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Technical terms of engine

What is Technical Terms of  Engine


Introduction :- 

when  a machine is developed than at the first the machine is faced some technical problems and some shortcomings and to describe working function of the machine give a name to the working function and also problems and shortcomings that is known as technical terms. 

Technical terms of engine

Technical Terms:-

The technical terms are follow as under:-

1.  TDC - Top Dead Centre:

Inside an engine cylinder the last upward movement of piston from this the piston cannot move upward any more, this last movement known as TDC. 

2.   BDC - Bottom Dead Centre:

Inside an engine cylinder the last downward movement of the piston from this the piston can not move downward any more, this last movement known as BDC. 


3.   Stroke:-  

The distance between TDC to BDC known as a stroke. In other words inside an engine cylinder when piston moves once between TDC to BDC or BDC to TDC known as a stroke. 

Four stroke engine have four stroke follow as under:-

  (i)  Suction Stroke. 
  (ii) Compression Stroke. 
  (iii) Power Stroke. 
  (iv) Exhaust Stroke. 

4. Detonation/Knocking/Picking:- 

Inside an engine cylinder compressed the entire air and fuel during the compression stroke and ignite this mixture according the ignition timing. But once a time will come when a another SIT (self ignition temperature) is take place inside the engine cylinder and start burning at other place inside the engine cylinder. When these both fire get contact with each other than we able to hear a noise of blast from the engine cylinder this is known as detonation. Remember this is a defect of the engine. 

 The loses of detonation:-

    (i)  Piston may be cracked. 
    (ii) Piston rings may be cracked. 
    (iii) The valve seating may be loose. 
    (iv) The valve may be cracked. 
    (v)  The blow-by may be take place. 

Some things may effects detonation:-

    (i)  Quality of fuel. 
    (ii) Compression ratio. 
    (iii) Ratio of air and fuel mixture. 
    (iv) Design of combustion chamber. 

5.  Thermal Efficiency:- 

The ration of fuel input and power output of the engine is known as thermal efficiency. Fuel have some heat capabilities. Inside the engine cylinder ignite the mixture of air and fuel during the power stroke, the heat take place inside the cylinder and some heat act on piston head and got power output. 
But no any engine which get 100% thermal efficiency yet. An engine get maximum 30% to 35% thermal efficiency. 

Distribution of heat of the engine:-

Cooling System  =  30%
Exhaust System =  30%
Friction               =  05%
Useful Work       =  35% 

Some things may effects thermal efficiency:-

(i)  Quantity of air fuel mixture. 
(ii) Compression ratio.
(iii) Low thermal efficiency in low speed and high thermal efficiency in high speed. 
(iv) Timing of valve opening & closing. 

6.  Volumetric Efficiency:-  

During the normal temperature and pressure inside an engine cylinder fresh air make entire by weight and in normal condition the air enter automatically, the ratio of both above condition is known as volumetric efficiency.

Some things may effects volumetric efficiency:-

(i)  Critical way for air passing. 
(ii) Law of inertia. 
(iii) Heat of cylinder wall. 
(iv) Speed of engine. 
(v)  High altitude area. 
(vi) Opening & closing time of valve. 
(vii) Ignition timing. 
(viii) Compression ratio. 
(ix)   Breathing capabilities of engine.
(x)    Condition of the accelerator. 

Method of increase the volumetric efficiency:-

(i)    By using the super charger. 
(ii)   By using the turbo charger. 
(iii)  By using the multiple Carburator. 
(iv)  By increase the valve numbers. 

7.  Horse Power  :-  

The power we need to lift 33000 Lbs weight for one minute and one feet upward from earth this power known as horse power. 

Type of horse power:-

(i)    IHP (Indicated Horse Power ) - The power which make moves the piston from TDC to BDC during power stroke, this power known as IHP. This power experience on the head of piston.

(ii)  BHP (Brake Horse Power ) -  After losses some power into friction the power we found on the flywheel, known as BHP. This power increase till the fix RPM thenafter it decrease. This power measure by proney brake and dynamometer.

(iii)  FHP ( Friction Horse Power ):-
The power which consume in engine friction, known as FHP.

(iv)  NHP ( Net Horse Power ) :-  The vehicle runs by a power this power known as NHP. This power we get on the wheel of the vehicle. 

 8.  Combustion:-  

In some easy words the combustion is a fire, but if we judge the combustion as a fire this is not enough. So in other words the chemical process which used oxygen known as combustion. Now we talk about an engine than burning of air and fuel inside an engine cylinder known as combustion. The fuel have hydrocarbon and air have oxygen particals these bothe are burn together into the engine cylinder in resulting produce the heat and we got power only by this heat. 
Formula  -   HC + O2  = H2O + CO2 + Heat 

Some things may effects combustion:-

(i)    Compression ratio.
(ii)   Temperature of intake air.
(iii)  Atmospheric pressure.
(iv)  Humidity.

9.  Piston Clearance:-  

The piston moves TDC to BDC and BDC to TDC inside an engine cylinder and does complete an otto cycle (4 stroke). So for easy moving of the piston there leave some running clearance between piston and cylinder wall, this running clearance known as piston clearance. The running clearance always should be between .001eanch to .004 eanch.

After increase the piston clearance the following defects occurred inside the engine:- 

(i)   Piston Slap:- Due to increase the piston clearance when piston comes from TDC to BDC then it not comes in straight, it comes in some tilt angle and while coming the piston bump with cylinder wall this is known as piston slap. 
(ii)  Blow By:- Due to increase piston clearance during the compression stroke and combustion some air and fuel mixture comes into the crank case,this is known as blow by.

Because of the blow-by the engine occured some defects:-

(a)   Oil dilution.
(b)   Oiling up.
(c)   Wastage of oil and fuel.
(d)   Spark plug is going to dirty.
(e)   Pre-ignition.

10.  Compression Ratio:-  

Maximum fresh air entire into the engine cylinder during the suction stroke and compressed the entire air during the compression stroke the ratio of the both above mentioned known as compression ratio. 

There are two method to increase the compression ratio:- 

(i)   To decrease the VC - Volume Clearance. 
(ii)  To increase the VS - Volume Swept. 

Advantage of more compression ratio:-

(i)   More power.
(ii)  Less fuel consumption.

Dis-advantage of compression ratio:-

(i)     Detonation.
(ii)    Pollution.
(iii)   Wear and tear of engine parts.
(iv)   Fire accident may be inside the engine.
(v)    Valve seating may be defective.

11.  Otto Cycle:-  

Maximum fresh air enter into the engine cylinder thanafter compressed the entire air after that burn it by giving some spark or diesel spray and finally release maximum exhaust gases into the atmosphere, these all process known as Otto cycle. An Otto cycle completed into four stroke and 780°.

12.  Ineffective Angle:-  

Inside an engine cylinder the piston has changed its own direction of motion after reached fully at TDC or BDC. While changing the direction of motion the piston has stoped for a few seconds and crank shaft still rotate continue, because of this experience a angle between big end of the connecting rod and crank pin, this angle known as ineffective angle. This angle is normally in 12°. 

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