articles with cavities or holes, not otherwise provided for in the preceding subgroups
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/12—Both compacting and sintering
    • B22F3/14—Both compacting and sintering simultaneously
    • B22F3/15—Hot isostatic pressing
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/04—Making non-ferrous alloys by powder metallurgy
    • C22C1/0433—Nickel- or cobalt-based alloys
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
    • F02M61/16—Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14
    • F02M61/166—Selection of particular materials
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
    • F02M61/16—Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14
    • F02M61/168—Assembling; Disassembling; Manufacturing; Adjusting
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
    • F02M61/16—Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14
    • F02M61/18—Injection nozzles, e.g. having valve seats; Details of valve member seated ends, not otherwise provided for

Definitions

  • the invention relates to a method of manufacturing a nozzle for a fuel valve for an internal combustion engine, particularly a large two-stroke engine, in which substantially isotropic, finely grained powder of such a composition that the finished nozzle possesses hot corrosion resistance is arranged in a form and is HIP-treated at a pressure of at least 800 bar and at a temperature of at least 1,000°C.
  • the nozzle of an internal combustion engine is exposed to a sudden pressure influence, when the internal bore of the nozzle at the opening of the valve is supplied with pressurized fuel which is sprayed out through the nozzle holes.
  • the fuel may have quite a heavy erosive influence on the nozzle, which makes great demands on the strength of the nozzle material, particularly in large two-stroke engines fuelled by heavy fuel oil, the particle content of which has a highly erosive effect.
  • the nozzle projects a distance down into the combustion chamber, it is also affected by the changing temperatures in the chamber.
  • the nozzle tip is in reality uncooled.
  • the high temperature level at combustion makes great demands on the nozzle material, which must have a suitable strength at high temperatures and must furthermore be resistant to hot corrosion.
  • Prior art nozzles consist of a material which is resistant to hot corrosion and erosive influences from the fuel.
  • Nozzles made of cast Stellite 6 are known. These nozzles are manufactured by precision casting, so-called investment casting, where a sand mould is created around a positive form of the nozzle in wax, which mould is baked simultaneously with melting out of the wax, whereupon the nozzle blank is cast.
  • the casting In consideration of the strength properties of the cast nozzle, the casting must be cooled very quickly in order to obtain a sufficiently fine grain structure in the finished nozzle.
  • the rapid cooling increases the risk of porosities and cold flow of the casting, i.e., a kind of lamination of the material without a proper complete metallurgical bonding between the individual layers.
  • the lamination reduces the fatigue strength of the nozzle. Therefore, there is a limit to the number of nozzle holes which can be machined into the material of the nozzle, as the holes weaken the material and give rise to stress concentrations.
  • known nozzles are not manufactured with closely adjacent nozzle holes. This limits the amount of fuel which can be injected per fuel valve per engine cycle.
  • EP-A-0 569 655 describes a nozzle consisting of a mechanically alloyed, dispersion strengthened nickel-based super alloy, i.e., a so-called ODS alloy (Oxide Dispersion Strengthened).
  • ODS alloy Oxide Dispersion Strengthened
  • the mechanical alloying takes place in high energy mills, such as large ball mills, where powder and/or flaky starting material consisting of a dispersion component of yttrium oxide and a nickel-based alloy component are mechanically kneaded into a material with a homogeneous, very fine microstructure. Then, in several stages, the material can be cold or hot forged into the desired shape and subsequently be heat treated to cause precipitation hardening.
  • this known nozzle has a relatively high strength at very high temperatures.
  • the manufacturing of these nozzles is very costly, and the forming of nozzle holes is difficult, as finely distributed, very hard yttrium oxides in the material render it difficult to machine.
  • Japanese patent application published under No. 1-215942 describes a nozzle manufactured by hot working, e.g. HIPping or hot extruding, and then isothermal forging from a sintered material of an intermetallic compound of TiAl and Ni 3 Al, which is well known as an extremely hard particle-precipitated component in alloys.
  • HIPping hot extruding
  • isothermal forging from a sintered material of an intermetallic compound of TiAl and Ni 3 Al which is well known as an extremely hard particle-precipitated component in alloys.
  • the HIP treatment cannot be completed to a compact nozzle blank, but must be followed by forging the nozzle blank into the desired shape and machining it into a finished nozzle.
  • the high-temperature resistance of the alloys Ni 3 Al and TiAl is insufficient in case of use in engines operated on heavy fuel oil.
