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Recent Development of Plain Bearings for Combustion Engines

2013 ． Nov ． 19. MITC2013. Recent Development of Plain Bearings for Combustion Engines. Taiho Kogyo Co., Ltd. TTRF Yoshio KUMADA. Contents 1 What is “ Plain Bearing for Internal Combustion Engine”? 1.1 Short History 1.2 Needs & Direction of Development

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Recent Development of Plain Bearings for Combustion Engines

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  1. 2013．Nov．19 MITC2013 Recent Development of Plain Bearings for Combustion Engines Taiho Kogyo Co., Ltd. TTRF Yoshio KUMADA

  2. Contents 1 What is “Plain Bearing for Internal Combustion Engine”? 1.1 Short History 1.2 Needs & Direction of Development 2 Higher Performance, Lead Free 2.1 Al-Sn-Si(-Pb) Alloy Bearing 2.2Microgrooved Bearing 2.3 Lead Free Overlay 3 Lower Fuel Consumption for Future 3.1 Bearing with Eccentric Oil Groove 3.2 Bearing withSurface Texture 3.3 Friction loss reduced by Fullerene/Graphene coating 4 Conclusion

  3. 1 Plain Bearings for Internal Combustion Engine Camshaft bearing Con-Rod small-end bearing Small-end Con-Rod big-end bearing Con-Rod Crankshaft bearing Big-end Con-Rod big-end bearing Crankshaft Crankshaft bearing

  4. 1.1 Short History Scientific Research – Modern age • 1687 I. Newton “Principia” • Newtonian fluid, viscosity law • 1883 B. Towerexperimental work • - discovery of oil film pressure • 1886 O. Reynolds theoretical work • - Reynolds’ equation • 1902 R. Stribeck Stribeck curve • A. J. W. Sommerfeld analytic solution of • Reynolds’ equation • 1904 A. G. M. Michell tilting pad bearing (patent) • 1910 A. Kingsbury

  5. Modern age – White Metal 1839 ～ 　 　　　 1908 J.Babbitt invention of White metal (1839, USA Patent) Babbitt metal (Sn-9Sb-2Cu) T-type Ford, from 1908 White Metal ・Tin base (Sn-Sb-Cu-Pb) Lead base (Pb-Sb-Cu-Sn) Soft,Low melting point Good : conformability, Anti-seizure Poor : heat resistance, Anti-Fatigue

  6. 6 20μm Modern age – Copper-Lead, Overlay 1920s Higher Load Carrying Capacity & Fatigue Resistance Soft lead phase dispersed in hard metallic matrix 　　　　　　　 　　　⇒　Basic concept of recent bearing materials thick-walled cast Cu alloy with 20-50%Pb afterward, centrifugal casting or direct casting on back-steel 1939Powder metallurgy : continuous sintering on back-steel Around Widely Expanded 1940 – quality, productivity, economic efficiency afterward, Cu-Pb with Overlay (electroplated, 20μm) Higher conformability & Anti-seizure aroundPb-Sn-Cu, Pb-Sn, Pb-Sn-In, Pb-In 1970 Ni intermediate layer

  7. 7 Aluminum Alloy Modern age – World War I Lack of Heavy Metals 1920s Rolls-Royce(GB) thick-walled castduralumin with Overlay, C/R, P/P 1930sUSA Al-6Sn with Sn Overlay VW(DE) Al-5Zn-SiCuPbMg 1950sUSA Bimetal GB Al-20Sn without Overlay 1970s USA, JPN Al-Pb Casting, Powder sintering Al-20Sn Bimetal As Cast

  8. Bearing alloy (Lining) 20μm 20μm Back Steel Bearing lining back steel Al alloy bearing Structure of Engine Bearing and Cross-Sectional View Overlay Ni barrier Cu-Pb alloy Al-12Sn-2.7Si-1Cu(-2Pb) Pb-6In-7Sn/Cu-23Pb Bearing lining back steel Cu-Pb alloy bearing with overlay

