Tuesday 27 January 2015

SUPERCHARGER



SUPERCHARGER:-

Superchargers, otherwise known as blowers, are a form of compressor driven by the engine’s crankshaft (often with a belt) to turn an impeller or rotors, which compress air to create boost.Originally built for World War II aircraft, superchargers have become very common in today's performance automotive world, and featured as original equipment on some new sports cars straight from the factory.Superchargers have become popular in recent years for several reasons, including cost efficiency, reliability, and of course, performance. Supercharging an engine often results in huge power increases in the range of 50% to 100%, making them great for racing, hauling heavy loads, or just having fun in your daily driver.

Heat exchangers (intercoolers) are frequently used in conjunction with superchargers. Compressing air increases its temperature thus making it less dense. By re-cooling the compressed volume of air before it enters, density is increased allowing even more air to be forced into the engine. Intercoolers are more important for turbo superchargers as there are two heating sources present, the act of compression and heat from exhaust gasses both increase air temperature.

What is the need of extra air by external means?

Engines combust (burn) fuel and use the energy of that combustion to do work. The more fuel that is combusted in any given time then the more energy is available to carry out the engines task. Fuel requires air (or the oxygen contained within air) to burn so if there isn’t enough air mixed with the fuel it will not burn. This also means that the amount of air entering an engine determines how much fuel can be burnt and consequently how much energy (or power) an engine can produce. Superchargers are essentially an air pump designed to cram extra air into an engine allowing it to combust more fuel than would otherwise be possible
.

Many people assume that running a supercharger, and hence added intake boost, puts added strain on an engine's engine parts. This is not necessarily true, because engine damage is almost always caused by RPM. Because a supercharger helps the engine produce more power at lower RPM, supercharged engines will make the same horsepower as their naturally aspirated counterparts at substantially lower engine RPM, where today's street engine's are designed to run (around 6000 RPM). Another concern some people have towards using a supercharger is that they think it will increase the engine's compression to the point that it will cause detonation inside the combustion chamber. Detonation exists when the combustion pressure is raised so high that the inlet charge ignites itself before the spark plug fires. When this happens, combustion takes place while the piston is still traveling up in the cylinder bore, which puts tremendous loads on the piston, rod, and crank. While it is true that a supercharged engine creates boost and increases the engine's compression, most supercharger kits include a boost timing retard chip that retards the engine's ignition timing under certain conditions to prevent detonation. With some kits, detonation is not a concern, in which case the kit will not include a boost timing retard chip.

Advantages:-

1.)Increased horsepower: adding a supercharger to any engine is a quick solution to boosting power.
2.)The supercharger does not have a delay. It is always operating at the speed of the engine.So Power delivery is immediate because the supercharger is driven by the engine’s crankshaft.
3.)Supercharging systems are less complex than turbos, which require extensive modification of the exhaust system.
4.)Low RPM boost: good power at low RPM in comparison with turbochargers.
5.)Because they are less complex, and easier to work on, they are thus cheaper to install and generally cost less to service and maintain.

DISC BRAKE


Disc brakes use a flat, disk-shaped metal rotor that spins with the wheel. When the brakes are applied, a caliper squeezes the brake pads against the disc (just as you would stop a spinning disc by squeezing it between your fingers), slowing the wheel.

Disc brakes use the same principle as bicycle handbrakes, but on a bike the brake pads press against the wheel itself. On a car, the disc is part of the hub to which the wheel is mounted. The disc, technically called a rotor, is clearly visible through spoked wheels.Disc brakes generate amazing stopping power even in the worst conditions because they utilize rotors (photo) attached to the wheel hubs, and calipers attached to the frame containing specially designed pads 



The main components of a disc brake are:
  • The brake pads
  • The caliper, which contains a piston
  • The rotor, which is mounted to the hub

How Disc Brakes Work?

On a disc brake, the fluid from the master cylinder is forced into a caliper where it presses against a piston. The piston, in turn, squeezes two brake pads against the disc (rotor) which is attached to the wheel, forcing it to slow down or stop. 




This process is similar to a bicycle brake where two rubber pads rub against the wheel rim to create stopping friction.



Why do disc brake have holes in them?