  • the object of the present invention is to provide a simpler method of manufacturing a nozzle in a material which, on one hand, permits simple mechanical machining into an accurate desired geometrical shape which yields an improved injection of the fuel, and on the other hand has a relatively high strength at high temperatures.
  • the first mentioned method is characterized in that the form is of substantially the desired external nozzle shape, that the HIP treatment lasts for at least one hour at the pressure and temperature mentioned, and that a flow passage with a central longitudinal bore and a number of nozzle holes is bored into the nozzle blank so HIP-treated, whereby the hole edges of the nozzle holes at the transition to the central bore become sharp.
  • the mass is dense when the material in the form has been brought up to the desired values for temperature and pressure during the holding time of at least 1 hour. With this holding time, the necessary bonds between the powder grains have become established by diffusion so that the nozzle blank has a homogeneous structure.
  • the finely grained, dense and homogeneous structure renders possible boring of the nozzle holes with sharp hole edges. Sharp hole edges at the transition to the central bore, i.e., at the inlet to the nozzle holes, promote the distribution of the fuel jet sprayed out from the opposite ends of the nozzle holes at the external side of the nozzle.
  • the finely grained powder is combined at the HIP (Hot Isostatic Pressure) treatment of the nozzle into a strong, cohesive material without causing the powder to melt.
  • HIP Het Isostatic Pressure
  • the result of the non-melting is that, in a manner known per se , the material in the nozzle retains the isotropic structure of the finely grained powder with very small crystal grains.
  • the fine grain size gives the material a high strength without at the same time imparting properties to the material which render difficult a mechanical machining.
  • the manufacturing of the nozzle is advantageously simple, as the HIP treatment can be carried out in a simple operation directly from the finely grained powder, and the nozzle holes can be bored into the blank with no complications and without any intermediate cumbersome and tool-demanding treatment.
  • the material of the nozzle is exposed to substantially the same treatment in all cross-sections so that local variations in the material properties of the nozzle blank are avoided.
  • the nozzle achieves a high fatigue strength seen in relation to the strength of a cast nozzle of a material with the same analysis.
  • the finely grained structure of the nozzle blank can be obtained independently of the actual composition of the alloy used.
  • the HIP treatment can be carried out with a starting material having a powder grain size in the interval of from 0 to 1000 ⁇ m and a pressure in the interval of from 900 to 1100 bar and a temperature in the interval of from 1100 to 1200°C.
  • these interval limits have proved to yield HIP-treated nozzle blanks with largely isotropic properties, i.e., uniform properties in all directions.
  • pressures above 1100 bar and temperatures above 1200°C will cause a risk of increased grain growth and incipient melting of the material, which would destroy the very small crystal grain size in the powdery starting material.
  • the lower limit of 900 bar and 1100°C and a holding time of at least 1 hour ensure for most alloys that the powder is bonded into a uniform body. Keeping the grain size, i.e., the largest outer dimension of the powder, at 1000 ⁇ m at the most, ensures that the starting material has very fine crystal grains.
  • the method is characterized in that the nozzle blank comprises an austenitic nickel phase, and that after the mechanical machining the blank is subjected to heat treatment at a temperature in the interval of 550-1100°C, preferably 700-850°C, for a period of at least 5 hours, whereby a solid phase transformation takes place in which ferritic ⁇ phase is particle-precipitated in a very fine distribution in the austenitic nickel phase.
  • the desired high hardness of the alloy and the consequent low machinability is thus only created when the mechanical machining of the HIP-treated blank is finished.
  • the invention also relates to a nozzle for a fuel valve for an internal combustion engine, particularly a large two-stroke engine, with a central longitudinal bore and a number of nozzle holes positioned in the side wall of the nozzle and constituting, together with the longitudinal bore, a flow passage for pressurized fuel, which nozzle is made of a material which is resistant to hot corrosion and erosive and cavitational influences from the fuel.
  • the fuel used may be heavy fuel oil, which subjects the nozzle to substantial erosive influences from particle content, etc., in the fuel, and additionally, the frequently sulphurous oil results in a very corrosive environment in the combustion chamber.
  • the nozzle is of large length and is substantially uncooled at its lower end.
  • the nozzle according to the invention is characterized in that it is made of a HIP-treated cobalt-based alloy comprising chromium and tungsten, such as Stellite 6, the flow passage for the fuel being bored after the HIP treatment, whereby the hole edges of the nozzle holes at the transition to the central bore become sharp.