  9. 1.2 Needs and Direction of Development 1.2.1 Bearing Pattern Prof. Norimune Soda said, “There is an effective method of using bearings, which is called the bearing law, that is the Bearing pattern”. 軸受には軸受法という法則があり，当たりこそ軸受法である．（曽田先生） Severity of engine bearings Maximum unit load : Pmax = 50 -100 MPa Minimum oil film thickness : hmin = 0.4 - 0.8 μm ＃1　　　 ＃2　　　 ＃3　　　 ＃4

  10. Pb Free １　Thin Overlay ２　Hard Particle in the Lining ３　Softer Middle Layer ４　Micro Regular Shape in the Surface Pb base Overlay 2.3 Pb free Overlay 2.1 Al-Sn-Si Alloy Al-Sn-Si Alloy + Underlay 2.2 Microgrooved Bearing 1.2.2 Conformability, Running-in Development of Bearings・・・the challenging theme how to make running-in of the bearing materials with higher strength Ref. : Y. Kumada, Journal of Japanese Society of Tribologist，41, 1 (1996) 28

  11. 1.2.3 Trends of Engines & Influences on Bearing Trend of Engines Influences on Bearing → Solution 2.1Al-Sn-Si alloy, 2.2 Microgrooved Bearing (2.3 Lead Free Materials) High performance ・Higher Unit Load (2.2 Microgrooved Bearing) (2.3 Lead Free Overlay) 3.1 Eccentric grooved Bearing 3.2 Surface texture ・Lower Rigidity of Housing ・Narrow Width → Higher Unit Load ・Lower Viscosity Oils ・Excessive wear Improve of Fuel Consumption ・Higher Oil Temp. ・Higher Unit Load Clean Exhaust Gas Reduction of Noise & Vibration 2.2 Microgrooved Bearing ・Smaller Diametral Clearance Reduction of Environmental Substances of Concerns 2.3 Lead Free Materials Others longer life, cost reduction ・Higher Durability ・Lower cost

  12. 2.1Al-Sn-Si Alloy Bearing 2.1.1 Seizure by Nodular Cast Iron Shaft Ref. : T. Fukuoka, H. Kato, S. Kamiya, N. Soda, SAE Technical Paper, 830308 (1983)

  13. 2.1.2 Lapping shaft surface by hard particles, Si Fig. seizure process of Al-alloy bearings and new concept Fig. seizure property of two kinds of Al-alloy bearings Ref. : T. Fukuoka, H. Kato, S. Kamiya, N. Soda, SAE Technical Paper, 830308 (1983)

  14. 20μm 20μm 2.1.3larger Si particle Size（2→5μm） 100 80 60 Wear amount ，mm 40 20 normal 0 1 2 3 4 5 Si Mean particle size, mm GO-STOP 50kcycles 2.2MPa 120C ATF SCM420H carburizing & quench Larger Si Al-12Sn-2.8Si Ref. : T．Desaki et al., JSAE Review, 21, 3 (2000) 321.

  15. 0.1～0.4 mm 3～6 μm ３ 2.2Microgrooved Bearing （MGB) Ref. : Y. Kumada, Dissertation in The University of Tokyo（1996）

  16. 2.2.1 Al alloy bearings (after engine endurance test) Look at the bearing pattern！ Normal Plain Bearing Microgrooved Bearing Engine: V6,3.0L 6,300r/min×WOT ×100h Bearing:Crankshaft bearing Al-Sn-Si alloy Block side Cap side ＃1　　　 ＃2　　　 ＃3　　　 ＃4 ＃1　　　 ＃2　　　 ＃3　　　 ＃4

  17. 17 180 Test condition 160 Engine：I-6, 2000cc, gasoline #4 crankshaft bearing was measured Load：W.O.T. Lubricant：7.5W-30　SE Oil temperature：130℃ 140 2.2.2Bearing temperature rise MGB G24 MGB G23 NPB NPB Lead Bronze with Overlay Seizure Bearing backside temp.,℃ Al-Sn-Si alloyNPB Al-Sn-Si alloyMGB G24 5000 6000 7000 8000 Rotational speed, r/min ΔT＝kQ/G Oil flow Heat generation Ref.：Y. Kumada et al., Tribology Trans., 39, 1 (1996)81

