Bicycle-Powered Charger

Bicycle-Powered Charger

Submission Date: May 11, 2016 Submitted To: Dr. Kevin Kilty

i TABLE OF CONTENTS Page LIST OF FIGURES ……… ii LIST OF TABLES ………. ii ABSTRACT ………... 1 INTRODUCTION ……….. 1 SYSTEM DESIGN ……….... 6 TESTING ………... 17

ECONOMICS AND COMMERCIAL VIABILITY ………. 20

LIFE CYCLE ANALYSIS ……… 22

CONCLUSIONS ……… 24 APPENDICES:

1. FMEA ………... I 2. SolidWorks Drawings of the Support Frame...………... IV

3. SolidWorks Drawings of the Shaft System....……….…….... VII

4. Cost Analysis Table ………..……….…………... XII

5. Test Results………. XIII

ii LIST OF FIGURES

Figure 1. Permanent magnet ATV magneto stator ………. 7 Figure 2. Visio model of a shunt regulator circuit ………..……... 8 Figure 3. SolidWorks model of the assembly of the bicycle, support frame and

charging system ……….………. 9

Figure 4. Typical retail bicycle trainer ………... 10 Figure 5. SolidWorks model of the designed support frame for the bicycle-powered

charger system ……….………... 11

Figure 6. SolidWorks model of the shaft system ………... 12 Figure 7. Typical bicycle odometer setup ……….. 14 Figure 8. Integration of various sub-systems of the bicycle-powered charger system .. 15 Figure 9. Unified electronics and control sub-system integration ………. 16 Figure 10. ATV magneto testing setup …..……… 18 Figure 11. Shunt regulated power supply testing results ………... 19 Figure 12. Life cycle for a commercially produced version of the bicycle-powered

charger system ……… 24

LIST OF TABLES

Table 1. Design constraints for each sub-system of the Bicycle-Powered Charger system ……….

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Table 2. Shaft system outputs for various wheel sizes …..………..……... 13 Table 3. Estimated material and manufacturing costs for the final design of the

bicycle-powered charger system …..……….………. 21

1 ABSTRACT:

Bicycles offer effective means of exercise and are popular forms of transportation. One fault of the current use of bicycles is that the mechanical energy generated by a moving bicycle is often wasted in the form of friction and expended heat. Wasted energy is troubling in the modern world now that energy is deeply integrated into peoples’ everyday lives – one of the most common energy consumers being small electrical devices such as cellphones. Our senior design project addresses this issue via a bicycle-powered charger system designed to operate similar to a normal commercial bicycle trainer while concurrently mitigating dependence on outlet electrical energy for charging. The system is composed of the frame (trainer) and the charging system. The trainer is based on a standard retail bicycle trainer to enable easy transition from road use to stationary exercise use. The charging system will be capable of charging a 12 V battery pack, which will then be able to charge multiple 5 V devices simultaneously. The bicycle wheel sets into the trainer while resting against a rotor which spins the shaft connected to a generator (a permanent magnet ATV magneto) which outputs a variable AC voltage RMS. This AC output from the generator will pass through a shunt voltage regulator and a boost power inverter, which connects to a removable battery pack capable of charging during system operation and stores charge for use after operation. The prototype we create will utilize a

purchased trainer for design, but this prototype is intended to evolve into a commercial product. We will discuss our design and estimate cost of a commercial product.

INTRODUCTION: Global/Societal Context

Our bicycle-powered charger is more than a simple mechanical product. Based on the needs of the end user, this product will address issues of physical, economic, and environmental conditions. With various technologies now readily accessible to millions of people, physical activity is no longer required. Since physical activity is no longer essential to survival, societies have become lax in their amounts of daily physical activity, which poses potential health issues. Our bicycle-powered charger will address this issue by encouraging our users to use their own physical energy to quickly charge their electronic devices like cellphones and tablets. People will be inclined to put in the effort to charge their devices using this method because of the other two issues this product addresses: those of economic and environmental conditions. Our bicycle-powered charger offers a cost-effective way to provide the electricity for those devices in that it can allow the users to decrease the amount of electricity they buy from commercial providers. This may also directly and indirectly reduce further pollution of the environment by removing some of the need for conventional electrical sources including coal, petroleum, and gasoline and by promoting the use of bicycles. Each of these issues addressed by our bicycle-powered charger prove it to be sustainable. Sustainability is essentially made up of three pillars: societal,

economic, and environmental. The physical activity provided by our bicycle-powered charger may improve the social aspect of many peoples' lives while the lower consumption of traditional

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electrical sources may reduce the economic burden on many people and may reduce further environmental pollution.

Background

Bicycles are a popular means of maintaining physical wellness and health. They are also a useful form of transportation for commute (short trips ranging from approximately 0-5 miles) and recreation (short and long trips ranging from 0-100 miles). Many people choose to bike as a means of reducing their ecological footprint, which is particularly useful in large cities where emissions tend to be concentrated. Many advancements have been made in internal combustion engines (vehicles) to reduce emissions such as hydrocarbons, carbon monoxide, particulates, nitrogen oxides, and carbon dioxide. Hydrocarbons, carbon monoxide, particulates and the various nitrogen oxides are toxic to human health, can cause acid rain and foul odors, and, in concentration, form ozone regions or photochemical smog in large cities. In moderate levels, carbon dioxide is not toxic to human health but is still considered a greenhouse gas and is a promoter of climate change.1

In the United States, vehicles are the second largest contributor to carbon emissions at 27%.2 Most modern internal combustion engines are equipped with a catalytic converter which substantially decreases the emissions of these compounds. The flaw with these devices, however, is that they do not operate efficiently if they are cold. It can take up to ten miles of driving for the catalytic converter to reach steady state conditions. Statistics show that approximately half of all the fuel used in the United States is used for trips less than ten miles. Furthermore, most of these short trips occur during commutes in large cities, where emission reductions are even more critical. For example, 70-90% of all hydrocarbon emissions in the U.S. stem from these trips alone.3 Hence, those individuals who regularly use a bicycle for transportation are significantly contributing to reductions in the human footprint.