  • a HIP-treated cobalt-based alloy comprising chromium and tungsten, such as Stellite 6, the flow passage for the fuel being bored after the HIP treatment, whereby the hole edges of the nozzle holes at the transition to the central bore become sharp.
  • the nozzle is made of a HIP-treated, nickel-based alloy which, in percentage by weight and apart from generally occurring impurities, comprises from 20 to 30% of Cr, from 0 to 8% of W, from 4 to 8% of Al, from 0.2 to 0.55% of C, from 0 to 2% of Hf, from 0 to 1.5% of Nb, from 0 to 8% of Mo, from 0 to 1% of Si, from 0 to 1.5% of Y and from 0 to 5% of Fe, the flow passage for the fuel being bored after the HIP treatment, whereby the hole edges of the nozzle holes at the transition to the central bore become sharp.
  • a HIP-treated, nickel-based alloy which, in percentage by weight and apart from generally occurring impurities, comprises from 20 to 30% of Cr, from 0 to 8% of W, from 4 to 8% of Al, from 0.2 to 0.55% of C, from 0 to 2% of Hf, from 0 to 1.5% of Nb, from 0 to 8% of Mo, from 0 to
  • This material has shown surprisingly good mechanical machinability and high fatigue strength and resistance to both hot corrosion and erosive influences from the fuel. At boring of the nozzle holes, no chipping off of flakes at the ends of the bore was observed. Likewise, tests have shown that the knife-edge inlets to the nozzle holes are retained, even after very long periods of operation.
  • the Cr content of the alloy is important to the ability of the nozzle to resist hot corrosion, and additionally, the Cr content provides a solution-strengthening effect which, in addition to the fine grain structure, contributes to increasing the strength of the alloy. If desired, this effect can be enhanced by adding Mo and/or W to the alloy.
  • Al forms a combined surface layer of Al 2 O 3 and Cr 2 O 3 which protects the nozzle against corrosion at high temperatures.
  • the Al content furthermore provides a ⁇ ' phase consisting of the intermetal Ni 3 Al, which causes precipitation hardening of the alloy, but is a relatively brittle phase.
  • Al contents of more than 8% involve a risk that the ⁇ ' phase becomes cohesive instead of being enclosed by a ductile austenitic phase which secures the high fatigue strength and good machinability of the material.
  • the Al content of the alloy can suitably be restricted to maximum 6 per cent, as most of the positive properties of Al have then been exploited without any risk of loss of strength owing to an incomplete enclosing of the ⁇ ' phase.
  • the nozzle cannot resist the corrosive influences at high temperatures. It may be possible to add more than 30% of Cr to the alloy, but this would not result in any noticeably improved resistance to high temperature corrosion. On the contrary, high Cr contents will impair the mechanical machinability of the nozzle, and so, preferably, the alloy comprises 24% of Cr at the most.
  • the possible Fe content of the alloy is kept at a maximum of 5% to prevent deterioration of the corrosion properties of the nozzle.
  • the finely grained structure of the powder used as a starting material at the HIP treatment is provided by pressure atomization of melted material into a relatively cold gas, where the atomized drops are subjected to quenching during simultaneous formation of extremely small crystal grains in the material. The quenching also results in an extremely small distance between the dendritic branches of the crystal grains.
  • the Si content of the alloy of up to 1% does not impart any special advantages to the finished nozzle, but has a deoxidizing effect during the powder production so that pollution of the powder with undesired oxides is avoided. Alternatively, other deoxidizing components may be used in small amounts.
  • the C content of the alloy is kept at a maximum of 0.55% to prevent precipitation of needle and plate-shaped carbides which may lower the ductility of the alloy.
  • the alloy does not achieve the hardness necessary to resist the erosive influences from the fuel.
  • Addition of up to 2% of Hf may modify unfortunate carbide precipitations into having more rounded shapes.
  • Addition of Nb in amounts of up to 1.5% may result in a finer precipitation of metal carbides, which presumably imparts greater ductility to the alloy.
  • the corrosion resistance of the nozzle at high temperatures can be improved by the addition of Y in amounts of up to 1.5%. Further addition of Y does not result in further improvement.
  • the C content is preferably at least 0.35% in consideration of the hardness of the alloy.
