The engine is the unit or source of power in the car, from which the movement and torque of all the moving parts of the car are derived. The engine is connected to the wheels via the axle, gearbox and clutch – and the engine is connected to the rotating parts (electric charger, water pump, steering pump compressor …. by means of belts and pulleys). And the motor is the source of the vibration of many systems (shake servo, door and chair control, some installation brake systems,…..). The engine exhaust is also used in a turbine to charge the engine.
Energy sources in the car
The cars use different power sources, and they are mostly:
– internal combustion engines IC
– Electric motor
– Two sources of energy (internal combustion engine / electric – hybrid car)
Engine rating
Internal combustion engines can be divided into types according to:
A- Engine design:
Motion method:
– reciprocating
engine – rotary (Wankel)
engine * The reciprocating engine can be divided into types according to:
Number of strokes:
– four-stroke
– two-stroke – stroke
Number of cylinders:
– Common: 4, 6, 8
– Uncommon: 2, 3, 5, 12, 16
Engine capacity:
– Fixed-capacity engine (liters, cc)
– Variable displacement POD
Cylinder arrangement:
– Straight in-line
– V
– Slant engine
– W
– Flat opposed Crankshaft
classification:
– Straight line engine crankshaft, connecting arm to each bearing bearing – Crankshaft
drive letter “V” Connecting arms for each bearing bearing
or
– internal balance (corresponding weights)
– external balance (corresponding weights, flywheel weights, and balance shafts)
Valve positioning:
Side in the block (flat head- L-head)
– Overhead valve
Number of valves:
– 2 valves
– 4 valve
control valves:
– Electronically controlled intake valve timing – Variable Valve Timing with Intelligent (VVT-i)
– Electronically controlled valve timing and distance for valve opening – Variable Valve Timing & Lift with Intelligent (VVTL-) i)
Types of valves:
– Conventional valve
– Sleeve valve Valve
control method:
– Electronically
controlled intake and exhaust valve timing (VVT-i) – Electronically controlled intake and exhaust valve timing (DVVT-i)
– To control the timing and opening distance Valves electronically (VVTL-i)
camshaft positioning:
– cam-in-block
– overhead cam (direct or by lever), 1 (SOHC) single , 2 (DOHC) dual
camshaft drives :
– Cogged rubber belt
– Chain
– Gear
Combustion chamber shapes:
– Pancake
– Wedge shape
– Hemispherical (hemi)
– Semi-hemi
– Swirl
– Crossflow
– Precombustion
B- Engine operating systems:
Fuel types:
– Gasoline
– Diesel
– Alternative fuels (methanol – ethanol – biodiesel) M85, E85, B20
– Multi-fuel (flex-fuel engines)
– CNG, LNG, LPG gas
– Hydrogen
Fuel injection method:
– carburetor
– Fuel injection (central, multi-injection) injection
Air intake method:
– normal aspiration
– algebraic / Mahn (turbo, super) turbocharged and supercharged engines
method of ignition:
– spark (traditional, electronic) of Spark Ignition the SI
– compression compression ignition CI
cooling method:
– cooling liquid (water) a liquid-Cooled
– Air Cooling air- cooled
mode Vehicle
Engine Front Drive/Front Wheel Drive FWD Front
Engine/Rear Wheel Drive RWD
Mid Engine/Rear Wheel Drive Rear
Engine/Rear Wheel Drive
Engine from earlier engines/WD or 4×4
Engine position relative to the axle direction
Longitudinal engine
Transverse width
Combustion requirements
The following must be met for combustion to take place:
– flammable material
– oxygen
–
fuel flame source :
the combustible material used in internal combustion engines: gasoline, diesel, biofuel, gas.
The material used for combustion must have a large heat capacity:
Heat capacity of the fuel:
| fuel condition | fuel type | Heat capacity (kilojoules/g) |
| solid | briquette | 33 |
| Charcoal | 25.33 | |
| Wood | 17 | |
| liquid | kerosene | 48 |
| petrol | 50 | |
| diesel | 45 | |
| ethanol | 30 | |
| Gas | Butane Gas (LPG) | 50 |
| methane | 55 | |
| hydrogen | 150 |
Oxygen:
There is oxygen in the air at a rate of 20.95% by volume and 23.20% by weight in the air, and the rest of the air consists of gases that do not participate in ignition (nitrogen and carbon dioxide).
