A Detailed Report On Energy Crisis

An energy crisis is any great bottleneck (or price rise) in the supply of energy resources to an economy. It usually refers to the shortage of oil and additionally to electricity or other natural resources. An energy crisis may be referred to as an oil crisis, petroleum crisis, energy shortage, electricity shortage electricity crisis. While not entering a full crisis, political riots that occurred during the 2007 Burmese anti government protests were initially sparked by rising energy prices.
Likewise the Russia- Ukraine gas dispute and the Russia-Belarus energy dispute have been mostly resolved before entering a prolonged crisis stage. Market failure is possible when monopoly manipulation of markets occurs. A crisis can develop due to industrial actions like union organized strikes and government embargoes. The cause may be ageing over-consumption, infrastructure and sometimes bottlenecks at oil refineries and port facilities restrict fuel supply. An emergency may emerge during unusually cold winters. emerging shortages Crisis that currently exist include;

• Oil price increases since 2003 - Cause: increasing demand from the U.S and China, the falling state of the U.S. dollar, and stagnation of production due to the U.S. occupation of Iraq. Iraq is #3 in the world (besides Saudi Arabia and Iran) for its oil reserves. However some observers have stated the global oil production peak occurred in December 2005. If this is correct it is also to blame.

• 2008 Central Asia energy crisis, caused by abnormally cold temperatures and low water levels in an area dependent on hydroelectric power

• South African electrical crisis Solution for Energy Crisis next time on the roads, don’t scoff at the speed-breakers. They could actually light up small villages

off the highway.

 

This project is about generation of electricity with the speed breakers. Generally when vehicle is in motion it produces various forms of energy like, due to friction between vehicle’s wheel and road i.e. Rough surface heat energy is produced, also when vehicle traveling at high speed strikes the wind then also heat energy is produced which is always lost in environment and of which we can’t make use it directly. we can say that all this energy that we can’t make use of is just the wastage of energy that is abundantly available around us. In this project we are just trying to make use of such energy in order to generate an electrical energy. This project will work on the principle of “potential energy to electrical energy conversion” potential energy can be thought of as energy stored within a physical system. This energy can be released or converted into other forms of energy, including kinetic energy. It is called potential energy because it has the potential to change the states of objects in the system when the energy is released if h is the height above an arbitrarily assigned reference point, then kinetic energy of an object is the extra energy which it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its current velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes. Negative work of the same magnitude would be required to return the body to a state of rest from that velocity.

The kinetic energy can be calculated using the formula: in this project a

Mechanism to generate power by converting the potential energy generated by a vehicle

Going up on a speed breaker into kinetic energy. When the vehicle moves over the

Inclined plates, it gains height resulting in increase in potential energy, which is wasted in

A conventional rumble strip when the breaker come down, they crank a lever fitted to a

Ratchet-wheel type mechanism (a angular motion converter). This in turn rotates a geared

Shaft loaded with recoil springs. The output of this shaft is coupled to a dynamo to convert kinetic energy into electricity. A vehicle weighing 1,000 kg going up a height of 10 cm on such a rumble strip produces approximately 0.98 kilowatt power. So one such speed-breaker on a busy highway, where about 100 vehicles pass every minute, about one kilo watt of electricity can be produced every single minute. “a vehicle weighing 1,000 kg going up a height of 10 cm on such a rumble strip produces approximately 0.98 kilowatt power. So one such speed-breaker on a busy highway, where about 100 vehicles pass every minute, about one kilo watt of electricity can be produced every single minute. The figure will be huge at the end of the day,” he said. The assam power ministry is expected to back the iit pilot project. Das says a storage module like an inverter will have to be fitted to each such

Rumble strip to store this electricity. The cost of electricity generation and storage per mega watt from speed-breakers will be nearly rs 1 crore as opposed to about rs 8 crore in thermal or hydro power stations.

Next time on the roads, don't scoff at the speed-breakers. They could actually light up small villages off the highway.an amateur innovator in guwahati has developed a simple contraption that can generate power when a vehicle passes over a speed breaker. Kanak gogoi, a small time businessman, has developed a mechanism to generate power by converting the potential energy generated by a vehicle going up on a speed breaker

Into kinetic energy. The innovation has caught the eye of the indian institute of technology (iit), guwahati, which will fund a pilot project to generate electricity from speed-breakers.

The idea is basic physics. Gogoi has welded five-metre-long metal plates into the

Speed-breaker instead of the conventional bitumen-and-stone-chip rumble strip. The plates are movable and inclined with the help of a spring-loaded hydraulic system. The fulcrum-attached plates are pushed down when a vehicle moves over them and bounce back to original position as it passes. "when the vehicle moves over the inclined plates, it gains height resulting in increase in potential energy, which is wasted in a conventional rumble strip," gogoi says. "when the plates come down, they crank a lever fitted to a ratchet-wheel type mechanism. This in turn rotates a geared shaft loaded with recoil springs. The output of

This shaft is coupled to a dynamo to convert kinetic energy into electricity," he explains.