  • the nozzle is made of a HIP-treated, nickel-based alloy which, in percentage by weight and apart from generally occurring impurities, comprises from 40 to 50% of Cr, from 0 to 0.55% of C, less than 1.0% of Si, from 0 to 5.0% of Mn, less than 1.0% of Mo, from 0 to less than 0.5% of B, from 0 to 8.0% of Al, from 0 to 1.5% of Ti, from 0 to 0.2% of Zr, from 0 to 3.0% of Nb, maximum 0.01% of O, maximum 0.03% of N, maximum 2% of Hf, maximum 1.5% of Y, a combined content of Co and Fe of maximum 5.0% and the balance Ni, the flow passage for the fuel being bored after the HIP treatment, whereby the hole edges of the nozzle holes at the transition to the central bore become sharp.
  • This material has a high fatigue strength and extremely high resistance to both hot corrosion and erosive influences from the fuel.
  • the Cr content of the alloy is important to the ability of the nozzle to resist hot corrosion, and the Cr content further has a solution-strengthening effect which, in addition to the fine grain structure, contributes to increasing the strength of the alloy. If desired, this effect can be enhanced by the addition of Mo and/or W to the alloy.
  • Al forms a combined surface layer of Al 2 O 3 and Cr 2 O 3 which protects the nozzle against corrosion at high temperatures.
  • the Al content furthermore provides a ⁇ ' phase consisting of the intermetal Ni 3 Al, which causes precipitation hardening of the alloy, but is a relatively brittle phase.
  • the Al content is higher than 2.5% to obtain suitable amounts of the desired surface layer.
  • Al contents of more than 8% involve a risk of the formation of a ⁇ phase which reduces the ductility of the alloy at room temperature and reduces the strength of the alloy at high temperatures.
  • the Al content of the alloy can suitably be restricted to maximum 6%, as most of the positive properties of Al have then been exploited without any risk of loss of strength owing to unsuitable structural components.
  • the possible Fe content of the alloy is kept at a maximum of 5% to prevent deterioration of the corrosion properties of the nozzle.
  • Fe and Co are both impurities in the alloy, and it is desired to limit their combined content to a maximum of 5.0%.
  • the finely grained structure of the powder used as a starting material at the HIP treatment is provided by pressure atomization of melted material into a relatively cold gas, where the atomized drops are subjected to quenching during simultaneous formation of extremely small crystal grains in the material. The quenching also results in an extremely small distance between the dendritic branches of the crystal grains.
  • the Si content of the alloy of up to 1% does not impart any special advantages to the finished nozzle, but has a deoxidizing effect during the powder production so that pollution of the powder with undesired oxides is avoided.
  • other deoxidizing components may be used in small amounts, such as Ti or Mn.
  • Mn is not quite such an efficient deoxidizing agent, and it is desired to restrict the amount thereof to a maximum of 5% in order not to dilute the effective components in the finished alloy.
  • Ti for example in amounts of at least 0.5%, the risk of formation of so-called prior particle boundaries (PPB) may be increased, particularly if the alloy comprises C and impurities from O and N, for which reason, simultaneously with Ti, an addition of HF of about 0.5% to the alloy is preferably made to counteract this tendency.
  • the B content has surprisingly turned out to be of importance for the achievement, by the nickel alloy with the high Cr content, of a high ductility advantageous to the fatigue strength.
  • B causes the solidification of the melted material to change from cellular solidification into dendritic solidification where the dendritic branches interlock and produce a geometrical locking of the structural components.
  • B is largely insoluble in the ⁇ and the ⁇ phases, and it is presumed that the solidification involves an eutectic with a number of borides. Larger contents of B may cause precipitation of the well-known and undesired low-melting eutectics of no great strength.
  • the alloy is exposed to a solid phase transformation, where chromium-comprising ferritic ⁇ phase is precipitated in the austenitic nickel phase as very finely distributed precipitates.
  • Nb influences the solid phase transformation into yielding globular precipitation rather than lamellar precipitation, which increases the ductility of the alloy.
  • the C content of the alloy is maintained at a maximum of 0.55% in order to counteract precipitation of needle and plate-shaped carbides which may reduce the ductility of the alloy.
  • the addition of up to 2% of Hf may modify unfortunate carbide precipitates into having more rounded shapes and may at the same time relieve a possible Nb content from being incorporated in the carbide formation.
