Improving engineering education through the design ...

International Society of communication and Development among universities www.europeansp.org Spectrum (Educational Research Service),ISSN:0740-7874

Improving engineering education through the design and manufacture of electric car for the Shell Eco-marathon competition "Simeon Iliev, Dancho Gunev, Vasko Dobrev,b," * University of Ruse, 8 Studentska Str., Ruse 7017, Bulgaria University of Ruse, 8 Studentska Str., Ruse 7017, Bulgaria

Abstract

Shell Eco-marathon (SEM) is a worldwide project for engineering students to design, build and race a small single seater racing car. The teams have to cope with rules and restrictions which concern specifications of the car such frame, electric motor and safety. SEM encompasses all aspects of a business including research, design, manufacturing, testing, developing, management, and fund raising. Promoting personal and professional skills is becoming an issue of interest and major concern in university environments and this is being driven by the demands of business. In this paper the university teachers present the basic features of the international competition Eco-Shell Marathon and analyze the way this competition help to promote basic skills in the students. © 2016 The Authors. Published by European Science publishing Ltd. Selection and peer-review under responsibility of the Organizing Committee of European Science publishing Ltd. Keywords: Engineering skills, Student competition, Engineering education, Shell Eco-marathon

1. Introduction 1.1. Problem Statement Renewable energy represents a vast palette of natural energy resources, encompassing usable energy from the sun, wind, biomass (plant materials and animal waste), water and the earth itself (geothermal energy). These are fundamentally different from conventional fuel sources in that they are renewed by nature over short time cycles and hence are not depletable, as are fossil fuels. Renewable energy sources are virtually infinite, offering great promise for our long-term energy needs. Technology is the key to making use of these abundant but challenging resources, as they tend to be more dispersed and lower in energy density than fossil fuels (Iliev, 2015). Energy efficiency can help meet our energy needs by reducing our demand for energy. Better power plants, advanced auto technology and energy-saving lighting and appliances have proven that economic growth can be achieved with lower energy consumption. More efficient technology under the hood can stretch a tank of gas by

* Corresponding author

© 2016 The Authors. Published by European Science publishing Ltd. Selection and peer-review under responsibility of the Organizing Committee of European Science publishing Ltd.

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Author name / Spectrum (Educational Research Service),ISSN:0740-7874(2017)101_108

many miles. Actions to reduce customer demand and consumption are the quickest and often the lowest-cost options for meeting short-term energy needs (Combs, 2008). Automotive transport is one of the major consumers of fossil fuel and one of the solutions that can be implemented is to optimize the engine efficiency and the maximize the usage of energy content of the fossil fuel. Vehicle efficiency can be increased through advanced technology, materials and aerodynamics features such as streamlined design. The idea of producing a better vehicle is embraced by Shell Global Corporation using Shell Eco-marathon competition. This event challenges university students from all over the world to design and build the most energy efficient vehicle. The competition provides an arena for students to test vehicles they design and build themselves. It aims to inspire young people to become scientists and engineers of the future. The challenge demands innovative problem-solving, creativity and collaboration. It is a unique, hands-on experience that equips students with invaluable skills and knowledge. Originated on the year of 1939 in USA, group of engineers compete each other for producing the vehicle with the highest mileage using the same amount of fuel (The Shell Global). The competition is split into two classes or categories. The Prototype class focuses on maximum efficiency, while passenger comfort takes a back seat. The Urban Concept class encourages more practical designs. Cars are also divided by energy type:  Internal combustion engine fuels include petrol, diesel, liquid fuel made from natural gas and ethanol  In the electric mobility category, vehicles are powered by hydrogen fuel cells and lithium-based batteries Table 1 shows the results for prototype battery electric categories in which this project will focus on particularly due to budget and other constraints. Accordingly, the aim of the project is to build a prototype battery electric vehicle with the performance of at least 430 km/kWh. Table 1. Top 10 teams in prototype battery electric. Country

Institute

Best attempt (km/kWh)

Spain

ECO-DIMONI1

747

Italy

Team Zero C

736

Germany

TUfast Eco Team5

635

France

Team Bayle Eco Mobile

632

France

Team Eco’Momes 31

550

Germany

Schluckspecht

537

France

Augustine

533

Germany

Ruppin-Jet

499

Austria

econia

462

France

Eco Motion Team by ESSTIN

426

2. Project development University of Ruse has a proud history of students taking an active part in the student life by organizing and running various clubs. The student clubs deal with various subjects, ranging from building robots and automobiles to creating parties for other students. Such student clubs have an important role in uniting students and create bonds that will last even after the students have graduated. The clubs also play an important role in the personal development of the student as well as in building up the students’ social network. Most of these student clubs are created on the initiative from students and the educational department of the university. In this context, the organization of a team of students was started by a professional club of professors and students from University of Ruse in the early 2014 as an opportunity to start an educational project based. The name of the club is “Avtomobilist”. Its main objectives would be the design and development of prototype battery electric