Additionally, a vast majority of the population relies on cellphones and other electronic devices for communication and entertainment. The “charge” for such devices is the electrical energy supplied by power companies which is transported to the user through electrical outlets. These power companies contribute to emissions through the production of this energy. Thirty percent of all the carbon in the United States comes from power company emissions; they are the largest contributor in the country.4 Based on data gathered from the individual members of this project and their advisor, iPhones and similarly small electronic devices consume as much as 5 W at peak power while most laptops range between 30 and 40 W. A chart of the data detailing

1 _{Pulkrabek, W. W. (2004). Engineering fundamentals of the internal combustion engine. Upper Saddle River, NJ:} Pearson Prentice Hall.

2 _{Wollums, C., Burke, I., Coddington, K., Godby, R., Minier, A., & Reavey, R. (2016, April 4). A Conversation on}

the Clean Power Plan’s Impact in Wyoming: Understanding the Challenges and Opportunities. Panel presented at

University of Wyoming, School of Energy Resources Panel Presentation in Wyoming Union Family Room, Laramie, WY.

3 _{Pulkrabek, 2004.} 4 _{Wollums et al., 2016.}

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these results is shown in Appendix 5. As such, for a person charging a 5 W cellphone every night out of the week, the yearly peak power consumption is approximately 1.8 kW. In 2014, the United States consumed 3,764,700 kilowatt-hours of electricity; 1,407,208 kilowatt-hours were used purely in the home.5 Small electronics, primarily cellphones, account for approximately 2% of electricity usage in the home due to charging necessities.6 _{Hence, those electronics consume}

approximately 28,144 kilowatt-hours every year.

From this background knowledge, the overall goal of our bicycle-powered charger

system is to harness the mechanical energy generated by a stationary bicycle via a trainer and use it to power everyday electronic devices. Such a design enables the user to continue using or begin the habit of using their bicycle for transportation, thus addressing the issue of vehicular pollution. The purpose of this bicycle-powered charger system is to charge various small electronic devices (typically 5 V). Thus, the usefulness of such a product is twofold. Not only will it promote less vehicular travel, it will also reduce reliance on power companies, which, in turn, may reduce the emissions from the two of the highest emission sources in the United States.

Also, the system will be able to fulfill the basic electronic charging needs of the average person who can maintain between 50 to 80 rpm7. It will consist of a bicycle (provided by the user), a support frame, a shaft system (to connect the bicycle tire to the generator), a generator, a unifying circuit (composed of an AC/DC convertor, voltage regulator, and buck boost power inverter), a battery pack, and a display (to inform the user of the status of their workout and the storage unit). The system will accommodate any standard adult sized bicycle. A system diagram for this plan is listed in Appendix 5.

Several main objectives and various design considerations were generated to address the goals of this design. Detailed considerations are provided in the following section. The

objectives include: increase user desirability, ensure system integrity, reduce overall cost, and provide various charge capabilities.

User Desirability: The first objective, increase user desirability, will be accomplished by

ensuring the product has pleasing aesthetics, is relatively easy for the consumer to assemble and to use, is economically viable for the consumer, and meets specific safety standards. The

aesthetics portion will focus on reducing the bulkiness of the system and making the surfaces of the system clean and smooth with pleasing color tones so that the final product is attractive and marketable to our users. Use of the system will be designed to be relatively easy for the

consumers by making it to be light-weight and able to smoothly integrate adult bicycles ranging from 24 to 29 inches in tire diameter. To ensure the system is commercially viable, the system

5_{U.S. Energy Information Administration. SAS Output. Retrieved April 18, 2016, from} http://www.eia.gov/electricity/annual/html/epa_01_01.html

6_{McAllister, J., & Farrell, A. E. (n.d.). Power in a Portable World: Usage Patterns and Efficiency Opportunities for}

Consumer Battery Chargers (pp. 11-107-11-118, Publication). University of California, Berkeley. Retrieved

April/May, 2016, from

http://www.eceee.org/library/conference_proceedings/ACEEE_buildings/2004/Panel_11/p11_10/paper 7_{Web. 9 Dec. 2015. <http://www.ontherunevents.com/ns0060.htm>.}

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must cost between $200 and $400 at retail. A section on safety is described in detail in the System Design section.

System Integrity: The second objective, ensure system integrity, will be accomplished through design and testing. The support frame will be wear and shock resistant, and structurally sound; the charging system will be robust and effective in charging outputs; the display will be accurate and long lasting while displaying relevant information to the user such as distance, instantaneous and average speed, heart rate, calories burned, and the charge status of the users’ small

electronics.

Overall Cost: The next objective, reduce overall cost, will be accomplished by utilizing the best available materials at the lowest price. Specifically, the budget for the prototype is $700, which was provided by University of Wyoming, Department of Mechanical Engineering associate professor Dr. Kevin Kilty.

Charge Capabilities: The last objective, providing various charge capabilities, will be accomplished by converting the variable AC voltage RMS output from the generator into consistent DC voltage which can then be applied to three outlet options. One outlet will be utilized to directly charge small electronic devices. A second outlet will be used to charge a removable 12 V lead-acid battery with multiple USB 5 V charge outlets. The last output will be a resistor to ground so that, in the case that some of our users are unable to generate sufficient voltage to sustain the first two options, they will still have some resistance to the pedals and the voltage that they do generate is still dissipated through the charging system

Design Considerations

Our bicycle-powered charger will have many design considerations, which fall under the basic categories of Manufactural, Environmental, and Ergonomic. Health and safety will be considered throughout the design. The underlying considerations and constraints for each category are summarized in Table 1.