  • the addition of Nb in amounts of up to 3.0% may result in a finer precipitation of metal carbides, which is presumed to impart greater ductility to the alloy, and at the same time a residual amount of free Nb will be present to influence the solid phase transformation.
  • the C content is maximum 0.1%, and the Hf content is less than 0.5%, as there is no need for a large excess of carbide modifiers.
  • Holding times at the HIP treatment or at a subsequent heat treatment at a temperature of above 550°C, preferably in the interval of 700-850°C may in this case be longer than 5 hours, so that there is time for the diffusion at the transformation to take place.
  • the corrosion resistance of the nozzle at high temperatures may be improved by the addition of Y in amounts of up to 1.5%. Addition of more Y does not result in further improvement.
  • the alloy comprises maximum 0.45% of Al, maximum 0.1% of C, and maximum 0.1% of Ti.
  • the precipitation of carbide networks, borides and/or intermetals, such as Ni 3 Al ( ⁇ '), in the basic matrix of the alloy is substantially suppressed, and therefore, after the HIP treatment the alloy will have a high ductility and low hardness so that the HIP-treated blank may be machined to the desired geometry with no problems.
  • the finished blank is then subjected to a heat treatment at a temperature in the interval of 550-1100°C, preferably 700-850°C, for a period of at least 5 hours.
  • phase transformation takes place, whereby ferritic ⁇ phase is particle-precipitated in a very fine distribution in the austenitic nickel phase ⁇ , whereby the alloy hardens and gets the desired high hardness which gives the nozzle good wear resistance.
  • the phase precipitates are so finely distributed that the microhardness of the matrix is largely evenly increased, which promotes both wear and hot corrosion resistances.
  • the holding time of the heat treatment may also be longer, such as at least 20 or at least 40-50 hours.
  • the alloy comprises at least 45% of Cr and from 0.15 to 0.40% of B, preferably maximum 0.25% of B.
  • the upper limit of 0.4% of B suitably ensures that at the solidification of the alloy the amount of hardness-increasing borides does not exceed a level where the alloy is embrittled, and the lower limit of 0.15% is suitable for a Cr content of 45%.
  • the alloy comprises from 1.0 to 2.0% of free Nb.
  • the advantageous change of the hardening mechanism into globular precipitation is strengthened if the free Nb content is at least 1.0%, and for financial reasons, the content of the relatively costly Nb may suitably be limited to the 2.0%, as a higher content of Nb usually does not substantially improve the properties of the alloy.
  • a number of nozzle holes may be provided closer to each other than has been possible previously.
  • the pressure of the fuel acts on the central bore of the nozzle with an excess pressure which produces tensile stresses in the nozzle material.
  • the higher fatigue strength of the nozzle permits an increase of the tensile stress level and thus an advantageously higher injection pressure, which can be used for injection of a larger fuel amount during an engine cycle.
  • the method and the nozzle according to the invention thus render it possible to manufacture engines with a higher cylinder output.
  • Fig. 1 shows the lower end of a fuel valve 1 having a housing 2 for mounting in a cylinder cover, not shown, in such a manner that an annular, inclined surface 3 at the lower end of the housing is pressed into abutment against a corresponding surface on the cover.
  • a nozzle 4 passes through a central hole in the housing 2 and projects down into the combustion chamber so that nozzle holes 5 in the side wall of the nozzle are located a suitable distance down in the combustion chamber.
  • the nozzle is substantially uncooled, and therefore the nozzle tip with the holes 5 is heated to a high temperature by the hot gases in the combustion chamber.
  • the nozzle has a central bore 6 extending from a flow passage 7 in the fuel valve to the nozzle tip at a lower level than the nozzle holes 5.
  • the bore 6 and the holes 5 form a flow passage for the fuel, which may be oil or gas.
  • each fuel valve 1 When the nozzle is intended for a two-stroke engine with a number of valves per cylinder, each fuel valve 1 is normally positioned near the vertical side wall of the combustion chamber. In that case, the fuel has to be injected in a fan-shaped cloud directed towards the middle of the combustion chamber, which means that the nozzle holes 5 are all formed in one side of the nozzle, and that the longitudinal axes of the nozzle holes form an angle of maximum 100° with each other. When two or three fuel valves per cylinder are used, the spherical angle is often limited to less than 80°.
  • the nozzle holes 5 are bored through the side wall of the nozzle to the central bore 6. The holes can also be produced in another manner, for example by spark machining, but boring is preferred because it is a rapid and simple mechanical machining.
