A New Approach to Flow Network Analysis of an Engine Lubrication System
اسلاید 1: A New Approach to Flow Network Analysis of an Engine Lubrication SystemProduced By:Ali Reza HosseinianMaster : Eng. Yousefi RadDepartment of Mechanical Engineering, University of KhayyamMay 22, 2012
اسلاید 2: In order to develop more efficient engines, it is essential to optimize the lubrication circuit of the power train systems.Two elements have been added to the lubrication circuit in the modified engine. These elements are hydraulic lifters and an Anti-drain valve.The analyses are done by Flowmaster7.6 and AVL EXCITE7.02 software and an accessory code. Finally, theoretical results are validated by a completely controlled lubrication functional test.Abstract
اسلاید 3: Lubrication CircuitBearing MapChain TensionerFlowmasterJournal BearingsKeywords
اسلاید 4: Modern engines are being designed to operate at high engine speeds and loads. In order to fulfill the requirements of developing new engines, lubrication system must be improved.Yiqing Yuan et al, in 2007, established a methodology for predicting lubrication flow in the rod bearings and oil circuits that can be used to guide engineering designs.Introduction
اسلاید 5: Yaguo Lu et al. [10], in 2009, developed a software for simulating aero-engine lubrication system.In this paper, two important components, chain tensioner and anti-drain valve, have been investigated as well as other components in the lubrication system.Introduction
اسلاید 6: There are three important reasons for improving the base engine to the modified engine: (1) using inexpensive and locally abundant CNG fuel, (2) demanding higher power and (3) modifying weaknesses of the base engine. The engine parameters are listed in table.Engine description
اسلاید 7: This test is applicable to Diesel and Gasoline engines.After installing the sensors in particular locations of lubrication circuit like the main gallery, oil pump outlet, oil filter inlet and outlet, the end side of the hydraulic lifter gallery, the engine is configured on the dynamometer and prepared for lubrication functional test. This test is divided into steady state and transient parts.Lubrication functional test
اسلاید 8: In the steady state part the oil temperature is fixed at 90 and 130 ◦C and for each temperature engine speed is swept from idle to rated speed and data acquisition is performed for each point. In the transient part, on the other hand, the time of delivering oil to different elements in the lubrication circuit is measured.
اسلاید 9: The Flowmaster is a one-dimensional fluid flow program based on the theory of stream lines. The physical basis for this program comprises empirical and analytical equations for mass, momentum, and energy plus an extensive database to describe the system parts.The flowmaster v7.6 program
اسلاید 10: Bearing calculations are carried out in AVL-EXCITE software by solving the Reynolds equation.The Flowmaster can find the needed oil flow rate of bearings by a simple formula and iterative method. Moreover, this allows the user to supply an oil flow rate map for bearings by supplementary software like AVL-EXCITE.Bearing calculation
اسلاید 11: One of the most important design parameters in bearing design which should always be verified is minimum oil film thickness. Our calculations in AVL-EXCITE software demonstrate that the value of this parameter for all bearings are in the safe margin and the requirements in accordance with design limitation are covered even in severe conditions.Bearing calculation
اسلاید 12: Chain tensioner comprises a plunger and cylinder which utilize oil to damp the rate of plunger reciprocating motion.The base engine has a chain tensioner made from NBR (Nitride Butyl Rubber) wearing unacceptably in hard conditions like durability cycles which is shown in Figure. Intensive wearing of the original chain tensioner had been frequently reported from after sale market. This defect was also found on the engine standard durability cycles in IPCOs laboratory.Chain tensioner
اسلاید 13: Consequently, the problem was considered in two points of view:improper materialinappropriate lubrication
اسلاید 14: Hydraulic lifterThe base engine is OHV (Overhead Valve) type and mechanical lifter is used in its valve train system.For in order to improve performance in the modified engine, hydraulic lifter is utilized.Anti-drain valve and piston cooling jetA new element added in the modified engine is an antidrain valve with a low hydraulic loss.This is used to avoid oil draining from hydraulic lifter gallery due to the gravity when engine is stopped.
