The development of a dynamic engine-testing facility

[摘要] ENGLISH ABSTRACT:The last two decades have seen many changes within the automotive industry. Manyadvances have been made in the design, research and development of the internalcombustion engine and technological progress made in the integrated-circuit and computerindustry has resulted in the availability of reliable low-cost electronic components. Thesecomponents have, over time, been incorporated into the very hearts of engines, therebyallowing for the accurate control of engine functions and processes to an extent that waspreviously impossible. Parallel to these developments is the growing concern for theenvironment and the realisation that resources are being consumed at ever-increasing rates.This has placed vehicle manufacturers under continual pressure to optimise their engines,not only for fuel efficiency, but also to reduce harmful emissions while continuing todeliver better performance and drivability characteristics.At the same time, engine testing equipment and facilities have had to keep abreast withthese advances and this has required the development of more sophisticated testingfacilities. One such facility is the dynamic engine test-bed. Among other features, thisfacility has the ability to subject test-bed mounted engines to loads similar to what wouldbe experienced in a vehicle on the road. This approach allows for the optimisation ofengine components and performance under more realistic conditions, yielding results farsuperior to those obtainable using more conventional steady-state testing and developmentprocedures.This document discusses the development of such a dynamic engine test-bed at the Centrefor Automotive Engineering at the University of Stellenbosch. The project was initiated byconducting a literature survey to establish the current state of technology in the field. Thedynamic test-bed was developed around an existing direct-current electric motor andindustrial speed controller configured in a regenerative manner. This setup enabled theunit to both absorb and deliver power, essential for the simulation of vehicle dynamics.Great care was taken to ensure that signals obtained from the test-bed were accurate anduseful for further computer manipulation. Anti-aliasing filters were designed andmanufactured to guarantee that signals could not be misinterpreted due to sampling effects.A computer-implemented vehicle model was developed to simulate, in real-time, vehicleresponse to torque developed by the engine on the test stand. The model included amanual transmission, clutch and a rigid drive-shaft. Driver input (accelerator, brake, clutchand gear selection) was by means of a set of pedals and hand-held gear selector switches.Various vehicle speed control strategies were investigated and recommendations maderegarding their possible future implementation. System evaluation was accomplished bythe simulated acceleration of a large truck. The simulations indicated that repeatableresults could be obtained from the system. The system was also found to be adequatelysensitive to reflect the effect of subtle changes made to engine parameters on vehicleacceleration. It was concluded that the dynamic engine test-bed did indeed offer thecapability to conduct research and testing not previously available in South Africa.Finally, recommendations were made for the future improvement and expansion of thesystem's performance and capabilities.

[发布机构] Stellenbosch University