[Rotating Equipment] Chapter 2 - IC Engine Design and Operation
133 flashcards · Other · by Ahmed Adil
What is the name of this?
Bedplate
What is bedplate?
The base and main frame housing for the engine
Bedplate is commonly made of cast Iron or cast Steel
What is the name of this?
Crankshaft
Crankshafts are made of?
Forged steel
What is the purpose of the crankshaft?
To convert the linear motion of the pistons into rotational motion for output power
Why high strength-to-weight ratio material is used to manufacture crankshaft?
1) To reduce vibration 2) To help rod journals spray the lubrication
What is the crankcase?
The area around the crankshaft that holds the oil lubrication
What is the name of this part?
Crankcase
What is the name of this?
Connecting rod (con-rod)
What is the purpose of the connecting rod?
It connects the pistons to the crankshaft
The connecting rod is made of forged steel
Wrist pins connect the piston to the con-rod
Each cylinder has one piston and one connecting rod
Identify the parts Black is flywheel Red is crankshaft Grey is piston Blue is cylinder
Cylinders are made from a variety of materials to withstand the pressure and temperature due to combustion
What the name of this?
Cylinder block
What is the name of this part?
Cylinder linings or cylinder sleeve
What is the purpose of cylinder linings/sleeve?
1) provide the machined surface for the pistons and rings 2) protects the cylinder block from wear
One feature of cylinder linings/sleeve of the wet type is
cooling water circulate through them
Is cylinder linings replaceable?
Yes, because it's cheap
What is the name of this part?
Piston head
What is the name of this part?
Piston rings
Piston rings must be staggered when installed
Piston head piston rings are made of?
Cast iron or aluminum alloy
Piston head has grooves cut into it where piston rings is fitted
The top ring of piston is for
compression
The Bottom ring of piston is for
preventing oil getting into the combustion chamber
Bottom ring is also called wiper ring or scraper ring
The middle ring of piston is for
a backup for top ring and bottom ring
Which part of the engine is this
Cylinder head
Cylinder heads are individually detachable
Cylinder head is made of heat resistant cast iron
Fuel is injected into the center of an open type combustion chamber
Camshaft
The camshaft is driven by the crankshaft by way of gears or chain
In OHV: There are cams/lobes on the camshaft to move the pushrods up and down which in turn move the intake and exhaust valves up and down via rocker arms
The job/function of the camshaft
to open and close inlet and exhaust valves at proper time
What does SOHC stand for
Single Over Head Cam
What does DOHC stand for
Double Over Head Cam
One advantage of SOHC
it has a simpler design that DOHC
One disadvantage of SOHC
Doesn't breath as good as DOHC
One advantage of DOHC
More valves than SOHC so engine can breath better (can produce more horsepower with smaller engine)
One disadvantage of DOHC
More parts than SOHC…more expensive
6 and 8 cylinder engines need dohc
sohc or dohc
Each valve has 2 springs and a renewable seat of heat-treated nickel iron alloy
First blank is a number
air filter
oil filter
Strainer vs Filter
strainer remove big particles filter remove small tiny particles
Air filter job
to prevent foreign particles entering the cylinder
Oil filter job
to prevent foreign particles entering the crankcase
4 cylinder engine firing order
1 3 4 2
What type of the coolant does water cooling system in IC engine use
water mixed with anti-freezing (glycol)
IC Engine cooling system 1) thermostat 2) radiator 3) drain tap 4) water pump 5) fan
In IC engines heat energy is converted into mechanical energy
1) cylinder head 2) water jacket
1) single 2) v twin 3) triple 4) straight 4 or inline 4 5) straight 5 6) v 5 7) v 6 8) v 8
only 30 to 35% of the heat is converted to mechanical work
the majority of heat is removed by circulating cooling water (glycol)
Engine cooling is done in 2 steps: 1- Circulating cooling water (glycol) removes heat from the pistons via water jackets in cylinder block 2- Heated glycol flows to radiator to be cooled by the fan
types of fuel used in IC engines
Liquid fuels (Gasoline/petrol) Gaseous fuels (natural gas/LPG) Oil fuels (diesel/kerosene)
Types of ignition in IC engines
spark ignition compression ignition
Types of IC engine design
straight/inline v
Types of engine based on strokes number
2 strokes 4 strokes
Spark ignition is found in gasoline or petrol engines and uses spark plug Compression ignition in found in diesel engines and uses fuel injector
What type of ignition uses spark plug for ignition
spark ignition
What type of ignition uses high compressible heat for ignition
compression ignition
Spark ignition: In this type, the compressed gas/air mixture is ignited by a spark near the end of the compression stroke
Spark ignition: A high voltage current (20,000+ volts) jumping across the gap creates the spark
What is the name of this part
spark plug
intake/exhaust valves: Each head has a relief valve and a provision to take pressure measurements