اسلاید 15: Analysis of results1- Validation of Simulation ResultsA precise way to evaluate the ability of the Flowmaster in predicting engine lubrication circuit is comparing calculated oil pressure at some important nodes and flow rate of main gallery with the measured ones.
اسلاید 16: Analysis of results2- Results of chain tensionerChain tensioner is a compound element in lubrication circuit. As considered in section 6 lubrication is one of the most important problems which had to be figured out properly. To solve this problem, oil flow rate in chain tensioner should be increased and oil pressure within chain tensioner ought to be decreased.
اسلاید 17: Analysis of results3- Results of Hydraulic LifterAs mentioned before, during the oil was delivered to the hydraulic lifter at the engine startup should be as low as possible.As can be noticed in Figures 13 and 14, the effect of different oil temperature on the oil delivery time at engine startup conditions is shown in these figures. When oil temperature rises, the oil viscosity is decreased and the adhesive force between oil molecules and gallery walls is decreased consequently. Due to this fact, the amount of the oil, delivery time reduces, too.
اسلاید 18: Analysis of results4- Results of Piston Cooling Jet (PCJ)Oil flow rate of each engine component is shown in Figure 15. As it can be considered, PCJs oil flow rate is definitely negligible in comparison with the total engine flow rate. Therefore, it does not have any defect on oil feeding of other components in the lubrication system. Therefore, the accuracy of the simulation without PCJs stays satisfactory.
اسلاید 19: Analysis of results5- Results of Oil PumpCorresponding to the changes made in the base engine, it should be verified if original oil pump covers the lubrication circuit requirements or not. These changes included:adding hydraulic lifters and PCJs as lubrication system componentsincreasing chain tensioner oil flow rateincreasing main and pin bearing clearances
اسلاید 20: The aim of this article is introducing a simple and robust methodology to simulate engine lubrication systems duringengine design and development process.Also, the effect of adding new elements like chain tensioner and antidrain valve on oil pump behavior and obligatory minimum pressure in networks vital nodes is verified.Conclusion
اسلاید 21: As a future work, it will be valuable if the dynamic behavior of oil pump and bearings be simulated at engine start up condition. To simulate this phenomenon, the reaction between air and oil as a two phase flow should be considered.Conclusion
اسلاید 22: [1] Lo R. S., Digital Simulation of Engine Lubrication Systems, SAEPaper 710205, 1971.[2] Neu E. A., Wade J. A. and Chu A. C., Simulating the LubricationSystem of a diesel engine, SAE Paper 770032, 1977.[3] Hass A., Esch T., Fahl E., Kreuter P., Pischinger F., Optimized designof the lubrication system of modern combustion engines, SAE 912407,1991.[4] Mian M., Design and analysis of engine lubrication system, SAE970637, p.219-32, 1997.[5] Chun, S. M., Park, Y. H., Jang, S., A study on engine lubricationsystem by optimized network analysis- part I: case study, SAE 2000-01-2921, 2000.References
اسلاید 23: [6] Chun S. M., Park Y. H., Jang S., A study on engine lubricationsystem by optimized network analysis- part II: parametric study, SAE2000-01-2923, 2000.[7] Felix, K. and Uwe, K., Simulating Engine Lubrication Systems with1-D Fluid Flow Models, SAE World Congress in Detroit, Michigan,March 6-9, 2000.[8] Chun, S.M., Network analysis of an engine lubrication system, TribologyInternational 36-2003, p.609–617[9] Yiqing Yuan, Wei Tao, Eysion A. Liu, Gary C. Barber et.al, Enginelubrication system analysis by considering aeration and cavitation withthe rotating oil supply passage, Tribology Transactions; Jan-Mar 2007;50, 1; ProQuest Science Journals pg. 39.[10] Yaguo L., Zhenxia L. and Shengqin H., Numerical Simulation ofAero-Engine Lubrication System, Journal of Engineering for Gas Turbinesand Power, MAY 2009, Vol. 131 / 034503-1.Reference
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