SparkIgnition SI Engines Introduction Internal combustion engine is irreplaceable Hauls food and water delivers passengers saves lives Principles of Thermodynamic Internal Combustion Engines ID: 644912
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Slide1
Chapter 10
Motive Power Types–
Spark-Ignition (SI) EnginesSlide2
Introduction
Internal combustion engine is irreplaceable.
Hauls food and water, delivers passengers, saves livesSlide3
Principles of Thermodynamic Internal Combustion Engines
(1 of 3)Science branch dealing with heat and energyUsed in internal combustion engineMoves vehicle down road and provides powerOnce powered all equipmentSteam enginesSlide4
Principles of Thermodynamic Internal Combustion Engines
(2 of 3)Steam engine.Stirling engine.Slide5
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Principles of Thermodynamic Internal Combustion Engines (3 of 3)Stirling engineInternal replaced external combustion.Gas and diesel enginesICE classified in two waysPiston engines are SI or CI engines.Slide6
Principles of Engine Operation
(1 of 9)Operate on physics and thermodynamicsUnderstanding will help diagnose.Tightly packed molecules increase expansion pressure.Burning black powder = fire. Slide7
Principles of Engine Operation
(2 of 9)Pressure and temperatureDirectly relatedCylinder with moveable plungerDiesel engines use same principle.Heating increases molecule movement.Slide8
Principles of Engine
Operation (3 of 9)Pressure changes temperature.Temperature changes pressure.Slide9
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Principles of Engine Operation (4 of 9)Temperature and energyMeasures energyLatent heat in various fuelsExpressed in BtuSlide10
Principles of Engine
Operation (5 of 9)Pressure and volumeInversely relatedSlide11
Principles of Engine
Operation (6 of 9)Force, work, and powerForce: effort to push or pullCompressed spring/cable moves to create work.Power: rate or speed at which work is performedSlide12
Principles of Engine
Operation (7 of 9)Power and torqueTorque: twisting forceUnit of measurement: ft-lb or newton metersAmount of torque at crankshaft and speed of turning1 hp = 33,000 ft-lb/minSlide13
Principles of Engine
Operation (8 of 9)Power and torque (cont'd)Calculate twisting by adding distance moved and time.Converting torque to work requires movement.Slide14
Principles of Engine
Operation (9 of 9)Torque vs. horsepowerTorque: twisting or turning force and horsepowerNaturally aspirated enginesEngine rpm rises faster as torque falls.Slide15
Four-Stroke Spark-Ignition Engines
(1 of 5)SI engines operate on four-stroke principle.Takes four strokes to complete one cycleCan be simple or complicatedSlide16
Four-Stroke Spark-Ignition Engines
(2 of 5)Basic four-stroke operationOne stroke out of the four delivers energy.Compression strokeIgnition occurs as piston reaches TDC.Exhaust stroke: end of power strokeSlide17
Four-Stroke Spark-Ignition Engines
(3 of 5)Engine measurement—sizeICEs designated by volume pistons displaceCylinder borePiston strokePiston displacementEngine displacementCompression ratioSlide18
Four-Stroke Spark-Ignition Engines
(4 of 5)Atkinson and Miller cycle enginesVariations on four-stroke engineUse larger throttle opening for powerAtkinson efficient within specific rangeLower max operating rpmCrankshaft mounted slightly off centerSlide19
Engine displacement.
Four-Stroke Spark-Ignition Engines(5 of 5)ScavengingUses column of moving airSlide20
The compression ratio of an engine is found by taking the volume of the cylinder at BDC and comparing it to the volume at TDC. In this example, a 9:1 compression ratio is found.
Components ofSpark-Ignition Engines (1 of 9) Widely used to power passenger vehiclesMain power plantGains in manufactureDivided into two assembliesSlide21
The engine contains many parts that work together to power the vehicle.
