Alternative Bike Power Sources by Bertie Johnstone

Blue Sky Project – Bertie Johnstone

Centre no. – 62415

2 Product Design – Alternative Bike Power Sources

Centre N : 62415 o.

Candidate N : 4201 1

Candidate No. – 4201

Bertie Johnstone Radley College

Design Unit 1.2 : Product Design

Blue Sky Project – Bertie Johnstone

Centre no. – 62415

Candidate No. – 4201

2 Product Design – Alternative Bike Power Sources

Design Unit 1.2 : Product Design

Blue Sky Project – Bertie Johnstone

Centre no. – 62415

Candidate No. – 4201

2 Product Design – Alternative Bike Power Sources

Chosen Idea: I have chosen to design a component that a bike can be built around or added to a standard bike that will generate charge to power personal portable devices used when cycling. These are low power devices which require only a small amount of charge so there will also be an incorporated battery to store excess power generated. I believe that there is no large market for these sorts of devices; however if it were to be efficient enough it would be in demand from many cyclists. It would boast the compatibility and the efficiency like no other similar product.

Design Brief: This system will be designed to generate power from a bike. It will only be generating small amounts of power to charge low power personal devices such as phone, GPS systems, LED lights and MP3 players. It will have a battery to store any excess power that might be generated and will have a two way USB connection to enable the product to power as wider range of devices as possible and enable it to be charged up from alternate power sources such as 12v car charger.

Target Market: 3.

The product can be so versatile that it has a very wide market. From casual cyclists, commuters, professionals, people touring; any one of their devices that they may be using while cycling will be able to be charged. This product is aimed at both genders so it either has to be neutral in looks to cater for both differently, mainly with the colour schemes used. IU myself when cycling wish I had some sort of device that would charge my phone as using the GPS always drains the battery.

Bottom Bracket (BB)

Design Unit 1.2 : Product Design

Design Criteria:

Form 1.1. Modern and simple design for any casings 1.2. An entire component that can have standard components attached to it i.e.: A frame 1.3. A replaceable component for a wide range of bikes i.e.: Bottom Bracket 1.4. An additional external accessory to fit a wide range of bikes 1.5. Have a unique selling point for the product Function 2.1. Generate power to mobile devices such as phones or GPS systems used while cycling 2.2. Only be designed to power a single device at one time 2.3. Have ways of storing excess power that might be generated User Requirements 3.1. Be compatible with different sizes of bikes 3.2. Have a USB connection which will work with a wide range of devices 3.3. Standard AC pin plug allowing the battery to be boosted from a charger (computer/car 12v/wall socket) 3.4. Some sort of indicator as to how much power is being generated/used/stored 3.5. Not restrict user movement/ability 3.6. Simple to use or apply to bike for a wide range of users 3.7. Easy to clean and maintain with few external costs 3.8. As few wires as possible on the bike Materials 4.1. Light weight modern composite materials or alloys 4.2. Similar to that of bikes (Aluminium/Caron fibre) 4.3. Range of colour schemes/casings aimed at riders of both genders 4.4. Materials compatible on a large scale production Performance Requirements 5.1. Generate enough power to charge portable devices associated with cycling 5.2. Not to decrease the aero dynamic efficiency of the bike 5.3. Must work at a wide range of temperatures in different conditions 5.4. Durable/shock proof to impact and fatigue against all sorts of riding 5.5. Water proof seals for adverse weather conditions/mud Sustainability 6.1. Some of the materials will be recyclable where possible 6.2. Mineral hydraulic brake oil is used 6.3. The component is generating power when it is used so it is replacing energy that was used to create it Production Costs 7.1. Easily made in large batches as there is not a huge market for this sort of product 7.2. CAM (inc. CAD, CFD & CNC machines) for manufacture, testing and quality assurance

Blue Sky Project – Bertie Johnstone

Initial Concept Ideas:

Centre no. – 62415

Candidate No. – 4201

Design Unit 1.2 : Product Design

2 Product Design – Alternative Bike Power Sources

Blue Sky Project – Bertie Johnstone

Inspiration and Design limits:

Centre no. – 62415

Candidate No. – 4201

2 Product Design – Alternative Bike Power Sources

There are limitations to all of the designs as they have to be compatible in some way with the relevant bike components so they can be widely used with current standard bikes

Road bike front fork

Bottom Bracket (BB) Rear shock

Single sided front fork Standard front fork 5

Design Unit 1.2 : Product Design

Blue Sky Project – Bertie Johnstone

Initial Idea 1: Suspension piston with hydraulic turbine

Centre no. – 62415

Candidate No. – 4201

2 Product Design – Alternative Bike Power Sources

The hook like feature on the top is to secure the piston to the top of the fork so when it expands the piston does also. When attached the piston must be put on at an angle and then swivelled round into place

Design Unit 1.2 : Product Design

The inspiration for this idea was to try and harness the huge amount of energy that is absorbed by the suspension on a mountain bike. This piston like design works in a similar way to any air suspension. However it works best with water or mineral oil (which is better as it is self lubricating and is also used in Hydraulic disc brakes) which can turn a mini turbine to generate electricity as it passes back and forth through the turbine. This can also be adapted to work on the rear shock of any full suspension mountain bike. 4.3 The lower casing can be a range of colours

1.5 + 1.2 The top of the cylinder is an ellipse as it has to protrude further in order to meet the suspension fork as can be seen in the picture (left). Lower down where the second strap would be attached the forks are wider so the piston must be slightly thinner (see below).