Due to following reasons :-

>These holes significantly increasing the grab or friction of the brake caliper pads. 
>Reduce the weight of whole assembly.
>For proper heat dissipation generated during braking.
>The holes are spaced in such a way that the calipers used in the brake wear out uniformly, to ensure maximum longevity.

SCREW JACK




A screw jack is a mechanical device that can increase the magnitude of an effort force.Screw jack is used in applications where linear motion is required. Lifting of any load, pushing or pulling of mechanical equipment, adjusting of tight clearances of mechanical parts can be done by screw jacks. Mechanical capacity of screw jacks is between 5kN and 2000kN. Jack screws can be used as linear motors, linear actuators, or mechanical lifts depending on type of motion.

The effort force for a screw jack when neglecting friction can be expressed as:-
F = (Q p) / (2 π R)         (1)
where
F = effort force at the end of the arm or handle (lb)
Q = weight or load (lb)
p = pitch distance or lead of thread in one turn  (in)
r = pitch radius of screw (in)
R = lever-arm radius (in)

Screw Jack Applications:-


Paper, press, printing industry
Gypsum factories
Sheet metal forming machinery
Mechanical lifting applications
Platform lifting applications
Food processing machinery
Construction sector
Bridge jacks for road and bridge lifting
Shipyards
Opening and closing of penstocks
Industrial process
Roll form machinery
Mining industry
Defense industry
Lift tables
Stage setup applications 

HVAC SYSTEM



HVAC SYSTEM:-
HVAC system stands for Heating Ventilation and Air Conditioning system.
Heating, Ventilating, and Air Conditioning (HVAC) equipment perform heating and/or cooling for residential, commercial or industrial buildings.

The HVAC system may also be responsible for providing fresh outdoor air to dilute interior airborne contaminants such as odors from occupants, volatile organic compounds (VOC’s) emitted from interior furnishings, chemicals used for cleaning, etc.
Usually a sensing device is used to compare the actual state (e.g., temperature) with a target state.
Then the control system draws a conclusion what action has to be taken (e.g., start the blower).
A properly designed system will provide a comfortable indoor environment year round when properly maintained.

VARIOUS COMPONENTS OF AN ENGINE


Internal combustion engines are made from various parts.Each part has its own location and function for proper working of engine.. There are hundreds of components which have to perform their functions satisfactorily to produce output power. The major components of the engine and their functions are briefly described below:-



1.)Cylinder Block:


The cylinder block is the largest part of the engine. Its upper section carries the cylinders and pistons. Normally, the lower section forms the crankcase, and supports the crankshaft.It is the main supporting structure for the various components. The cylinders of a multicylinder engine are cast as a single unit, called cylinder block.It is the portion of the engine between the cylinder head and sump (oil pan)and is the supporting structure for the entire engine. All the engine parts are mounted on it or in it and this holds the parts in alignment.Cylinder blocks made of aluminum are lighter than cast-iron blocks of the same size. They usually have cast-iron liners which provide a hard-wearing surface for pistons and piston rings.

Function- In the bore of cylinder the fresh charge of air-fuel mixture is ignited,compressed by piston and expanded to give power to piston.

2.)Cylinder Head:

It carries inlet and exhaust valve.Fresh charge is admitted through inlet valve and burnt gases are exhausted from exhaust valve.In case of petrol engine,a spark plug and in case of diesel engine,a injector is also mounted on cylinder head.
3.)Cylinder: 
As the name implies it is a cylindrical vessel or space in which the piston makes a reciprocating motion.The varying volume created in the cylinder during the operation of the engine is filled with the working fluid and subjected to different thermodynamic processes. The cylinder is supported in the cylinder block.
4.)Piston:
This is a pressure-tight cylindrical plunger which is subjected to the expanding gas pressure.It is fitted into the cylinder forming the moving boundary of the combustion system. It fits perfectly into the cylinder providing a gas-tight space with the piston rings and the lubricant. It forms the first link in transmitting the gas forces to the output shaft.
Function-During suction stroke,it sucks the fresh charge of air-fuel mixture through inlet valve and compresses during the compression stroke inside the cylinder.This way piston receives power from the expanding gases after ignition in cylinder.Also forces the burnt exhaust gases out of the cylinder through exhaust valve.

