University of Pisa Piaggio & C. S.p.A. Lubrication system model of a small single cylinder engine with GT-SUITE Federico Uperi University of Pisa GT Suite conference Turin 18.03.2013 Presentation for GAMMA Technologies
Content Aim of Analysis System Description GT-SUITE Model Results Conclusion and Future Developments Turin 18/03/2013 Federico Uperi University of Pisa 2
Aim of Analysis Purpose: in order to reduce fuel consumption in a new single cylinder engine, a new configuration of oil lubrication circuit needs to be developed less oil pump power consumption Finding pump flow rate and camshaft jet diameter to obtain the same bulb pressure in two different engine; current 125cc (tappet rocker arm) with flywheel and piston cooling jet opened and future 125cc (roller rocker arm) where cooling jet are closed. Characterization of the oil circuit of a small single cylinder engine with GT-SUITE. Comparison of GT model results with experiments, in terms of bulb pressure and flow rate through the camshaft. Turin 18/03/2013 Federico Uperi University of Pisa 3
Work Flow CAD models GT models Experimental tests GT model Calibration Validated model New configuration Turin 18/03/2013 Federico Uperi University of Pisa 4
System Layout Single cylinder 4 strokes current engine 125cc Turin 18/03/2013 Federico Uperi University of Pisa 5
System Description: Oil Circuit CAD model Turin 18/03/2013 Federico Uperi University of Pisa 6
CVT schematization: No tension imposed to compare GT results with experimental data GT-SUITE Scheme Cylinder Pressures (GT-Power) Cranktrain model Torque due to camshaft chain (GT Suite, in house). Bearing speed and loads passed to the lubrication model Costant bearing radial clearance Modified Martin equation and Martin-Xu Conrod equation Oil circuit Oil pump characteristic Oil filter characteristic By-pass valve characteristic Turin 18/03/2013 Federico Uperi University of Pisa 7
GT-SUITE Model: Cranktrain Turin 18/03/2013 Federico Uperi University of Pisa 8
Input Data (Main Bearing Forces) Graph below shows forces imposed to bearings from journals. 7000 RPM * Normalized values Turin 18/03/2013 Federico Uperi University of Pisa 9
Input Data (Big-end Bearing Forces) Graph below shows forces imposed to bearing from journal. 7000 RPM * Normalized values 7000 RPM * Normalized values Turin 18/03/2013 Federico Uperi University of Pisa 10
GT-SUITE Model: Oil Circuit Turin 18/03/2013 Federico Uperi University of Pisa 11
Flow Rate [l/min] Input Data (Pump) Modeled with an EndFlowInlet to impose Flow rate vs RPM according to experimental data (H8 mm axial width of the rotor). H8 0 1000 2000 3000 4000 5000 6000 7000 8000 RPM Turin 18/03/2013 Federico Uperi University of Pisa 12
Agip Acer MV 10 main data: Input Data (Oil) Characteristics Acer MV 10 Density @ 15 C [kg/m 3 ] 865 Kin viscosity @ 40 C [cst=mm 2 /s] 10.5 Kin viscosity @ 100 C [cst=mm 2 /s] 2.7 This oil, used for experimental tests with motored engine, has a low viscosity at low temperature(60 C) to simulate the oil used during firing engine tests (120-130 C). Turin 18/03/2013 Federico Uperi University of Pisa 13
Pressure drop [bar] Modeled with a PressureLossConn according to experimental data. Input Data (Filter) 0 0.5 1 1.5 2 2.5 3 Flow rate [l/min] Turin 18/03/2013 Federico Uperi University of Pisa 14
Pressure Drop [bar] Input Data (By-pass Valve) Modeled with a PressureLossConn according to experimental results. 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 flow rate [l/min] Turin 18/03/2013 Federico Uperi University of Pisa 15
Configurations C1 (125cc current ) Experimental Configurations Tested Camshaft jet diameter [mm] Piston cooling jet diameter [mm] Flywheel cooling jet diameter [mm] Oil pump axial width[mm] 0.8 1 0.5 8 C3 0.8 Closed Closed 8 C5 0.5 Closed Closed 8 C7 0.4 Closed Closed 8 Target? Closed Closed? Other configurations have been tested but these are the more important configurations; C1 to C7 have been used to calibrate GT lubrication model and target is the configuration for the future engine. Turin 18/03/2013 Federico Uperi University of Pisa 16
Results: Comparison against Experimntal Data Plots below show comparison between GT and experimental data as regards bulb pressure. 1.200 1.000 0.800 SPM: experimental tests 0.600 0.400 C1 SPM C1 GT 0.200 0.000 0 2000 4000 6000 8000 RPM 1.200 1.000 0.800 0.600 0.400 C3 SPM C3 GT * Normalized values 0.200 0.000 0 2000 4000 6000 8000 RPM Turin 18/03/2013 Federico Uperi University of Pisa 17
Results: Comparison against Experimntal Data Plot below shows comparison between GT and experimental data as regards flow rate to camshaft. 1.200 1.000 0.800 0.600 0.400 SPM C3 GT C3 0.200 0.000 0 1000 2000 3000 4000 5000 6000 7000 8000 RPM *Normalized values Turin 18/03/2013 Federico Uperi University of Pisa 18
Results: Bulb Pressure Target configuration (with cooling jets closed and lower oil pump) gives the same bulb pressure when compared to configuration 1. 1.2 1 0.8 0.6 0.4 C1 Target 0.2 0 0 1000 2000 3000 4000 5000 6000 7000 8000 RPM *Normalized values Turin 18/03/2013 Federico Uperi University of Pisa 19
Flow Rate [l/min] Results: New Oil Pump New oil pump (H4.5mm) with different axial width: H8 H4.5 0 1000 2000 3000 4000 5000 6000 7000 8000 RPM Camshaft jet diameter = 0.4 mm Turin 18/03/2013 Federico Uperi University of Pisa 20
0.14 0.12 Results: Main Bearings Flow Rate Plots below show main bearings flow rate vs. engine speed in current engine (C1) and future engine (Target). 0.1 0.08 T.S.: trasmission side F.S.: flywheel side 0.06 0.04 C1 T.S. Target T.S. 0.02 0 0 2000 4000 6000 8000 RPM 0.14 0.12 0.1 0.08 0.06 0.04 C1 F.S. Target F.S. * Normalized values 0.02 0 0 2000 4000 6000 8000 RPM Turin 18/03/2013 Federico Uperi University of Pisa 21
Results: Flow Rate to Camshaft Plot below shows flow rate going to the camshaft vs. engine speed in current engine (C1) and future engine (Target). 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 C1 Target 0.02 0.01 0 0 1000 2000 3000 4000 5000 6000 7000 8000 * Normalized values RPM Turin 18/03/2013 Federico Uperi University of Pisa 22
Conclusion The initial aim has been reached by obtaining the same bulb pressure in target configuration as C1 configuration. Flow rate to camshaft in target configuration is less than C1; this is acceptable (in comparison with similar engines) because the new roller rocker arm (future 125cc) needs less oil flow rate to work well than the tappet rocker arm (current 125cc). Main bearings and big end bearing flow rates are the same for both engines; this is correct because the 2 engines configurations don t differ for this aspect. Lower pump dimension in future 125cc engine reduction in power loss. Turin 18/03/2013 Federico Uperi University of Pisa 23
Future Development Lemon bore (non-constant) bearing clearance evaluation Mechanical By-pass valve 1D Oil pump 1D schematization Simulated firing engine Introducing CVT forces Turin 18/03/2013 Federico Uperi University of Pisa 24