Internal Combustion Engines – The DieselObjectivesThe Diesel is a HackerEngine UsesThermodynamic PrinciplesStructural ComponentsSlide 7Moving ComponentsSlide 9Slide 10Slide 11OperationSlide 13Four-Stroke Diesel EngineSlide 15Slide 16Two-Stroke Diesel EngineSlide 18Slide 19Two vs. Four-Stroke EnginesGasoline vs. Diesel EngineSupporting SystemsSlide 23Safety PrecautionsQuestions?Internal Combustion Internal Combustion Engines –Engines –The DieselThe DieselObjectivesObjectives•Uses for internal combustion engines•Thermodynamic principles involved•Components and purposes of each•Operation of systems•Two stroke engines•Four stroke enginesThe Diesel is a HackerThe Diesel is a HackerEngine UsesEngine Uses•Emergency Diesel Generators (EDG)•Propulsion•Certain amphibious landing ships•Mine warfare ships•Patrol craft•Tug boats•Small boats•Outboard motorsThermodynamic Thermodynamic PrinciplesPrinciples•All internal combustion•Open cycle, heated engine•Gasoline (Otto) engine•Spark ignition•Compresses air-fuel mixture•Diesel engine•Compressed ignition•Compresses air onlyStructural ComponentsStructural Components•Cylinder Block•Part of engine frame that contains cylinders in which piston moves•Supports liners & headStructural ComponentsStructural Components•Cylinder Head/Assembly•Serves to admit, confine, and release fuel/air•Cover to cylinder block•Supports valve train•Crankcase•Engine frame section that houses the crankshaft•Oil sump•Reservoir for collecting and holding lube oilMoving ComponentsMoving Components•Three Groups – according to motion•Reciprocating only (pistons and valves)•Reciprocation & rotary (connecting rods)•Rotary only (crankshafts and camshafts)Moving ComponentsMoving Components•Piston•Acted on by combustion gases•Lightweight but strong/durable •Piston Rings•Transfer heat from piston to cylinder•Seal cylinder & distribute lube oil•Piston Pin•Pivot point connecting piston to connecting rod•Connecting Rod•Connects piston & crankshaft•reciprocating rotating motionMoving ComponentsMoving Components•Crankshaft•Combines work done by each piston•Drives camshafts, generator, pumps, etc.•Flywheel•Absorbs and releases kinetic energy of piston strokes -> smoothes rotation of crankshaftMoving ComponentsMoving Components•Valves•Intake: open to admit air to cylinder (with fuel in Otto cycle)•Exhaust: open to allow gases to be rejected•Camshaft & Cams•Used to time the addition of intake and exhaust valves•Operates valves via pushrods & rocker armsOperationOperation•Increased pressure of combustion gases acts on piston -> converted to rotary motion•Can be 2 or 4 stroke engines•2-stroke: 1 power stroke per 1 crankshaft rev•4-stroke: 1 power stroke per 2 crankshaft revOperationOperation•Engine stroke•A stroke is a single traverse of the cylinder by the piston (from TDC to BDC)•1 revolution of crankshaft = 2 strokes of pistonFour-Stroke Diesel Four-Stroke Diesel EngineEngine•Intake stroke•Intake valve open, exhaust valve shut•Piston travels from TDC to BDC•Air drawn in•Compression stroke•Intake and exhaust valves shut•Piston travels from BDC to TDC•Temperature and pressure of air increaseFour-Stroke Diesel Four-Stroke Diesel EngineEngine•Power stroke•Intake and exhaust valves shut•Fuel injected into cylinder and ignites•Piston forced from TDC to BDC•Exhaust stroke•Intake valve shut, exhaust valve open•Piston moves from BDC to TDC•Combustion gases expelledFour-Stroke Diesel Four-Stroke Diesel EngineEngine•Strokes•Intake•Compression•Power•ExhaustTwo-Stroke Diesel Two-Stroke Diesel EngineEngine•1 power stroke every crankshaft revolution (vice every two w/ 4-stroke)•Uses pressurized air to simultaneously supply new air and expel combustion gases•Scavenging•Exhaust valve open, inlet port exposed•Pressurized air enters, expels combustion gases•Piston near BDCTwo-Stroke Diesel Two-Stroke Diesel EngineEngine•Compression•Intake and exhaust valves shut•Piston travels from BDC to TDC•Temperature and pressure of air increase•Power stroke•Intake and exhaust valves shut•Fuel injected into cylinder and ignites•Piston forced from TDC to BDCTwo-Stroke Diesel Two-Stroke Diesel EngineEngine•Strokes•Compression•Power•(Intake/Exhaust)Two vs. Four-Stroke Two vs. Four-Stroke EnginesEngines•Two-stroke advantages•Higher power to weight ratio•Less complicated valve train•Four-stroke advantages•More efficient burning process•As size increases, power-to-weight ratio improvesGasoline vs. Diesel Gasoline vs. Diesel EngineEngineSupporting SystemsSupporting Systems•Air system•Supplies & removes air/gases•Air supplied at constant pressure by blower/compressor•Fuel System•Carburetor: mixes air & fuel in proper proportion (NOT on diesels)•Fuel injector: sprays fuel in (more efficient)Supporting SystemsSupporting Systems•Ignition system•Diesel has compression ignition•Gasoline has spark plugs•Cooling system•Uses fresh water and/or salt water to cool•Lubrication system•Provide lubrication and cooling•Drive Train – Direct or IndirectSafety PrecautionsSafety Precautions•Noise•Fuel Flammability•Maintenance•Water