|Politecnico di Torino|
|Academic Year 2014/15|
Powertrain components design
Master of science-level of the Bologna process in Automotive Engineering - Torino
Regarding the engine, the aim is to provide students the basic knowledge for the structural design, sizing and verification of main engine components by using analytical, semi-empirical and numerical approaches.
Regarding the transmission, the goal is to provide the basic knowledge for the design and application of transmissions, describing the architectural solutions and the main components, stating the methodologies used to proceed to their size. Basic concepts for development of control strategies of automatic transmissions are also introduced.
Expected learning outcomes
The skills acquired by students will be the knowledge of issues and methods in design engine, transmission and their main components, as well as the methodologies essential to the development of control strategies of some transmission systems.
Prerequisites / Assumed knowledge
To better understand the topics covered by the teaching, the basic knowledge and operative competence on materials mechanical behaviour, structural and applied mechanics, stress state and strain state, machine design are recommended..
Crank mechanism: Centred and offset layout; Displacement, velocity and acceleration of the piston; Angular speed and acceleration of the connecting rod; Forces on the crank mechanism; Reduction of the connecting rod; Reciprocating inertial force; Centrifugal inertial force; Resultant force on the crank Differential and splitters: construction details of differential drive axle and splitters wheel drive for design and experimentation. Influence of the differential and the splitter (ideal cases and controlled friction) on the dynamic behaviour of a vehicle; development of possible control strategies.
Transmissions and couplings: rigid axle shafts, transmission shafts for independent suspensions, universal joints and constant velocity joints.
Automatic and semi-automatic gearboxes: technical solutions for cars (ordinary gearing, planetary gearing, continuously variable ratio) and for commercial vehicle (ordinary and planetary gearing.).
Strategies for control of automatic gearboxes: functions of the control system; methods for determining the instantaneous optimal transmission ratio; elements for modeling of transient gear shift; adaptive systems.
mechanism; Forces on the connecting rod; Engine torque; Forces and moments on the cylinder block; Multi-cylinder engine and most stressed crank; Engine degree of irregularity.
Wrist pin: Shape and geometry; Materials; Design guidelines; Numerical analysis (FEA).
Connecting rod: Architecture and geometry; Materials; Load analysis; Design guidelines.
Crankshaft: Architecture and geometry; Design guidelines; Classical static analysis; Classical dynamic analysis; Numerical dynamic analysis (FEA-MBA).
Main bearings: Architecture and geometry; Classical analysis; Numerical analysis (FEA-MBA).
Piston: Architecture and geometry; Materials; Design guidelines; Numerical analysis (FEA); Piston Slap.
Cylinder head: Architecture and geometry; Cooling circuit; Head gasket, Head cover; Residual stresses; Design guidelines; Numerical analysis (FEA).
Cylinder block: Architecture e geometry; Deck; Liners; Fastening of cylinder head and main caps; Residual stresses; Design guidelines; Numerical analysis (FEA).
Oil pan: Function and examples; Optimization methodology.
Thermo-mechanical fatigue: Introduction; Isothermal fatigue tests; Thermo-mechanical fatigue tests (TMF tests); TMF damage: mechanical fatigue, creep, oxidation; TMF residual life; Constitutive models for TMF; Damage models for TMF; General guidelines for numerical analysis (FEA).
Exhaust manifold: Design guidelines; Geometries and materials; Working conditions; Experimental tests on test bench; Life estimations with multi-axial damage models.
Distribution system: Timing chain, timing belt and timing gear; Rocker arm and cam to cam systems; Numerical analysis (MBA) of timing chain; Camshaft; Valvetrain; Valve spring design; Valves.
Transmission functions and architectures: Automotive transmission characteristics (functions, requirements and constraints, specific characteristics and technology); Transmission evolution and current trends (overview); Transmission architectures; Transmission components.
Gear ratios definition: Resistance to motion; Top and bottom, intermediate gear ratios definition; Intermediate gear ratios definition; Gear ratios influence on vehicle acceleration and fuel consumption.
Manual Transmissions: Main configurations (forward speeds, reverse speed); Efficiency (power loss contributions, maps and measurement); Passenger cars layout schemes and practical examples (single, double and triple stage); Industrial vehicles layout schemes and practical examples (single and multiple range).
Mission and components development process: Mission of vehicle and transmission (endurance, load profile); Assumptions and steps for a preliminary design; Product development steps.