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vehicle (PBEV) and their participation in specific races for this type of vehicles. From the beginning, it was looked for and raised the collaboration with small business located in an area close to the University of Ruse to help in the manufacturing process of the prototypes and to allow the students to have the experience of working in a real production environment. The initial project was based on two working purples: the design, manufacturing of PBEVs and the participation in a few of the competitions held annually in Europe. Both purples are closely connected. First, the design of the vehicle is carried out according to the regulations of these competitions, which limit many of its features such as physical dimensions, engine power, battery type, etc. and they also have very strict specifications and regulations regarding safety such as the characteristics of the braking system, safety switches, etc. (The Shell Eco-marathon 2016-official rules). On the other hand, the involvement in races is an ideal benchmark to evaluate the performance of the designed and manufactured vehicles. The experience gained in these races is used to identify problems and needs and to seek solutions for them, which will be tested and analyzed again in future races. In order to come to a decision for this vehicle many factors must be taken into consideration for building. Some of the major factors that rest upon us are the aerodynamic shape of the vehicle and the total weight of the vehicle. Many other factors such as an energy efficient electric motor and driver skills are also a limiting factor but not as important as the first two mentioned. A good aerodynamic shape of the vehicle would provide great energy efficiency. To attain a good aerodynamic shape a good drag to weight ratio must be applied. In simple terms less drag would create a sleeker smoother run of the vehicle. The other limiting factor is its overall weight. Creating a light weight model would significantly increase its efficiency. Plans for reduction of weight would call for a light weight cassis and driver. After conducting a little research into the designs of commonly used marathon vehicles and comparing their uses with those that this vehicle would need, it was decided that a conventional lightweight design would be used. Being that this car would need to drive at least 20 km/h of driving, a conceptual design seemed like the most feasible option. In the design process of the electric vehicle was used complex analysis of consequences of every design solution not only from engineering, but from product design, ergonomics, maintenance, cost management, etc. points of view. This approach leads to what we call variable chain of consequences Fig. 1 which main goal is to put more weight on that point of view which will give more advantages to the whole engineering project. Taking decisions on every step of the design process from different point of view (not only engineering) makes it more flexible, effective but at the same time more difficult because every engineering solution is about interaction between two or more elements or characteristics of the product which leads to very big number of possibilities.

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Author name / Spectrum (Educational Research Service),ISSN:0740-7874(2017)101_108 Fig. 1. Variable chain of consequences.

As an example there will be described the process of vehicle body creation. Every vehicle body is based on a package which describes spatial placement of main elements materializing product’s main function. On Fig. 2 is shown frontal view of Ruse university electric vehicle’s package made in compliance with the rules of Shell Ecomarathon. If only aerodynamic efficiency and ergonomics (mainly driver visibility) set of characteristics is taken for simplicity, first major engineering solution must be made answering the question where to put the accent – on aerodynamic efficiency or ergonomics?

Fig. 2. Frontal view of electric vehicle’s package .

The electric vehicle is created for record and seems logical to put more weight on aerodynamics of the car. Following this way there will be smooth, streamlined, monovolume body with not much clear vision about next steps in design process. Defining the place and area of glazing, way of ingress and egress of the pilot, accessibility of suspension and powertrain etc. very often are made by improvisation with accidental final result. On the other hand if the accent is put on ergonomics (which is not so obvious), keeping in mind next steps in design process (already mentioned above) there could be two-volume vehicle body and some small extensions for wheel fairings, where second volume is extension of the main one, for the pilot’s head with crush helmet. Analyzing consequences of this engineering solution, following conclusions could be made:  Even the two-volume body solution is based mainly on ergonomic reasons Fig. 3 shows that there are benefits in aerodynamic direction with reduction of the frontal area of the vehicle (two gray fields) thus lowering aerodynamic drag force.


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Fig. 3. Frontal area redaction.

