Design & Fabrication of machanism for recovery of kinetic energy in bicycle using flywheel

Kinetic energy recovery system (KERS) is a technology used in formula-1 cars for recovering the energy lost in braking of the car and thus providing boost to the vehicle motion. Same concept i.e. regenerative braking can be applied in bicycle which uses a flywheel which will be mounted between the frames of the bicycle, the flywheel can store the braking energy by rotating and this energy can be given back to the system which will reduce the pedaling power required to drive the bicycle.

This Flywheel Energy Storage (FES) system uses flywheel with suitable clutch mechanism along with sprocket and chains. Further this project concludes about efficiency and pedaling power in flywheel 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. The rider can charge the flywheel when slowing or descending a hill and boost the bike when accelerating or climbing a hill. The flywheel increases maximum acceleration and nets 10% pedal energy savings during a ride where speeds are between 12.5 and 15 mph.

KERS is a collection of parts which takes some of the kinetic energy of a vehicle under deceleration, stores this energy and then releases this stored energy back into the drive train of the vehicle, providing a power boost to that vehicle.

KERS (Kinetic energy recovery system) is a type of regenerative braking concept which is primarily used in formula-1 cars for the purpose of speed boosting. The energy which is applied for braking purpose of a vehicle is normally wasted; however this energy can be saved and effectively utilized as and when required. Generally when the brakes are applied, the braking energy gets converted into heat which is wasted however in this scenario when the brakes are applied the energy is passed to the motors which are mounted on the front wheels. The motors at this stage act as generator converting the mechanical energy to electrical which is then passed to motors/flywheel arrangement resulting in rotation of flywheel. This rotational energy as and when required can be restored by the means of motors to the wheels thus providing the necessary boost in speed. This principle can be successfully implemented in a passive system such as bicycle for serving the purpose of reduction in pedaling power by using a flywheel and a mechanism for engaging and disengaging the same.

Objectives

  • Reduction in pedaling power required to drive bicycle
  • Increase the system efficiency
  • Imparting the simplest possible operation & mechanism

Components Designed

  1. Flywheel
  2. Selection of clutch mechanism
  3. Shaft
  4. Frame
  5. Bearing Selection

COMPONENTS

Sprocket

A sprocket or sprocket-wheel is a profiled wheel with teeth, cogs, or even sprockets that mesh with a chain, track or other perforated or indented material. The name 'sprocket' applies generally to any wheel upon which are radial projections that engage a chain passing over it. It is distinguished from a gear in that sprockets are never meshed together directly, and differs from a pulley in that sprockets have teeth and pulleys are smooth.

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Selection of the sprocket

  • Large sprocket = 4x
  • Small sprocket = x
  • Ratio of the sprocket = 1:4
  • Speed of the sprocket
  • N4 = 1.01 X 4
  • N4 = 4.04 rps

Bearings

A bearing is a machine element, which supports another machine element. It permits a relative motion between the contact surfaces, while carrying the load. In this automobile gearbox roller bearings are adopted. The ball or roller bearing consists of an inner race, which is mounted on the shaft or journal, and the outer race, which is carried by the housing or casing. In between the inner and outer race there are balls or rollers. A No. of balls or rollers is used and these are helped at proper distance by retainers so that they do not touch each other. The retainers are this strip and usually in two parts, which are assembled after the ball bearings are used for light loads and roller bearings, are used for heavier loads.

Bearings are classified as

Depending upon the direction of load to be supported

  • Radial bearing: The loads act perpendicular to the direction of the motion of the moving elements.
  • Thrust bearing: The loads act perpendicular to the direction of the motion of the moving elements.

Shaft

A shaft is a rotating element, which is used to transmit power from one place to another. The power is delivered to the shaft by some tangential force and the resultant torque or tensional moment set up within the shaft permits the power to be transferred to various machines linked up to the shaft, in order to transfer the power from one shaft to another the various members such as pulleys, gears etc, are installed on it. This member causes the shaft to bending. In other words we may say that a shaft is used for the transmission of torque and bending. The various members are mounted on the shaft by means of keys or splines.

Materials Used

The material used for ordinary shafts is mild steel where high strength is required. An alloy steel such as nickel, nickel chromium or chrome vanadium steel is used.

Flywheel

A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a significant moment of inertia and thus resist changes in rotational speed. The amount of energy stored in a flywheel is proportional to the square of its rotational speed. Energy is transferred to a flywheel by applying torque to it, thereby increasing its rotational speed, and hence its stored energy. Conversely, a flywheel releases stored energy by applying torque to a mechanical load, thereby decreasing its rotational speed.

WORKING

The components used in the system are flywheel, clutch, chain drive, Bearing, frame. Flywheel which is mounted on the frame is driven by the rear wheel through the chain drive and clutch mechanism. When one has to apply the brakes the mechanism is such that clutch gets engaged with the flywheel and it starts rotating thus storing the braking energy. The mechanism designed is such that by manually pressing the lever (Rear brake lever of the bicycle) the clutch can engage with the flywheel this depends upon the convenience of the biker. The stored energy is utilized when the speed of bicycle decreases below the average range of speed i.e. rear wheel speed. The flywheel energy by the means of chain in this case can be restored back to the bicycle thus fulfilling its torque requirement. Consider for instance riding on a slope or in the case of mountain biking, when the speed of bicycle is more than average speed range the engagement of flywheel is facilitated and the flywheel keeps on rotating for a certain period of time mainly due to inertia this motion can be transferred back to the rear wheel thus assisting the forward motion of the bicycle.