Iit guwahati has evaluated the machine and recommended it to the assam ministry of power for large scale funding. A k das, a professor at iit's design department says it is a 'very viable proposition' to harness thousands of mega watts of electricity untapped across the country every day.

"a vehicle weighing 1,000 kg going up a height of 10 cm on such a rumble strip produces approximately 0.98 kilowatt power. So one such speed-breaker on a busy highway, where about 100 vehicles pass every minute, about one kilo watt of electricity can be produced every single minute. The figure will be huge at the end of the day," he said.

The assam power ministry is expected to back the iit pilot project.

Das says a storage module like an inverter will have to be fitted to each such rumble strip to store this electricity. The cost of electricity generation and storage per mega watt.

BASIC PRINCIPLES:

·         Simple energy conversion from mechanical to electrical.

·         To generate electricity using the vehicle kinetic energy as input we can develope electricity from speed breakers

·         They are using 3 different mechanisms:

I. Roller mechanism

II. Rack- Pinion mechanism

III. Crank-shaft mechanism

1.1  ROLLER MECHANISM:

ake use of….OR directly we can say that

A roller blind mechanism for winding and unwinding a rollable blind, the mechanism comprising a support element, a drive sprocket which is rotatably mounted on the support element for transmitting rotational movement to a blind supporting member, and a manually-movable elongate flexible drive element which includes a plurality of interlinked tooth-engaging elements, the drive sprocket including a plurality of flexible teeth engagable with the tooth-engaging elements of the flexible drive element. A roller blind mechanism as claimed in claim 1, wherein a radial extent of the teeth of the drive sprocket is equal to or greater than a maximum dimension of the tooth-engaging elements of the flexible drive element. A roller blind mechanism as claimed in claim 2, wherein the radial extent is equal

to or greater than twice the maximum dimension of the tooth-engaging elements of the

flexible drive element. A roller blind mechanism as claimed in claim 1, wherein the teeth of the drive sprocket flex in a circumferential direction of the sprocket.

1.2  RACK AND PINION MECHANISM:

Rack and pinion gears normally change rotary motion into linear motion, but sometimes we use them to change linear motion into rotary motion. They transform a rotary movement (that of the pinion) into a linear movement (that of the rack) or vice versa. We use them for sliding doors moved by an electric motor.The rack is attached to the door and the pinion is attached to the motor. The motor moves the pinion which moves the rack and the door moves.

1.3  CRANKSHAFT MECHANISM:

The crankshaft is a mechanism that transforms rotary movement into linear movement, or vice versa. For example, the motion of the pistons in the engine of a car is linear (they go up and down).But the motion of the wheels has to be rotary. So, engineers put a crankshaft between the engine and the transmission to the wheels. The pistons of the engine move the crankshaft and the movement becomes rotary. Then the rotary movement goes past the clutch and the gear box all the way to the wheels.

Out of all these arrengements the rack and pinion arrengement have a higher efficiency than others so we chose to make a hybrid mechanism of it by using a hybrid technology to increase the development of power as compared to the conventional model.

HYBRID SYSTEMS: A hybrid system is usually consist of two or more energy sources used together to provide increased system efficiency as well as greeater balance in energy supply.

                                      LITERATURE REVIEW

2.1  ELECTRICITY GENERATION FROM SPEED BREAKER USING A HYBRID  MODEL:

In the present scenario power becomes major need for human life. Due to day-to-day increase in population and lessen of the conventional sources, it becomes necessary that we must depend on non-conventional sources for power generation. While moving, the vehicles posses some kinetic energy and it is being wasted. This kinetic energy can be utilized to produce power by using a special arrangement called “power hump”. The kinetic energy of moving vehicles can be converted into mechanical energy of the shaft through rack and pinion mechanism. This shaft is connected to the electric dynamo and it produces electrical energy proportional to traffic density. This generated power can be regulated by using zenor diode for continuous supply .all this mechanism can be housed under the dome like speed breaker, which is called hump. The generated power can be used for general purpose like streetlights, traffic signals. The electrical output can be improved by arranging these power humps in series this generated power can be amplified and stored by using different electric devices. The maintenance cost of hump is almost nullified. By adopting this arrangement, we can satisfy the future demands to some extent.