Tubes for oil

4.1 + 2, 6.1 This shows the large range of colours that anodised aluminium is available in which all the main exterior components would be constructed from. It is very light, widely available and easy to cast.

1.4 This picture and drawing show how the piston might be attached to the rear of the bike fork with 3 separate rubberised strips of Velcro in different vital places and a hook over the top of the fork so when it expands it is sure to take the piston with it even if the rubber Velcro fails to grip.

Hook for top of fork

5.4 Guides for Power cable

Velcro/rubber straps

Protective rubber housing

Below: a turbine and generator

Turbine housing

Tubes for oil

6.2 Mineral oil will be used as it will lubricate the moving parts, it is less viscous than other oils, is widely available as is also used in brakes and is less damaging to the environment.

2.1 This cross section shows the piston is compressed and the oil is forced out of the bottom, through a micro water turbine (above) in the small box on the side and into the top chamber. This happens back and forth as the suspension moves generating a DC current. 6

Cross section of a rear shock with 2 chambers

Design Criteria

Form 1.1. Modern simplistic design – yes, sleek design 1.2. Standard component size – attaches to a standard front fork 1.3. Replacing a component 1.4. Accessory which fits with any bike – fits to any suspension bike 1.5. Unique new feature – nothing like this on the market Function 2.1. Power generation – from piston 2.2. One device – only 1 USB 2.3. Power storage – Li-Ion battery User Requirements 3.1. Size compatible – only for adult bikes 3.2. USB connection - yes 3.3. Booster charger - yes 3.4. Power indicator - yes 3.5. User movement – not restricted 3.6. Wide range of users – used by any MTB rider 3.7. Clean and maintain – fully sealed, only visual 3.8. Few wires – yes, only 2 Materials 4.1. Lightweight – made from low density materials 4.2. Aluminium/Carbon fibre – Ali cylinder 4.3. Colour – any anodised ali colour 4.4. Production Scale Performance Requirements 5.1. Sufficient generation 5.2. Aerodynamic efficiency – behind fork arm 5.3. Temperature range 5.4. Durability – rubberised in places for protection 5.5. Waterproof – fully sealed Sustainability 6.1. Materials – Aluminium = recyclable 6.2. Mineral oil – yes, see brake fluid Production Costs 7.1. Large batches 7.2. CAM

This is a plan view of the piston connected to the fork of a bike; notice the hook over the top of the fork. [The black line is where an additional cable tie or strip of Velcro could be used to secure the piston] 5.2 + 3.5 behind the original fork out of the way.

Blue Sky Project – Bertie Johnstone

Centre no. – 62415

Initial Idea 2: Top tube air tunnel

Candidate No. – 4201

Design Unit 1.2 : Product Design

2 Product Design – Alternative Bike Power Sources

Inspiration: This design is essentially inspired around a wind tunnel with a small turbine in middle [1.1, 1.5 & 2.1] which air is being funnelled through when travelling at high speeds. This design is also limited to road bikes as it is the only time the cyclist will be moving fast enough to generate an amount of useful energy. Secondly due to the design of MTB frames it will only work with road bikes which have straight top tubes. With a large air intake at the front to funnel as much air through a smaller diameter turbine to increase pressure and a wide exhaust like on a car pull the air through at the other end; this works by creating a higher pressure in the turbine than the atmosphere and the air is ‘sucked’ through the remainder of the tunnel best known as an exhaust ‘pulse’. Mini air turbine

Below: a turbine and generator

Design Criteria Problems with design: 1.4 Both the intake for the air and the exhaust with 1. Form 1.1. Modern simplistic design – looks similar to this design have to go through other components, these are the steering a standard frame tube and the saddle post which if this design was used would have to be 1.2. Standard component size – yes, other redesigned to have a hole through the middle and have enough structural components fit to it strength even with a large hole in the middle. To solve this flaw in the design 1.3. Replacing a component – replaces the the, aerodynamic air intakes would have to come out of the frame at the frame front similar to any sports car. At the rear, larger exhaust exit holes would 1.4. Accessory which fits with any bike have to wrap around the saddle post fixing which are out of the way of the 1.5. Unique new feature – no bike frame uses user leg movements and without having to direct the air around too many this corners which will reduce the efficiency of the design. 2. Function

Air flow 3.

