RICERCA ITALIANA     

Research program

THE ENHANCEMENT OF MECHANICAL TRANSMISSIONS FOR THE REDUCTION OF THE ENERGY CONSUMPTION

University Co-ordinator

Università degli Studi di ROMA "Tor Vergata" - INGEGNERIA MECCANICA - ROMA(RM)

Research Unit Leader

Pier Paolo VALENTINI

Description

The Research Unit of Rome Tor Vergata will contribute to the global theme with a research plan with three main topics:
1. Optimization of cam surface shapes which come in contact during relative motion
2. Design of new solutions concerning cam-follower systems for automotive applications
3. Implementation of software instruments in order to improve the design methodology and allow simulation of cam efficiency and durability
Activities in details:
a) The first activity is about the set up of new methodologies for geometrical optimization of cam surfaces in high-speed mechanisms. The target is to optimize pressure angles and relative velocities in contact points in order to maximize force transmission and minimize the power losses due to friction. To achieve this goal the Unit will use modern parametric CAD modeller which, together with kinematic and dynamic analyses, can be useful to apply powerful numerical optimization procedures. Moreover many optimization criteria and numerical strategies will be compared and a sensitivity analysis to the most important parametric variations will be performed. A careful experimental investigation concerning the surface roughness and roundness will be performed using two measurement instruments owned by the Research Unit in order to assess the wear effects on contact geometries. For this target the Research Unit of Turin will provide new and old cams of an automotive robotized gearbox in order to test the wear models measuring surface roughness after different working conditions. These analyses will concern both force-closure cams and shape-closure cams for which this study is an important topic to improve performance for high speed actuators.
b) The second activity concerns the conceptual design of a new barrel cam actuator for automotive high efficiency application. The target of the study is the optimization of a spatial cam for sleeve movement in a robotized gearbox. The activity will include the comparison between different actuation strategies in order to obtain a good compromise among shifting speed, reliability and energy efficiency. This activity will be performed in cooperation with the Research Unit of Florence in order to test different solutions using its test rig and with the Research Unit of Turin in order to embed the dynamic models into the HIL simulator for analyzing full vehicle performance (which is the fifth stage of Turin Unit's project). A careful study will be performed for optimizing motion laws and contact surfaces geometry including the possibility of impacts. Other design requirements will be the small size of the entire cam mechanism assembly and the weight reduction with respect to present solutions.
c) The third activity is about the development of software instruments to improve the design methodologies and virtual comparison among different solutions (including those discussed in the previous activities). The main target is to build up a virtual test rig where different solutions can be tested, optimized and validated using physical prototype assembled by Florence Research Unit. The Research Unit of Tor Vergata will pay particular attention to all the problems concerning fretting and fatigue wear, durability, energy efficiency and the sensitivity of these performances to possible assembling errors and geometrical and dimensional tolerances. This software instrument will be interlaced to the numerical codes developed by the Research Unit of Bari about the mathematical model of EH Lubrication useful to simulate contact between cam and follower surfaces. The developed instrument can be a valid alley to the designer in order to reduce the time to build a new solution and propose high energy efficiency mechanical solutions.
Duration and costs:
Activity A: duration 8 months – cost 8500 euros.
Activity B: duration 10 months – cost 12000 euros.
Activity A: duration 8 months – cost 11500 euros.