In the present scenario power becomes the major need for human life .the availability and its percapita consumptions is regarded as the index of national standard of living in the present day civilization. Energy is an important input in all the sectors of any countries economy. Energy crisis is due to two reasons, firstly the population of the world has been increased rapidly and secondly standard of living of human beings has increased. India is the country, which majorly suffers with lack of sufficient power generation. The capital energy consumption of u.s.a. Is about 8000 k.w.h., where as per india is only 150 k.w.h. U.s.a. With 7% of world population consumes 32% of total power generation where as india as developing country with 20% of world population consumes only 1% of total energy consumed in the world. The availability of regular conventional fossil fuels will be the main sources for power generation, but there is a fear that they will get exhausted eventually by the next few decades. Therefore, we have to investigate some approximate, alternative, new sources for the power generation, which is not depleted by the very few years. Another major problem, which is becoming the exiting topic for today is the pollution. It suffers all the living organisms of all kinds as on the land, in aqua and in air. Power stations and automobiles are the major pollution producing places. Therefore, we have to investigate other types of renewable sources, which produce electricity without using any commercial fossil fuels, which is not producing any harmful products. There are already existing such systems using renewable energy such as solar wind), otec (ocean thermal energy conversions) etc…for power generation. The latest technology which is used to generate the power by such renewable energy can be extracted from speed breakers.

Whenever the vehicle is allowed to pass over the dome it gets pressed downwards then the springs are attached to the dome are compressed and the rack which is attached to the bottom of the dome moves downward in reciprocating motion. Since the rack has teeth connected to gears, there exists conversion of reciprocating motion of rack into rotary motion of gears but the two gears rotate in opposite direction. A flywheel is mounted on the shaft whose function is to regulate the fluctuation in the energy and to make the energy uniform. So that the shafts will rotate with certain r.p.m. These shafts are connected through a belt drive to the dynamos, which converts the mechanical energy into electrical energy. The conversion will be proportional to traffic density. Whenever an armature rotates between the magnetic fields of south and north poles, an e.m.f (electro motive force) is induced in it. So, for inducing the e.m.f armature coil has to rotate, for rotating this armature it is connected to a long shaft. By rotating same e.m.f, is induced, for this rotation potential energy of moving vehicles is utilized. The power is generated in both the directions; to convert this power into one way a special component is used called zenor diode for continuous supply. Also the pizo-electric material which is kept below the supporting springs of the speed breaker also generate a small amount of charge which can be utilized for the storage purpose so that more amount of energy can be developed from the same system. All this mechanism can be housed under the dome, like speed breaker, which is called hump. The electrical output can be improved by arranging these power humps in series. This generated power can be amplified and stored by using different electrical devices.

2.2   ORIGIN OF THE PROPOSAL:

           

Before starting I have one question to you all who is really very happy with the current situation of the electricity in India? I suppose no one . so this is my step to improve the situation of electricity with a innovative and useful concept ie Generating Electricity from a Speed breaker First of all what is electricity means to us? Electricity is the form of energy. It is the flow of electrical Power . Electricity is a basic part of nature and it is one of our most widely used forms of energy. We get electricity, which is a secondary energy source, from the conversion of other sources of energy, like coal, natural gas, oil, nuclear power and other natural sources, which are called primary sources. Many cities and towns were built alongside water falls that turned water wheels to perform work. Before electricity generation began slightly over 100 years ago, houses were lit with kerosene lamps, food was cooled in iceboxes, and rooms were warmed by wood-burning or coal-burning stoves. Direct current (DC) electricity had been used in arc lights for outdoor lighting. In the late-1800s, Nikola Tesla pioneered the generation, transmission, and use of alternating current (AC) electricity, which can be transmitted over much greater distances than direct current. Tesla's inventions used electricity to bring indoor lighting to our homes and to power industrial machines. How is electricity generated?

Electricity generation was first developed in the 1800's using Faradays dynamo generator. Almost 200 years later we are still using the same basic principles to generate electricity, only on a much larger scale. The rotor(rotating shaft) is directly connected to the prime mover and rotates as the prime mover turns. The rotor contains a magnet that, when turned, produces a moving or rotating magnetic field. The rotor is surrounded by a stationary casing called the stator, which contains the wound copper coils or windings. When the moving magnetic field passes by these windings, electricity is produced in them. By controlling the speed at which the rotor is turned, a steady flow of electricity is produced in the windings. These windings are connected to the electricity network via transmission lines.

Now I m throwing some light on the very new and innovative concept i.e. GENERATING ELECTRICITY FROM A SPEED BREAKER . Producing electricity from a speed breaker is a new concept that is under going research. The number of vehicles on road is increasing rapidly and if we convert some of the potential energy of these vehicle into the rotational motion of shaft then we can produce considerable amount of electricity, this is the main concept of this project. In this project, a rack and pinion arrengement is fitted between the case anh the shaft of a generator when a vehicle passes over speed breaker it rotates the pinon. This movement of pinion which is connected to shaft of D.C. generator by the help of drive or a pulley which is there to provide 1:5 speed ratio . As the shaft of D.C. generator rotates, it produces electricity. This electricity is stored in a battery. Then the output of the battery is used to lighten the street lamps on the road. Now during daytime we don?t need electricity for lightening the street lamps so we are using a control switch which is manually operated .The control switch is connected by wire to the output of the battery.