Air funnel/tunnel

Wide exhaust Mini hand held air turbine

Wide air intake

Air is funnelled through as shown in the picture, as shown above the technology already exists to have very small air powered turbines as this is a personal one aimed at charging electronic devices such as mobile phones. 2.1& 2.2 The turbine works in a similar way to the turbine powered by liquid, the liquid in this design is replaced by higher pressure air. Although this turbine would also be water tight so it can be washed through if it becomes filled with dirt. NB: The wires (coloured green) are not actually visible from the outside of the frame as they are all wired to the necessary places internally.

Lithium-ion battery built into the frame of the bike Wires to turbine and handle bars – inside the

Bottom bracket

Amount of battery visible LED charge indicator 3.4

On/Off button for LED indicator

12v boost charger socket 3.3

Car air intake

Materials: 6.1 The frame could either be double butted welded aluminium or carbon fibre which would be easy to produce in batches once all the necessary jigs and moulds have been constructed.

A carbon fibre bike frame

The battery 2.3 (see left) for this design is built into the frame as the air tunnel is also built in so there is no point in having an external battery. It is the same size Li-ion battery, however only a small bit is visible to see how much charge there is and for the 12v booster socket. 3.8

Without diffuser

With diffuser A section of carbon fibre

2.1. Power generation – wind tunnel & turbine 2.2. One device – only 1 USB 2.3. Power storage - internal battery User Requirements 3.1. Size compatible – can be made in all standard sizes 3.2. USB connection – up on handle bars 3.3. Booster charger – yes, see battery 3.4. Power indicator - yes, see battery 3.5. User movement – not affected 3.6. Wide range of users any road bike riders 3.7. Clean and maintain - all water proof 3.8. Few wires – only 1 external wire Materials 4.1. Lightweight – Carbon fibre 4.2. Aluminium/Carbon fibre – whichever is easier to construct with wind tunnel 4.3. Colour – different frame colours 4.4. Production Scale Performance Requirements 5.1. Sufficient generation 5.2. Aerodynamic efficiency – same aero dynamics as normal frame 5.3. Temperature range 5.4. Durability 5.5. Waterproof – all sealed Sustainability 6.1. Materials – Carbon fibre = lighter than other materials so less energy needed 6.2. Hydraulic fluid Production Costs 7.1. Large batches 7.2. CAM

Air flow: With this design it is particularly important to make sure that any air flowing into the wind tunnel is laminar flow, this is direct flow ensuring that as little energy is lost as it passes through. Otherwise known as streamline flow, occurs when a fluid flows in parallel layers, with no disruption between the layers. There are no cross currents perpendicular to the direction of flow, nor eddies or swirls of fluids. In laminar flow the motion of the particles of fluid is very orderly with all particles moving in straight lines parallel to the pipe walls. In fluid dynamics, laminar flow is a flow regime characterized by high momentum diffusion and low momentum convection. When a fluid is flowing through a closed channel such as a pipe or between two flat plates, either two types of flow may occur depending on the velocity of the fluid: laminar flow or turbulent flow. Laminar flow is the opposite of turbulent flow which occurs at higher velocities where eddies or small packets of fluid particles form leading to lateral mixing which is less efficient. (See diagram) The flow of the air through a tunnel this shape can be tested using CFD [7.2].

Blue Sky Project – Bertie Johnstone

Centre no. – 62415

Initial Idea 3: Bottom Bracket dynamo

Candidate No. – 4201

Design Unit 1.2 : Product Design

2 Product Design – Alternative Bike Power Sources

The original idea was to try and harness some of the wasted energy from the momentum of the pedals; the energy is harnessed within the Bottom Bracket (BB) 1.2 & 1.3 [NB: non-cartridge bottom bracket only]. This idea uses the same technology as a dynamo but I have redesigned it to be more compact to fit into a standard size bottom bracket for a bike 3.1, dynamos have the potential to be much more efficient, currently standard dynamos are only ~66% efficient. If one wanted to generate even more energy, this same more efficient dynamo could be used in both the front and rear wheels of any bike (MTB/Road) 3.6 as there is more momentum and there is constant movement which why they have traditionally been placed there – this is just an alternative. This dynamo is different to others as the commutator is within the two magnets to make it more compact and to generate as much energy as there is space to have the magnets around the outside of the bottom bracket. To do this the commutator must be made of carbon fibre as it does not have a magnetic field but it will conduct electricity to interfere as little as possible with the dynamo. A cross section of the bottom bracket component:

Power cable to external battery 3.8 Rare-earth magnets in BB cavity

Magnets around BB Inside here are the sealed ceramic bearings

Above: What the bottom bracket would look like Rare-earth magnets

Pedal crank shaft going through the BB

magnets

Rare-earth magnets are strong permanent magnets made from alloys of rare earth elements. Rare-earth magnets are the strongest type of permanent magnets made, substantially stronger than ferrite or alnico magnets. The magnetic field typically produced by rare-earth magnets can be in excess of 1.4 teslas, whereas ferrite or ceramic magnets typically exhibit fields of 0.5 to 1 tesla. These magnets would be used to gain the maximum amount of energy when wrapped around a bottom bracket the central cavity as very thin magnets so the bottom bracket still fits into a standard frame. 2.1

Crank arm

The screw thread to fix in BB

Crank shaft 5.

