JP6052336B2 - Manufacturing method of sintered bearing for motor type fuel pump excellent in corrosion resistance, wear resistance and conformability - Google Patents
Manufacturing method of sintered bearing for motor type fuel pump excellent in corrosion resistance, wear resistance and conformability Download PDFInfo
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- JP6052336B2 JP6052336B2 JP2015105136A JP2015105136A JP6052336B2 JP 6052336 B2 JP6052336 B2 JP 6052336B2 JP 2015105136 A JP2015105136 A JP 2015105136A JP 2015105136 A JP2015105136 A JP 2015105136A JP 6052336 B2 JP6052336 B2 JP 6052336B2
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- 239000000446 fuel Substances 0.000 title claims description 35
- 238000005260 corrosion Methods 0.000 title claims description 32
- 230000007797 corrosion Effects 0.000 title claims description 32
- 238000004519 manufacturing process Methods 0.000 title claims description 7
- 239000000843 powder Substances 0.000 claims description 23
- 229910045601 alloy Inorganic materials 0.000 claims description 21
- 239000000956 alloy Substances 0.000 claims description 21
- 229910001128 Sn alloy Inorganic materials 0.000 claims description 19
- 229910052759 nickel Inorganic materials 0.000 claims description 15
- 229910020888 Sn-Cu Inorganic materials 0.000 claims description 12
- 229910019204 Sn—Cu Inorganic materials 0.000 claims description 12
- 229910052718 tin Inorganic materials 0.000 claims description 12
- 229910052698 phosphorus Inorganic materials 0.000 claims description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 10
- 239000006104 solid solution Substances 0.000 claims description 10
- 229910052725 zinc Inorganic materials 0.000 claims description 10
- 229910052802 copper Inorganic materials 0.000 claims description 9
- 239000011148 porous material Substances 0.000 claims description 9
- 229910002804 graphite Inorganic materials 0.000 claims description 8
- 239000010439 graphite Substances 0.000 claims description 8
- 239000012535 impurity Substances 0.000 claims description 8
- 239000002994 raw material Substances 0.000 claims description 7
- 238000001816 cooling Methods 0.000 claims description 4
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- 150000007524 organic acids Chemical class 0.000 description 20
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 19
- 229910052717 sulfur Inorganic materials 0.000 description 19
- 239000011593 sulfur Substances 0.000 description 19
- 239000000758 substrate Substances 0.000 description 11
- 235000005985 organic acids Nutrition 0.000 description 10
- 239000012085 test solution Substances 0.000 description 10
- 230000008859 change Effects 0.000 description 9
- 238000005245 sintering Methods 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 239000007788 liquid Substances 0.000 description 7
- 239000002184 metal Substances 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 229910000990 Ni alloy Inorganic materials 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 4
- 238000010894 electron beam technology Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 230000013011 mating Effects 0.000 description 4
- 229910002482 Cu–Ni Inorganic materials 0.000 description 3
- 229910001297 Zn alloy Inorganic materials 0.000 description 3
- 229910000905 alloy phase Inorganic materials 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 239000002253 acid Substances 0.000 description 2
- 238000000635 electron micrograph Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000005486 sulfidation Methods 0.000 description 2
- 239000004215 Carbon black (E152) Chemical group 0.000 description 1
- 229910017518 Cu Zn Inorganic materials 0.000 description 1
- 229910017752 Cu-Zn Inorganic materials 0.000 description 1
- 229910017888 Cu—P Inorganic materials 0.000 description 1
- 229910017943 Cu—Zn Inorganic materials 0.000 description 1
- 229910018054 Ni-Cu Inorganic materials 0.000 description 1
- 229910018481 Ni—Cu Inorganic materials 0.000 description 1
- 229910018605 Ni—Zn Inorganic materials 0.000 description 1
- 229910001096 P alloy Inorganic materials 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 150000001735 carboxylic acids Chemical class 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- TVZPLCNGKSPOJA-UHFFFAOYSA-N copper zinc Chemical compound [Cu].[Zn] TVZPLCNGKSPOJA-UHFFFAOYSA-N 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 229930195733 hydrocarbon Chemical group 0.000 description 1
- 150000002430 hydrocarbons Chemical group 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000004445 quantitative analysis Methods 0.000 description 1
- 238000004513 sizing Methods 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
- 230000007480 spreading Effects 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
Landscapes
- Sliding-Contact Bearings (AREA)
- Powder Metallurgy (AREA)
Description
本発明は、優れた耐食性と耐摩耗性を示すＺｎ−Ｐ−Ｎｉ−Ｓｎ−Ｃ−Ｃｕ系焼結合金で構成されたモータ式燃料ポンプの軸受に関するものである。 The present invention relates to a motor type fuel pump bearing made of a Zn—P—Ni—Sn—C—Cu based sintered alloy exhibiting excellent corrosion resistance and wear resistance.