  • a nozzle according to the invention has been manufactured by HIP treatment of an isotropic finely grained powder of Stellite 6, where the powder grains are less than 300 ⁇ m.
  • Stellite 6 has an approximate analysis of 1.14% of C, 1.06% of Si, 28.5% of Cr, 0.43% of Fe, 4.65% of W and the balance Co.
  • the HIP treatment was carried out at a temperature between 1100 and 1200°C and a pressure between 900 and 1100 bar, and with a holding time of 2 hours.
  • the central bore 6 was bored into the HIP-treated blank, whereupon the nozzle holes 5 were bored from the outside to the central bore.
  • the nozzle was examined by means of the endoscope, which showed smooth hole edges at the openings of the nozzle holes in the central bore.
  • the HIP-treated Stellite 6 has a substantially better machinability than cast Stellite 6.
  • the smoother hole edges cause smaller stress concentrations in the nozzle.
  • a HIP-treated nozzle was manufactured in the same manner as above.
  • the endoscope examination of the nozzle has been shown in Figs. 4-6, where it can be seen that the edges of the nozzle holes at the openings into the central bore 6 are sharp and without chippings.
  • HIP-treated nozzles have then been tested by operating tests in a trial engine, which showed that both types of HIP-treated nozzles have greater resistance to hot corrosion and the formation of microcracks than the known cast nozzles of Stellite 6. In the area between the two mutually closest nozzle holes, a few very small cracks in the material were observed in the HIP-treated nozzle of Stellite 6, while the HIP-treated, nickel-based nozzle was completely crack-free.
  • HIP-treated nozzles have also been manufactured in the cobalt-based alloy Celsit 50-P with the approximate analysis showing 2% of C, 28% of Cr, 6.5% of Ni, 10% of W, 3.7% of Mo, 1.6% of Cu and the balance Co. Operating tests with these nozzles showed that the fatigue strength and the resistance to hot corrosion were on a par with nozzles of HIP-treated Stellite 6.
  • the HIP-treated nozzle material is both substantially stronger and substantially more ductile than the cast nozzle material, just as the HIP-treated material has a substantially improved fatigue strength.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
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  • General Engineering & Computer Science (AREA)
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  • Metallurgy (AREA)
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  • Powder Metallurgy (AREA)

Claims (16)

  1. Procédé de fabrication d'un ajutage pour clapet d'admission de carburant pour moteur à combustion interne, en particulier moteur deux-temps de grande taille, selon lequel une poudre essentiellement isotrope à granulométrie fine, d'une composition telle que l'ajutage fini présente une résistance à la corrosion à chaud, est disposée dans un moule et est soumise à un traitement thermique sous pression isostatique d'une valeur d'au moins 800 bar à une température d'au moins 1.000°C, caractérisé en ce que le moule présente essentiellement la forme externe souhaitée pour l'ajutage, en ce que le traitement thermique sous pression isostatique dure au moins une heure sous la pression et la température mentionnées, et en ce que le passage d'écoulement avec un alésage central longitudinal (6) et un nombre d'orifices d'ajutage (5) est alésé dans l'ébauche ainsi traitée thermiquement sous pression isostatique, les bords des orifices d'ajutage à la transition à l'alésage central devenant ainsi tranchants.
  2. Procédé selon la revendication 1, caractérisé en ce que l'ébauche d'ajutage présente une phase nickel austénitique et en ce qu'après l'usinage mécanique, l'ébauche est soumise à un traitement thermique sous une température se situant dans la gamme de 550 à 1100°C, de préférence 700 à 850°C, pour une période d'au moins 5 heures, une transformation de phase solide ayant alors lieu, dans laquelle la phase ferrite α se trouve précipitée en particules à distribution très fine dans la phase nickel austénitique.
  3. Ajutage (4) pour clapet d'admission (1) de carburant pour moteur à combustion interne, en particulier moteur deux-temps de grande taille, présentant un alésage central longitudinal (6) et un nombre d'orifices d'ajutage (5) situés dans la paroi latérale de l'ajutage et constituant, avec l'alésage longitudinal, un passage d'écoulement de carburant sous pression, ledit ajutage (4) étant constitué d'un matériau résistant à la corrosion à chaud et aux effets érosifs du carburant, caractérisé en ce que l'ajutage (4) est constitué d'un alliage à base de cobalt, soumis à traitement thermique sous pression isostatique, comprenant du chrome et du tungstène, par exemple Stellite 6, le passage d'écoulement de carburant étant alésé après le traitement thermique sous pression isostatique, les bords des orifices d'ajutage à la transition à l'alésage central étant ainsi rendus tranchants.