A traditional hub dynamo

Cavity on normal BB Below: The hybrid ceramic ball bearings either side of the bottom bracket. On the left is the sealed replaceable bearing, and on the right is the ceramic bearings opened up.

Bottom bracket in place on a bike

Below: What the bottom bracket would look like

Split ring commutator

Coils of wire inside crank shaft

Materials: Bottom Brackets are a very light component and mostly made from aluminium, some of the less expensive ones which tend to be sealed cartridge bottom brackets tend to be stainless steel. The aluminium for high quality ones then to be cast anodised aluminium. 4.1, 4.2 + 6.1

Dynamo: [1.5 & 2.1] A dynamo is an electrical generator which produces immediate current. Left is a diagram of how a dynamo works, the coils which would be part of the crank shaft rotate inside the magnetic field, this generates a current which is carried away from the dynamo using a commutator to separate the positive and negative voltage. However if it was used in wheels the coils and magnet would have to switch movement. By using a fixed through axle which stays stationary and the magnets placed on the inside of a dynamo wheel hub which rotates around the axle.

Design Criteria

Form 1.1. Modern simplistic design - NA 1.2. Standard component size - yes 1.3. Replacing a component – Bottom bracket 1.4. Accessory which fits with any bike – any with standard BB 1.5. Unique new feature – internal dynamo Function 2.1. Power generation - dynamo 2.2. One device – only 1 USB 2.3. Power storage – External battery User Requirements 3.1. Size compatible – can be made in all standard sizes 3.2. USB connection – up on handle bars 3.3. Booster charger – yes, see battery 3.4. Power indicator - yes, see battery 3.5. User movement – not affected 3.6. Wide range of users – MTB/Road 3.7. Clean and maintain – no need 3.8. Few wires only 2 external wires Materials 4.1. Lightweight - aluminium 4.2. Aluminium/Carbon fibre 4.3. Colour - NA 4.4. Production Scale Performance Requirements 5.1. Sufficient generation 5.2. Aerodynamic efficiency - no change from standard bike 5.3. Temperature range 5.4. Durability 5.5. Waterproof – standard seals Sustainability 6.1. Materials – easily cast & recycled 6.2. Hydraulic fluid Production Costs 7.1. Large batches 7.2. CAM

Blue Sky Project – Bertie Johnstone

Initial Idea 1, 2 & 3 Cont. (Battery & Computer)

Centre no. – 62415

Candidate No. – 4201

2 Product Design – Alternative Bike Power Sources

Design Unit 1.2 : Product Design

Processes – Extruding/CNC Metal Lathe

Aluminium can be constructed through extrusion; the aluminium is pushed or drawn through a die which is a reversed cross section of the desired shape. Extrusion has very low tolerances, it creates a very good finish surface and very complex shapes can be formed. Once extruded the main cylinder could be turned on a CNC lathe to add in the final details. Especially where the straps wrap around the piston to fix it to the fork; this would be a quick way to finish off the cylinder as once the CAD has been constructed it can easily be adjusted many times over.

This monitor and battery overlap for more than one design

Ideas 1, 2 & 3 would use these components as part of the design which are accessories that are bought with the product

2.3, 5.4 & 3.2 This is an end view of the battery with a protective rubber casing around it and the Velcro straps to attach it to the frame. On the end there is the option of standard USB or mini USB for connectivity. There is a pin plug for charging from the power source. This battery that can be easily mounted under the top tube on any bike would be used alongside initial idea 1 & 3.

This computer is similar to any bicycle trip computer, however it displays the information of how much energy you are generating at the time (GE), the percentage of the battery that is charged in your device (DE) and how full the battery storing unused power is. This Computer that can be easily mounted on the handle bars for any bike would be used alongside initial idea 1, 2 & 3. Time = TI Generation = GE

Button

Indicator 2.1, 3.4 A lithium ion battery attached to the underside of the top tube by the Velcro straps with a power indicator at the touch of a button.

Device = DE (Mode selected) Battery = BA The screen would be a super-AMOLED screen which gives the best colour display even in direct sunlight. The modes can be selected by simply touching the desired one in the touch screen area at the bottom of the display.