The flashpoint for petrol/gasoline is -45oC
2-stroke engine: Uses three ports which are either covered or uncovered by the piston (no valves, camshafts is used) Complete cycle in one revolution of shaft (360o) Ignition fires on every revolution so 2 stroke engine is more powerful than 4 stroke of the same size (this only applies to small engines)
2 Stroke petrol/gasoline engine 1) intake port 2) transfer port 3) exhaust port
Applications of 2 stroke engine
4-stroke petrol/gasoline engine cycle:
1. Intake Stroke: Inlet valve opens. Piston moves from Top Dead Center (TDC) to Bottom Dead Center (BDC). Fuel and air mixture is drawn into the cylinder. 2. Compression Stroke: Inlet valve closes. Piston moves from BDC to TDC, compressing the fuel and air mixture. Spark plug ignites the compressed mixture at the end of the stroke. 3. Power Stroke: Piston moves from TDC to BDC because of the explosion, generating power and transmitted to the crankshaft. Exhaust valve opens toward the end of thi…
Name every cycle of the 4-stroke petrol/gasoline engine: 1st stroke – intake 2nd stroke – compression 3rd stroke – power 4th stroke – exhaust
4-stroke gasoline engine: - Complete cycle in two revolution of shaft (720o) - Compression ratio is 8:1 to 12:1 - The Otto cycle. Named after Nikolaus Otto who invented it in 1876
4 Stroke engine applications
Lubrication methods in IC Engine: 1. pumped under pressure to the bearing surfaces 2. splashed by rotation of the crankshaft
Compression ignition in diesel engines: The temperature of the compressed air is 540oC to 650oC. Compression in this type is higher than in regular petrol engines and the fuel has a higher flash point (52° C) than regular petrol (-45° C) The compression ratio for this type of engine is 20:1
Explain the 2-stroke diesel engine cycle:
1. Intake and compression Stroke: Only air enter through the intake port. The air travel through the transfer port. Piston moves from BDC to TDC, compressing the air. Fuel is injected to the cylinder as a mist which will ignite immediately due to the high pressure and temperature of compressed air. 2. Power and Exhaust Stroke: Piston moves from TDC to BDC due to the explosion of the ignition. New air enters through the intake port. Piston moves from BDC to TDC, pushing out the burnt mixture thr…
Scavenging types in 2 stroke engine: 1) Uniflow scavenge - no valve is used 2) Loop scavenge - valve is used
Explain the 4 stroke diesel engine cycle
1. Intake Stroke: Inlet valve opens. Piston moves from Top Dead Center (TDC) to Bottom Dead Center (BDC). Only air is drawn into the cylinder. 2. Compression Stroke: Inlet valve closes. Piston moves from BDC to TDC. The air is compressed by the piston. Just before the compression is finished the fuel is injected to the cylinder as a mist. The fuel ignites because if the high pressure and heat of the air. 3. Power Stroke: Piston moves from TDC to BDC because of the explosion, generating power an…
The compression ratio of diesel engine is higher than a petrol/gasoline engine
What is glow plug
a wire that heats the combustion chambers and raises the air temperature in very cold weather so that the engine can start
Fuel injection systems in petrol/gasoline engines: Fuel injection in spark ignition engines provides excellent atomization or misting of a fuel for efficient combustion - Can be of 3 types: 1. Single point injection 2. Multi point injection 3. Direct injection
Single point injection (Fuel injection type in petrol/gasoline engines): - Also called throttle body type - Fuel injected through an injector situated above the throttle valve
Multi-point injection (Fuel injection type in petrol/gasoline engines): Each cylinder has it’s own injector which is situated in the intake manifold upstream of the intake valve
Advantages of Multi-point (fuel injection type):
- Accurate mixing of air/fuel because of ECM (Engine Control Module) computer - Immediate response to acceleration/deceleration - Vibration minimized - Improved mileage
Direct injection (Fuel injection system in petrol/gasoline engines): - Separate injectors that spray fuel directly into every combustion chamber - Atomization takes place directly in the combustion chamber
Advantages Direct (fuel injection type):
- No condensation of fuel collecting in the intake manifold is possible - Very lean mixture can be burned for idle and part-throttle operations
1 Revolution of 2-stroke engine = 1 power 2 Revolutions of 4-stroke engine = 1 power
Compression ratio =
volume before compression / volume after compression
Petrol/Gasoline fuel system 1) fuel tank 2) fuel filter 3) fuel pump 4) carburetor 5) air filter
What is carburetor
a device for used for mixing fuel and air and supplying the mixture to the combustion chamber of cylinder
Lean mixture: less fuel, more air
Rich mixture: more fuel, less air
Ratio of fuel and air air -> 14:1 <- fuel
IHP (indicated horsepower): actual horsepower in the cylinder BHP (brake horsepower): available horsepower in the wheels FHP (friction horsepower) friction horsepower of various rotating elements IHP = BHP + FHP