モータ式燃料ポンプが組込まれている電子制御式ガソリン噴射装置は、自動車の省燃費、排出ガスのクリーン化に効果があることから広く使用されている。 Electronically controlled gasoline injection devices incorporating motor fuel pumps are widely used because they are effective in saving fuel and cleaning exhaust gases.
近年の自動車エンジンの小型軽量化指向は強く、これに伴い図３に示した燃料ポンプも小型化され、燃料ポンプに用いられる軸受も小寸法化及び薄肉化されている。一方、モータの吐出性能は従来どおり維持されている。このため、モータ式燃料ポンプに用いられる軸受は、ガソリンの高圧高速流に晒された環境下であっても、優れた耐摩耗性が要求されている。 In recent years, the trend toward miniaturization and weight reduction of automobile engines is strong, and accordingly, the fuel pump shown in FIG. 3 is also miniaturized, and the bearings used for the fuel pump are also miniaturized and thinned. On the other hand, the discharge performance of the motor is maintained as before. For this reason, the bearing used for a motor type fuel pump is required to have excellent wear resistance even in an environment exposed to a high-pressure and high-speed flow of gasoline.
ところで、近年の自動車市場のグローバル化に伴って、世界各地に自動車が普及しているが、世界各国で使用されるガソリン等液体燃料の品質は様々で、燃料の中に硫黄や有機酸が多く含まれている粗悪ガソリンを使用せざる得ない地域も少なくない。そして、これら硫黄や有機酸を含む粗悪ガソリンを使用した場合、硫黄や有機酸によりモータ式燃料ポンプの軸受が腐食し、モータロックによる故障や軸受の強度低下等により軸受寿命が短くなってしまうという問題があった。 By the way, with the recent globalization of the automobile market, automobiles are spreading all over the world. However, the quality of liquid fuels such as gasoline used in various countries varies, and the fuel contains a lot of sulfur and organic acids. There are many areas where it is necessary to use the bad gasoline included. And, when these poor gasolines containing sulfur and organic acids are used, the bearings of motor type fuel pumps are corroded by sulfur and organic acids, and the bearing life will be shortened due to failure due to motor lock, reduction of bearing strength, etc. There was a problem.
上記の問題について、硫黄又はその化合物を不純物に含む燃料に対しては、例えば、特許文献１、２にＣｕ−Ｎｉ系焼結合金で構成されたモータ式燃料ポンプの軸受が開示されており、有機酸等を含む粗悪なガソリン等の燃料に対しては、例えば、特許文献３にＳｎ高濃度合金相が形成された組織を有するＣｕ−Ｎｉ系焼結合金からなる軸受が開示されている。 Regarding the above problem, for fuel containing sulfur or a compound thereof as an impurity, for example, Patent Documents 1 and 2 disclose motor type fuel pump bearings made of a Cu-Ni based sintered alloy, For fuels such as poor gasoline containing organic acids and the like, for example, Patent Document 3 discloses a bearing made of a Cu—Ni-based sintered alloy having a structure in which a Sn high-concentration alloy phase is formed.
しかし、特許文献１〜２に開示された軸受では、優れた耐摩耗性を有し、硫黄を含む粗悪ガソリンに対して優れた耐食性を示すが、有機酸を含む粗悪ガソリンに対する耐食性は十分ではなかった。また特許文献３の軸受では、優れた耐摩耗性を有し、有機酸を含む粗悪ガソリンにおいても優れた耐食性を示すが、モータ式燃料ポンプの軸受としては、特許文献１〜２に示す軸受よりも相手シャフト材とのなじみ性が悪い事から、モータ運転初期の負荷が高くなる場合があり、モータ電流過多などの問題があった。 However, the bearings disclosed in Patent Documents 1 and 2 have excellent wear resistance and excellent corrosion resistance against bad gasoline containing sulfur, but the corrosion resistance against bad gasoline containing organic acid is not sufficient. It was. In addition, the bearing of Patent Document 3 has excellent wear resistance and excellent corrosion resistance even in poor gasoline containing an organic acid. However, as a bearing of a motor-type fuel pump, the bearings described in Patent Documents 1 and 2 are used. However, since the compatibility with the mating shaft material is poor, the load at the initial stage of motor operation may become high, resulting in problems such as excessive motor current.
そこで、本発明は、上記の問題を一掃し、硫黄や有機酸を含む粗悪ガソリンに対して耐食性を有し、耐摩耗性かつ相手シャフトとのなじみ性に優れるため小型化された燃料ポンプにおいても好適に用いることのできる、新規のＺｎ−Ｐ−Ｎｉ−Ｓｎ−Ｃ−Ｃｕ系焼結合金で構成されたモータ式燃料ポンプ用焼結軸受を提供することを目的とする。 Therefore, the present invention eliminates the above problems, has corrosion resistance against bad gasoline containing sulfur and organic acids, and is excellent in wear resistance and compatibility with the mating shaft. It is an object of the present invention to provide a sintered bearing for a motor type fuel pump which can be suitably used and is composed of a novel Zn—P—Ni—Sn—C—Cu based sintered alloy.