5.)Piston rings:
 These are circular rings which seal the gaps made between the piston and the cylinder, their object being to prevent gas escaping and to control the amount of lubricant which is allowed to reach the top of the cylinder.
Function-It prevents the compressed charge of fuel-air mixture from leaking to the other side of the piston.Oil rings,is used for removing lubricating oil from the cylinder after lubrication.This ring prevents the excess oil to mix with charge.
5.)Connecting Rod: 
It interconnects the piston and the crankshaft and transmits the gas forces from the piston to the crankshaft. The two ends of the connecting rod are called as small end and the big end. Small end is connected to the piston by gudgeon pin and the big end is connected to the crankshaft by crankpin.
Function-It changes the reciprocating motion of piston into rotary motion at crankshaft.This way connecting rod transmits the power produced at piston to crankshaft.

6.)Crankshaft:
It converts the reciprocating motion of the piston into useful rotary motion of the output shaft. In the crankshaft of a single cylinder engine there are a pair of crank arms and balance weights.A simple crankshaft consists of a circular-sectioned shaft which is bent or cranked to form two perpendicular crank-arms and an offset big-end journal. The unbent part of the shaft provides the main journals. The crankshaft is indirectly linked by the connecting-rod to the piston - this enables the straight-line motion of the piston to be transformed into a rotary motion at the crankshaft about the main-journal axis.
Function-Receives oscillating motion from connecting rod and gives a rotary motion to the main shaft.It also drives the camshaft which actuate the valves of the engine

7.)Camshaft:
The camshaft and its associated parts control the opening and closing of the two valves. The associated parts are push rods, rocker arms, valve springs and tappets. This shaft also provides the drive to the ignition system. The camshaft is driven by the crankshaft through timing gears.
Function-It takes driving force from crankshaft through gear train or chain and operates the inlet valve as well as exhaust valve with the help of cam followers,push rod and rocker arms.

8.)Spark Plug
Function-This device is used in petrol engine only and ignite the charge of fuel for combustion.

9.) Fuel Injector
Function-This device is used in diesel engine only and delivers fuel in fine spray under pressure

CNG ENGINE


CNG engine uses compressed natural gas to power the car. CNG is a substitute for gas and diesel fuel, and is considered to be much cheaper and cleaner than gas or diesel. Natural-gas-powered vehicles burn compressed natural gas (CNG) instead of conventional gasoline.




Why Use Compressed Natural Gas?

The benefits of CNG are lower operating costs, lower fuel costs, improved gasoline-gallon fuel economy, and almost zero smog-forming emissions. One example of a vehicle that uses CNG for its fuel is the Honda Civic Natural Gas Sedan.In addition, the CNG engine is considered to be more environmentally friendly. There are considerably less pollutants associated with compressed natural gas being ignited, and studies show that it gives off 40 percent less greenhouse gas.



The CNG Engine:-


The CNG engine uses a second fuel tank which has to be attached to the car, and is usually placed in the trunk (or other place where there is suitable room). This tank is usually very large, as it has to keep the gas used compressed. The amount of pressure may vary from engine to engine, but it is usually compressed to around 3,600 pounds per square inch. The driver can then decide which of the fuels they wish to use by simply pressing a switch on the dashboard. This means that the car can alternate between the different tanks, drawing fuel from either.Having a dual fuel system will ensure adequate fuel reserves in between natural gas fills. Compared to having only a gasoline engine, this additional fuel reserve will extend the vehicle’s driving range. Drivers can switch from CNG to gasoline even while driving, idling or parked. Some CNG systems will automatically switch to gasoline when the natural gas level reaches a preset low pressure setting.



How the CNG Engine works?

Once the driver selects the CNG tank, CNG is fed into the high pressure cylinders through the natural gas receptacle.The compressed gas in the tank is pulled through a series of highly pressurized lines until it reaches the regulator.Inside the regulator, the pressure on the gas is lessened until it matches the amount needed by the fuel injection system of the car's engine. Once the gas has reached an acceptable pressure, the solenoid valve allows the gas to move into the fuel injection system and from there into the engine.Just as with gasoline, once the engine has received the gas, it is ignited in the combustion chamber, and this provides the energy to power the car forward.

You can also convert your gas engine to CNG, a diesel conversion though doesn't have problems with predestination or need knock sensors like a gas conversion. Diesel engines is built for heavy duty use, exploding diesel with heat and combustion not spark. This all makes diesel engines the ideal CNG conversion candidate.