Human Generated Power for B9 Better Water Maker

Human Generated Power for B9 Better Water MakerP13417

Introduction to the Team

Team Members:

Kreag Bradley ISE

Diane Kang ISE

Emily Belonga ME

Nicholas Higgins ME

Jordan Lahanas EE

Trang Pham EE

Guides:

Vincent Burolla

Leo Farnand

Customer:

B9 Plastics

Table of Contents• Project Overview• Problem Statement• Customer Needs• Specifications• Current Design• Testing• Preliminary Concepts• Concept Selection• Conclusions

Project Overview• B9 Plastics:

A not for profit organization dedicated to social and environmental improvement through the use of certain materials (plastics).

• Better Water Maker (BWM):A water treatment device used in the developing world to kill water microbes by using ultraviolet light. The device uses a human powered crank to generate power for the device at 12v.

Problem Statement• Our project, in conjunction with B9 plastics, is to redesign the

power generator to ease the use of this device for women and children. The current design seems to be too physically demanding to maintain the proper power output for the time required to cleanse a moderate amount of water (over 1 gallon).

Customer Needs

Specifications

V02 Testing

Current Design

Current BOM

Current BOM

Preliminary Concepts

Concept Selection• New Gear Box

• To obtain better gear ratio • Maintain/reuse all electrical work • Motors still experience same input rpms

• New Motors• To obtain better gear ratio• Ease cost• Reduce losses due to friction • Significant increase in total lifetime

Goal: Each proposal is to decrease input crank rpms

*Both proposals include using legs/feet to pedal generator

Maximum allowable leg force required to power generator

• Current generator requires 50in*lbs of torque to maintain required rpms

• Equates to 9 lbf at crank arm handle which is 40% of maximum arm force of women (21 lbf)

• Maximum leg force of average woman is 63 lbf

• Allowable force = 40% of 63 lbf

• 25 lbf experienced at crank arm handle (pedal)

New Gear Box Comparison

Current New Gear Box Design

New Gear Box

Torque Equations

Basic Stress and Deflection Analysis of Crank Arm

Current Design

Type: Apply normal forceValue: 4.11 lbf

Ultimate Strength of “Harbec plastic” is 10,700psi

• Large Gear with 9 lbf applied to crank handle

Proposed Design• Large Gear with 25 lbf applied to crank handle

(pedal)

Current Crank Arm• 9 lbf applied

Current Crank Arm• 25 lbf applied

Gear Small Radius• 25 lbf applied to crank arm pedal

Proposed Gear Box

Proposed Generator Cover

Proposed Generator Cover DRW

Proposed Motor Mount Box

Proposed Motor Mount Box DRW

Proposed New Gear (Small Radius) DRW

Proposed New Gear (Large Radius) DRW

Proposed Steel Axle DRW

Proposed Crank Arm Pedal DRW

New Gear Box

Current Motor• Mabuchi RS-555PC• Short lifetime

• <6000 hours

Mabuchi RS-555PC

New Motor• CF Motor RS-390PH

• Brushed motor• Longer lifetime• More efficient

• 4 of these motors in a configuration with 2 parallel • Desired voltage/power of 12 V/17 W • Desired RPMs of ~1650

Proposed Changes• Reverse diode across inductor

• Incentive: circuit integrity• Currently the circuit contains an inductor near the input that has

no alternative current path, should the transistor in series with it turn off

• Adding a reverse diode in parallel with this inductor ensures a discharge path for this current

• Replacement of potentiometer by low tolerance resistors • Incentive: cost• The current circuit uses an op-amp comparator and a 5V

reference to control powering of a power LED • This LED turns on when a sufficient voltage is generated (>12 V)

Pump Circuit• Existing Pump Circuit

• Accepts a variable input voltage• 12 V/19 W required to power the ballast and pump • After 10 seconds, pump will activate, moves water through device

Proposed Changes• Smoothing RC network (“electrical flywheel”)

• Incentive: efficiency, easiness of use• Add smoothing smoothing RC network for charge storage • The time allowed for not cranking the generator and keeping the

pump on was decided to be 1.0 seconds • Time constant

• This time constant can be achieved with a 100 µF effective capacitance and a 135 kΩ effective resistance.

Motor Alternative BOM

Motor Alternative BOM

Seat Design Proposal• Preliminary concepts:

Proposed Seating Position Assembly

Proposed Seating Position Assembly (Hidden Lines View)

Proposed Plywood Insert Geometry DRW

Proposed Seat Back Rest DRW

Proposed Bucket Seat DRW

Entire proposed gearbox and seat modification

Conclusion• New Gear box requires major tool changes

• Adds expense• New motors requires less tool changes

• Less expensive• Overall more efficient