Heat source:
spark ignition engines, the source of the flame is the spark from the spark plug.
Compression ignition engines, the heat generated at the end of the compression stroke is sufficient for the fuel to self-ignite when injected into the chamber.
Engine Operating Requirements
Air-Fuel Ratio:
Gasoline Engines: The correct air-to-fuel ratio is 14.7:1 Air:Fuel by weight. The engine operates at an air/fuel ratio between 7 and 20, a ratio of 7:1 is for a rich mixture, a ratio of 20:1 is a for a poor mixture.
Diesel engines: The ratio is between 100: 1 at empty load, 20: 1 at maximum load.
Shipment entry:
The higher the amount of air inside the engine, the higher the engine power. The amount of air inside the engine depends on the engine capacity (depends on the dimensions and number of cylinders), and the efficiency of the fill (depends on the method of air intake, the number and timing of valves, valve clearances).
Charge pressure / air: the
compression stroke works on the charge pressure, the amount of charge pressure depends on the compression ratio of the engine, (air volume before compression / air volume after compression). The pressure stroke brings the charge particles closer, and raises their temperature.
Ignition timing:
In addition to the power and duration of the spark, the timing of the spark is an important factor in controlling the efficiency of the fire.
Correct ignition timing allows for sparking, charge ignition, and the flame front reaching the piston surface when the crankshaft is 10 degrees beyond the upper dead point. Therefore, the spark occurs several degrees before the upper dead point, and the timing of the spark (the number of degrees before the upper dead point) depends on (the power of the mixture, engine speed, …). Providing the spark without combustion problems (slapping) leads to an increase in engine power. Spark delay leads to a loss of energy as the combustion will last longer which will allow the heat energy to seep into the engine body and from it to the cooling water and charge out. Spark delay leads to engine overheating, and combustion problems.
Combustion problems
– misfire: They
occur due to the inability of the spark to occur between the poles of the candle, and it causes a loss of power and an increase in the rate of gasoline consumption.
Several factors cause spark failure:
Weak ignition coil, high compression ratio with increased spark plug pole clearances, carbon deposits or oils on the candle poles.
No Combustion:
No Sparking, Rich Mixture, Poor Mixture, Excessive Sparking, Excessive Spark Delay.
Pre-ignition: It
occurs due to the presence of a hot spot in the engine, as a result of the presence of a hot spot inside the combustion chamber that ignites the fire before the spark occurs. The result is:
1- Glowing carbon parts inside the cylinder
2- Overheating of the engine (cooling system problems)
3- Poor fuel
4- Spark plug with high temperature range
5- Exhaust valve overheating (weak spring, low valve clearance, valve is not tight) lock)
– slap detonation occurs:
Occurs at the end of normal combustion, the spontaneous ignition of the charge end (explosion) occurs. High pressure slapping may lead to damage to the piston, damage to the connecting shaft, alloys,….. and cause the following slaps to occur:
– slow combustion
– fuel with a low octane degree
– an increase in the compression ratio due to the presence of carbon deposits inside the combustion chamber, straightening the surface of the cylinder head
– High engine temperature
– damage to the screws or valve interlocks, and oil entering and igniting inside the room.
– Increasing charge pressure (forced charging)
– Advance ignition timing (combustion pressure hits the piston surface as the piston rises)
Dimensions and specifications of the engine
– Upper dead point: the highest point the piston reaches inside the cylinder
– lower dead point: the lowest point the piston reaches inside the cylinder
– stroke length: the distance traveled by the piston during the stroke (the distance between the lower dead point and the upper dead point, equal to 2 crankshaft attachment lengths)
– engine capacity: equal to the volume of the cylinder x the number of cylinders ( Cylinder volume = piston area x stroke length)
– compression ratio: equals the volume of air before compression divided by the volume of air after compression (cylinder volume + combustion chamber volume) / combustion chamber volume
– filling efficiency: (inlet air volume / cylinder volume)
– Engine torque: (the amount of torque at the crankshaft output)
– engine power: a measure of the engine’s ability to do work
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