 Creating second volume in an aircraft cockpit canopy style e.g. from transparent plastic, will be ideal from ergonomic point of view – the pilot will have the best possible visibility, but the cost of this solution is high because of the molds and special vacuum machine needed. There is also dimension restrictions and the weight of the final part is usually bigger due to technological constrains.  Taking into account that transition between two body volumes could be very close to horizontally extended conoidal shape and this shape could be unfolded in a plane it is very easy to decide to interpolate this transition part of outside surface into conoidal one and cut the glazing from thin plastic (0.8 mm) sheet and wrap it around the crush helmet of the pilot. It’s lighter and there is almost 360 degrees undistorted visibility. But there’s no visibility upwards – is it right or wrong? By the rules it’s OK and from ergonomic point of view it is better because the roof part reduces greenhouse effect in a cockpit and works in a direction of a better pilot comfort Fig. 4.

Fig. 4. Pilot’s visibility.

 Dividing vehicle body into two parts through border of the two sub-volumes e.g. lower edge of the glazing brings excellent solution of ingress and egress of the pilot Fig. 5.

Fig. 5. Vehicle roof opening.

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The same process of analyzing consequences of the engineering solutions was applied on every step of the electric vehicle design. Another method which helps students to think “out of the box” way is what we call overlapped functional spaces. The idea behind this approach is simple – where it is possible in sake of efficient way of using space in a construction to “compress” engineering structures by putting their parts one in another, partly or fully, enhancing by this, quality of the final engineering solution. As an example there will be described design of the front axle. The unique construction of the front axle is based on central carbon fiber beam with weight of only 860 g. In both left and right ends of the beam are mounted supporting units with two fixed A-arms. Between these A-arms sits kingpin unit extended inside, so to form volume for the brake discs and to “move” wheels inside too. As a result wheels and hard suspension elements operate or sits respectively in a volume needed for turning steering wheels in left-hand and right-hand directions which makes whole front axle very compact Fig. 6.

Fig. 6. Front axle.

As a result wheel hub, kingpin and suspension arms occupy single volume which is part of wheel pocket volume, i.e. there is no need of space for wheel suspension. (fig.7)

Fig. 7. Wheel pockets volume.

The same approach was used for fire extinguisher’s placement seeking better weight distribution – it shears volume with the pilot’s seat; for space for electronics and batteries and roll bar Fig.8.


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Fig. 8. Fire extinguisher’s placement and battery compartment.

Fig. 9. Drive train

Although it is known engineering solution, the driver train is implemented the principle of variable chain of consequences (Dobreva & Haralanova, 2013). For drive train system, it is actually designed simultaneously with the design process of the other parts to allow proper integration with the other vehicle parts (Dobreva, 2013). Fig. 9 shows the final design of the drive train system. 3. Conclusion The main conclusion after the third year of the team was the confirmation of the great opportunities offered by the PBEV design to generate a much more ambitious educational project, involving not only the students that are finishing their degrees, but also those on the first year of the engineering curriculum. This type of educational methodology is increasing in popularity because it allows students to have an overview of engineering from the beginning, perceiving it as an integration of different specialties and not only as a set of independent disciplines. During the three years this project has been active, more than 40 students have been associated with the project either directly in the team or indirectly through associated projects. In addition, participation in this and similar projects are also seen as a means to enhance students’ motivation and their retention in engineering. In parallel with the organization of the new team’s staff, it was planned the development of a new prototype of a PBEV. The authors hope that this article can inspire teachers at other universities to start up new project works.

References Iliev S. (2015). Developing of a 1-D Combustion model and study of engine performance and exhaust emission using ethanol-gasoline blends. Transaction on engineering technologies, (pp. 85-98). Springer Science+Business Media Combs, S. (2008). The energy report 2008: Hydropower. Annual report, Texas: Window on state government The Shell Global: Shell Eco - Marathon 2016. The Shell Eco-marathon - 2016-official rules, Chapter1-010715 Dobreva, A (2013). Methods for Improving the Geometry Parameters and the Energy Efficiency of Gear Trains with Internal Meshing. VDI – Berichte, No 2199.2, pp. 1291 – 1302, ISSN 978-3-18-092199-0. Dobreva, A (2013). Theoretical Investigation of the Energy Efficiency of Planetary Gear Trains. Mechanisms and Machine Science, No 13, pp. 289-298, ISSN 978-94-007-6558-0.

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Dobreva, A., V. Haralanova (2013). Measuring and Evaluation in Machine Science and Design Education, based upon Diagnostic Research. Procedia - Social and Behavioral Sciences, WCLTA, Brussels, 3rd World Conference on Learning, Teaching and Educational Leadership, 2013, No Volume 93, pp. 1190-1194, ISSN 1877-0428.