Rubberised Velcro

Connection grip to attach to handlebars

Rubber casing

Connectivity

A similar design with multifunctional USB connection but no specific way of power generation.

Blue Sky Project – Bertie Johnstone

Centre no. – 62415

Evaluation of initial ideas:

2 Product Design – Alternative Bike Power Sources

Criteria points met: 27/30

Idea 1:

Idea 2:

Analysis against criteria: •

•

The design is not modern but has scope to be changed as it was first designed to look the same as a standard MTB shock. It is the only design which needs to be well protected as it is than external accessory. Design itself is not aerodynamic but is fixed in the slipstream of the fork.

•

• •

Disadvantages of idea: • •

•

The cylinder can be modified from being a single direction piston to a double action cylinder (DAC). It is the most portable because it can easily be taken on or off with the straps around the fork. Can actually be used in two different places on a full suspension bike. The energy that is absorbed by suspension on a MTB is waste energy so trying to turn it into electricity is not going to make cycling any harder.

It is the bulkiest of all the designs. The turbine is inefficient on this design as it has to change directions very time the suspension changes direction. Is higher maintenance than the other designs as the hydraulic fluid will need topping up/renewing dependant on amount of use. The amount of cables/pipes are venerable to being caught up in vegetation when riding single track.

Opinion:

Without being able to test the product I believe that this design has the most scope and will generate the most amount of energy and will have relatively cheap production costs as well as being more user friendly.

Idea 3:

Design Unit 1.2 : Product Design

Criteria points met: 25/30

Criteria points met: 25/30 Analysis against criteria: •

Advantages of idea: •

Candidate No. – 4201

Only idea that will reduce the aero dynamic efficiency of the entire bike. The battery does have a booster socket but it is not portable in the same way the external battery can be unstrapped and carried where ever the user likes. Will reduce the users ability while cycling.

•

Advantages of idea: • • • •

Nothing of this sort has been used before on a bike. The mini turbines used can be very efficient when air is funnelled through in this way. The battery is built into the frame and there are fewer wires than the other ideas. Very little maintenance needed, only to be washed through once in a while

Disadvantages of idea: • •

• •

A decent speed is needed to make the most of the air tunnel. The user has to buy whole frame which is n expensive component – especially with the extra weight added to it. With this particular design other main components have to be customised to allow it to work. Aerodynamic efficiency of the bike is reduced in turn for generating electricity.

Opinion:

Theoretically the idea would work but it is unlikely that most users would be going fast enough to make use of the generator as there would only be a very small amount of air pressure to move the turbine. It would also be very expensive as a product.

Analysis against criteria: • • •

There may only be two wires on the bile when it is in use but they do run the whole length of the frame. There is little modern design to this idea as it is designed to look and be as similar to a standard component as possible in order to be compatible. Will reduce the users ability while cycling.

Advantages of idea: • • • • • •

Cheap component. Easily replaceable. Light weight. Universal fit to all bikes. Uses reliable dynamo technology. Current produced can either be ac or dc.

Disadvantages of idea: • • •

•

Too much resistance will dramatically affect pedal power. Might not generate sufficient power. Also involves new pedal crank shafts which are also fixed to crank arms – other components are needed in conjunction. User will not keep a consistent pace throughout a ride; most of the time will be going too slow.

Opinion: It is good place to experiment with power generation as the cadence is

high but if there was too much resistance from the dynamo it would directly affect the speed of the bike. However it is an easily replaceable and cheap component to fit to most bikes.

Conclusion: Having seen that idea 2 would be a very expensive component to buy, another problem with the design amongst other flaws is that if any internal component were to fail there would be no accessibility in order to fix it. However the turbine technology already exists and still has the potential to become much more efficient when placed in a wind tunnel with increased pressure. Idea 3 is a practical solution as it is so easy to fit to any bike as well as being an affordable solution being such a small and simple component. However it is likely that it would not generate sufficient energy without increasing the resistance of the dynamo which would then have clear affects on the amount of energy needed to cycle at the same place as usual. Not only does idea 1 adhere to the most of the design criteria it is the most practical solution to the problem of generating electricity while cycling as it is portable, user friendly to take on and off, simple technology which can maintained by most bike mechanics which means it is the appropriate technology. Having a portable battery is also useful as it can be taken off the bike if it is left in public and used to charge devices when on foot. It is also the only design reusing wasted energy to make useful energy. Therefore I am going to develop idea 1. 10

Blue Sky Project – Bertie Johnstone

Centre no. – 62415

Candidate No. – 4201

2 Product Design – Alternative Bike Power Sources

Development:

Design Unit 1.2 : Product Design

Where a strap would be fixed around the top of the fork so the piston

Considering that idea 1 is over developed as an initial idea, the main form of the developing design will relate very contracts when the suspension does, instead of fixing it by the circular disk closely to the original initial idea. I have researched and found that the basic shape as a standard circular cylinder is best; especially due to efficiency and Top securing arm production costs. Research has also gone into the different types of cylindrical piston can be used to generate the power needed. The Housing over the original design incorporated a single action cylinder which would function very similarly to a standard bike suspension top of the fork fork. However the other option is a Double Acting Cylinder (DAC). The way in which the unit would be attached to the bike has been reviewed and I have implemented a neater and more Both arm and top user friendly strap system. of piston made of a The final product can still be produced in several different sizes depending on different amounts of suspension travel, single piece of cast commonly 120mm, 140mm, 150mm travel. aluminium Cylinder Shape: Triangular pros: • • •

• •

Not ergonomic in hand Not as aerodynamic as the generator sticks out

Most ergonomic to hold in hand Is a smaller more portable accessory

•

The cylinder is wider than the forks causing problems o Aerodynamics o Colliding with wheel Hard to fix to the circular fork

be developed into, the best shape to remains a circular cylinder as it is widely available for spare parts; it is not new technology and has both ergonomic and practical properties. It can be easily fixed to the bike forks using concave rubber spacer. I think that it is the most conventional shape for bike parts so would Main chamber blend in more on a bike and it might appeal more to a potential buyer.

Triangular Cylinder

Rubber spacer Outer cylinder protection Strap velcro/cable tie 11

Bike fork

Ways of attaching the unit to forks of a bike has been looked in development to try and find the best solution. To start with the straps will be obstructed from view within an outer casing on the cylinder which will make the design more aesthetically pleasing and ensure that the straps can’t slip on the unit. For the most user friendly fixing, Velcro straps with rubber on the inside can be used, in this way the unit will be very easy to attach to the bike and take off. As an alternative, cable ties could be used, this would be more permanent fixing but would provide a better grip on the bike if the user was doing some very aggressive riding and wanted the assurance the unit would not fall off.

NB: The top securing arm seen on the initial idea but not on the final CAD or model would still be included on the final product but it has not been redesigned as it was originally in its strongest form and is still needed to ensure the piston expands with the suspension travel. Depending which way the securing arm is attached determines which side of the bike fork the unit must be fixed onto.

Generator

Conclusion: Although I have researched into other shapes that the piston could

Straps/Fixing:

Strap emerging from gap between two cylinders

Seal

Elliptical cons:

Triangular cons:

Seal

Outer cylinder protection

The flat edge is easy to fix to the fork The generator is easy to attach to the fork The triangular shape is weaker

Elliptical pros:

Elliptical Cylinder

Piston arm

This component is a concave rubber spacer to ensure there is a solid and strong fix between the cylinder of the fork and the cylinder of the piston. This gives extra grip, adjustment of where it can be placed and no roll between the two opposing cylinders. Bottom view of model on a bike, showing how the concave rubber spacer ensures a good fit to the bike.

Strap velcro/cable tie Strap emerging from tunnel Generator

Rubber spacer

Where strap travels between the two cylinders to be obstructed from view

Rubber spacer

Blue Sky Project – Bertie Johnstone

Centre no. – 62415

Type of Cylinder: There are two types of cylinder that could be used in the piston; originally a single acting cylinder was incorporated into the design. However this proved to be inefficient as the hydraulic fluid was simply travelling back and forth from one chamber to another via the same turbine, this meant that the turbine had to stop and change direction with the slightest change in the direction of movement – this wastes energy. The other option was to use a double acting cylinder (DAC). This type of piston has two separate chambers where the hydraulic fluid is continually flowing in one direction through the turbine. As one chamber empties the other is filled up by the lower pressure drawing it in.

Piston arm

Input pipes of hydraulic fluid into the generator Support piece for the thin piston arm to keep it going in a reciprocating manner

Changing the type of cylinder that was going to be used was the largest aspect of the development stages, it also called for a redesign of the piston and generator. The piston arm had to be made a lot thinner which put it at the risk of snapping if too much force was applied in a different direction. The main piston chamber had to be expanded to accommodate two chambers inside what was originally a single one. The generator still only has one pipe in and one pipe out but the turbine inside it only works in one direction. There are double as many pipes connecting to the piston; an in and out for each chamber and on both of the pipes returning the fluid to the chamber there must be valves which do not allow the fluid back down the pipe when the piston is compressed. This could be a problem as there is a higher chance of one of them getting snagged by the undergrowth when riding off road, also one of the aims in the design criteria was too have as few wires/pipes as possible for that reason – as well as aesthetic qualities and generally looking tidy.

