Spark Plug in IC Engines

Spark Plug in IC Engines

A spark plug in IC engines is a device used to produce spark for igniting the charge of petrol engines. It is always screwed into the cylinder head. It is, usually, designed to withstand a pressure upto 35 bar and operate under a current of 10 000 to 30 000 volts. The spark plug gap is kept from 0.3 mm to 0.7 mm.

Super chargers by prof moses dhilipkumar

    Super chargers

Super charger acts as an air compressor. It is used to increase the density and pressure of the air that is supplied to the internal combustion engine. In the engine, during the intake of the cycle it takes more oxygen and burn more fuel to accomplish the work. This is due the power increase.

By using the belts, gears, shafts, chains all of these are connected to the engines crank shaft to produce super charge.

We can see two types of the super chargers. To that matter after super charging, the air enters into the engine. After compression the pressure in the air is compressed and it super charges the system by 1.5 to 2 times to increase the entry of the pressure.

In one type of the super charger the engine shaft is mechanically linked to the shaft. The shaft energy must turn into useful work input for the super charger.

In another type of the super charger the compressor is attached to the turbine. Exhaust gas must be allowed to enter into the turbine. The turbine drives the super charger; this type of super charger is known as the turbo 

Super charger drive types:

They are divided into mechanical, exhaust gas turbine and other types:

Mechanical drives are divided into four types they are belt drive, chain drive, direct drive and gear drive.

Exhaust gas turbines are divided into two types they are radial turbine and axial turbine.

And the other type of the drives is electrical motor and auxiliary power unit.

Advantages of supercharger:

• The work output and the overall efficiency of the engine must be increased by 50% of the supercharger.
• At the higher heights, the low density air is converted into the normal density air.
• In the supercharge engine the specific fuel consumption is saved
• In the volumetric efficiency of the super charger engine will be higher
• To run the super charger, exhaust gas must be re-circulated in the engine. In this case the work input will be increases.
• In the super charged engine the scavenging is improved.

Disadvantages of supercharger:

• On the engine, different moving parts are observed like the thermal stress, mainly on the bearing of the engine shafts.
• So it results in the wear and tear in the moving parts
• We need to replace the parts frequently in the engine
• During the time of compression stroked by the piston there is a leakage of the air in the super charge engine
• Due to the super charging, the temperature of the air entering the engine cylinder will be higher.
• The detonation tendency of the engine increases.
• In the petrol engine, the detonation reduces so inter coolers are used to increases the size of the engine.

Bolt | Types, Parts, Manufacturing, Material Selection, Applications

Bolt | Types, Parts, Manufacturing, Material Selection, Applications

 

 

 

A bolt is a type of threaded fastener (like a screw) and is a male part. It is generally made of a metal. It is used to keep two or more hardware parts together (in a specific position).

Shank of the bolt is only partially threaded, just to accommodate a nut.

A bolt is sometimes also known as through bolt.

Note: Those who don’t know ‘shank’. It is discussed later in this article.

Note: Those who don’t know ‘What is a fastener?’. A fastener is a hardware device which mechanically affixes or joins two or more parts together.

However, there are many similarities between bolts and screws, there are some differences too.

Differences between screws and bolts
You can find some differences between screws and bolts, just by looking above figures. Below are some other differences.

A screw can have a tapered shank but a bolt can’t because it has to be assembled with a nut
Bolt require nut to have a grip on the joining parts but screw doesn’t.


Bolts are used to assemble two non-threaded parts together (unlike screw).
Screws are smaller in size when compared to bolts.
Screws have a large variety of head whereas bolts have either hexagonal or square head.

As shown in above diagram a bolt can be divided into following parts.

Head: It is the part of a bolt from where a spanner can hold it (to make it tight or loose).
Shank: A bolt can be broadly divided into two parts head and shank. Shank is partially threaded (as shown in figure) to accommodate a nut.