  4. Ajutage (4) pour clapet d'admission (1) de carburant pour moteur à combustion interne, en particulier moteur deux-temps de grande taille, présentant un alésage central longitudinal (6) et un nombre d'orifices d'ajutage (5) situés dans la paroi latérale de l'ajutage et constituant, avec l'alésage longitudinal, un passage d'écoulement de carburant sous pression, ledit ajutage (4) étant constitué d'un matériau résistant à la corrosion à chaud et aux effets érosifs du carburant, caractérisé en ce que l'ajutage (4) est constitué d'un alliage à base de nickel, soumis à traitement thermique sous pression isostatique, alliage qui, en pourcentage en poids et hormis des impuretés apparaissant généralement, comprend 20 à 30% de Cr, 0 à 8% de W, 4 à 8% d'Al, 0,2 à 0,55% de C, 0 à 2% de Hf, 0 à 1,5% de Nb, 0 à 8% de Mo, 0 à 1% de Si, 0 à 1,5% d'Y et 0 à 5% de Fe, le passage d'écoulement de carburant étant alésé après le traitement thermique sous pression isostatique, les bords des orifices d'ajutage à la transition à l'alésage central étant ainsi rendus tranchants.
  5. Ajutage selon la revendication 4, caractérisé en ce que l'alliage comporte au maximum 6% d'Al.
  6. Ajutage selon la revendication 4, caractérisé en ce que l'alliage comporte 0,35 à 0,55% de C.
  7. Ajutage selon la revendication 4, caractérisé en ce que l'alliage comporte au maximum 24% de Cr.
  8. Ajutage (4) pour clapet d'admission (1) de carburant pour moteur à combustion interne, en particulier moteur deux-temps de grande taille, présentant un alésage central longitudinal (6) et un nombre d'orifices d'ajutage (5) situés dans la paroi latérale de l'ajutage et constituant, avec l'alésage longitudinal, un passage d'écoulement de carburant sous pression, ledit ajutage (4) étant constitué d'un matériau résistant à la corrosion à chaud et aux effets érosifs du carburant, caractérisé en ce que l'ajutage (4) est constitué d'un alliage à base de nickel, soumis à traitement thermique sous pression isostatique, alliage qui, en pourcentage en poids et hormis des impuretés apparaissant généralement, comprend 40 à 50% de Cr, 0 à 0,55% de C, moins de 1,0% de Si, 0 à 5,0% de Mn, moins de 1,0% de Mo, 0 à moins de 0,5% de B, 0 à 8,0% d'Al, 0 à 1,5% de Ti, 0 à 0,2% de Zr, 0 à 3% de Nb, au maximum 0,01% d'O, au maximum 0,03% de N, au maximum 2% de Hf, au maximum 1,5% d'Y, un taux combiné de Co et Fe d'au maximum 5,0%, le reste étant du Ni, le passage d'écoulement de carburant étant alésé après le traitement thermique sous pression isostatique, les bords des orifices d'ajutage à la transition à l'alésage central étant ainsi rendus tranchants.
  9. Ajutage selon la revendication 8, caractérisé en ce que l'alliage comporte au maximum 6% d'Al.
  10. Ajutage selon la revendication 8, caractérisé en ce que l'alliage comporte au moins 2,5% d'Al.
  11. Ajutage selon les revendications 8 ou 9, caractérisé en ce que l'alliage comporte au maximum 0,1% de C et au maximum 0,5% de Hf.
  12. Ajutage selon la revendication 8, caractérisé en ce que l'alliage comporte au maximum 0,45% d'Al, au maximum 0,1% de C et au maximum 0,1% de Ti.
  13. Ajutage selon la revendication 8, caractérisé en ce que l'alliage comporte au moins 0,5% de Ti et, de préférence, au moins 0,5% de Hf.
  14. Ajutage selon l'une quelconque des revendications 8 à 13, caractérisé en ce que l'alliage comporte au moins 45% de Cr et 0,15 à 0,40% de B, de préférence au moins 0,25% de B.