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Item Considerations Other Constraints

Support Frame

Must support standard retail bicycles (focusing on wheel sizes) and be useable for a range of riders from the 95% male to the 5% female

Weight, Size, Strength, Safety, Cost, Aesthetics, Ease of Use ATV

Magneto

Must generate power required for 12V

charging system Size, Level of Resistance, Cost

Battery Pack

Must store 12V DC and have multiple

removable charge outlets Longevity of Charge Cycles, Safety, Cost Unified

Electronics

Must increase/decrease input voltage to meet battery voltage requirements

Compatibility, Safety, Cost Display Must show calories burned, distance covered,

current speed, and charge accumulated

Weight, Durability, Safety, Readability, Ease of Use, Cost Regarding manufacturability, we had to consider several constraints relating to the materials we would be using. The material used for the support frame must be able to be welded, and shaped all the while without hindering its structural integrity; the material must be able to be polished or painted to meet our aesthetic objectives; and the material should be available and inexpensive to meet our economic objectives. In our case, we have opted for aluminum and steel materials for the majority of the design system components.

Environmental constraints to reduce environmental pollution must also be considered. For instance, if powder coating is used instead of spray painting on the support frame, the volatile organic compounds released into the atmosphere is reduced, the risk of cancer from contact is decreased, and the probability of fire is lessened since powder coating is less

flammable.8 Also, powder coating has a much longer lifespan than spray painting which means the environment will be effected less often.9 _{Further effect to the environment due to}

manufacturing may be reduced by limiting the amount of manufacturing necessary. Since our bicycle charger requires only two major components, the support frame and the charging system, which can both be easily handled by a single adult without mechanical aid in most cases, the amount of manufacturing will be minimal. From an operation standpoint, by using a system which utilizes energy from a person exercising, we reduce the use of power from conventional sources (coal, petroleum, and gasoline) and, thereby, reduce the environmental impacts which typically accompany such sources.

Our ergonomic constraints allow our product to work for the larger population of consumers while also helping to seek out product data from various regulatory agencies. The larger population of consumers considered must be limited by age and health level ranges in order to allow our bicycle-powered charger to be built to the highest of safety levels while still remaining low in cost. These safety levels will be achieved by following the design codes of several different regulatory agencies including the Consumer Product Safety Commission and

8 _{"How Is Powder Coat Better than Spray Paint?" Seattle Powder Coat. Seattle Powder Coat, 2012. Web.} <http://www.seattlepowdercoat.com/why_not_just_spray_paint>.

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the American Society for Testing and Materials. In addition, we may consider other agencies which are deemed to be appropriate after further design and testing of our current bicycle-powered charger system. The codes from the different agencies will allow our design to be monitored during the testing phase.

The constraints explained above must all be considered in order for our bicycle-powered charger to be feasible. In essence, our bicycle-powered charger must be low-cost, structurally sound, small, up-to-code, safe, and durable.

SYSTEM DESIGN: Generator

The power output was one of the greatest concerns of the design team. The generator should be able to quickly and efficiently charge all small electronics requiring approximately 5 watts. Ideally, the design team would like the generator to be capable of fully charging or partially charging some larger applications like tablets and small laptops that can require

anywhere from 15 to 30 watts. The design team determined that a stepper motor or an alternator would be appropriate generators for the bicycle-powered charger system. Knowing this, the design team decided to use an ATV magneto, which was already available, for the prototype so that testing could begin. The ATV magneto originated from another senior design team (Baja) and was missing both the rotor and an appropriate cover. The rotor was purchased and the cover was designed by the team for manufacture in the University of Wyoming Engineering shop (hereafter referred to simply as the shop). Additionally, a custom shaft was designed and

manufactured to connect the generator to a PVC roller spun by the rear wheel of the consumers’ bicycles. It was expected that the magneto would be a 12-V, three-phase, eight-magnet, two-output, AC voltage RMS generator. The two voltage outputs were the charging output used to charge the battery of the ATV and the spark plugs outlet used for the ignition of the ATV. The charging output would be used for this project design, which would output a variable AC voltage RMS. There was some concern by the team that this generator would have too high of a

resistance for our users to exercise with. The team decided that if this was discovered to be true after testing, two of the magnets and their windings would be removed to reduce the overall resistance of the magneto. The ATV magneto obtained by the design team is shown in Figure 1.

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Figure 1: Permanent magnet ATV magneto stator.

Energy Storage and Charging Capabilities

A 12 V lead-acid battery was chosen for our energy storage outlet. We intended it to be able to function attached to the system during exercise and separate from the system for use at a later time or location. Allowing this separation was necessary for individuals wishing to utilize their produced energy on-the-go. In addition, the lead-acid battery pack would be capable of charging multiple devices at once, including the display. With the battery being 12 V, it would be capable of charging multiple devices simultaneously since the team found that most small electronic devices charge and operate at 5 V. We intended the battery to be one of three outlets with the other two outlets being direct charge to small electronic devices and a resistor. The resistor was necessary to produce some resistance for exercise in case the individual using the system did not produce enough voltage for either of the other two outlets.

In order to connect the ATV magneto to our three outlets, we had to design a unified electronics and control circuit composed of a processor and shunt regulator. The micro-processor would guide the voltage to the desired outlet. Specifically, the micro-micro-processor would be programmed to direct the voltage to the three desired outputs of the design with the preference being to directly charge the users’ electronics first, then, once those devices were fully charged, to the battery, and, lastly, to a resistor to ground. Figure 2 shows an example diagram of the shunt regulator we would utilize.

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Figure 2: Visio model of a shunt regulator circuit. This would convert the variable AC voltage output of the ATV magneto to a constant DC voltage.

Since the generator utilizes variable output AC voltage, a bridge rectifier is placed at the beginning of the circuit shown in Figure 2. The bridge rectifier acts to convert AC voltage to DC voltage. 10 The various other electronic components are added as controls to achieve a constant, useful voltage. Resistor 1 is one ohm and functions to decrease the current further. The 490 micro-fared capacitor stores the excess energy that the users may produce and releases is steadily back into the system. The Zener diode, a key component to the circuit, regulates the voltage. It accomplishes this by operating at its breakdown voltage – the voltage which remains constant within a specified range of current.11 For our application, we selected a 5.1 V Zener diode with an operating range of 10 to 100 mA. Resistor 2 is around 70 ohms to reduce the amount of current that passes through the Zener diode. To reduce the current output to the various outlets, the NPN transistor is used. This transistor operates by turning on when a small amount of current passes through its base terminal (the node between the Zener diode and Resistor 2). When on, the transistor allows large current to pass through its collector terminal (the top side of the circuit shown in Figure 2) to its emitter terminal (the bottom side of the circuit shown in Figure 2).12 The data sheet on the specific transistor used for this example shunt regulator is available in Appendix 7.