Grip length: It is the part of bolt that accommodates the parts which are to be assembled. Grip length should be equal to the combined thickness of joining parts.
Thread length: It is the part of bolt that accommodates the nut.
Nominal length: It is the sum of thread length and grip length (as shown in figure).
Type of bolt heads
Following are some most common types of bolt heads

Hexagon flange head
Hexagon (trimmed) head
Indented hexagon washer head
Indented hexagon head
Square shoulder head
Types of bolts
Following are some most common types of bolts

U-Bolt
Shoulder bolt or Stripper bolt
Sex bolt or Chicago Bolt
Rock bolt
Lag bolt
J bolt
Hex bolt
Hanger bolt
Elevator bolt
Carriage bolt
Arbor bolt
Anchor bolt
Flange bolt
Machine bolt
Plow bolt
Square head bolt
Stud bolt
Timber bolt
T-head bolt
Toggle bolt
Selection of bolt material
Following materials are generally used for manufacturing the bolts


Nylon Bolts: They are lightweight and water resistant
Bronze and Brass Bolts: They are water resistant
Stainless Steel Bolts: They have good strength and are corrosion resistant
Steel Bolts: They have good strength
Titanium Bolts: They are strong, light and corrosion resistant
Plastic Bolts: They are inexpensive and corrosion resistant. They are generally used for light loads.
Copper alloy Bolts: They are wear resistant and have good load capacity.
Aluminium Bolts: They are thermally and electrically conductive. They are light and easy to manufacture.
Apart from above material, sometimes finishing material is also applied to the bolts. Finishing material provides durability and corrosion resistance to the bolt. Here are some finishing materials used for bolts.

Zinc: Its coating acts as a sacrificial anode, protecting the underlying metal. It is applied as fine white dust.
Black oxide: Its coating is mostly used for aesthetic purpose. It does not enlarge the dimensions of the bolt. It is a processed black rust.


Chrome: Its coating gives a bright, reflective finish. It is decorative and very durable. It is applied by electroplating.
Manufacturing of Bolts
There are three major steps in the manufacturing a bolt.

Heading
Thread rolling
Coating
Bolts are normally made from wire. The wire is then cut to the proper length for the type of bolt being made. Heading produces the head of the bolt. The shape of the die in the machine dictates the features to be pressed into the bolt head for example a round head bolt uses a round die.

The threads are generally produced via thread rolling. However, some are machined.

Finally, a coating, such as electroplating with zinc or black oxide, is applied to prevent corrosion.

Applications of Bolt (or Through Bolt)
Bolt can be used in following conditions

When the parts that are fastened, require frequent dismantling and reassembly.
When the parts that are fastened, are made of material which is too weak to make durable threads.
When the parts that are fastened have medium thickness. For example, beams, flanges or plates etc.


When there is a place available for bolt head and nut.
When there is a place available for spanner.
Relative advantages and disadvantages of screws and bolts
Screws are cheaper compared to bolts.
Bolts are good for frequent dismantling and reassembling, unlike screws.
Bolts carry load on a larger shank area when compared to screw

no blade turbines (tesla turbine)

    No blade turbines (tesla turbine)

The Tesla turbine is a bladeless centripetal flow turbine patented by Nikola Tesla in 1913. It is referred to as a bladeless turbine because it uses the boundary layer effect and not a fluid impinging upon the blades as in a conventional turbine. The Tesla turbine is also known as the boundary layer turbine, cohesion-type turbine, and Prandtl layer turbine (after Ludwig Prandtl). Bioengineering researchers have referred to it as a multiple disk centrifugal pump. 

The job of any engine is to convert energy from a fuel source into mechanical energy. Whether the natural source is air, moving water, coal or petroleum, the input energy is a fluid. And by fluid we mean something very specific -- it's any substance that flows under an applied stress. Both gases and liquids, therefore, are fluids, which can be exemplified by water. As far as an engineer is concerned, liquid water and gaseous water, or steam, function as a fluid.

At the beginning of the 20th century, two types of engines were common: bladed turbines, driven by either moving water or steam generated from heated water, and piston engines, driven by gases produced during the combustion of gasoline. The former is a type of rotary engine, the latter a type of reciprocating engine. Both types of engines were complicated machines that were difficult and time-consuming to build.

Consider a piston as an example. A piston is a cylindrical piece of metal that moves up and down, usually inside another cylinder. In addition to the pistons and cylinders themselves, other parts of the engine include valves, cams, bearings, gaskets and rings. Each one of these parts represents an opportunity for failure. And, collectively, they add to the weight and inefficiency of the engine as a whole.

Bladed turbines had fewer moving parts, but they presented their own problems. Most were huge pieces of machinery with very narrow tolerances. If not built properly, blades could break or crack.

Tesla's new engine was a bladeless turbine, which would still use a fluid as the vehicle of energy, but would be much more efficient in converting the fluid energy into motion.