  15. Ajutage selon l'une quelconque des revendications 8 à 14, caractérisé en ce que l'alliage 1,0 à 2,0% de Nb libre.
  16. Ajutage selon l'une quelconque des revendications 3 à 15, caractérisé en ce que l'ajutage comprend six ou sept orifices d'ajutage, ou plus, l'ensemble de ces orifices ayant leurs axes longitudinaaux situés dans un angle sphérique de 100° au maximum, de préférence 80° au maximum.
EP95911230A 1994-03-10 1995-03-09 Procede de fabrication d'un ajutage pour clapet d'admission de carburant et cet ajutage Expired - Lifetime EP0749365B1 (fr)

Applications Claiming Priority (7)

Application Number Priority Date Filing Date Title
DK28294 1994-03-10
DK282/94 1994-03-10
DK28294A DK174073B1 (da) 1994-03-10 1994-03-10 Fremgangsmåde til fremstilling af en forstøver til en brændselsventil samt en sådan forstøver
DK142994 1994-12-13
DK1429/94 1994-12-13
DK142994 1994-12-13
PCT/DK1995/000112 WO1995024286A1 (fr) 1994-03-10 1995-03-09 Procede de fabrication d'un ajutage pour clapet d'admission de carburant et cet ajutage

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EP0749365A1 EP0749365A1 (fr) 1996-12-27
EP0749365B1 true EP0749365B1 (fr) 1998-04-29

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EP (1) EP0749365B1 (fr)
JP (1) JP3355190B2 (fr)
KR (1) KR100324398B1 (fr)
DE (1) DE69502277T2 (fr)
HR (1) HRP950114B1 (fr)
NO (1) NO314170B1 (fr)
RU (1) RU2124417C1 (fr)
WO (1) WO1995024286A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001048371A1 (fr) 1999-12-28 2001-07-05 Robert Bosch Gmbh Procede pour produire une soupape destinee a un dispositif d'injection de carburant

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DK1353061T3 (da) * 2002-04-11 2008-06-23 Waertsilae Nsd Schweiz Ag Dysehoved til brændstofindspröjtningsdyse
AU2003269842A1 (en) * 2002-10-07 2004-04-23 Man B And W Diesel A/S Method of manufacturing a nozzle for a fuel valve in a diesel engine, and a nozzle
US20070131803A1 (en) * 2005-12-13 2007-06-14 Phadke Milind V Fuel injector having integrated valve seat guide
JP5559962B2 (ja) 2008-09-05 2014-07-23 日立オートモティブシステムズ株式会社 燃料噴射弁及びノズルの加工方法
RU2477670C1 (ru) * 2011-12-27 2013-03-20 Открытое акционерное общество "Всероссийский институт легких сплавов" (ОАО "ВИЛС") Способ изготовления изделий из гранулируемых жаропрочных никелевых сплавов
CN103240412B (zh) * 2013-05-22 2014-10-15 北京科技大学 一种近终形制备粉末超合金的方法
CN109652732B (zh) * 2019-02-15 2021-06-15 南通理工学院 一种3dp法镍基合金空心圆柱立体打印工艺
CN109988956B (zh) * 2019-05-22 2020-12-29 山东理工大学 高硬度钴基合金及其制造方法

Family Cites Families (2)

* Cited by examiner, † Cited by third party
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EP0446673A1 (fr) * 1990-03-14 1991-09-18 Asea Brown Boveri Ag Procédé de préparation d'un article fritté avec une couche externe compacte et une surface lisse
US5403373A (en) * 1991-05-31 1995-04-04 Sumitomo Electric Industries, Ltd. Hard sintered component and method of manufacturing such a component

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001048371A1 (fr) 1999-12-28 2001-07-05 Robert Bosch Gmbh Procede pour produire une soupape destinee a un dispositif d'injection de carburant

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NO963760L (no) 1996-09-09
EP0749365A1 (fr) 1996-12-27
HRP950114A2 (en) 1997-02-28
RU2124417C1 (ru) 1999-01-10
WO1995024286A1 (fr) 1995-09-14
DE69502277T2 (de) 1998-09-10
JP3355190B2 (ja) 2002-12-09
NO963760D0 (no) 1996-09-09
KR100324398B1 (ko) 2002-10-18
DE69502277D1 (de) 1998-06-04
HRP950114B1 (en) 2000-08-31
JPH09509984A (ja) 1997-10-07
NO314170B1 (no) 2003-02-10
KR970701605A (ko) 1997-04-12

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