As a final component for charging, a boost power converter may be necessary to step up the voltage produced to 13.4 volts if the user does not produce enough voltage to charge the battery. The boost power converter selected is a switched mode converter that utilizes an n-channel MOSFET as the switching mechanism. When the MOSFET is switched on, an inductor

10 _{"Technical Article: How a Motorcycle Charging System Works." ElectroSport. Web. 1 Dec. 2015.}

<http://www.electrosport.com/technical-resources/technical-articles/how-motorcycle-charging-system-works>. 11_{Kuhn, K. A. (2013, April 7). Zener Diode Voltage Regulators (Publication). Retrieved April/May, 2016.} 12_{S. (2012). Transistor NPN animation. Retrieved May 11, 2016, from}

https://www.youtube.com/watch?v=aVJrTMuzlL4 Bridge Rectifier AC Terminal AC Terminal Resistor 1 Resistor 2 Capacitor Transistor Zener Diode + DC Terminal - DC Terminal Testing Port

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is used to store energy. When the MOSFET switches off, the combined input voltage and inductor voltage supply the load (battery) and charge a capacitor. The MOSFET then switches back on to store more energy while the capacitor discharges and supplies an almost constant voltage to the load. 13

Support Frame

The support frame is meant to hold both the rear tire of the users’ bicycle and the roller, shaft and generator system. The setup of the frame containing these two modules is shown in Figure 3 from various viewpoints.

Figure 3: SolidWorks model of the assembly of the bicycle, support frame and charging system. Two support frames were analyzed during the initial design process of the

bicycle-powered charger system: one purchased specifically for the prototype and one designed for the final commercial product. The first frame was necessary due to some very sophisticated and, therefore, time-consuming components of the designed frame and also the inability of the shop to perform the heat treating necessary for welding aluminum. A typical retail bicycle trainer, shown in Figure 4, was reverse engineered for the designed support frame.14 The dissipater on the retail trainer provides resistance to the bicycle user and prevents the pedals from “running away” from

13 _{Eric Coates. “Boost Converts.” Learn About Electronics: Power Supplies. (2016). Web. 10 May 2016.} 14_{"Bicycle Trainer - Google Search." Bicycle Trainer - Google Search. Web. 9 Dec. 2015.}

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the user. The dissipater was not included in the designed support frame due to the prediction that the ATV magneto would have sufficient resistance to warrant its exclusion.

Figure 4: Typical retail bicycle trainer. Since a member of the group has one of these trainers, the design will be modeled after this trainer.

A SolidWorks drawing of the final design of the support frame is shown in Figure 5 with a further breakdown of all the sub-assembles used in this design available in Appendix 3. It was decided to construct this frame mainly of 1020 aluminum alloy due to its lightweight compared to typical steel retail trainers. A 1020 aluminum alloy assembly is less than half the weight of a steel assembly. To verify this, the designed support frame’s weight was first calculated for aluminum and then for steel. The aluminum frame was 16.35 lbs. while the steel frame was 38.31 lbs. The components altered for this calculation included the back and front uprights, the floor pieces, and the covers. To fulfill the design objective of accommodating a range of bicycles between 24 and 29 inches in wheel diameter involved the incorporation of height adjustments into the design and may require the user to level their bicycle. Commercial products are available for such purposes. The frame in question will be designed to be structurally sound no matter if the user takes the measures to level his/her bicycle or not.

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Figure 5: SolidWorks model of the designed support frame for the bicycle-powered charger system. This model is comprised of the final assembly and three sub-assemblies, as shown in Appendix 3. Among the sub-assemblies are the two top structures which

are alike except for the wheel supports. One wheel support is designed for increased stability for the user while adjusting the lateral position of the bicycle.

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For the prototype, the support frame was not manufactured exactly as described in Figure 5. Instead, a retail aluminum trainer was purchased by the team and modified to meet the team’s specifications. This action was decided upon for several reasons, the most prominent of which was the lack of aluminum heat treating abilities in the shop. Without proper heat treatment, the attachment method of choice, welding, would reduce the stiffness of the aluminum to make it structurally unsound during the welding process. Another reason for purchasing a pre-built trainer for the initial prototype was time restrictions. The shop had many demands on its time, including graduate level projects, and the team was informed that construction of the designed support frame would be queued until further notice, significantly delaying the testing stage. Due to these dilemmas, the design team elected that purchasing a trainer and modifying that trainer for the design was a viable alternative.

Shaft System

Figure 6 depicts the SolidWorks model of the shaft system. It is composed of a shaft connected to the ATV magneto and a larger cylinder (roller) supported by two pillow-block bearings located where the dissipater is on retail trainers. The rear wheel of the users’ bicycle will rest against the large cylinder and allow transfer of the wheel rotation to shaft rotation. The design team chose a diameter of 4 inches for the cylinder because that diameter would likely accommodate all the desired tire sizes and also increase the ratio between the roller and the tire. The shaft system is adjustable to accommodate 24″ to 29″ tires.

Figure 6: SolidWorks model of the shaft system.

The shaft was constructed from steel, the cylinder was constructed from PVC, and the frame connection components were constructed from aluminum. Each piece was built according to the

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SolidWorks model specifications and utilized available materials in the shop. SolidWorks drawings for each part can be found in Appendix 3. An outer aluminum shield will be added to the final product to reduce the risk of injury to the user. The calculated outputs for applying various wheel sizes to the shaft system are available in Table 2 below. The output speed of the average user was estimated to be three wheel rotations per second, disregarding wheel diameter. A range of metric tire diameter sizes similar in range to that chosen by the design team was also analyzed. The bicycle chosen for testing, provided by one of the members of the design team, had a tire diameter of 700 mm x 25 mm.