  18. 18 Prof. Kimura says, ■Contribution to improving fuel consumption, lower cost et al. It is common that a plain bearing has plane surface in order to carry the load by oil film pressure. An engineer of Taiho Kogyo in which I have taught Tribology for forty years, proposed the idea in a confident attitude. “The idea, which Surface has many grooves, is not common. That is very interesting.” 2004.2.24 Asahi Newspaper ●Received the first JAST award (1996. 5) Main stream of Engine Bearings （around 75% of worldwide Taiho engine bearings）

  19. 2.3 Lead Free Materials 2.3.1 Lead Amount of Typical Plain Bearings Pb amount in a piece of bearing (mass%) Category Composition 1 2 3 4 5 6 7 8 9 Sn base Pb base White Metal Pb base Sn base Overlay Overlay Lining Back steel Al-Sn Al-Sn-Si-Pb Al-Pb-Si Al-Zn-Si-Pb Al-Cd Al alloy Cu-Pb-Sn Cu-Sn Cu-Graphite Cu alloy Ref.：S. Kamiya, Document of 47th Contingence-Composite session meeting, JSTP (2001)

  20. 2.3.2 Pb Free Bearing Materials Taiho Kogyo other companies Al-20Sn-1Cu Al-(12-15)Sn-3Si-1Cu-Cr,Zr,V,Mn Al-(6-7)Sn-3Si-(1-1.5)Cu-Cr,Zr,V,Mn Aluminum Alloy Overlay Copper Alloy Overlay Al-(4-5)Zn-Si-Cu PAI-72MoS2 (Solid PAI-(18-20)MoS2-(10-18)Gr,WS2 Lubricant Overlay) PTFE-MoS2-Gr Cu-4Sn-7Bi Cu-(4-10)Sn-(4-8)Bi-Mo2C,Zn,Ni Cu-6Sn-Ag Cu-(5-8)Sn-Ni,P Cu-20Zn-Ni,Al,Mn,Fe PAI-72MoS2 (S.L.O)Sputter (Al–20Sn) BiBi/Ag, Bi Sn Sn-(2-8)Cu

  21. 2.3.3 Solid Lubricant Overlay PAI+MoS2 Overlay Cross-section of Overlay Good conformability for initial running-in Low friction by solid lubricant, MoS2 PAI(thermosetting resin) for binder + MoS2 (solid lubricant) 40vol% Thickness 6μm “Pb free bearings” JSME “Technology Award” in 2003

  22. Fatigue resistance of Al-Sn-Si alloy bearing with solid lubricant overlay better Al-7Sn-2.7Si-1.5Cu-Cr-Zr/ PAI-72MoS2 Ref.：Y. Kumada et al.,VDI-Berichte Nr. 1906 （2006）113

  23. 23 Touareg Adopted for VWW12 crankshaft bearings Ref. : R.Szengel, F.T.Metzner & M.Dehmke, Aachener Kolloquium. “Fahrzeug und Motorentechnik” (2003) TAIHO

  24. 24 Taiho Kogyo developed Crankshaft bearings having super low frictional property for Mini-vehicle -- Bearings with solid lubricant overlay -- Ref. : Nikkei Monodukuri，8 (2012) 92.

  25. sputtered Al-20Sn overlay Cu-Sn alloy Sputter (SEM Image) 2.3.4 Al-Sn Sputter • Al-Sn sputter (GB, DE, Austria) • Higher Load Carrying Capacity • Slightly Lower Conformability • High production Cost (PVD)

  26. 26 Conventional Eccentric Oil flow in oil groove parting end 3.1 Eccentric oil-grooved bearing for low fuel assumption Ref. : Y. Hikita et al., ITC KOBE 2005, Book of Synopses (2005) 24.

