Thesis (MScEng.)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: The last two decades have seen many changes within the automotive industry. Many
advances have been made in the design, research and development of the internal
combustion engine and technological progress made in the integrated-circuit and computer
industry has resulted in the availability of reliable low-cost electronic components. These
components have, over time, been incorporated into the very hearts of engines, thereby
allowing for the accurate control of engine functions and processes to an extent that was
previously impossible. Parallel to these developments is the growing concern for the
environment 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 to
deliver better performance and drivability characteristics.
At the same time, engine testing equipment and facilities have had to keep abreast with
these advances and this has required the development of more sophisticated testing
facilities. One such facility is the dynamic engine test-bed. Among other features, this
facility has the ability to subject test-bed mounted engines to loads similar to what would
be experienced in a vehicle on the road. This approach allows for the optimisation of
engine components and performance under more realistic conditions, yielding results far
superior to those obtainable using more conventional steady-state testing and development
procedures.
This document discusses the development of such a dynamic engine test-bed at the Centre
for Automotive Engineering at the University of Stellenbosch. The project was initiated by
conducting a literature survey to establish the current state of technology in the field. The
dynamic test-bed was developed around an existing direct-current electric motor and
industrial speed controller configured in a regenerative manner. This setup enabled the
unit 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 and
useful for further computer manipulation. Anti-aliasing filters were designed and
manufactured to guarantee that signals could not be misinterpreted due to sampling effects. A computer-implemented vehicle model was developed to simulate, in real-time, vehicle
response to torque developed by the engine on the test stand. The model included a
manual transmission, clutch and a rigid drive-shaft. Driver input (accelerator, brake, clutch
and 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 made
regarding their possible future implementation. System evaluation was accomplished by
the simulated acceleration of a large truck. The simulations indicated that repeatable
results could be obtained from the system. The system was also found to be adequately
sensitive to reflect the effect of subtle changes made to engine parameters on vehicle
acceleration. It was concluded that the dynamic engine test-bed did indeed offer the
capability to conduct research and testing not previously available in South Africa.
Finally, recommendations were made for the future improvement and expansion of the
system's performance and capabilities. / AFRIKAANSE OPSOMMING: Die laaste twee dekades het baie veranderinge in die outomobiel industrie megebring.
Groot vooruitgang is gemaak in die ontwerp, navorsing en ontwikkeling van die
binnebrand enjin, terwyl tegnologiese vooruitgang in die geïntegreerde-stroombaan en
rekenaar industrië betroubare elektroniese komponente teen lae koste beskikbaar gemaak
het. Hierdie komponente is mettertyd in enjins geïnkorporeer en het die akkurate beheer
van enjin funksies en prosesse moontlik gemaak. Saam met hierdie ontwikkeling, is daar
toenemende kommer oor die omgewing en 'n bewuswording dat hulpbronne verbruik word
teen 'n groeinde tempo. Hierdie feite plaas voertuig vervaardigers onder volgehoude druk
om enjins te optimeer vir brandstof doeltreffendheid, maar ook om skadelike emissies te
bekamp terwyl beter werksverrigting en bestuurbaarheid vereis word.
Enjin toetstoerusting en fasiliteite moes terselfdetyd met hierdie vooruitgang byhou en het
die ontwikkeling van meer gesofistikeerde toetsfasiliteite vereis. Een sodanige fasiliteit is
die dinamiese enjin toetsbank. Een van die kenmerke van hierdie fasiliteit is dat dit
toetsbank-gemonteerde enjins kan onderwerp aan 'n las soortgelyk as wat ondervind sou
word in 'n voertuig op die pad. Hierdie benadering stel ingenieurs in staat om enjin
komponente en werksverrigting te optimeer onder meer realistiese kondisies en lewer
resultate van 'n baie hoër gehalte as wat verkry kan word deur gebruik te maak van meer
konvensionele gestadigde-toestand toets- en ontwikkelings-prosedures.
Hierdie dokument bespreek die ontwikkeling van so 'n dinamiese enjin toetsbank by die
Sentrum vir Automobielingenieurswese aan die Universiteit van Stellenbosch. Die projek
is geïnisieer deur 'n literatuurstudie te doen om die huidige stand van tegnologie in die
gebied vas te stel. Die dinamiese enjintoetsbank is ontwikkel rondom 'n bestaande
gelykstroom-motor en industriële spoed beheerder wat in 'n regeneratiewe konfigurasie
opgestel is. Hierdie opstelling het die absorpsie en lewering van drywing moontlik
gemaak, 'n vereiste vir die simulasie van voertuig dinamika. Baie tyd is gespandeer om te
verseker dat seine afkomstig van die toetsbank akkuraat en bruikbaar was vir verdere
rekenaar manipulasie. Anti-aliaseringsfilters is ontwerp en vervaardig om te verseker dat
seine nie verkeerd geïnterpreteer kon word as gevolg van diskritiserings effekte nie. 'n Rekenaar ge-implementeerde voertuigmodel is ontwikkel om 'n voertuig se reaksie op
draairnoment ontwikkel deur die enjin op die toetsbank intyds te simuleer. Die model het
'n handrat transmissie, koppelaar en starre dryf-as ingesluit. Bestuurder intree
(vernellingspedaal, rem, koppelaar en rat seleksie) is bewerkstellig deur middel van 'n stel
pedale en 'n hand geoperateurde rat skakelaar. Verskeie voertuig spoed-beheerders is
ondersoek en aanbevelings is gemaak aangaande die toekomstige implementering daarvan.
Die sisteem is geëvalueer deur die versnellingsimulasie van 'n groot vragmotor. Die
simulasies het daarop gedui dat herhaalbare resultate van die sisteem verkry kon word.
Daar is ook bevind dat die sisteem sensitief genoeg was om subtiele veranderinge aan
enjinparameters in die resultate te weerspieël. Die gevolgtrekking is gemaak dat die
dinamiese enjin toetsbank inderdaad die vermoëns gebied het om ontwikkeling en
toetswerk te doen wat nie voorheen in Suid-Afrika moontlik was nie. Voorstelle is
laastens gemaak aangaande die toekomstige verbetering en uitbreiding van die sisteem se
vermoëns.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/52509 |
| Date | 11 1900 |
| Creators | Conradie, P. A. (Petrus Alwyn) |
| Contributors | Taylor, A. B., Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 159 p. : ill. |
| Rights | Stellenbosch University |
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