Table 2. Shaft system outputs for various wheel sizes. Operation was estimated to be three wheel rotations per second to simplify calculations.

As may be observed from Table 2, the output may vary by approximately 300 rpm for the various wheel sizes.

Display

The display will provide similar information to the user as most retail bicycle odometers and will utilize the energy output of the design itself for operation. Specifically, the display will inform the user of their speed, both instantaneous and average, and distance and the charge accumulated in the battery while exercising. To increase interest in our consumer base, heath statistics will also be added to the display, like calories burned and heart rate. A display of particular interest to the team is a 132x132 Serial Color Graphic LCD. This display is taken from the 6610 Nokia phones and may be purchased from gravitech.us for approximately $36. This display is desired due to its aesthetics, simplistic use, and relatively inexpensive price.15 To

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determine the speed and equivalent distance travelled by the user a typical bicycle odometer setup will be utilized. A magnet or reflective tape will be placed into the spokes of the rear wheel of the bicycle and a sensor will be mounted onto the frame of the bicycle. The sensor will record the times the magnet or reflective tape passes in front of it and the display will show the

calculated speed and distance. An image of this system is provided below in Figure 7.

Figure 7: Typical bicycle odometer setup. This system is used for recording the speed and distance of a moving bicycle. The odometer for the bicycle-powered charger will be mounted to

the rear wheel.

Since the design team will have no way of measuring the exact weight, height, sex, etc. needed to calculate calories burned and heart rate, a range of these variables will be selected based on our user base and the range of bicycle tire sizes used in this design.

System Integration

The system integrations of the components discussed in the previous sections is shown in the system diagram displayed in Figure 8, where the support frame holds the bicycle with a user, and the shaft system and connected generator. The generator then outputs to the unified

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Figure 8: Integration of various sub-systems of the bicycle-powered charger system. The system diagram of the unified electronics and control is shown in Figure 9. The variable AC RMS voltage from the ATV magneto outputs into the bridge rectified of the shunt regulator which mediates the charge for transfer throughout the rest of the charging system. The micro-processor then directs the charge to the three options of direct charge to the users’ electronics, storage in the lead-acid battery and resistor to ground. A boost power inverter is needed for the lead-acid battery, which also serves as the power source for the display for the system.

16 Project Budget

The project budget for the bicycle-powered charger was set at $700 and, therefore, the prototype must cost less than this amount. The prototype budget was provided by mechanical engineering associate professor Dr. Kevin Kilty. This budget objective will be accomplished by economizing and designing the system so the best materials are obtained at the lowest overall cost. As such, the incomplete permanent motorcycle magneto was acquired from the Baja design team at no cost due to the multiple missing parts. Also, the designed support frame materials will consist of durable, low cost aluminum and steel. To avoid construction fees, the assembly and construction of the prototype is intended to be performed by the design team. A cost analysis table for the bicycle-powered charger prototype is available in Appendix 4. Since commercial viability is a desired outcome for this design project, an economic analysis on the projected final design was performed by the team and will be discussed in detail later. The design team found that the average market price of a bicycle trainer is between $200 and $400 and, hence, set the target price of the final bicycle-powered charger product to fall within this range.

Safety

Safety for the user is a serious consideration for the design team. Most of the moving parts of the final design of this system will be covered or partly covered (i.e. the generator, the battery pack, the electrical circuitry and connections) according to American Society for Testing and Materials (ASTM) standards. The risks posed by parts which cannot be covered or are covered but still are not completely benign will be addressed by safety labels also according to ASTM standards. Particularly, there will be warning and caution labels placed on the parts of the system posing potential harm to the user and the user will be advised to keep the entire charging system away from small children and pets, especially during operation. Some familiarity of the user with bicycles and how to operate them safely must be assumed by the design team in order to maintain the feasibility of this project. A Failure Mode and Effects Analysis (FMEA) for this system and each of its individual components is provided in Appendix 1. The design team deduced five areas which posed potential safety hazards to be: the support frame, the generator, the shaft system, all the electrical components and the lead-acid battery. Hence, an FMEA was done for each. The testing aspect of each of the FMEAs is likely to change as the design evolves from the prototype to the final. The rankings of severity, probability, and detectability assigned for these FMEAs are also included in Appendix 1.16

TESTING

17 Frame

The frame used for prototype testing was purchased from MetalsDepot, a company out of China, for $59.99. The frame was tested using a 700 mm x 25 mm testing bicycle (approximately 27 inch diameter) to ensure that it met the various size, weight, and stability requirements set by the design team.

Results, Discussion and Recommendations

The design team found the frame to be able to accommodate bicycle tire sizes up to thirty inches in diameter (this is total size of both the wheel frame diameter with the tire thickness added), so the trainer met the size requirements. The strength and stability of the purchased trainer was found to be suitable to support both the testing bicycle with a user and the prototype charging system and, hence, was adequate for prototype testing.

The final design however would require significantly more testing as indicated in the FMEA in Appendix 1. The final frame design generated by the design team would likely be distributed to a contracted manufacturer (this was done for cost reasons as will be discussed in the Economic Viability section). After the frame is manufactured, the design team would do extensive testing on the yield, ultimate and stress limits of the system. The integrity of the welds would be tested and, lastly, the stability of the system would also be tested on a variety of various floor surfaces to ensure that the system remains stationary during use in all scenarios.

Shaft System

The shaft system was designed to attach to the purchased frame and to accommodate 24″ to 29″ tires. The shaft system was attached to the frame and the same 700mm x 25mm testing bicycle was used to test its functionality and range.

Results, Discussion and Recommendations

The custom shaft system’s effectiveness at transferring the rotational energy from the rear bicycle tire to the generator was tested by pedaling the bicycle at a range of speeds produced by the user. The shaft system was found to transfer all of the rotational energy from the tire to the generator with no slipping for the whole range of speeds. However, there was some clunking and movement between the shaft and the generator due to the shaft being designed with the wrong taper. This could be eliminated by redesigning the shaft using more accurate and precise measurement techniques. The slippage of the shaft system would need to be tested further once the final generator has been designed and selected by the project team.

