1. Power Generation System for the Better Water Maker
Detailed Design Review
By P14418 on December 10, 2013
Erika

2. Scope
The power generation portion of the Better Water Maker.
Objective
To provide a low cost, efficient power generation system for the Better Water Maker that does not easily tire the user, while still being fun and easy to use.

3. Concept Selection
The selection of a recumbent seating redesign was chosen in the interest of increasing the efficiency through leg power and a higher gear ratio.
Pugh analysis, pros vs. cons, and group discussion concluded this decision
The higher gear ratio was chosen to increase the RPM at the motor in order to increase motor efficiency
This was later modified to 1:28 due to the motor’s inertial effects that would be translated to user
Decrease the motors to 3 to reduce torque, trade-off in higher RPM
Jess

4. Engineering Requirements
Function
Importance
Units
Range
Goal Value
CN Fulfilled
Proof of concept
ER1
Cost 9
USD
0-100 75
CN7, CN8
Analysis and sourcing
ER2
Generated Power
W, V
23-29
27.5, 14.3
CN1, CN14, CN17
Motor Analysis and Testing
ER4
Training Time 3
minutes
5-30 10
CN16
User Testing
ER5
Assembly
20-60 30
CN7, CN10, CN16
Testing
ER6
Effort Required
lbf
10-20 15
CN2, CN12, CN13
Testing with Force Gauge- Before and After
ER7
Weight lb
5-10
7.5
CN3, CN16
Weight by component
ER8
Number of Installers
People
1-3 1
CN3, CN7, CN10, CN16
ER9
Number of Tools for User
Tools
1-5
CN7
Assembly Design
ER10
Unit Life
Gallons Treated
200, ,000
>180,000
CN5, CN6, CN9, CN10, CN15, CN16
Fatigue Analysis on Gearbox
ER11
Support User
40-200
130
CN5, CN12
Analysis and Testing
ER12
Can Hook Up to 12V Car adapter
Binary
Yes
CN14
Sourcing and Analysis
Liz

5. Project Plan
Jacob
I understand this slide and the next slide is difficult to see but it is important to recognize the process that we went through to complete everything we have for you today.
We were behind schedule on a lot of these tasks and after all of our slack was used up at the preliminary DDR we had a small set back.
We worked through the set back put in more resource hours and were able to accomplish this part of the project.

6. Project Plan
Jacob

7. Seating and Adjustable Track
Jacob

8. Jacob

9. Track Analysis
The positions for the gearbox were based on the length of the legs of our expected users
Statistics on leg lengths for children and women were obtained for all the countries in which the BWM is currently used
Census data
Developed 13 positions for the gearbox along the adjustable track
Jacob
We got statistics from census data and calculated the average inseam for the individuals we are designing for. From there we...

10. Ergonomics Research
Jacob

11. Ergonomics Research
We obtained the average height statistics and from there used the averages to calculate the hip to ground height to help us design the track
Jacob

12. SIDE VIEW OF GEARBOX AND TRACK
Erika
A wood bracket dimensioned 3.5” by 4” will be screwed onto each side of the gearbox, towards the bottom
The bracket will have two holes to insert two eye bolts through and match up with the holes on the track
The track will be attached to the inside of the bucket
Three self tapping screws into pilot holes in the track and bucket
Specifically 6” eyebolts will be used and wing nuts will be used to hold in place

13. drawings of track and dimensions go here
Erika
We should show the design explain that its simply a 2”x4” that is approximately 47” long.
The holes were placed by design to accomodate for the average leg length of majority of the users.
Then from these four or five main holes we added holes every 2.4” to leave many adjustement options.

