THE TOILET GNOME

1. THE TOILET GNOME Kimberly AlbertsBrian Lockwood David LomaxJohn McFaddinDavid McGinnisChad Medlin

2. Agenda • Problem Statement • Design Objectives • Conceptual Designs • Mid-Term Review • Engineering Analysis • Prototype/Design Timeline • Comparison Prototype/Final Design • Future Considerations • Conclusion

3. Problem Statement Our goal as the Toilet Gnomes is to produce a product that is essential to all cohabitating households. With a self-closing toilet seat, we solve the problem of males leaving the seat in the upright position and the seat spontaneously falling during use by providing a product that slowly closes the toilet seat after flushing.

4. Design Objectives • Universal to all toilet seats • No interference for normal use of toilet • No external power source • Minimum use of moving parts • Slow descent when closing • Comparable cost to normal toilet seat • Self-contained

5. Conceptual Designs • 3 Subsystems of System • Locking Mechanism • Timing Mechanism • Lowering Mechanism • 5+ Designs for each Subsystem • Created Overall Conceptual Designs from these • Best Locking: Spring/ball bearing, Lever, and None • Best Timing: Kitchen Timer, Falling Liquid/Sand • Best Lowering: Springs • Presented at Mid-Term Presentation

6. Mid-Term Review • Issues/Suggestions from Mid-Term: • Different lengths of time for toilet use • Resetable when new user comes in before time is up • Possible use of washer friction for lowering • Flush actuation • Possible ability to disable • Changed Design to solve issues • Flush actuated instead of timing mechanism • Rotary Dampers used for lowering mechanism • Equilibrium chosen as locking mechanism

7. Updated Design from Mid-Term • Timer / Actuator : Lowering of water in the toilet tank • Allows user to control timing and removes some mechanical complication • Floater drops as tank drains pulling cable down with it • Floating weight drops relatively large distance providing possibility for decent mechanical advantage • Still were not sure about triggering

8. Toilet Gnome Idea Created Gnome (Similar to Garden Gnome) Gnome Hangs By Suspenders Leg Kicks Out To Lower Seat Hinge Attached To Cable Attached To Weighted Float

9. Toilet Gnome Design Cable • Leg in upright position when tank is full • Weighted float drops with water when toilet is flushed pulling on cable • Pulling cable triggers gnome to close seat by kicking toilet seat over • Gnome’s leg is reset into place by opening seat which presses leg back into upright locked position for toilet use Weighted Float

10. F L d θ mg Pivot Engineering Analysis Analysis of the Seat: m = mass of the seat g = gravity F = force from Gnome kick P = pivot point L = length of the seat The sum of the moments about point P gives: Therefore:

11. Pivot T Lf F Engineering Analysis • Analysis of the leg: • Leg powered by torsion spring so need to know how much torque • From diagram, torque must be larger than moment caused by force pushing over seat. • Spring parameters: • Coils: 5 • Wire Diameter: .135 in • Wire Material: Music Wire • Young’s Modulus: 30500 ksi • Length of Each Leg: 1 in • Coil Diameter: 1 in • Overall Width: 0.675 in • Parameters provide max torque of over 20 lb-in with rotation of 45° • Ensures ability to tip 3 lb toilet seat over when contact point is half way up seat

12. Lowering Mechanism • Rotary Damper used • Slows descent of closing seat but does not obstruct raising of seat • Smooth motion throughout descent • One damper on each side for final design

13. Engineering Analysis • Max Torque: 24.75 lb-in • Desired Speed: 5-10 RPM • ACE F1 Series Chosen

14. Final Prototype • Custom seat • Gnome to attach to tank portion of toilet with hinged leg for closing seat • Latching device to keep leg in upright position when toilet in use • Weight to cause triggering when toilet flushed • Rotary damper plus friction damping for smooth lowering of seat

15. Latching Mechanism • Latch catches pin in leg when seat is raised to hold leg in upright position until toilet is flushed • Other end of latch attached to cable coming from weight in tank • Pulling of cable releases latch when weight drops due to flushing Latch

16. Functioning Prototype

17. Final Design/Prototype Comparison • 2 smaller rotary dampers instead of one large one • Latching mechanism incorporated into leg instead of external • Floating weight made out of buoyant, heavier material than wood • Gnome covered by plastic coating to prevent corrosion • Roller on end of leg to allow smooth kicking and easy reset FINAL DESIGN PROTOTYPE

18. Future Considerations • Creating changeable appearances of the gnome for different holidays or seasons • Manufacture own rotary damper to lower cost • Manual override for disabling system • Slimmer gnome to allow seat to move further past vertical when in raised position

19. Conclusion • Went against our design objectives of being universal to all seats and being self-contained • Final design includes: • flush actuated timing mechanism • equilibrium locking mechanism • rotary damper lowering mechanism • Final design improves upon prototype with: • 2 rotary dampers • Non-corrosive part materials • Locking mechanism incorporated into leg • Future considerations include: • Changeable gnome appearances • Manufacturing own rotary damper • Manual override • Slimmer gnome

20. QUESTIONS ?