特許文献３に示された軸受のなじみ性改善にはＮｉあるいはＳｎ量低減が有効と考えられたが、しかし、硫黄や有機酸を含む粗悪ガソリンに対する耐食性はＮｉあるいはＳｎ量低減に伴い低下する。すなわちＮｉあるいはＳｎ含有量に対し、なじみ性と耐食性は相反する性質である。そこで、ＮｉあるいはＳｎ量低減によるなじみ性改善と硫黄や有機酸を含む粗悪ガソリンに対する耐食性の両立のために鋭意研究した結果、合金成分をＺｎ−Ｐ−Ｎｉ−Ｓｎ−Ｃ−Ｃｕ系とし、Ｚｎ−Ｎｉ−Ｓｎ−Ｃｕ合金の固溶体相からなる素地の粒界に質量％で１５％以上のＳｎを含有するＳｎ合金相を形成し、素地には８％〜１８％の割合で気孔を分散分布させ、前記気孔内に遊離黒鉛を分布させた金属組織とすることで、優れた耐摩耗性を有しながら優れた相手シャフト材とのなじみ性と硫黄や有機酸を含む粗悪ガソリンに対する優れた耐食性を有する軸受材料を見出したのである。 Reduction of Ni or Sn content was considered to be effective for improving the conformability of the bearing shown in Patent Document 3, however, the corrosion resistance against poor gasoline containing sulfur and organic acids decreases as Ni or Sn content decreases. That is, conformability and corrosion resistance are contradictory properties with respect to Ni or Sn content. Then, as a result of earnest research for the compatibility of Ni or Sn content reduction and corrosion resistance against poor gasoline containing sulfur and organic acids, the alloy component was Zn-P-Ni-Sn-C-Cu system, -An Sn alloy phase containing 15% or more of Sn by mass% is formed at the grain boundary of the base composed of a solid solution phase of Ni-Sn-Cu alloy, and pores are dispersed and distributed in the base at a ratio of 8% to 18%. By having a metal structure in which free graphite is distributed in the pores, it has excellent wear resistance and compatibility with excellent mating shaft materials and excellent corrosion resistance against poor gasoline containing sulfur and organic acids The present inventors have found a bearing material having
すなわち、本発明のモータ式燃料ポンプ用軸受の製造方法は、質量％で、３〜１３％のＺｎと、０．１〜０．９％のＰと、１０〜２１％のＮｉと、３〜１２％のＳｎと、１〜８％のＣとを含有し、残部がＣｕ及び不可避不純物からなるとともに、Ｚｎ−Ｎｉ−Ｓｎ−Ｃｕ合金の固溶体相からなる素地の粒界に質量％で１５％以上のＳｎを含有するＳｎ合金相が形成され、かつ、８〜１８％の気孔率を有し、さらに前記気孔内には遊離黒鉛が分布している組織を有しているモータ式燃料ポンプ用焼結軸受の製造方法であって、前記Ｓｎ合金相を、原料粉末を圧粉成形し８４０〜９３０℃の温度で焼結した後、直ちに冷却速度１５℃／分以上で冷却することで形成するものである。 That is, the manufacturing method of the motor type fuel pump bearing of the present invention is 3% to 13% Zn, 0.1 to 0.9% P, 10 to 21% Ni, and 3% by mass. It contains 12% Sn and 1-8% C, with the balance being Cu and inevitable impurities, and 15% by mass in the grain boundary of the base consisting of the solid solution phase of Zn—Ni—Sn—Cu alloy. is Sn alloy phase formed containing more than Sn, and has a porosity of 8-18%, more motor fuel pump that has a tissue free graphite are distributed in the pores a method of manufacturing a sintered bearing, the Sn alloy phase, after sintering the raw material powder at a temperature of the powder molded 840-930 ° C., to form by immediately cooled at the rate 15 ° C. / min or more Is.
また、前記質量％で１５％以上のＳｎを含有するＳｎ合金相は、質量％で、０．１〜５．０％のＺｎと、０．４〜１．５％のＰと、２０〜３５％のＣｕと、２０〜４３．５％のＮｉとを含有し、残部がＳｎ及び不可避不純物からなるものである。 The Sn alloy phase containing 15% or more of Sn by mass% is 0.1% to 5.0% Zn, 0.4 to 1.5% P, and 20 to 35% by mass. % Cu and 20 to 43.5% Ni, with the balance being Sn and inevitable impurities.
