Objective The project consists of designing a dry operating power transmission belt having having a trapezoidal cross-section. This belt combined with a variable speed belt drive bith biconical flanges is intended to regulate the drive of an average or high capacity utility vehicle's engine accessories. It shall work in the range of 25 to 35 kW. Since the available room for the variable speed belt drive is limited, the usage of the elastomer based conventional indented trapezoidal belt for the transmission function of such powerful engines appears inadequate. This fact led to build metal reinforcements into the elastomer matrix. These reinforcements located in the belt's teeth offer a great anisotropy allowing to :- increase the transversal stiffness of the belt against compressing forces due to the squeezing of the pulley's flanges.- preserve a good longitudinal flexibility.The first tests of the belt have been carried out on test benches fitted with an electric motor and fixed transmission ratio without resisting torque. Testing conditions have been determined following the specifications sheet. The only applied load during these tests was radial load (computed from the maximal resisting torque to be transmitted).At that load level the operating time of the belt is evaluated to be 25% of the required total life span. TOTAL LIFE SPAN OPERATING TIME PARTIAL LIFE SPAN (h) time (h) Minimum 1000 25% 250Maximum 3000 25% 750In these testing conditions, the best performances were about 600 hours of partial life span. During tests carried out lately on benches with resisting torque these results havenot been confirmed. More realistic load levels led us to rectify some minor points of the initial design concept. This is the object of the present work.The start of this project has been preceded by a preliminary study concerning the feasibility of the product. This study allowed to work out the reinforcement's profile satisfying the belt's operating conditions.The development of the proejct has been scheduled in two phases :PHASE 11.1 Manufacturing of the prototypes During this first phase, we selected the different belt composing materials : - short fiber reinforced elastomer matrix - traction carrying component made out of cord fabric (polyester or aramid) This step was followed by the design of the manufacturing tools for each manufacturing step : - preparation of rubber bonding on the metal reinforcements - construction of the belt sleeve on a lathe especially adapted to this operation - vulcanization of the sleeve in autoclave under a pressure/temperature cycle appropriate to the used compound - cutting grinding of the belts on a grinding machine.1.2 FATIGUE TEST Previously the belt'squalitative and dimensional control was carried out with the help of several difference devices : profile projector, microscope. Then the fatigue tests are taking place on two types of test benches : - test bench with fixed transmission ratio without resisting torque - test bench with resisting torque. Testing conditions are described in the specifications sheet. By analyzing the results, yield, life span, and failure mechanism after these first tests on bench, we will be able to make eventual modifications and improvements in our product. All the end of phase 1, the obtained results on the test bench should confirm the validity of our belt's design concept.PHASE 2This phase concerns the management of the project's demonstration. The first step will be set-up of a measuring bench fitted with a computer assisted variable speed belt drive. We will try to measure with high precision the stresses, the yield, the friction coefficient and the temperature raise of the belt. Some laws could be concluded from the test results.Next, the demonstration experiments will take place on a test bench having a variable speed belt drive and on vehicles. The following criteria will be measured : - the yield of the belt/variable speed belt drive - energy consumption with and without variable-speed belt drive and depending on the involved accessories. Programme(s) ENG-ENDEMO C - Programme (EEC) of demonstration projects and industrial pilot projects (EEC) in the energy field, 1985-1989 Topic(s) 3.5 - TRANSPORT Call for proposal Data not available Funding Scheme DEM - Demonstration contracts Coordinator GERTH EU contribution No data Address 232 AV. NAPOLEON BONAPARTE 92500 Rueil Malmaison France See on map Total cost No data