The control switch has ON/OFF mechanism which allows the current to flow when

needed.

2.3  OBJECTIVES OF THE PROJECT:

The main objectives of this project are:

·         Tapping of potential energy of the vehicles - The potential energy during the running of the vehicles should be tapped so as to make the model work accordingly this can be done is very simple manner as in by making an arrangement of a shell type dome which is supported by the springs, this dome will go in downward direction whenever a vehicle step on it and the spring force will keep the dome into its initial position after a vehicle pass by the speed breaker.

·         Structural formation of a power generating unit – A power generating unit is to be designed which can develop sufficient amount of power with the arrangement most feasible with the model for an optimal power generation. The structure of the power generating unit includes the shaft and the rotor arrangement which is connected to the generator assembly also the piezo-electric material have some rectifier circuit to have a steady output of current.

·         Design and development of a hybrid power generation – A design it made to make a hybrid model to generate power through it using two energy resources and tapping maximum energy from the power generating unit by the use of alternative methods.

·         Reduce power and friction losses – By using alternative methods and hybrid model the power loss and frictional losses can be minimized up to a large extent and the maximum power can be generated with reduced losses in the energy.

·         Less corrosion and erosion – A model is to be made such that to reduce the corrosion in the components and less erosion or wearing rate of the components.

·         Easy maintenance – To develop a power generation system which has easy maintenance as well as improved quality of work can be obtained by the system.

·         To develop a system this is always in standby mode.

·         Development of a power generation system which is more economical than other methods.

 Technical Details

While moving, the vehicles possess some potential energy and it is being wasted. This potential energy can be utilized to produce power by using a special arrangement. It is an Electro-Mechanical unit. It utilizes both mechanical technologies and electrical techniques for the power generation and its storage. This is a dome like device likely to be speed breaker.

                                                           

Whenever the vehicle is allowed to pass over the dome it gets pressed downwards then the springs are attached to the dome are compressed and the rack which is attached to the bottom of the dome moves downward in reciprocating motion. Since the rack has teeth connected to gears, there exists conversion of reciprocating motion of rack into rotary motion of gears but the two gears rotate in opposite direction. A flywheel is mounted on the shaft whose function is to regulate the fluctuation in the energy and to make the energy uniform. So that the shafts will rotate with certain R.P.M. these shafts are connected through a belt drive to the dynamos, which converts the mechanical energy into electrical energy. The conversion will be proportional to traffic density. Whenever an armature rotates between the magnetic fields of south and north poles, an E.M.F (electro motive force) is induced in it. So, for inducing the E.M.F armature coil has to rotate, for rotating this armature it is connected to a long shaft. By rotating same e.m.f, is induced, for this rotation kinetic energy of moving vehicles is utilized.

The power is generated in both the directions; to convert this power into one way a special component is used called zenor diode for continuous supply. All this mechanism can be housed under the dome, like speed breaker, which is called HUMP. The electrical output can be improved by arranging these speed breakers in series. This generated power can be amplified and stored by using different electrical devices.

The various machine elements used in the construction of power hump are:

·         RACK & PINION

·         SPUR GEAR

·         FLY WHEEL

·         BEARINGS

·         SHAFT

·         SPRINGS

·         ELECTRIC DYNAMO

·         PIEZO-ELECTRIC UNIT

The basic principle of working of above components is as follows:

3.1 RACK AND PINION:

Its primary function is to convert translatory motion into rotary motion in other words A rack and pinion is a type of linear actuator that comprises a pair of gears which convert rotational motion into linear motion. A circular gear called "the pinion" engages teeth on a linear "gear" bar called "the rack"; rotational motion applied to the pinion causes the rack to move, thereby translating the rotational motion of the pinion into the linear motion of the rack. It must have higher strength, rigidity and resistance to shock load and less wear and tear.

The rack and pinion arrangement is commonly found in the steering mechanism of cars or other wheeled, steered vehicles. This arrangement provides a lesser mechanical advantage than other mechanisms such as recirculating ball, but much less backlash and greater feedback, or steering "feel". The use of a variable rack (still using a normal pinion) was invented by Arthur Ernest Bishop, so as to improve vehicle response and steering "feel" especially at high speeds, and that has been fitted to many new vehicles, after he created a specialised version of a net-shape warm press forging process to manufacture the racks to their final form, thus eliminating any subsequent need to machine the gear teeth. For every pair of conjugate involute profile, there is a basic rack. This basic rack is the profile of the conjugate gear of infinite pitch radius.

A generating rack is a rack outline used to indicate tooth details and dimensions for the design of a generating tool, such as a hob or a gear shaper cutter.