本発明のモータ式燃料ポンプ用焼結軸受は、ガソリンなど通常の液体燃料の他、特に硫黄や有機酸を高濃度に含む粗悪なガソリンなどの液体燃料中であっても優れた耐食性、耐摩耗性及び相手シャフト材とのなじみ性を発揮するものであり、粗悪な液体燃料を用いても長期信頼性のモータ式燃料ポンプを提供することができる。 The sintered bearing for a motor type fuel pump of the present invention has excellent corrosion resistance and wear resistance even in ordinary liquid fuel such as gasoline, and particularly in liquid fuel such as poor gasoline containing high concentration of sulfur and organic acids. The motor-type fuel pump with long-term reliability can be provided even if poor liquid fuel is used.
本発明のモータ式燃料ポンプ用焼結軸受は、質量％で、３〜１３％のＺｎと、０．１〜０．９％のＰと、１０〜２１％のＮｉと、３〜１２％のＳｎと、１〜８％のＣとを含有し、残部がＣｕ及び不可避不純物からなるとともに、Ｚｎ−Ｎｉ−Ｓｎ−Ｃｕ合金の固溶体相からなる素地中の粒界に質量％で１５％以上のＳｎを含有するＳｎ合金相が形成され、かつ、８〜１８％の気孔率を有し、さらに前記気孔内には遊離黒鉛が分布している組織を有している。素地にＺｎ−Ｎｉ−Ｓｎ−Ｃｕ合金の固溶体相とし、粒界にＳｎ合金相を形成することで、相手シャフト材とのなじみ性に優れ、耐硫黄性、耐有機酸性を示すとともに優れた耐摩耗性を有するモータ式燃料ポンプの軸受となる。 The sintered bearing for a motor type fuel pump of the present invention is 3% to 13% Zn, 0.1 to 0.9% P, 10 to 21% Ni, and 3 to 12% by mass. It contains Sn and 1 to 8% of C, the balance is made of Cu and inevitable impurities, and at least 15% by mass in the grain boundary in the substrate made of a solid solution phase of Zn—Ni—Sn—Cu alloy. An Sn alloy phase containing Sn is formed, has a porosity of 8 to 18%, and has a structure in which free graphite is distributed in the pores. By forming a solid solution phase of Zn-Ni-Sn-Cu alloy on the substrate and forming an Sn alloy phase at the grain boundary, it has excellent compatibility with the mating shaft material, exhibits sulfur resistance and organic acid resistance, and has excellent resistance to resistance. It becomes the bearing of the motor type fuel pump which has wearability.
以下、本発明のモータ式燃料ポンプ用焼結軸受の組成等について、詳細に説明する。なお、以下で説明される含有量は、すべて質量％である。 Hereinafter, the composition of the sintered bearing for a motor type fuel pump of the present invention will be described in detail. In addition, all content demonstrated below is the mass%.
（１）Ｚｎ：質量％で３〜１３％
Ｚｎは、硫黄を含むガソリンに対して耐食性を有し、焼結によりＮｉ、Ｓｎ、ＣｕとともにＺｎ−Ｎｉ−Ｓｎ−Ｃｕ合金の固溶体相を形成して、軸受に優れた耐食性、なじみ性を具備せしめる作用があるが、Ｚｎの含有量が３％未満では所望の耐食性及びなじみ性が得られない。一方、Ｚｎの含有量が１３％を超えると有機酸を含むガソリンに対して耐食性が低下するようになるので好ましくない。
(1) Zn: 3 to 13% by mass
Zn has corrosion resistance to gasoline containing sulfur, and forms a solid solution phase of Zn-Ni-Sn-Cu alloy together with Ni, Sn, Cu by sintering, and has excellent corrosion resistance and conformability to the bearing. Although it has a caking action, if the Zn content is less than 3%, desired corrosion resistance and conformability cannot be obtained. On the other hand, if the Zn content exceeds 13%, the corrosion resistance of gasoline containing an organic acid is lowered, which is not preferable.
（２）Ｐ：質量％で０．１〜０．９％
Ｐは、圧粉体の焼結性を促進し、軸受の強度を向上させる。焼結後は金属組織の粒界に多く含まれている。Ｐ含有量が０．１％未満では十分な焼結性効果を得ることができない。一方、Ｐ含有量が０．９％を越えると焼結時の寸法変化が大きくなり、軸受製品の寸法精度が低下するので好ましくない。
(2) P: 0.1 to 0.9% by mass%
P promotes the sinterability of the green compact and improves the strength of the bearing. After sintering, it is abundant in the grain boundaries of the metal structure. If the P content is less than 0.1%, a sufficient sinterability effect cannot be obtained. On the other hand, if the P content exceeds 0.9%, the dimensional change during sintering becomes large and the dimensional accuracy of the bearing product is lowered, which is not preferable.