The adjustability of the shaft system was found to be easy and effective. It takes less than a minute to adjust the shaft system to the tire size and it stays put once adjusted. The range of the shaft system did not meet our objectives because it could only accommodate 24″ to 27.5″ tires. The shaft system would need to be redesigned to accommodate tires up to 29″, but this would be a simple task.

18 ATV Magneto Generator

The generator was tested once the frame, the roller and shaft and the magneto were all assembled. The outputs of both the charging wires and the spark plug wires were tested using an ammeter and an oscilloscope for various user cadences. The system assembled for testing is shown in Figure 10.

Figure 10: ATV magneto testing setup. Included in the setup are the assembled bicycle (700x25), support frame, shaft and generator sub-systems.

Results, Discussion and Recommendations

The design team found that the ATV magneto was a one-phase, 6 V generator, not a three-phase, 12 V generator as previously assumed. Due to this misassumption, the design team also found that the resistance of the generator was not sufficient to provide a high enough pedal resistance to the user because the testing operator was moving the pedals at maximum speed with ease. Hence, the operator was effortlessly maintaining a cadence of approximately 100 rpm which surpasses the target range set by the design team of 50 to 80 rpm, the range of speeds an average person can sustain. This cadence corresponded to a shaft rotational speed of 1800 rpm which surpassed the predicted speed of the shaft system for a bicycle tire of a diameter of

approximately 27 inches. At this maximum speed, the output of the system was approaching 7 V and the current was 2 amperes, resulting in a maximum power output of 14 W. (The output of the spark plug wires was also measured and was found to be 140 V, but, since the design team knew that the outlets were meant for spark ignition and would therefore have a very high resistance and almost negligible current, other data was not gathered about the outputs for fear of compromising the design team’s testing equipment.) Hence, the team found that the ATV magneto, while helpful for prototyping of this project design, is not a suitable or adequate generator for this system. It was a viable option to pursue because it is being manufactured as an after product already and, although not powerful enough, it was useful in making the design team aware of various issues and possible adjustments to the overall system to be made for the final design. Hence, it is the suggestion of the design team that the final design should include design

19

of the generator by the team specifically for integration of this system, since there are not any appropriate products currently being manufactured. The designed generator should meet the specifications discussed (lightweight, reduced bulkiness, ease of use, safe for the user) while also being able to generate 20 W or more during operation. Furthermore, the designed generator should incorporate the additional resistance that the ATV magneto failed to adequately induce to the user. If incorporating the added resistance into the final generator design jeopardizes the integrity of the design, the design team suggests the consideration of adding the commercial dissipater back into the system integration. However, adding this component back into the design would greatly reduce the efficiency of the system.

Shunt Regulator

As a final test for our prototype, we analyzed the effect of our shunt regulator circuit on the produced voltage. For this test, we represented the ATV magneto as a Thevenin equivalent circuit with a standard 7 V RMS AC source and a one ohm resistor. By altering the load resistance we were able to produce the load line shown in Figure 11.

Figure 11. Shunt regulated power supply testing results. Results, Discussion and Recommendations

From the produced load line, we would be able to determine the optimum operating conditions for specific loads placed on our system. With the output of the ATV magneto being only 7 V RMS we would need to custom design a generator to produce more voltage for future systems, as mentioned previously.

ECONOMICS AND COMMERCIAL VIABILITY 0 1 2 3 4 5 6 7 8 9 10 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 DC VO LT A G E O UTPU T (V) AC (A)

Load Line

20

Hence, from the prototype testing results and discussion of possible future and final design changes, the team performed an economic analysis to ensure that the final bicycle-powered charger product could be marketed to the consumers at a desirable price. Since the design is mainly an integration of parts, the design team would purchase many of the necessary components in bulk. Additionally, for the custom parts specifically designed by the team

(support frame, generator, shaft system), the designs would be sent to a contracted manufacturer to be produced in bulk at wholesale. The shaft system, since it is a more complex design, would be custom constructed at a local business to ensure the integrity of the system. With these

assumptions, the team estimated the total cost of each sub-assembly of the system and, therefore, the total cost of the whole system, which can be viewed in Table 3. The final cost to the design team shown in Table 3 is that of manufacturing and material costs only. It does not incorporate labor costs for the integration of the system or for the necessary programming of the display.

21

Table 3: Estimated material and manufacturing costs for the final design of the bicycle-powered charger system. The total cost to the design team is $164.06. Labor costs of assembly are not included in this economic analysis.

Item Quantity Cost Item Quantity Cost Unified Electronics and Control Roller System

Bridge Rectifier 1 $ 1.00 Shaft 1 $ 4.94 1 V Power Resistor 2 $ 3.95 Adujuster Brace 1 $ 12.13 400 mF Capacitor 1 $ 6.02 Bearing Base 1 $ 2.78 75 V Power Resistor 1 $ 1.69 Roller 1 $ 3.98 5.1 V Zener Diode 1 $ 0.90 Pillow Block Bearings 2 $ 12.69 Transistor 1 $ 2.90 Shims 2 $ 2.47 Total $ 16.45 Bolts 4 $ 4.54 Charging System Nuts 4 $ 0.68 12 V Lead Acid Battery 1 $ 16.00 Washers 8 $ 2.56 Boost Power Inverter 1 $ 2.50 Set Screws 2 $ 0.34 Removable Battery Pack 1 $ 7.00 Total $ 47.12 Power Supply 1 $ 2.50 Contracted Generator

Micro-processor 1 $ 2.50 Core 1 $ 2.50 Charger 1 $ 2.50 Windings 1 $ 7.50 5 V USB 1 $ 2.50 Encasing 1 $ 10.00 Total 1 $ 35.50 Total $ 20.00 Display 1 $ 15.00 Contracted Frame

Frame Total 1 $ 30.00

Total Integration Cost 1 $ 164.06

22

The total cost to the design team was found to be approximately $164 for manufacture and material costs of the various sub-systems. Hence, the team could market this product in the range of $300 to $400. This is a desirable price range to the consumers because most affordable retail bicycle trainers are sold at prices in the range of $200 to $400 as outlined previously. Our product could be sold in this range and also offers more to the consumers than just the frame. Furthermore, this product, if used regularly as discussed in the ensuing life cycle assessment section, could significantly reduce our users’ dependence on electrical power generation plants and, therefore, reduce their monthly and yearly electricity household costs. Consequently, our product is desirable in that it offers a way to accelerate health and exercise, and reduce

dependence on power plant generation and, correspondingly, residential costs all at an affordable upfront price.