Components ofSpark-Ignition Engines (2 of 9) Short block and long blockSubassembly may be used.Slide22
Components of
Spark-Ignition Engines (3 of 9) Cylinder block, crankshaft, flywheelBlock is largest part of engine.Oil pan completes crankcase.Crankshaft is composed of cast iron or steel.Crankshaft has main journals.Slide23
Components of
Spark-Ignition Engines (4 of 9) Connecting rod and pistonConnecting rod is made of cast iron, steel, aluminum, or titanium.Rod causes piston movement.Piston is composed of aluminum or synthetic materials.Head is exposed to heat and pressure.Slide24
Components of
Spark-Ignition Engines (5 of 9) Ring landsAreas between the ring grooves that support the rings as the piston movesSlide25
Components of
Spark-Ignition Engines (6 of 9) The oil panSeals and holds oilHouses oil pumpSlide26
Components of
Spark-Ignition Engines (7 of 9) The cylinder headMade of cast iron or aluminumSlide27
Components of
Spark-Ignition Engines (8 of 9) Engine cam and camshaftICE uses poppet valves.Flathead engines had valves in block.Camshaft is mounted on top of cylinder head.Lobes open to hold and close valve.Slide28
Components of
Spark-Ignition Engines (9 of 9) Camshaft specificationsBase is rounded bottom part.Duration is used when designing lobe.High-performance engines have overlap.Two listings for cam specsSlide29
Valves
(1 of 8)Open or close cylinder headsIntake controls flow of air/fuel in combustion chamber.Valve head is disc shaped.Slide30
Valves
(2 of 8)Intake and exhaust valvesControl ICESlide31
Valves
(3 of 8)Mechanical and hydraulic valve trainCombo of parts open and close engine valves.Adjustments are made by lifter.Slide32
Valves
(4 of 8)Valve clearanceAmount of slack between rocker arm and valve stemSlide33
Valves
(5 of 8)Valve train drivesDriven by camshaftChains louder than beltsFreewheeling engineTiming chain differs between cam-in-block and OHC.Slide34
Valves
(6 of 8)Valve train drives (cont'd)OHC requires longer timing chains.Belts use toothed or cogged belt.Slide35
Valves
(7 of 8)Intake manifoldPart of air intake/inductionMany changesSlide36
Valves
(8 of 8)Exhaust manifoldOutput side of engine breathing apparatusSlide37
Two-Stroke Spark-Ignition Engines
(1 of 2)Produce large power to weight ratioEvery other stroke is power.Slide38
Two-Stroke Spark-Ignition Engines
(2 of 2)Basic two-stroke cycle engine principlesDiffers from four-stroke SI engineOne revolution for every cycle in two-strokePiston movement creates suction.Piston moves up to TDC.Piston moves up, compression in cylinder Slide39
Rotary Combustion
Spark-Ignition Engines (1 of 2)Fewer parts usedIncreased power and smaller engineRotary combustion in many applicationsSlide40
Rotary Combustion
Spark-Ignition Engines (2 of 2)Basic principlesNot as commonNo reciprocating pistonSmooth and vibration freeBasic principles as rotary engineIntake cycleSlide41
Summary
(1 of 9)Internal combustion engines are common.Combustion engines are piston or rotary.Piston engines are spark or compression ignition.Pressure and temperature are directly related.Internal combustion engines heat a gas.Pressure and volume are inversely related.Slide42
Summary
(2 of 9)Force causes movement.Work = distance moved × force applied.Power = distance × force/time in minutes.Engine power is measured in torque.Torque is called engine output.Horsepower is the speed of torque.Slide43
Summary
(3 of 9)Load factor = time a vehicle can operate at max speed and powe.Piston stroke = distance traveled from TDC to BDC Internal engines are two- or four-stroke.Five events must occur in a four-stroke engine.Compression ratio is based on cylinder volume.Slide44
Summary
(4 of 9)Piston displacement: bore squared × 3.14 × stroke ÷ 4.Engine displacement: piston displacement × number of engine cylinders.Miller and Atkinson are variations of the four-stroke engine.Miller has engine-driven compressor.Atkinson has lower power output and torque.Slide45
Summary
(5 of 9)Valve overlap: time intake and exhaust valves are openThere are 11 major components of an internal combustion engine.Cylinder block includes additional parts.Crankshaft: converts piston's reciprocating motion into rotary motionFlywheel stores energy from piston. Slide46
Summary
(6 of 9)Connecting rod connects piston to crankshaft.There are seven components of the piston.Gases can leak past piston rings.Intake manifolds deliver air to cylinder head.Oil is stored in the oil pan.Camshaft opens valves.Slide47
Summary
(7 of 9)
There are
four
parts to a camshaft.
Engineers must consider several issues when designing camshaft lobes.
There are
four
parts of an intake valve.
Intake valve is large and runs cool.
Exhaust valves are small and run hot.Slide48
Summary
(8 of 9)Valve clearance must be accurate.ECM controls variable cam timing.Engines are freewheeling or interference.Two-stroke engines use piston to open and close exhaust ports.Slide49
Summary
(9 of 9)Internal combustion engine events are controlled by a piston.Rotary and Wankel engines use a rotor in place of a piston.Rotary engines have two spark plugs.Rotary engines have four phases.Faces of the rotor have a combustion chamber.Slide50
Credits
Unless otherwise indicated, all photographs and illustrations are under copyright of Jones & Bartlett Learning.