（３）Ｎｉ：質量％で１０〜２１％
Ｎｉは、優れた強度、耐摩耗性及び耐食性を付与し、焼結によりＺｎ、Ｓｎ、ＣｕとともにＺｎ−Ｎｉ−Ｓｎ−Ｃｕ合金の固溶体相を形成し、さらにＰ、Ｓｎ、Ｃｕとともに粒界にＳｎ合金相を形成して、軸受に優れた強度、耐摩耗性及び耐食性を付与する。Ｎｉ含有量が１０％未満では、優れた耐食性が得られない。一方、Ｎｉ含有量が２１％を超えても耐食性向上の効果が少なく、原料コストが高くなるため好ましくない。
(3) Ni: 10 to 21% by mass
Ni imparts excellent strength, wear resistance and corrosion resistance, and forms a solid solution phase of Zn-Ni-Sn-Cu alloy together with Zn, Sn, Cu by sintering, and further at grain boundaries together with P, Sn, Cu An Sn alloy phase is formed to impart excellent strength, wear resistance and corrosion resistance to the bearing. If the Ni content is less than 10%, excellent corrosion resistance cannot be obtained. On the other hand, even if the Ni content exceeds 21%, the effect of improving the corrosion resistance is small and the raw material cost is increased, which is not preferable.
（４）Ｓｎ：質量％で３〜１２％
Ｓｎは、焼結によりＮｉ、Ｓｎ、Ｐとともに粒界にＳｎ合金相を形成し、さらにＺｎ、Ｎｉ、Ｐ、ＣｕとともにＺｎ−Ｎｉ−Ｐ−Ｓｎ−Ｃｕ合金の固溶体相からなる素地を形成することで軸受に優れた耐食性を付与する。Ｓｎ含有量が３％未満では粒界相が十分形成されず、所望の耐食性が得らない。一方、Ｓｎ含有量が１２％を超えても耐食性向上に効果が少なく、かえって焼結時の寸法変化が大きくなり、軸受製品の寸法精度が低下するので好ましくない。
(4) Sn: 3 to 12% by mass
Sn forms a Sn alloy phase at the grain boundary together with Ni, Sn, and P by sintering, and further forms a substrate composed of a solid solution phase of Zn—Ni—P—Sn—Cu alloy together with Zn, Ni, P, and Cu. This gives the bearing excellent corrosion resistance. If the Sn content is less than 3%, the grain boundary phase is not sufficiently formed, and desired corrosion resistance cannot be obtained. On the other hand, even if the Sn content exceeds 12%, the effect of improving the corrosion resistance is small, and on the contrary, the dimensional change during sintering becomes large and the dimensional accuracy of the bearing product is lowered, which is not preferable.
（５）Ｃ：質量％で１〜８％
Ｃは黒鉛に由来するものである。Ｃは、主に、素地中に分散分布している気孔内に遊離黒鉛として存在し、軸受に優れた潤滑性を付与し、耐摩耗性を向上させる。Ｃ含有量が１％未満では所望の効果が得られない。一方、Ｃ含有量が８％を越えても耐摩耗性向上の効果が少なく、軸受の強度が急激に低下するので好ましくない。
(5) C: 1 to 8% by mass%
C is derived from graphite. C mainly exists as free graphite in pores dispersed and distributed in the substrate, imparts excellent lubricity to the bearing, and improves wear resistance. If the C content is less than 1%, the desired effect cannot be obtained. On the other hand, if the C content exceeds 8%, the effect of improving the wear resistance is small, and the strength of the bearing is abruptly lowered.
（６）気孔率：８〜１８％
気孔は素地に分散し、液体燃料の高圧高速流通下で軸受が受ける強い摩擦を緩和し、軸受けの摩耗を抑制する効果があるが、気孔率が８％未満ではその効果が十分でなくなる。一方、気孔率が１８％を超えると強度が著しく低下するので好ましくない。
(6) Porosity: 8-18%
The pores are dispersed in the substrate and have an effect of reducing the strong friction received by the bearing under the high-pressure and high-speed flow of the liquid fuel and suppressing the wear of the bearing. However, when the porosity is less than 8%, the effect is not sufficient. On the other hand, when the porosity exceeds 18%, the strength is remarkably lowered, which is not preferable.
（７）１５質量％以上のＳｎを含有するＳｎ合金相
素地の粒界に形成された、質量％で１５％以上のＳｎを含有するＳｎ合金相は、有機酸を含む粗悪ガソリン中における優れた耐食性を付与する。
(7) Sn alloy phase containing 15% by mass or more of Sn The Sn alloy phase containing 15% or more by mass of Sn formed at the grain boundary of the substrate is excellent in poor gasoline containing organic acids. Provides corrosion resistance.