14. Erika

16. Seat Design and Mitigation Plan
Makes use of a bucket support insert that consists of two plywood sheets and a 2”x4”
Same as current but allows for additional room at the bottom of the bucket for inserting the track
135 degree angle with the bucket lid
To reduce costs, more ergonomic options were not viable
Prototyping, user testing, and final cost will play a part in whether or not more ergonomic options are revisited
Liz

17. Liz

18. Liz

19. Testing Plans Test for Ease of Assembly
Provide volunteers with a user manual
Discretely time volunteers to avoid any pressure regarding assembly time
Ask volunteers to rate the clarity of the user manual and difficulty of assembly
Test for Ease of Gearbox Repositioning
Have volunteers change the current position of the gearbox to the position that fits them
Ask volunteer to rate the difficulty
Erika

20. Testing Plans IV. Test for Comfort
III. Test for Ease of Power Generation
Ask users to power the device by pedaling for 5 minutes, if volunteers cannot sustain this after three attempts, make note otherwise measure the level of water sanitized
Ask users to rate the difficulty of use
IV. Test for Comfort
After using the device for an extended period of time, ask volunteers to rate the comfort of the seat and the positioning of their body during use
Erika

21. Electronics
Chris

22. Generator Circuit
2 stages
Regulation
LEDs
Chris

23. Chris

24. Regulator Stage
Chris

25. LED Circuit
Chris

26. Gearbox

27. Gearing Decisions Original 1:72 gear ratio deemed unreasonable
Original Design
Original 1:72 gear ratio deemed unreasonable
Modeling of system proved difficult
Final decision to increase ratio slightly from original product (1:28) using a symbolic analysis of the inertia
Kyle

28. Case
Made of ¼” PVC sheets
Cost
Wood not viable
Weight

29. Pedal Interface OTS crank arm considered ½” aluminum stock due to cost
Keyed shaft for power transmission
Jess

30. Tolerancing Stack
Bearings have a light press fitting with the PVC housing
Shafts have a close fit with the bore of the bearings
Kyle

31. Gearbox Test Plans Motor Testing User Testing VO2 Testing
Height, weight, and age
Survey users
VO2 Testing
Verify effort required
Jess

32. Stress Analysis of Gearbox
Shaft Bending Analysis
Kyle

33. Bill of Materials/Drawings
BOM
Drawings
Jess

34. Gearbox Assembly Process
Gearbox Sub-Assembly
Jess

35. Jacob

36. Jacob

37. Assembly Process
Jacob
Jess-Gearbox

38. Estimate of Assembly Time
Jacob

39. Labor Costs
Estimated manufacturing costs for the parts in the gearbox and the woodworking
High estimate of labor rate
Used DFA assembly time estimation methods
Currently working on ways to further reduce assembly time and cost
Labor Costs and Assembly Time (1 unit)
Total Assembly Time
11.05
min
Machining Time
1.2 hr
Total Manufacturing Time
1.384
Rate 20
$/hr
Labor Price
27.68
dollars
Jacob

40. Cost Analysis
Liz

41. Prototype Budget
Liz

42. Risk Assessment
Jacob
Risk Assessment

43. Project Plan for MSD II
Jacob

44. Project Plan for MSD II
We recognize that we only have approximately 3 days of slack for the next semester
Jacob
In the plan I allotted for retesting and modifications.

45. Lessons Learned
Actions-Issues-Decisions log rather than simply action items list
Track risk and manage risk carefully to ensure that every step of the process is eliminating risk and not creating more
Project Plan Adhesion
Review each sub-committee’s work as a team to identify risks-QA/QC
Itemize action items by person and date
Seek advice of faculty early on in process
Jacob/Jess

46. Suggestions for MSD I Program
Quicker assignment of individual projects so we can become familiar with them
The first few classes should be exercises to get to know our teammates. A good time for the (very successful) Team Values and Norms exercise
There should be a better explanation of how to use EDGE (Maybe a technical support team)
A better explanation of what to do with our notebooks
Online lecture more effective than 3-hour in class lectures

47. Questions

48. Backup slides

49. Wooden dowel (same diameter as a broomstick)
Pool noodle section
Wooden dowel (same diameter as a broomstick)
2” x 4”
5-gallon bucket
Erika

50. Jacob