Mini generator with single direction turbine inside

Pipe returning hydraulic fluid back into the piston chambers Valve on the input pipe into the chamber to stop any fluid flowing back when not under pressure

Design Unit 1.2 : Product Design

2 Product Design – Alternative Bike Power Sources

Development continued:

Top platform which the top securing arm is joint to

Candidate No. – 4201

Power out cable going to the battery

Piston when compressed

Input pipes of hydraulic fluid into the generator Main cylinder of the piston

Extruded aluminium with nylon inside keeps the thinner piston arm reciprocating in a linear fashion Top of extruded aluminium cylinder

These auxiliary components are still part of the main product; they have not been re designed during development as there is little need as they are of little importance to the actual suspension piston unit. The monitor remains wireless from the battery with all the data to save having more unnecessary wires on the bike. The battery itself has a en extruded aluminium case which has a rubber case on top of that to make it extra durable and to grip to the underside of the top tube and not move about too much when riding over rough surfaces. Velcro straps

Power output

Wider section of pipe is where valve is situated to stop any fluid travelling back down in the wrong direction when under pressure Standard out pipe leading to the turbine

Indicator and indicator button

Power input

Rubber seals for the piston similar to the ones for suspension bushings

Rubber case

Top of extruded aluminium cylinder

Standard USB Micro USB

Aluminium case Handle bar connection

AC pin plug

Blue Sky Project – Bertie Johnstone

Model:

Centre no. – 62415

2 Product Design – Alternative Bike Power Sources

Evaluation of Model: Positive points: • • • • • • •

Candidate No. – 4201

Top disc of piston arm onto which the securing arm is attached

The model is full scale1:1 Accurately measured against a standard bike Fits well to the bike All wires/pipes are present for a working model The pipes, main cylinder and piston arm are made from the aluminium/rubber that would be used in the final unit The design is robust but at the same time is aesthetically pleasing There is still scope to improve the more subtle aesthetic aspects of the product

Piston arm

Main cylinder fixed behind and in the slipstream of the fork Rubber spacers ensure a good fit

Negative points: •

• • •

Generator The model does not include the top securing arm to hold it on to the top of the fork so the piston arm will casing – move up and down with the suspension Carbon fibre The model has been attached to the bike using double sided sticky tape instead of showing where the straps would actually be The upper rubber spacer (foam in model) needs to be re-considered as being thinner than the smaller one so the top if the piston arm is much nearer to the top of the suspension instead of leaving a large gap The model may even be a bit larger the final product may need to be as materials can be refined and purpose made to fit Seals/bushings on the

Problem - gap between the top disc and the top o the bike fork

Design Unit 1.2 : Product Design

Generator casing – Power cable going to battery

Main extruded aluminium cylinder

suspension – down to where the suspension can travel

Top of cylinder (turned nylon) with support piece for piston arm

Generator casing – Power cable going to battery

Rubber spacers joining the two cylinders together

Problems with particular model: •

•

• •

It does not sit parallel with the fork of the bike, this needs to be adjusted in later versions, this can be simply done by making the rubber spacers smaller allowing it to sit closer. The generator casing is probably much larger than it will need to be to fit the turbine in as they can already be made very small similar to the hand held wind generator (right). The large casing just emphasises where all the pipes will have to be going in and out. The pipes on the design are joint, but for the model it was better to keep them separate as it looks neater rather than trying to join the together which would have looked messy. Straps were not used as it was not possible to find two thin enough aluminium tubes to thread the straps through to keep the out of sight. 13

Hydraulic pipe out of the bottom of the piston from the second chamber

Materials used for model: Main cylinder & piston arm = Aluminium Rubber spacers and Generator casing = Modelling foam Ends of cylinder & top disc = Nylon Pipes/wires = Rubber tubing

Two hydraulic pipes going to the turbine from the piston chambers- in actual design the pipes merge

Mini generator Piston arm guide Top securing disc Piston arm Main cylinder 14

Carbon fibre box Carbon fibre Cast aluminium Extruded Aluminium Extruded Aluminium

Bertie Johnstone Bertie Johnstone

28/02/11 28/02/11

Radley College Design & Technology Department

GA without wires No. 1

Blue Sky Project – Bertie Johnstone

Materials & Processes:

Centre no. – 62415

Candidate No. – 4201

2 Product Design – Alternative Bike Power Sources

Design Unit 1.2 : Product Design

Aluminium Extrusion: Aluminium is the chosen material for the majority of the unit as it is a light weight material that can easily be extruded in to the desired shape needed for the cylinder and piston arm and it does not rust (does not react with water). It is also used commonly on bikes and can be finished in many aesthetically pleasing ways including anodising. Aluminium is a very abundant material so is not too expensive but it requires a lot of energy to extract from its ore form to pure aluminium. Process: Extrusion is a process used to create objects of a fixed cross-sectional profile. A material is drawn through a die of the desired cross-section. The main advantages of this process over other manufacturing processes are its ability to create very complex cross-sections, work materials that are brittle and it is quick and efficient process which is not too expensive to set up. It also forms finished parts with an excellent surface finish.