質量％で１５％以上のＳｎを含有するＳｎ合金相は、原料粉末に、Ｃｕ−Ｎｉ合金粉末又はＺｎ−Ｎｉ−Ｃｕ合金粉末と、Ｓｎ粉末、Ｃｕ−Ｐ粉末、Ｃｕ−Ｚｎ粉末、黒鉛粉末を、質量％で、３〜１３％のＺｎと、０．１〜０．９％のＰと、１０〜２１％のＮｉと、３〜１２％のＳｎと、１〜８％のＣとを含有し、残部がＣｕ及び不可避不純物からなる成分組成となるように配合し、混合した原料粉末を用いて圧粉成形し、次いで行う焼結の温度範囲を８４０℃〜９３０℃に制御して焼結した後、直ちに冷却速度１５℃／分以上で急冷することで、効率よく素地の粒界に形成される。上記の条件により形成されたＳｎ合金相は、質量％で、０．１〜５．０％のＺｎと、０．４〜１．５％のＰと、２０〜３５％のＣｕと、２０〜４３．５％のＮｉとを含有し、残部がＳｎ及び不可避不純物とを含有する。 The Sn alloy phase containing 15% or more of Sn by mass% includes, as raw material powder, Cu—Ni alloy powder or Zn—Ni—Cu alloy powder, Sn powder, Cu—P powder, Cu—Zn powder, and graphite powder. 3% to 13% Zn, 0.1% to 0.9% P, 10% to 21% Ni, 3% to 12% Sn, and 1% to 8% C. Contained so that the balance is a component composition consisting of Cu and inevitable impurities, compacted using the mixed raw material powder, and then controlled to a temperature range of 840 ° C. to 930 ° C. for sintering. Immediately after ligation, it is rapidly cooled at a cooling rate of 15 ° C./min or more, so that it is efficiently formed at the grain boundaries of the substrate. The Sn alloy phase formed under the above conditions is 0.1% to 5.0% Zn, 0.4 to 1.5% P, 20 to 35% Cu, 20 to 20% by mass. It contains 43.5% Ni, and the balance contains Sn and inevitable impurities.
以下、本発明のモータ式燃料ポンプ用焼結軸受の具体的な実施例について説明する。なお、本発明は、以下の実施例に限定されるものではなく、種々の変形実施が可能である。 Hereinafter, specific examples of the sintered bearing for the motor type fuel pump of the present invention will be described. In addition, this invention is not limited to a following example, A various deformation | transformation implementation is possible.
（１）モータ式燃料ポンプ用焼結軸受の製作
原料粉末として、いずれも３０〜１００μｍの範囲内の所定の平均粒径を有するＣｕ−３０質量％Ｎｉ合金粉末、Ｃｕ−２５質量％Ｎｉ合金粉末、Ｃｕ−２０質量％Ｎｉ合金粉末、Ｃｕ−１５質量％Ｎｉ合金粉末、Ｃｕ−８質量％Ｐ合金粉末、Ｓｎ粉末、Ｃｕ−３０質量％Ｚｎ合金粉末、Ｃｕ−２０質量％Ｚｎ合金粉末、Ｃｕ−４０質量％Ｚｎ合金粉末、Ｃｕ−Ｎｉ−Ｚｎ合金粉末、黒鉛粉末、Ｃｕ粉末を用意した。これらの原料粉末を表１に示す組成になるように配合し、Ｖ型混合機にて２０分混合した後、所定の圧力でプレス成形して圧粉体を製作した。この圧粉体を、天然ガスと空気を混合し、加熱した触媒に通すことで分解変成させたエンドサーミックガス（吸熱型ガス）雰囲気中で、８４０〜９３０℃範囲内の所定の温度で焼結し、１５℃／分以上の冷却速度で急冷し、続いてサイジングを行った。以上の工程により、外径：１０ｍｍ×内径：５ｍｍ×高さ：５ｍｍの寸法を有し、表１に示す組成成分の本発明軸受（以下、本発明例という）、従来軸受、及び比較軸受を製作した。
(1) Manufacture of sintered bearing for motor type fuel pump As raw material powder, Cu-30 mass% Ni alloy powder and Cu-25 mass% Ni alloy powder each having a predetermined average particle size in the range of 30-100 μm Cu-20 mass% Ni alloy powder, Cu-15 mass% Ni alloy powder, Cu-8 mass% P alloy powder, Sn powder, Cu-30 mass% Zn alloy powder, Cu-20 mass% Zn alloy powder, Cu −40 mass% Zn alloy powder, Cu—Ni—Zn alloy powder, graphite powder, and Cu powder were prepared. These raw material powders were blended so as to have the composition shown in Table 1, mixed in a V-type mixer for 20 minutes, and then press molded at a predetermined pressure to produce a green compact. This green compact is sintered at a predetermined temperature in the range of 840 to 930 ° C. in an endothermic gas (endothermic gas) atmosphere that is decomposed and modified by mixing natural gas and air and passing through a heated catalyst. Then, it was rapidly cooled at a cooling rate of 15 ° C./min or more, followed by sizing. Through the above steps, the bearing of the present invention (hereinafter referred to as the present invention), the conventional bearing, and the comparative bearing having dimensions of outer diameter: 10 mm × inner diameter: 5 mm × height: 5 mm and having the composition components shown in Table 1 are obtained. Produced.
