Ghayath Housseini, Gabriel Mak, and Selmaan
Qureshi, Mechanical Engineering, University of Ottawa
Objective
Our project is an
exercise bike that can return power back to the power grid. The
motivation for this project is the fact that power costs too
much and that people lack motivation to exercise. With this
project people will be motivated to exercise due to the fact
that they would be reducing their power bill.
Our prototype is
a regular bicycle where the back wheel is lifted off the ground
so the tire can spin freely. To the back a squirrel cage
induction motor is attached. Using a pulley of 1 inch diameter
on the motor, the wheel is able to spin the shaft. The motor
spins at 3600 rpm at the highest gear ratio and in order to
produce power the cyclist must pedal over 200 rpm at the bike
wheel. With this setup the energy needed by cyclist to be able
to produce power is really high.
To fix this problem we must put
into consideration that when a regular bicycle is in motion on
the road it is easier to pedal due to the fact that the human
has momentum. This means that the inertia would remain much
longer with a flywheel on the bike. When the bike is stationary
it lacks that inertia effect so in order to fix that problem a
flywheel needs to be added.
Materials
·Bike
·Squirrel
cage induction motor
·Bike
Tachometer
·Base
to hold the bike
·Power
meter
·Pulleys
to adjust gear ratio
·Flywheel
Design Steps
Design a base which lifts the rear
tire off the ground.
The base should also support a motor with the shaft facing the
wheel.
Figure 1: Base attached to
bike
Test that the back wheel can
turn freely without any obstacles in the way
Attach the motor to the base
and calculate the gear ratios to figure out what size pulley
would be most suitable for the application.
Figure 2: Motor
Figure 3: Base with motor.
For more
efficient production a flywheel should be placed on the motor
(like in the picture) or if an exercise bike is used the wheel
should already be a flywheel.
To
measure the rpm and the speed attach a tachometer/speedometer to
the bike.
Figure 4: Bike set up.
Attach the power meter and the ammeter to be able
to take measurements. In this picture for the current the wire
was wrapped three times to be able to get a
reading. This means the displayed current is actually divided by
3
Figure 5: Ammeter
Do
some tests to ensure that when you are ready to take the results
you know how fast you need to pedal to change the motor into a
generator.
Using the
Microwin program you can view the results and understand when
you will be producing power.
Figure 6: Results from a trial.
Results
From our results it can be seen that
the voltage is constant and the sinusoidal wave is not very
contaminated. The current fluctuates due to the fact that the
pedaling is not very steady. When the power factor is negative
the biker is producing power.
Problems
Inefficiencies: position of biker,
very little residual kinetic energy without flywheel, electrical
losses.
Size of flywheel, gear ratio issues
(only worked on highest gear).
Motor initially consumes power
instead of generating it.