Components design and testing. Gears: Gear types; Endurance (fatigue phenomena, failures, damage accumulation); Noise (gear whine, gear rattle). Other components: Shafts; Bearings; Lubrication; Housings and seals. Testing technologies.
Synchronizers: Function; Mechanical description (simple and multiple synchronizers, gearshift process); Design criteria (geometric and functional).
Shifting mechanisms: Functions; Internal shifting mechanisms (specific functions, interlocking devices); External shifting mechanisms (specific functions, bar and cable mechanisms); Shifting mechanism attributes.
Start-up devices. Friction clutches (for MT): Functions; Components (disengagement mechanism, driven plate, thrust bearing); Design criteria. Start-up devices for non-MT: General characteristics; Double clutch units; Hydraulic clutches and torque converters (schemes, equations, characteristic curves, performance on a vehicle, lock-up clutch).
Differentials, final drives and transfer boxes: Differentials and final drives (rear and front wheel driven cars, industrial vehicles); All wheel drive transfer boxes (modified rear and front wheel drives); Differential theory outline (friction free differential, differential with internal friction); Self-locking differentials (definition, types, ZF, Torsen and Ferguson systems); Differential effect on vehicle dynamics.
Shafts and joints: Shafts (propeller shafts, half shafts); Joints (universal and constant speed joints).
Automatic transmissions: General issues (automation level, gearshift mode, stepped and continuously variable transmissions); Car transmissions with fixed rotation axis (with synchronizers, multi disc clutches, dual clutch); Car epicycloidal transmissions (simple and compound epicycloidal gear trains, production examples); Car CVTs (steel belt, rolling bodies); Industrial vehicles automatic transmissions (semi and full automatic transmissions); Control strategies (input/output parameters, speed selection for minimum consumption or comfort, speed choice in real driving conditions, brakes and clutches actuation).
Transmissions historical evolution: Manual transmissions; Friction clutches; Automatic transmissions.
Current transmissions overview and trends: Market and production trends; Technologies trends and comparison; Application on car segments; Future trends.
Practice – Analysis of a pin and a crankshaft by using analytical calculation and FE numerical simulation withcommercial codes (LaIB); write short technical reports (effective and concise, as considered appropriate to substantiate and explain the problem addressed). Analysis of a manual gearbox for passenger cars; rough design of the main components with simplified methods of calculation, preparation of brief technical reports.
Laboratory – Experimental Modal Analysis (EMA) of a crankshaft by using a dedicated experimental station (Mechanics Lab, DePEC box). Write a short technical report on the subject.
The aim of the training is to give the students the order of magnitude of the main parameters and to improve their degree of understanding.
Texts, readings, handouts and other learning resources
The lectures subjects, text of exercises as well as reference didactic material are available on Corse Website.
Reference textbooks for improving the study:
- Makartchouk A., Diesel Engine Engineering, ISBN: 0-8247-0702-8, Marcel Dekker Inc., New York, NY, USA, 2002
- Hoag K.L., Vehicular engine design, ISBN: 0-7680-1661-4, SAE International, Warrendale, PA, USA, 2006
- Stone R., Introduction to internal combustion engines, ISBN 0-7680-0495-0, SAE International, Warrendale, PA, USA, 1999
- Taylor C.F., The internal-combustion engine in theory and practice, The M.I.T Press, Cambridge, UK, 1997
- G. Genta, L. Morello, The Automotive Chassis – vol. I and II, Springer, New York, 2009
- G. Lechner, H. Naunheimer, Automotive Transmissions, Fundamentals, Selection, Design and Application, Springer, Berlin, 1999
- J. Fenton, Handbook of Automotive Powertrain and Chassis Design, Professional Engineering Publishing, London, 1998
- By various authors, Design Practices: Passenger Car Automatic Transmissions, SAE, Warrendale (PA), 1994
Assessment and grading criteria
The exam is composed by the evaluation of the technical reports performing during the course and the discussion of two oral questions on both parts (Engine and Transmission) of the course.
Each element is separately evaluated and the overall score is the mean of these five elements.
The oral exam is selected in order to understand the actual level of comprehension of the topics; schemes and formulas have to be demonstrated and discussed and methodological steps of topic development have to be highlighted.
The exam lasts about 30 minutes.
Programma definitivo per l'A.A.2014/15