Introduction to Kinetic Energy Recovery System in Bicycle (KERS Bicycle):
Kinetic Energy Recovery System (KERS) is a system for recovering the moving vehicle’s kinetic energy under braking and also to convert the usual loss in kinetic energy into gain in kinetic energy. When riding a bicycle,a great amount of kinetic energy is lost while braking, making start up fairly strenuous.Here we used mechanical kinetic energy recovery system by means of a flywheel to store the energy which is normally lost during braking, and reuse it to help propel the rider when starting.
Regenerative braking by means of Flywheel Energy Storage :
Flywheel energy storage (FES) works by accelerating a rotor (flywheel) to a very high speed and maintaining the energy in the system as rotational energy. When energy is extracted from the system, the flywheel’s rotational speed is reduced as a consequence of the principle of conservation of energy; adding energy to the system correspondingly results in an increase in the speed of the flywheel.
Necessity of Regenerative Braking :
• To improve cars’ environmental friendliness
• To lessen the CO2 output by reducing the energy required
• According to Bosch Rexroth and Parker Hannifin companies, using this technology can diminish brake wear and reduce fuel consumption by 25-50%
• Reduce CO2 Emissions and Pollutants – by recovering and re-using energy, KERS reduces fuel usage, saves money, and lowers the quantity of CO2 and pollutants emitted by the vehicle
• Low Cost and Practical – typically around 1/3 the cost of an equivalent power electric system, KERS can also be integrated into existing vehicle architectures and fitted line side by OEMs; it can even be retrofitted to existing vehicles already in service
• Significantly Shorter Payback Period – an equivalent electric system fitted to a bus typically requires the entire vehicle life span (or even more) in order to pay back, while KERS can provide a return on investment in under 5 years
• Environmentally Sound – KERS is readily recycled and has a low embedded CO2 content, with no rare earth metals or highly processed battery acids as often found in HEVs
• Enhanced Performance – KERS can enhance vehicle performance for short periods of time with no increase in fuel consumption, and can also deliver handling benefits such as part-time all wheel drive
• Ease and Safety of Manufacture – all of the components and materials are commonly available, safe and easy to work with, and easily recyclable; they require no special training or garage equipment
• The Delhi Metro saved around 90,000 tons of carbon dioxide (CO2) from being released into the atmosphere by regenerating 112,500 megawatt hours of electricity through the use of regenerative braking systems between 2004 and 2007.
A crank wheel connected to the rear wheels always rotates the gear mechanism, connected in the flywheel axle. For the transmission, chain transmission at a specified gear ratio is used which helps to increase the overall speed of flywheel. For normal riding the flywheel is kept in disengaged position.
We have used a spring loaded sliding gear mechanism which engages and disengages the gear with the flywheel. Now at a time when a speed reduction is required, flywheel is engaged with the help of spring loaded sliding gear which makes the contact between the gear and flywheel. Then the flywheel starts rotating, also the speed of bicycle is decreased. Thus a regenerative braking system is achieved. On course energy is stored in flywheel. In case the brake has to be applied fully then after flywheel rotations gear is disengaged and the brake is applied. Now when we again ride the bicycle during which we would apply gear mechanism at this time as rear wheel rotation is lesser compared to flywheel the energy gets transmitted from the flywheel to the wheels. Now also we can reduce the overall pedalling power required in course of overrides by having clutch fully engaged.
We can reduce overall pedalling power by 10 per cent. Also situation arises such as traffic jam, down climbing a hill where we do not intend to apply brake fully. For such cases we can apply our smart braking system which would allow us to decelerate and allow us to boost acceleration after this during normal riding and distance that can be covered by pedalling can also improve.
During normal rides situations may arise we need to reduce the speed without braking fully such as traffic jams taking turns etc. we can store the energy that would normally be wasted due to speed reduction by the application of gear mechanism.
When the gear is engaged that time due to initial engage the flywheel rotation consumes energy which would result in speed reduction thus a braking effect. After some instances the energy is being stored in the flywheel this can be reused by the engage of gear mechanism and energy transfer from the flywheel occurs whenever the rotation is high enough to rotate rear wheel. Thus if sudden braking then applied we can disengage the flywheel connections so that flywheel energy is not wasted and going to take ride the speed of rear wheel is null and hence engage would help in returning the energy from the flywheel to rear wheel. While riding downhill we always use braking for allowing slowdown. This is the best case where we can store maximum amount of energy in our flywheel. The flywheel can be engaged for full downhill ride and after all for some distance we need not ride the bicycle which would be done by the flywheel. During long drive the engage can be made full time. This will help in reducing the overall pedalling effort. It has been found that the pedalling power can be reduced by 10 per cent during long drives. Also this would help in avoiding pedalling effort at some points of ride.
KERS system has a wide scope for further development and the energy savings. The use of more efficient systems could lead to huge savings in the economy of any country. Here we are concluding that the topic KERS got a wide scope in engineering field to minimize the energy loss. As now a day’s energy conservation is very necessary thing. Here we implemented KERS system in a bicycle with an engaging and disengaging clutch mechanism for gaining much more efficiency.
Modifications can be made to the design to make it hypothetically more efficient. The flywheel would spin faster and the gear shift mechanism would be more standard. The flywheel itself could be heavier to store more energy. This would mean it is harder to accelerate initially, but would give greater boosts to the rider during the trip. When more is known about the measured output of the flywheel, including its energy stored and the efficiency of the transmission, an optimal weight could be selected for maximum efficiency. But this doesn’t mean that a person wouldn’t want to have additional weight on the flywheel to make it less efficient but more fit to the specific rider’s desires.
Sachin is a B-TECH graduate in Mechanical Engineering from a reputed Engineering college. Currently, he is working in the sheet metal industry as a designer. Additionally, he has interested in Product Design, Animation, and Project design. He also likes to write articles related to the mechanical engineering field and tries to motivate other mechanical engineering students by his innovative project ideas, design, models and videos.