A ‘rack and pinion’ gears system looks quite unusual. However, it is still composed of two gears. The ‘pinion’ is the normal round gear and the ‘rack’ is straight or flat. The ‘rack’ has teeth cut in it and they mesh with the teeth of the pinion gear. The pinion rotates and moves the rack in a straight line - another way of describing this is to say ‘rotary motion’ changes to ‘linear motion’.

In this project this rack and pinion assembly is used to convert the downward motion of the rack into the rotator motion of the pinion gear.

3.2   SPUR GEAR:

It is a positive power transmission device with definite velocity ratio. In volute teeth profile is preferred for adjusting some linear misalignment. Spur gears or straight-cut gears are the simplest type of gear. They consist of a cylinder or disk with the teeth projecting radially, and although they are not straight-sided in form, the edge of each tooth is straight and aligned parallel to the axis of rotation. These gears can be meshed together correctly only if they are fitted to parallel shafts.

The pinion is the smallest gear and the larger gear is called the gear wheel. A rack is a rectangular prism with gear teeth machined along one side- it is in effect a gear wheel with an infinite pitch circle diameter.   In practice the action of gears in transmitting motion is a cam action each pair of mating teeth acting as cams.  Gear design has evolved to such a level that throughout the motion of each contacting pair of teeth the velocity ratio of the gears is maintained fixed and the velocity ratio is still fixed as each subsequent pair of teeth come into contact.   When the teeth action is such that the driving tooth moving at constant angular velocity produces a proportional constant velocity of the driven tooth the action is termed a conjugate action.   The teeth shape universally selected for the gear teeth is the involute profile.

Spur gears are the most common type of gears. They have straight teeth, and are mounted on parallel shafts. Sometimes, many spur gears are used at once to create very large gear reductions.Spur gears are used in many devices that you can see all over , like the electric screwdriver, dancing monster, oscillating sprinkler, windup alarm clock, washing machine and clothes dryer. But you won't find many in your car.
This is because the spur gear can be really loud. Each time a gear tooth engages a tooth on the other gear, the teeth collide, and this impact makes a noise. It also increases the stress on the gear teeth

Spur Gear Design:

The spur gear is is simplest type of gear manufactured and is generally used for transmission of rotary motion between parallel shafts.  The spur gear is the first choice option for gears except when high speeds, loads, and ratios direct towards other options.  Other gear types may also be preferred to provide more silent low-vibration operation.  A single spur gear is generally selected to have a ratio range of between 1:1 and 1:6 with a pitch line velocity up to 25 m/s.  The spur gear has an operating efficiency of 98-99%.  The pinion is made from a harder material than the wheel.  A gear pair should be selected to have the highest number of teeth consistent with a suitable safety margin in strength and wear.   The minimum number of teeth on a gear with a normal pressure angle of 20 degrees is 18.

Design Process

To select gears from a stock gear catalogue or do a first approximation for a gear design select the gear material and obtain a safe working stress e.g Yield stress / Factor of Safety. /Safe fatigue stress

• Determine the input speed, output speed, ratio, torque to be transmitted
• Select materials for the gears (pinion is more highly loaded than gear)
• Determine safe working stresses (uts /factor of safety or yield stress/factor of safety or Fatigue strength / Factor of safety )
• Determine Allowable endurance Stress S_e
• Select a module value and determine the resulting geometry of the gear
• Use the lewis formula and the endurance formula to establish the resulting face width
• If the gear proportions are reasonable then - proceed to more detailed evaluations
• If the resulting face width is excessive - change the module or material or both and start again

The gear face width should be selected in the range 9-15 x module or for straight spur gears-up to 60% of the pinion diameter.

Materials used for spur gears design: Mild steel is a poor material for gears as it has poor resistance to surface loading.   The carbon content for unhardened gears is generally 0.4 %( min) with 0.55 %( min) carbon for the pinions.  Dissimilar materials should be used for the meshing gears - this particularly applies to alloy steels.  Alloy steels have superior fatigue properties compared to carbon steels for comparable strengths.  For extremely high gear loading case hardened steels are used the surface hardening method employed should be such to provide sufficient case depth for the final grinding process used.

Contact Ratio for spur gear:

The gear design is such that when in mesh the rotating gears have more than one gear in contact and transferring the torque for some of the time.   This property is called the contact ratio.  This is a ratio of the length of the line-of-action to the base pitch.   The higher the contact ratio the more the load is shared between teeth.  It is good practice to maintain a contact ratio of 1.2 or greater. Under no circumstances should the ratio drop below 1.1.

A contact ratio between 1 and 2 means that part of the time two pairs of teeth are in contact and during the remaining time one pair is in contact.   A ratio between 2 and 3 means 2 or 3 pairs of teeth are always in contact.   Such as high contact ratio generally is not obtained with external spur gears, but can be developed in the meshing of an internal and external spur gear pair or specially designed non-standard external spur gears.