  27. 27 Ratio of friction loss Accessory Water pump Piston & Con-rod Oil pump 16% Crankshaft Valve train 3.1.1 Background

  28. Engine : L4 1.5L Oil temperature : 100ºC 20 Valve train Connecting rod bearing Oil flow , L/min 10 Crankshaft bearing 0 2000 4000 6000 Rotational speed , rpm Crank pin journal Connecting rod bearing Upper Lower Crankshaft bearing(Upper) Crush relief Crankshaft bearing (Lower) Crank main journal

  29. 29 Conventional Eccentric Oil flow in oil groove Side flow is parting end reduced large Crush relief area (Clearance is large) 3.1.2 Eccentric oil-grooved bearing

  30. 30 1.2 Conventional 1 0.8 Center Depth , mm 0.6 0.4 0º No. 1 q No. 2 0.2 No. 3 90º 0 Parting end 0 30 60 90 θ , º (Center) (Parting end) Oil groove end 0.1 Conventional 0 No. 1 Friction torque difference , Nm Eccentric -0.1 No. 2 No. 3 -0.2 2 4 6 8 10 Oil flow , L/min 3.1.3Relationship of oil groove end and friction torque

  31. 31 4 Conclusion & Future Issues 1 Al-Sn-Si alloy, Microgrooved Bearings were adopted in almost all automotive engines, and have become standard ones. 2 Regarding Lead free bearings, we have to develop high performance engine bearings, that is, the bearings satisfying both of running-in property and material hardness. 3 It is desired that mechanical loss caused by bearing friction will be near zero, so near zero friction bearings have to be developed near future.

  32. 33

  33. by K. Niwa

  34. 35 Trends of Automotive Engines & Influences on Bearing Influences on Bearing Needs Trend of Engines No. ・Direct ignition & higher cylinder pressure (Gasoline) ・High pressure fuel jet & higher cylinder pressure (Diesel) ・Higher Unit Load 　→①Al-Sn-Si alloy, 　　 ②Microgrooved Bearing High performance 1 ・Down-size, Thin wall, Light weight Materials (Al alloy) ・Reduction of Friction Loss ・Increase of Start–Stop Operation ・Lower volume of Oil Pump ・Lower Rigidity of Housing ・Narrow Width → Higher Unit Load ・Lower Viscosity Oils ・Excessive Wear ④Eccentric grooved Bearing Improve of Fuel Consumption 2 ・EGR ・Direct ignition & higher cylinder pressure ・Higher Oil Temp. ・Higher Unit Load 3 Clean Exhaust Gas ・Smaller Diametral Clearance ②Microgrooved Bearing Reduction of Noise & Vibration ・Reduction of bearing slap noise 4 Reduction of Environmental Substances of Concerns ・Less or Free of lead ・③Lead Free Materials 5 Others longer life, cost reduction ・Higher Durability ・Commoditizing, Lower cost ・Higher Reliability ・Commoditizing 6

  35. 36 ４　今後の課題と方向 Trend of Engines No. Needs Influence on Bearings　　年頃 ・Direct ignition & higher cylinder pressure (Gasoline) ・High pressure fuel jet & higher cylinder pressure (Diesel) ・ higher unit load 　→鉛青銅系ライニング、 　　　鉛系オーバレイ 1970年～ 2000年 High performance 1 ・ マイクログルーブ軸受（MGB） ・Down-size, Thin wall, Light weight Materials (Al alloy) ・Reduction of Friction Loss ・Increase of Start–Stop Operation ・Lower volume of oil pump ・Lower Rigidity of Housing ・Narrow Width → Higher Unit Load ・Lower Viscosity Oils ・Excessive Wear Improve of Fuel Consumption 2 1995年～ 現在 ・EGR ・Direct ignition & higher cylinder pressure ・Higher Oil Temp. ・Higher Unit Load Clean Exhaust Gas 3 ・Reduction of bearing slap noise Reduction of Noise & Vibration ・Smaller Diametral Clearance 1990年～ 2000年 4 1995年～ 現在 Reduction of Environmental Substances of Concerns 5 ・Less or Free of lead ・Lead Free Materials ・Higher Durability, Commoditizing, Lower cost Others -- longer life, cost reduction ・Higher Reliability ・Commoditizing 6 1975年～ 2005年