LIFE CYCLE ASSESSMENT

A commercially produced version of our bicycle-powered charger would have several stages in its life cycle: raw material extraction and production, sub-system construction, sub-system integration, operation, and afterlife. At each stage, we analyzed the environmental impacts and human impacts. For the first stage, raw material extraction and production, we focused on the primary materials used for the custom-built components – aluminum and steel. The other materials were not considered due to their small amount relative to aluminum and steel and to reduce the complexity of this assessment. For the environmental impacts, aluminum extraction and production produces perfluorocarbons, polycyclic aromatic hydrocarbons, fluoride, sulfur dioxide, and carbon dioxide, all of which are greenhouse gases.17 Another environmental impact comes from the produced sulfur dioxide in the form of acid rain which, as is known, can harm plant life.18 Steel production has a very small impact on the environment due to the large emphasis on reusing or recycling its residuals.19 _{The human impacts associated with}

aluminum and steel stem from similar areas as the environmental impacts. For aluminum, the polycyclic aromatic hydrocarbons are considered carcinogenic and so have the potential to cause cancer.20 Another human impact comes from the released sulfur dioxide which can contribute to difficulty breathing, respiratory illness, and aggravated cardiovascular disease of an individual if it is found in large concentrations.21 _{The people most likely to feel these effects are children, the}

17_{Aluminum - The Environmental Literacy Council. (2015). Retrieved from} http://enviroliteracy.org/special-features/its-element-ary/aluminum/

18 _Ibid.

19 _{Fact sheet: Steel industry by-products. (2014, October). Retrieved from}

https://www.worldsteel.org/publications/fact-sheets/content/01/text_files/file/document/Fact_By-products_2014.pdf

20 _{Toxic substances portal - polycyclic aromatic hydrocarbons (PAHs). (2014, August 28). Retrieved from} http://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=121&tid=25

23

elderly, and people with existing respiratory conditions.22 Additionally, the acid rain resulting from sulfur dioxide emissions can have an effect on humans by corroding structures such as buildings.23 With enough acid rain, the structural integrity of a building could become significantly reduced and thereby increase the safety risk to humans.

The environmental and human impacts from sub-system construction would stem from the need for heat-treatment of the support frame but also a small amount could come from the construction of the shunt regulator circuit discussed previously. For the shunt regulator circuit, each individual electrical element was connected by lead soldering. Lead can negatively impact the developing nervous system in adolescents and reduce the memory and learning capabilities of individuals.24 _{This is not a significant risk, however, since the electrical components will be}

covered to avoid electrical injury. Sub-system integration, however, would not result in any significant environmental impacts since we would primarily use bolts to integrate each sub-system. Similarly, there would be very little negative environmental and human impacts from the operation stage since our bicycle-powered charger is designed to be operated by a person

exercising. The only residuals in that stage would be the respiration and perspiration from the individual and some amount of heat due to the inevitable inefficiency in mechanical to electrical energy conversion. We predict that an average user would operate the system for approximately 144 hours per year – three hours per week. More testing would show the full effect of our system on the environmental impacts associated with charging small electronic devices. With

modifications to our generator, we could reduce the potential amount of heat produced. The largest impacts to humans at that stage would be the dual benefits of improving health due to exercise and the charging voltage produced via our system.

The afterlife, as the final stage in the life cycle of a commercially produced version of our bicycle-powered charger, would have very little environmental and human impacts. This is due to the design of our bicycle-powered charger. By limiting the variety of materials used and integrating the subsystems using bolts, we enabled our system to be easily separated into its sub-systems thereby allowing easy reuse of sub-sub-systems or recycling of materials. Aluminum is very recyclable.25 Steel, also, is very recyclable.26 By reusing and/or recycling the subsystems and materials from used bicycle-powered chargers, we can essentially eliminate the negative environmental and human impacts from the first two stages: raw material extraction and production and sub-system construction. A life cycle diagram of a commercially produced version of our bicycle-powered charger is shown in Figure 12.

22 _{Sulfur Dioxide (SO2). (2016, February 22). Retrieved from https://www3.epa.gov/airtrends/aqtrnd95/so2.html} 23 _Ibid.

24 _{Striebig, B. A., Ogundipe, A. A., and Papadakis, M. (2016). Engineering applications in sustainable design and}

development (First ed.). Boston, MA: Cengage Learning.

25 _{Aluminum - The Environmental Literacy Council. (2015). Retrieved from} http://enviroliteracy.org/special-features/its-element-ary/aluminum/

26 _{Fact sheet: Steel and raw materials. (2014, October). Retrieved from}

https://www.worldsteel.org/publications/fact-sheets/content/00/text_files/file0/document/fact_raw materials_2014.pdf

24

Figure 12: Life cycle for a commercially produced version of the bicycle-powered

charger system. At each stage, energy input is required and some form of residuals (by-products) are released.

CONCLUSIONS

With successful design and completion of this bicycle-powered charger system, the possibility for a healthier population with a lower environmental footprint becomes greater. Improved health will come from more physical exercise due to increased cycling. It has been found that cycling has positive psychological effects and boosts productivity in the workplace.27 A lower environmental footprint will come directly from increased bicycle usage. This system will encourage an increased usage of bicycles because, as users become more familiar with the system and realize its potential, they will enjoy operating it more. This may lead individuals to opt for bicycle transportation rather than vehicular transportation for short-distances, which is made possible by the easy transition from stationary use to road use.