For an optimal performance of the spur gear it should have low wear and tear, high shock-absorbing capacity.

3.3  FLYWHEEL:

The primary function of flywheel is to act as an energy accumulator. It reduces the fluctuations in speed. It absorbs the energy when demand is less and release the same when it is required.

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 causing its rotational speed, and hence its stored energy, to increase. Conversely, a flywheel releases stored energy by applying torque to a mechanical load, which results in decreased rotational speed.

Flywheels have three predominant uses:

• They provide continuous energy when the energy source is not continuous. For example, flywheels are used in reciprocating engines because the energy source (torque from the engine) is not continuously available.
• They deliver energy at rates beyond the ability of an energy source. This is achieved by collecting energy in the flywheel over time and then releasing the energy quickly, at rates that exceed the capabilities of the energy source.
• They control the orientation of a mechanical system. In such applications, the angular momentum of a flywheel is purposely transferred to a load when energy is transferred to or from the flywheel.

Flywheels are typically made of steel and rotate on conventional bearings; these are generally limited to a revolution rate of a few thousand RPM. Some modern flywheels are made of carbon fiber materials and employ magnetic bearings, enabling them to revolve at speeds up to 60,000 RPM

Flywheels are often used to provide continuous energy in systems where the energy source is not continuous. In such cases, the flywheel stores energy when torque is applied by the energy source and it releases stored energy when the energy source is not applying torque to it. For example, a flywheel is used to maintain constant angular velocity of the crankshaft in a reciprocating engine. In this case, the flywheel—which is mounted on the crankshaft—stores energy when torque is exerted on it by a firing piston, and it releases energy to its mechanical loads when no piston is exerting torque on it. Another example of this is friction motors, which use flywheel energy to power devices such as toy cars.
A flywheel may also be used to supply unsustained pulses of energy at energy transfer rates that exceed the capabilities of its energy source, or when such pulses would disrupt the energy supply (e.g., public electric network). This is achieved by accumulating stored energy in the flywheel over a period of time, at a rate that is compatible with the energy source, and then releasing that energy at a much higher rate over a relatively short time. For example, flywheels are used in punching machines and riveting machines, where they store energy from the motor and release it during the punching or riveting operation.

The phenomenon of precession has to be considered when using flywheels in vehicles. A rotating flywheel responds to any momentum that tends to change the direction of its axis of rotation by a resulting precession rotation. A vehicle with a vertical-axis flywheel would experience a lateral momentum when passing the top of a hill or the bottom of a valley (roll momentum in response to a pitch change). Two counter-rotating flywheels may be needed to eliminate this effect. This effect is leveraged in momentum wheels, a type of flywheel employed in satellites in which the flywheel is used to orient the satellite's instruments without thruster rockets.

3.4  BEARINGS:

A bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can handle.

There are at least six common principles of operation of bearings:

• plain bearing, also known by the specific styles: bushings, journal bearings, sleeve bearings, rifle bearings
• rolling-element bearings such as ball bearings and roller bearings
• jewel bearings, in which the load is carried by rolling the axle slightly off-center
• fluid bearings, in which the load is carried by a gas or liquid
• magnetic bearings, in which the load is carried by a magnetic field
• flexure bearings, in which the motion is supported by a load element which bends.

Reducing friction in bearings is often important for efficiency, to reduce wear and to facilitate extended use at high speeds and to avoid overheating and premature failure of the bearing. Essentially, a bearing can reduce friction by virtue of its shape, by its material, or by introducing and containing a fluid between surfaces or by separating the surfaces with an electromagnetic field.

• By shape, gains advantage usually by using spheres or rollers, or by forming flexure bearings.
• By material exploits the nature of the bearing material used. (An example would be using plastics that have low surface friction.)
• By fluid exploits the low viscosity of a layer of fluid, such as a lubricant or as a pressurized medium to keep the two solid parts from touching, or by reducing the normal force between them.
• By fields exploits electromagnetic fields, such as magnetic fields, to keep solid parts from touching.

Combinations of these can even be employed within the same bearing. An example of this is where the cage is made of plastic, and it separates the rollers/balls, which reduce friction by their shape and finish.

ROLLING ELEMENT BEARINGS:

Rolling element bearing life is determined by load, temperature, maintenance, lubrication, material defects, contamination, handling, installation and other factors. These factors can all have a significant effect on bearing life. For example, the service life of bearings in one application was extended dramatically by changing how the bearings were stored before installation and use, as vibrations during storage caused lubricant failure even when the only load on the bearing was its own weight; the resulting damage is often false brinelling. Bearing life is statistical: several samples of a given bearing will often exhibit a bell curve of service life, with a few samples showing significantly better or worse life. Bearing life varies because microscopic structure and contamination vary greatly even where macroscopically they seem identical.