  36. 38 3.3　鉛フリー軸受 3.3.1　従来（Pb含有）軸受の性能位置付け　 コンロッド軸受最高出力時 120 今後の開発エンジンの領域（予測） 100 【材料記号説明】 　オーバレイ材／ライニング材 ディーゼル エンジン 80 最大軸受面圧　，MPa LN750/HD150 60 LN760/HD240 スポーツタイプ ガソリンエンジン Pb基ｵｰﾊﾞﾚｲ 付き銅鉛合金 or 鉛青銅 LN762 40 SA161 SA151 一般ガソリン 　エンジン 20 Al-Sn-Si-Pb合金 8 12 16 20 24 周速　，m/s

  37. 39 Concept of Pb Free Bearing Boundary Lubricity Conformability ・Addition of Solid lubricants ・Lower hardness addition of Soft components Gr，MoS2，PTFE・・ ・Surface Modification Sn electroplating 　①Solid Lubricant Coating〔 RA500 〕 ②Microgrooved Bearing ・Hard Particle Enlarged Si，Fe-P，AlN・・・ Graphite(Gr) MoS2, WS2 PTFE Sulfide：Cu2S，AgS・・・ ・Addition of Low Melting Point Metal Bi，Sn，In ・Addition ofAg 〔 HS100，HS210〕

  38. 40 Snリッチ オイル中の S，O Ag3Sn-Sn共晶 部分的に数μm厚さ のCu2O ,CuSO4 応力や 摩擦熱 （AgS,SnS等） 表面 CuSO4 Cu2O，SnO2 の薄い層 表面へのSn,Agの富化 金 合 Ag 受 Sn,Agを固溶した 非平衡Cuマトリックス Sn 軸 Cu ③-1　トライボケミカル反応の利用-Agの添加 5Sn-1Ag thin layer 摺動メカニズム：油中のS,Oの存在と摩擦熱とによって、極表面に約0.1～0.2μmの厚さで次の物質が形成される．(ESCA，AES，EPMA分析結果) 出典：神谷荘司，名古屋大学学位論文 　　　　（1999）

  39. 42 モーター 供試軸受 1300 回転数 [r/min] オイルバス 油圧ピストン 0 45 　 90 135 175 220 〔min〕 50 40 30 軸受面圧 　　[MPa] 45min毎に 10MPaステップアップ 20 10 5 ひずみゲージ 0 45 　 90 135 175 220 〔min〕 軸 【試験方法】 試験機 ： 高面圧軸受試験機 軸受材質 ： SA162, RA530/SA250 軸受寸法 ： 内径φ42×幅17mm 給油温度 ： 140℃ 試験軸 ： S55C 焼入れ 　　　　　　表面粗さRzJIS 0.5μm 硬さ 500 - 600HV10 試験機 荷重パターン 混合潤滑領域の摩擦係数，焼付き面圧を確認

  40. 1.1 Short History Industry Revolution 1750 Half bearing (←Leonardo da Vinci at the Renaissance) 　～ 　 　　　 :replaceable in case of excessive wear 1850 Bearing Materials : cast iron, bronze, brass, pewter (Alloy of tin, lead and zinc) Brass half bearing Ref. : D．Dowson, History of Tribology 2nd edition, Professional Engineering Pub. (1998) 201.

  41. 5μm 5μm 2.3.5 Sn,Bi electroplating Cross Overlay Overlay Crystal size Hardness -section surface fracture s. BP100X Sn /Cu-6Sn-1Ag 12HV 基材 Size：１-５μm Granule PK1 Bi:5μm Bi/Ag /Cu-10Sn-4Bi-Mo2C Bi 22HV Ag:5μm CX4 Ag 5μm 基材 基材 裏金 Size：-１μm Dendrite Fine

  42. [ Test conditions ] Engine : L4, 1.5L Rotational Speed : 6400rpm Oil Temp. : 120ºC 1 0.8 0.6 Embedded Rate 0.4 0.2 0 Conventional No.1 No.2 3.1.4temperature increase and embeddability of Eccentric oil-grooved bearing A : Crank pin lower side B : Crankshaft bearing back side 150 +1.5ºC +1.4ºC +0.8ºC 145 140 Temperature , ºC +2.5ºC 135 +2.1ºC +1.2ºC 130 125 No. 3 No. 1 No. 2 Conventional Eccentric Embedded rate of foreign particles on connecting rod bearings

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