なお、本発明例において、電子線マイクロアナライザーによる金属組織観察を行った結果、金属組織中にＺｎ−Ｎｉ−Ｓｎ−Ｃｕ合金の固溶体相からなる素地及び素地中の粒界に質量％で１５％以上のＳｎを含有するＳｎ合金相が形成されおり、８〜１８％の気孔率を有し、前記気孔内には黒鉛が分散分布した組織を有していた。 In the examples of the present invention, as a result of observing the metal structure with an electron beam microanalyzer, it was found that the metal structure was made of a Zn-Ni-Sn-Cu alloy solid solution phase and the grain boundary in the substrate was 15% by mass. The Sn alloy phase containing the above Sn was formed, had a porosity of 8 to 18%, and had a structure in which graphite was dispersed and distributed in the pores.
（２）耐摩耗試験
上記の本発明例と従来例及び比較例の軸受について、ガソリンが狭い空間を高速で流通し、これを生起せしめるモータの高速回転によって軸受が高圧を受け、かつ速い流速のガソリンに曝される条件で耐摩耗試験を行った。
(2) Wear resistance test With respect to the bearings of the above-described present invention example, the conventional example and the comparative example, gasoline is circulated at high speed in a narrow space, and the bearing is subjected to high pressure by the high-speed rotation of the motor that causes this, and the high flow velocity An abrasion resistance test was conducted under conditions exposed to gasoline.
外側寸法が長さ：１１０ｍｍ×直径：４０ｍｍの燃料ポンプに軸受を組み込み、この燃料ポンプをガソリンタンク内に設置した。インンペラの回転数：５，０００〜１５，０００ｒｐｍ、ガソリンの流量：５０〜２５０リットル／時、軸受が高速回転より受ける圧力：最大５００ｋＰａ、試験時間：５００時間の条件にて実機実験を行った。試験後の軸受面における最大摩耗深さを測定した。その結果を表１に示す。 A bearing was incorporated into a fuel pump having an outer dimension of length: 110 mm × diameter: 40 mm, and this fuel pump was installed in a gasoline tank. An actual machine experiment was conducted under the conditions of the impeller rotation speed: 5,000 to 15,000 rpm, the gasoline flow rate: 50 to 250 liters / hour, the pressure that the bearing receives from high-speed rotation: a maximum of 500 kPa, and the test time: 500 hours. The maximum wear depth on the bearing surface after the test was measured. The results are shown in Table 1.
本発明例における軸受の最大摩耗深さは２．８μｍ以下であり、優れた耐摩耗性を有していることが確認された。 The maximum wear depth of the bearing in the example of the present invention was 2.8 μm or less, and it was confirmed that the bearing had excellent wear resistance.
（３）耐食試験
上記の本発明例と従来例及び比較例の軸受について耐食試験を行った。
(3) Corrosion resistance test Corrosion resistance tests were performed on the bearings of the present invention example, the conventional example, and the comparative example.
ガソリンに、硫黄を添加して疑似粗悪ガソリンを想定した硫黄試験液と、ガソリンにＲＣＯＯＨ（Ｒは水素原子又は炭化水素基）で表されるカルボン酸を添加して、擬似粗悪ガソリンを想定した有機酸試験液を製作した。この硫黄試験液及び有機酸試験液を６０℃に加熱した後、硫黄試験液及び有機酸試験液それぞれに本発明例と従来例及び比較例の軸受を５００時間浸漬した。そして、硫黄試験液及び有機酸試験液に浸漬する前の質量と浸漬後の質量の変化率を測定した。表１に耐食試験による質量変化の結果を示す。 Sulfur test solution that assumed pseudo bad gasoline by adding sulfur to gasoline, and organic that assumed pseudo bad gasoline by adding carboxylic acid represented by RCOOH (R is a hydrogen atom or hydrocarbon group) to gasoline. An acid test solution was prepared. The sulfur test solution and the organic acid test solution were heated to 60 ° C., and then the bearings of the present invention example, the conventional example, and the comparative example were immersed in the sulfur test solution and the organic acid test solution for 500 hours. And the change rate of the mass before being immersed in a sulfur test liquid and an organic acid test liquid and the mass after immersion was measured. Table 1 shows the result of mass change by the corrosion resistance test.
本発明例において、軸受の硫黄試験液における質量変化は０．１２％以下であり、また、有機酸試験液における質量変化は０．３８％以下であり、耐硫化性と耐有機酸性の両方の耐食性が高いことが確認された。 In the example of the present invention, the mass change in the sulfur test solution of the bearing is 0.12% or less, and the mass change in the organic acid test solution is 0.38% or less. It was confirmed that the corrosion resistance was high.