PLAIN BEARINGS:

For plain bearings some materials give much longer life than others. Some of the John Harrison clocks still operate after hundreds of years because of the lignum vitae wood employed in their construction, whereas his metal clocks are seldom run due to potential wear.

FLEXURE BEARINGS:

Flexure bearings rely on elastic properties of material. Flexure bearings bend a piece of material repeatedly. Some materials fail after repeated bending, even at low loads, but careful material selection and bearing design can make flexure bearing life indefinite.

It is a machine element, which supports another machinery. It permits relative motion between the contacting surfaces while carrying the loads. They reduce the friction and transmit the motion effectively. These bearings are used in the shaft attached to the flywheel.

They are useful in friction less movement of the shaft.

3.5  SHAFTS:

A shaft is a rotating member usually of circular cross-section (solid or hollow), which is used to transmit power and rotational motion. Axles are non rotating member. Elements such as gears, pulleys (sheaves), flywheels clutches, and sprockets are mounted on the shaft and are used to transmit power from the driving device (motor or engine) through a machine. The rotational force (torque) is transmitted to these elements on the shaft by press fit, keys, dowel, pins and splines. The shaft rotates on rolling contact or bush bearings. Various types of retaining rings, thrust bearings, grooves and steps in the shaft are used to take up axial loads and locate the rotating elements.

It is a rotating element, which is used to transmit power from one place to another place. It supports the rotating elements like gears and flywheels. It must have high torsional rigidity and lateral rigidity.

3.6 SPRINGS:

A spring is an elastic object used to store mechanical energy. Springs are usually made out of spring steel. Small springs can be wound from pre-hardened stock, while larger ones are made from annealed steel and hardened after fabrication. Some non-ferrous metals are also used including phosphor bronze and titanium for parts requiring corrosion resistance and beryllium copper for springs carrying electrical current (because of its low electrical resistance).
When a spring is compressed or stretched, the force it exerts is proportional to its change in length. The rate or spring constant of a spring is the change in the force it exerts, divided by the change in deflection of the spring. That is, it is the gradient of the force versus deflection curve. An extension or compression spring has units of force divided by distance, for example lbf/in or N/m. Torsion springs have units of force multiplied by distance divided by angle, such as N·m/rad or ft·lbf/degree. The inverse of spring rate is compliance, that is: if a spring has a rate of 10 N/mm, it has a compliance of 0.1 mm/N. The stiffness (or rate) of springs in parallel is additive, as is the compliance of springs in series.
Depending on the design and required operating environment, any material can be used to construct a spring, so long as the material has the required combination of rigidity and elasticity: technically, a wooden bow is a form of spring.

SPRINGS CAN BE CLASSIFIED DEPENDING ON HOW THE LOAD FORCE IS APPLIED TO THEM:

• Tension/Extension spring – the spring is designed to operate with a tension load, so the spring stretches as the load is applied to it.
• Compression spring – is designed to operate with a compression load, so the spring gets shorter as the load is applied to it.
• Torsion spring – unlike the above types in which the load is an axial force, the load applied to a torsion spring is a torque or twisting force, and the end of the spring rotates through an angle as the load is applied.

THEY CAN ALSO BE CLASSIFIED BASED ON THEIR SHAPE:

• Coil spring – this type is made of a coil or helix of wire
• Flat spring – this type is made of a flat or conical shaped piece of metal.
• Machined spring - this type of spring is manufactured by machining bar stock with a lathe and/or milling operation rather than coiling wire. Since it is machined, the spring may incorporate features in addition to the elastic element. Machined springs can be made in the typical load cases of compression/extension, torsion, etc.

THE MOST COMMON TYPES OF SPRING ARE:

·         Cantilever spring – a spring which is fixed only at one end.

• Coil spring or helical spring – a spring (made by winding a wire around a cylinder) and the conical spring – these are types of torsion spring, because the wire itself is twisted when the spring is compressed or stretched. These are in turn of two types:
• Compression springs are designed to become shorter when loaded. Their turns (loops) are not touching in the unloaded position, and they need no attachment points.
• A volute spring is a compression spring in the form of a cone, designed so that under compression the coils are not forced against each other, thus permitting longer travel.
• Tension or extension springs are designed to become longer under load. Their turns (loops) are normally touching in the unloaded position, and they have a hook, eye or some other means of attachment at each end.
• Hairspring or balance spring – a delicate spiral torsion spring used in watches, galvanometers, and places where electricity must be carried to partially-rotating devices such as steering wheels without hindering the rotation.
• Leaf spring – a flat spring used in vehicle suspensions, electrical switches, and bows.
• V-spring – used in antique firearm mechanisms such as the wheellock, flintlock and percussion cap locks.

