Final Designs

Friction Drive with Rotary Pump

Final Design

Functional Requirements:

• 1. Be powered by an average rider of 50 kg (110 lb)

     1. Average power output assumed to be 100W (150W max)

  2. Pump water at a minimum flow rate of 0.32 L/s (5 GPM) under “ideal pumping conditions.”

• • 1. “Ideal pumping conditions” defined as:

       1. Suction height of 1 m (inlet 1 m below pump).

       2. Flow rate at outlet measured at surface (pump level).

• 3. Be implemented with most bike model (adaptable design).

  4. Meets low cost, low maintenance, and simple design restrictions of sponsor:

• • 1. Pump must be less than $100.

• 5. Minimal maintenance and instructional training required by user.

Mounted Bicycle to Friction Drive System

Close-up Centrifugal Pump System Overview

Hardware Performance

• • Flow Rate at Ideal Conditions: 0.30 L/s (4.7 GPM)

  • Pump 1: 0.30 L/s (4.7 GPM)

  • Pump 2: 0 L/s (0 GPM)

• Tested Negative Suction Head: 1 m

Future Recommendations

• Increase pump size so only one pump is needed instead of two

  • This will:

    • Raise flow capacity

    • Reduced system complexity

    • Reduce amount of tubing to haul around

    • Be more expensive

• Machine custom friction drive (a custom friction drive should be made regardless of having one or two pumps attached)

  • This will:

    • Increase the lifetime of the friction drive

    • Increase the reliability of the friction drive

Recommended Modifications for Centrifugal Pump

CAD Model of Current Slider-Crank + Diaphragm Pump System

Hardware Performance:

• Flow Rate at Ideal Conditions: 0.20 L/s (3.2 GPM)

• Stroke Rate: 45 strokes/min

• Maximum Positive Pressure Head: 4.3 m (14.1 ft)

• Maximum Negative Suction Head: 4.3 m (14.1 ft)

Annotated Slider-Crank + Diaphragm Pump System

Future Recommendations:

• Replace Slider/Slot with Rotary Shaft and Linear Ball Bearing to:

  • Reduce Fabrication Time

  • Reduce Part Tolerances

  • Reduce Maintenance

  • Increase Lifetime

• Increase leg clearance by mounting the pump further from the user

• Replace timing belt with sealed chain to accommodate size and slippage constraints

Recommended Modifications for Slider-Crank + Diaphragm Pump

Power Generation Apparatus

Final Design

Functional Requirements:

• • Engage/disengage system with bike tire as needed

  • Charge a 12V battery while bike is mobile (if system engaged)

  • Battery and charge controller must be transportable and not interfere with user’s biking ability

    The power generation apparatus consists of a 1.27 cm (0.5”) flywheel connected to the rear bike tire that engages with a 12V DC motor, acting as a generator while the bike is in motion to charge a 12V battery. The generator can be engaged or disengaged from the bike tire using the spring attachment to provide the user with an option to store the energy they generate while biking. 

CAD of Power Generation Apparatus Attached to Rear Bike Wheel

CAD of Power Generation Friction Wheel for Motor Shaft

Hardware Performance

    The travel speed of the bike was specified to be 19.4 km/hr (12 mph) in the project deliverables, which is greater than the 17.6 km/hr (11.0 mph) speed needed to charge the battery. Traveling at 12 mph corresponds to operating the motor at 8021 rpm which is much greater than the required 6366 rpm from the theoretical model. Hence, it was verified that operating the bike at the project deliverable travel speed will reliably generate more than 12 V from the motor to charge the 12 V battery. 

    Pedaling the bike at 12 mph, the current flow into the battery was measured as 0.3 A using an ammeter. Therefore, based on the 7Ah rating on the battery, it would theoretically take 23.3 hours (just under a day of pedaling) to completely charge the 12V battery. In terms of practical application, this fully charged battery could power a typical 12V light bulb in a household for a day assuming the bulb draws power at 3.6 W.

Summary

• Practical Motor Speed to Generate > 12V: 7280 rpm

• Corresponding Bike Speed: 17.6 km/hr (11.0 mph)

• Project Deliverable Speed: 19.4 km/hr (12.0 mph)

• Battery Charge Rate: 0.3 A

• Time to Full Charge: 23.3 hours (12 V, 7 Ah Battery)

Power Generation Apparatus Final Assembly