Extruded aluminium ladder

Extruded aluminium tube

Carbon Fibre moulding: Carbon fibre is the chosen material for the generator casing, is strong, resistant and light and many other bike components are made from it. It has been selected over plastic as it has a high strength-toweight ratio when in a very thin form. Although carbon fibre is expensive it would not alter the price too much as only a very small amount is being used and the manufacturing techniques are constantly improving reducing the costs and the manufacture time. Process: Smaller jobs can be produced in small moulds, but these take half a day to produce and are labour intensive, for a component that will be produced in batches there is another method; compression moulding. This is a two-piece (male and female) mould usually made out of fibre glass or aluminium that is bolted together with the fabric and resin between the two. The benefit is that, once it is bolted together, it is relatively clean and can be moved around or stored without a vacuum until after curing. However, the moulds require a lot of material to hold together through many uses under that pressure. Rubber pipe (extrusion):

Left: woven carbon fibre and vacuum Above: Carbon fibre box Rubber pipes

The same rubber coated pipes sold by Jagwire® that are used for hydraulic brake systems on bikes will be used as this will be less costly than setting up machines to make them when they can be bought. It also means it is easier for a user to replace them from most well stocked bike shops. The rubber used is synthetic so that the mineral oil used will not have any reactions with the rubber. This can also come in a range of colours. The rubber pipe is made by the process of extrusion in the same way the aluminium is shaped.

Extrusion process

Rubber coated hydraulic brake cable

Generator/turbine: A reaction water turbine is used which is moved by the movement of the hydraulic fluid. A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work. The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and impart rotational energy to the rotor. Water turbines are efficient to nearly 90%. The micro turbine used is an external component which will be fixed inside the carbon fibre case.

Working piston

Water turbines

Blue Sky Project – Bertie Johnstone

Centre no. – 62415

Evaluation against original criteria: 1.

Candidate No. – 4201

2 Product Design – Alternative Bike Power Sources Design Criteria:

Conclusion: This design for the final product adheres to all bar three of the original design criteria points (1.2, 1.3 & 3.8). Other designs may have met thee points but are likely to not have adhered to as many of the other points. This idea has been accurately built around bikes in order to be compatible in as many ways possible and theoretically work with most mountain bikes that can be purchased today. 16

Design Unit 1.2 : Product Design

Design Analysis:

Form 1.1. The outer casing of the cylinder is sleek and simple 1.2. No, refer to 1.4 1.3. No, refer to 1.4 1.4. Is an additional accessory that will fit a wide range of different size bikes 1.5. There are no electricity generating products currently using suspension as a power source Function 2.1. Will generate sufficient power to charge most portable devices 2.2. Small battery included only holds enough charge to power 1 device 2.3. Lithium ion battery bought with product to store excess power User Requirements 3.1. Will work with bikes with a range of fork travel 3.2. Has standard and micro USB out on the battery in order to work with the widest range of devices possible 3.3. AC pin plug is for charging from suspension cylinder or an alternative charger i.e. 12v or a wall socket 3.4. There is a handle bar mounted monitor and an indicator on the battery 3.5. Is fixed behind the front fork in the slip stream and out of the way of the user 3.6. Velcro/cable tie straps can be used and are easy for many people to apply 3.7. Major place of cleaning is by the seals and the hydraulic fluid can be checked/bled/topped up at any bike shop 3.8. There are only 3 major wires connected to the component which are kept as short as possible Materials 4.1. It is constructed from aluminium and carbon fibre with rubber pipes 4.2. Most mountain bikes are commonly constructed form aluminium 4.3. Any aluminium components can be anodised many colours to customers choice at a premium price 4.4. All on the components need simple dies or moulds Performance Requirements 5.1. Smaller turbines already sold today can produce ample power to charge similar devices 5.2. It is fixed behind the fork so not to disrupt aerodynamics 5.3. Mineral oil has a low freezing point and will work at all temperatures a user might be cycling in 5.4. Being behind the fork it will take less damage and can have a protective rubber casing all round 5.5. The whole unit is sealed for all types of off road riding conditions Sustainability 6.1. Rubber pipes, mineral oil and aluminium can all be recycled – Carbon fibre can’t, it could be re-used 6.2. Mineral hydraulic brake oil is the best and most readily available fluid to use 6.3. The component is generating power when it is used so it is replacing energy that was used to create it Production Costs 7.1. Moulds, dies and jigs will be used in large scale production to save costs – economies of scale 7.2. CAM will be used wherever possible except for the carbon fibre generator casing

Blue Sky Project – Bertie Johnstone

Alternative CAD presentation:

Front View

Centre no. – 62415

Candidate No. – 4201

2 Product Design – Alternative Bike Power Sources

Right Side View

Back View

Left Side View

Rendered support piece 17

Design Unit 1.2 : Product Design