Analysis of Piston Oil Film Behavior by Using Laser Induced Fluorescence Method Shuzou Sanda, Akinori Saito ( Laser Induced Fluorescence Method LIF ) LIF Scanning -LIF Abstract Analysis of the oil film behavior between a piston and a cylinder liner is of great importance for reducing the friction loss and oil consumption in reciprocating engines. Laser-induced-fluorescence (LIF) technique has recently attracted much attention as a new method for the analysis. In this study, an advanced LIF method has been developed, in which an observed point is scanned using fiber optics and a rotating polygonal mirror. This Scanning- LIF system has made it possible to observe changes in the piston axial oil film distribution during the operation. The accuracy of the system in measuring oil film thickness has been improved by using the optimal fluorescent dye. Characteristics of the oil film behavior were clarified in relation to operating conditions and piston ring specifications as follows; (1) Starvation frequently occurs in the top-ring oil film during the firing operation. (2) Oil volume on the piston third land increases with the decrease in the tangential force of the oil ring and flattening of its profile. (3) Oil film rupture often occurs in the piston skirt area just before the top dead center due to the piston slap motion.
38 30 40 ( Laser Induced Fluorescence LIF ) LIF ( ) Scanning-LIF LIF ( LIF ) I 0 1 exp ( ECt ) }( 1 r 1 ) (1) I 0 E C t r 1 F q I 0 1 exp ( ECt ) } ( 1 r 1 ) (2) F q ( PMT ) PMT ( S r / 4π ) F l F f F q I 0 { 1 exp ( ECt ) } ( 1 + r 1 ) F f F l S r ECt << 1 C t 1 exp ( ECt ) ECt Schematic view of Laser induced fluorescence method.
39 PMT S t S Kt K ( S r / 4π ) F l F f F q I 0 ( 1 + r 1 ) ECG a (6) G a PMT ( / ) K6 F q K 5 PMT PMT S t F q F q ( Bleach Effect ) 1 5 LIF a Fig. 3 (a) LIF b ( ) Fig. 3 (b) PMT Bleach effect. Fixed point LIF method.
40 Richardson Shaw II Shaw II Scanning-LIF - Scanning LIF PMT ( Scan ) He-Cd ( 442nm 90mW ) 442nm ( ) 500nm 3 ( ) Coumarin-6 Coumarin-6 ( ) ( SG ) Coumarin-6 ( 442nm ) PMT 530 10nm 10µm Fig. 6 (a) Fluorescent dyes. Maximum Maximum Dye adsorption radiation Coumarin 6( ) 458nm 497nm Coumarin 7 437 488 Coumarin 337 443 488 ( ) Selected Scanning-LIF method. Characteristics of dye Coumarin-6.
41 2µm Scanning 10µm Fig. 6 (b) 200µm ( 1 ) ( 2 ) ( 3 ) ( ) ( 4 ) Scanning-LIF ( 5 ) ( 6 ) ( 1 ) 8 10 4 mol/l 70µm 4 Coumarin-64 8 10 4 mol/l( 0.14 0.28g/l) 7 10 4 mol/l ( 2 ) 0.5mm 16065 ( 3 ) ( ) 150 2 12 12 Influence of dye concentration on fluorescence. Method of calibration. Influence of oil film temperature.
42 ( 4 ) 60 ( 5 ) 5 20m/s 20m/s 4kHz ( 6 ) Scanning S r ( (5) ) 25 Scanning-LIF 2 ( 72mm 73mm ) 1 10mm SG 4l ( Coumarin-6 ) 4l 1g ( 7 10 4 mol/l ) LIF TDC90 Fig. 11 Influence of irradiation angle. Influence of surface reflectivity. Oil film thickness adjacent to top and second rings measured by fixed point LIF method.
43 ( Oil Film Region ) ( Leading Edge ) LIF Fig. 12 A B 15µm A B LIF Scanning-LIF Oil film behavior observed by Scanning-LIF method. Oil film thickness in piston skirt area measured by fixed point LIF method. Oil film behavior in piston skirt area observed by Scanning-LIF method.
44 Fig. 13 Scanning-LIF ( ) ( ) PMT T a ( ) T b Fig. 141 ( ) ( ) 300rpm 4 T c LIF ( Fig. 12 ) T c T c ( P ) LIF ( 86mm 86mm ) 4mm LIF ( ) Effect of operating condition on oil film distribution.
45 Scanning-LIF ( ) ( ) ( b ) ( a ) 1.4 ( c ) ( ) ( ) 1 Fig. 16 1 ( E ) Fig. 17 2 Effect of tangential force of oil control rings on oil film behavior.
46 Scanning-LIF 1 0.1mm ( ) 0.6mm Effect of tangential force of oil control rings on oil volume between rings. 1 LIFFig. 15 ( 120µm ) 0.1mm Scanning- LIF 2 LIF LIF 2µm Scanning LIF Scanning-LIF LIF Effect of surface profile of oil control rings on oil volume between rings. ( LIF ) ( 1 ) Coumarin-6 ( 2 ) ( 3 )
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