一方、比較例において、比較例５は軸受の硫黄試験液における質量変化は０．３５％で耐食性が低く、その他の比較例は０．１５％以下であり、耐硫化性が高い一方で、有機酸試験液における質量変化は０．５６〜０．７０％であり、本発明例よりも大幅に耐食性が低かった。 On the other hand, in Comparative Example 5, in Comparative Example 5, the mass change in the sulfur test solution of the bearing is 0.35%, which is low in corrosion resistance, and in other Comparative Examples, which is 0.15% or less. The mass change in the acid test solution was 0.56 to 0.70%, and the corrosion resistance was significantly lower than that of the examples of the present invention.
また、従来例において、Ｓｎを含まない従来例１は、耐硫化性が高い一方で、耐有機酸性が本発明例よりも大幅に低く、Ｓｎを含むＮｉ含有量が本発明例よりも多い従来例２は耐硫化性及び耐有機酸性とも本発明例とほぼ同等の耐食性を示した。 Further, in the conventional example, the conventional example 1 containing no Sn has a high resistance to sulfidation, while the organic acid resistance is significantly lower than that of the example of the present invention, and the Ni content containing Sn is higher than that of the example of the present invention. In Example 2, both the resistance to sulfidation and the resistance to organic acid showed almost the same corrosion resistance as that of the present invention.
（４）なじみ性試験
上記の本発明例３と従来例１、２の軸受をモータに組み込み、連続運転させた時の消費電流を３０分測定した。図１にその結果を示す。本発明例３の軸受及びＳｎを含まない従来例１の軸受を用いたモータの電流値は、Ｎｉ含有量が多くＳｎを含有する従来例２の軸受よりも短い時間で低下し、安定を示した。さらに、安定後の電流も低かった。このことから、本発明軸受は従来例２軸受よりも初期なじみ性が優れていることが確認された。
(4) Familiarity test The bearings of the present invention example 3 and the conventional examples 1 and 2 were incorporated into a motor, and the current consumption when continuously operated was measured for 30 minutes. The result is shown in FIG. The current value of the motor using the bearing of Example 3 of the present invention and the bearing of Conventional Example 1 that does not include Sn decreases in a shorter time than the bearing of Conventional Example 2 that has a high Ni content and contains Sn, and exhibits stability. It was. Furthermore, the current after stabilization was low. From this, it was confirmed that the bearing according to the present invention has better initial conformability than the conventional example 2 bearing.
（５）電子線マイクロアナライザー分析
本発明例３の合金について、電子線マイクロアナライザー（ＥＰＭＡ）を用いて、
Ｚｎ−Ｎｉ−Ｓｎ−Ｃｕ合金の固溶体相からなる素地及び粒界の質量％で１５％以上のＳｎを含有するＳｎ合金相について、Ｚｎ、Ｐ、Ｎｉ、Ｓｎ、Ｃｕを定量分析した。分析条件は加速電圧１５ｋＶ、ビーム径をφ１μｍに設定し、一例として図２の電子顕微鏡組織写真（ＣＯＭＰＯ像）に示すようにＺｎ−Ｎｉ−Ｓｎ−Ｃｕ合金相及び粒界のＳｎ合金相をそれぞれ５箇所測定して平均値を算出した。その結果を表２に示す。なお、本分析結果は、金属組織中の特定部位を分析したものであり、全体組成を示しているものではない。また、合金成分元素であるＣは素地中に分散分布する気孔内に遊離黒鉛としてほとんど存在しているため、定量分析元素から除外した。
(5) Electron beam microanalyzer analysis About the alloy of this invention example 3, using an electron beam microanalyzer (EPMA),
Zn, P, Ni, Sn, and Cu were quantitatively analyzed with respect to the Sn alloy phase containing 15% or more of Sn at a mass% of the grain boundary and the substrate composed of a solid solution phase of Zn—Ni—Sn—Cu alloy. The analysis conditions are an acceleration voltage of 15 kV and a beam diameter of φ1 μm. As an example, as shown in the electron micrograph (COMPO image) of FIG. 2, the Zn—Ni—Sn—Cu alloy phase and the Sn alloy phase at the grain boundary are respectively shown. The average value was calculated by measuring 5 points. The results are shown in Table 2. In addition, this analysis result analyzed the specific site | part in a metal structure, and does not show the whole composition. Further, C, which is an alloy component element, was almost excluded as free graphite in pores dispersed and distributed in the substrate, and thus was excluded from quantitative analysis elements.
本発明例３の合金には素地にＺｎ−Ｎｉ−Ｓｎ−Ｃｕ合金相と粒界の質量％で１５％以上のＳｎを含有するＳｎ合金相が存在することが確認された。 In the alloy of Invention Example 3, it was confirmed that a Zn—Ni—Sn—Cu alloy phase and a Sn alloy phase containing 15% or more of Sn by mass% of the grain boundary existed on the substrate.
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