27_{Heesch, Kristiann C., Billie Giles-Corti, and Gavin Turrell. "Cycling for Transport and Recreation: Associations} with Socio-economic Position, Environmental Perceptions, and Psychological Disposition." Preventive Medicine: 29-35. Print. Raw Material Extraction and Production • Aluminum • Steel Sub-system Construction • Support Frame • Shaft System • Shunt Regulator Sub-system Integration • Completed Bicycle-Powered Charger

Operation • Human Exercise

• Electrical Device Charging

Afterlife • Recycle

I Appendix 1: FMEA

Figure A1.1: Failure Mode and Effects Analysis of the bicycle-powered charger system where potential failure stems from five areas: the generator, the support frame, the shaft system, the electrical components collecting and directing the charge outputted by the generator, and the lead-acid battery. These were then ranked based on the severity of a failure if it were to occur, the probability of a

failure occurring and the detectability of a failure or imminent failure to the users. Descriptions of the rankings of the severity, probability and detectability are shown in Tables A1.1-A1.3.

II

Table A1.1: Ranking of the severity to both the users and the system if a failure were to occur.

Effect SEVERITY of Effect Ranking

Hazardous without warning

Very high severity ranking when a potential failure mode

affects safe system operation without warning 10

Hazardous with warning

Very high severity ranking when a potential failure mode

affects safe system operation with warning 9

Very High System inoperable with destructive failure without

compromising safety 8

High System inoperable with equipment damage ₇

Moderate System inoperable with minor damage ₆

Low System inoperable without damage ₅

Very Low System operable with significant degradation of performance ₄

Minor System operable with some degradation of performance ₃

Very Minor System operable with minimal interference ₂

None No effect ₁

Table A1.2: The ranking of various probabilities of failures of a system

PROBABILITY of Failure Failure Prob Ranking

Very High: Failure is almost inevitable >1 in 2 ₁₀

1 in 3 ₉

High: Repeated failures 1 in 8 8

1 in 20 7

Moderate: Occasional failures 1 in 80 6

1 in 400 5

1 in 2,000 4

Low: Relatively few failures 1 in 15,000 3

1 in 150,000 2

III

Table A1.3: Ranking of the likelihood of the users detecting failure or imminent failure of the system.

Detection Likelihood of DETECTION by Design Control Ranking

Absolute Uncertainty

Design control cannot detect potential cause/mechanism and

subsequent failure mode 10

Very Remote Very remote chance the design control will detect potential

cause/mechanism and subsequent failure mode

9

Remote Remote chance the design control will detect potential

cause/mechanism and subsequent failure mode

8

Very Low Very low chance the design control will detect potential

cause/mechanism and subsequent failure mode

7

Low Low chance the design control will detect potential

cause/mechanism and subsequent failure mode 6

Moderate Moderate chance the design control will detect potential

cause/mechanism and subsequent failure mode 5

Moderately High Moderately High chance the design control will detect

potential cause/mechanism and subsequent failure mode 4

High High chance the design control will detect potential

cause/mechanism and subsequent failure mode 3

Very High Very high chance the design control will detect potential

cause/mechanism and subsequent failure mode 2

Almost Certain Design control will detect potential cause/mechanism and

IV Appendix 2: SolidWorks Drawings of the Support Frame

Figure A2.1: Back assembly of the complete bicycle charging system assembly consisting of a back floor support and two back uprights to be fitted and bolted into covers welded onto the front uprights. The covers will allow the frame to fold up for greater

V

Figure A2.2: One of two top assemblies attached to the final frame design. Both top assemblies have adjustment abilities so that the user can set their bicycle in the lateral plane anywhere they desire so that the system fits into the bicycle however is necessary for operation. Both top assemblies are constructed from steel rather than aluminum for strength purposes. These steel top assemblies are

then connected the remainder of the aluminum frame by way of a hollow steel slotted piece designed to drop into the hollow part of the top of the front uprights and bolted into place. This top assembly differs very slightly from the other top assembly in that the steel

wheel support is designed to offer more support than the other. The purpose of this variation is so the user can place the bicycle into the frame and steady it while making adjustments using this top assembly and the other.

VI

Figure A2.3: The other top assembly designed exactly like the other with the small wheel support variation and intended primarily adjustment purposes and support of the bicycle after the final placement has been made.

VII Appendix 3: Solid Works Drawing of the Shaft System.

VIII

IX

X

Figure A3.4: The roller goes on the shaft and rests against the bicycle tire. It uses friction to transfer the rotational energy from the rear tire to the shaft and ultimately the generator.

XI

XII Appendix 4: Cost Analysis Table

Table A4.1: Table showing costs to the design team for design, construction and integration of first prototype of the bicycle-powered charger system.

Item Cost Estimate General Information

Generator $0 3 phase permanent magnet motorcycle magneto stator

Permanent magnets $40-80 Rotor (estimate, will be constructed in the shop)

Battery Pack _{$30 - $80} 12V NiMH/NiCd; Rechargeable;

Range from 1600mAh to 5000mAh

Power inverter $10 Buck-Boost system

Bridge rectifier $8 Convert AC to DC

Support Frame $3-$6 Aluminum Square Tube, cost per foot

Gear $13 Steel Plate, cost per square foot

Shaft $6 6061 Aluminum, cost per foot

Bicycle Computer $11 Odometer included

XIII Appendix 5: Test Results

Figure A6.1 shows the peak power consumption for various small household electronic devices. Each member of the team participated in measuring their personal devices in order to gather this data.

Figure A5.1: Electronic device peak power consumption. Values were self-obtained from personal electronics. 44 40 35 25 ₂₄ 8 ₇ 5 5 3 3 _{2 2} 0 5 10 15 20 25 30 35 40 45 50 P ea k P ow er (W )

XIV Appendix 6: Transistor Data Sheets