It is defined as an elastic body whose function is to distort when loaded and to recover its original shape when the load is removed. It cushions, absorbs or controls energy either due to shocks or due to vibrations.

3.7  ELECTRIC DYNAMO/ ELECTRIC GENERATOR:

Electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge (usually carried by electrons) to flow through an external electrical circuit. It is analogous to a water pump, which causes water to flow (but does not create water). The source of mechanical energy may be a reciprocating or turbine steam engine, water falling through a turbine or waterwheel, an internal combustion engine, a wind turbine, a hand crank, compressed air or any other source of mechanical energy.The reverse conversion of electrical energy into mechanical energy is done by an electric motor, and motors and generators have many similarities. In fact many motors can be mechanically driven to generate electricity, and very frequently make acceptable generators.

Before the connection between magnetism and electricity was discovered, electrostatic generators were invented that used electrostatic principles. These generated very high voltages and low currents. They operated by using moving electrically charged belts, plates and disks to carry charge to a high potential electrode. The charge was generated using either of two mechanisms:

• Electrostatic induction.
• The triboelectric effect, where the contact between two insulators leaves them charged.

Because of their inefficiency and the difficulty of insulating machines producing very high voltages, electrostatic generators had low power ratings and were never used for generation of commercially significant quantities of electric power. The Wimshurst machine and Van de Graff generator are examples of these machines that have survived.

Simple loop generator is having a single-turn rectangular copper coil rotating about its own axis in a magnetic field provided by either permanent magnet or electro magnets. In case of without commutator the two ends of the coil are joined to slip rings which are insulated from each other and from the central shaft. Two collecting brushes ( of carbon or copper) press against the slip rings. Their function is to collect the current induced in the coil. In this case the current waveform we obtain is alternating current ( you can see in fig). In case of with commutator the slip rings are replaced by split rings. In this case the current is unidirectional (observe in fig).

Generator working :
In figure see the case when the coil is rotating in anticlock-wise direction without commutator. As the coil assumes successive positions in the field, the flux linked with it changes. Hence, an e.m.f is induced in it which is proportional to the rate of change of flux linkages (e=-N dΦ/dt). When the plane of the coil is at right angles to lines of flux then flux linked with the coil is maximum but rate of change of flux linkages is minimum.

It is so because in this position, the coil sides do not cut or shear the flux, rather they slide along them i.e they move parallel to them.Hence,there is no induced e.m.f in the coil.Generaly this no e.m.f is taken as the starting position i.e zero degrees position.The angle of rotation or time wil be measured from this position.

As the coil continues rotating further, the rate of change of flux linkages (and hence induced e.m.f in it) increases till the coil rotates 90° from its starting position. Here the coil plane is vertical (see in fig) i.e parallel to the lines of flux. As seen, the flux linked with the coil is minimum but rate of change of flux linkages is maximum. Hence, maximum e.m.f is induced in the coil when in this position.

In the next quarter revolution i.e. from 90° to 180°,the flux linked with the coil gradually increases but the rate of change of flux linkages decreases .  Hence, induced e.m.f decreases gradually till it becomes zero.

So,we find that in the first half revolution of the coil, no e.m.f is induced in it at 0°, maximum when the coil is at 90° position anno e.m.f when coil is at 180°.The direction of this induced e.m.f can be found by applying Fleming's Right hand rule.

In the next half revolution i.e. from 180° to 360°, the variations in the magnitude of e.m.f are similar to those in the first half revolution . Its value is maximum when coil is at 270° and minimum when the coil is at 360° position . But it will be found that the direction of induced current is reverse of the previous direction of flow.

Therefore, we find that the current which we obtain from such a simple generator reverses its direction after every half revolution. Such a current undergoing periodic reversals is known as alternating current . It should be noted that alternating current not only reverses its direction, it does not even keep its magnitude constant while flowing in any one direction.The two half- cycles may be called positive and negative half-cycles respectively.

Now see when the coil is rotating with commutator . In this case the slip rings are replaced by split rings. The split rings are made out of a conducting cylinder which is cut into two halves or segments insulated from each other by a thin sheet of mica or some other insulating material .As before, the coil ends are joined to these segments on which rest the carbon or copper brushes.

In case of split rings, the positions of the segments of split rings have also reversed when the current induced in the coil reverses i.e. when the current direction reverses the brushes also comes in contact with reverse segments as that of positive half-cycle. Hence, this current is unidirectional. It should be noted that the position of the brushes is so arranged that the changeover of segments from one brush to other takes place when the plane of the rotating coil is at right angles to the plane of the lines of flux. It is so because in that position, the induced e.m.f in the coil is zero. You can observe this in two cases by pausing the waveform.

Another important point is that now the current induced in the coil is alternating as before. It is only due to the rectifying action of the split-rings (also called commutator) that it becomes unidirectional in the external circuit.