CLASSIFICATION OF HEAT ENGINES G P SRINAGAR Mahesh 3 CLASSIFICATION OF I.C. ENGINES G P SRINAGAR Mahesh 4 THEN NOW G P SRINAGAR Mahesh 5 THEN NOW G P SRINAGAR Mahesh 6 History of IC Engines 1860 Lenoir’s engine (a converted steam engine) combusted natural gas in a double acting piston, using electric ignition G P SRINAGAR Mahesh 7 1876 Nikolaus Otto patented the 4 cycle engine, it used gaseous fuel 1882 Gottlieb Daimler, an engineer for Daimler, left to work on his own engine. His 1889 twin cylinder V was the first engine to be produced in quantities. Used liquid fuel and Venturi type carburetor, engine was named “Mercedes” after the daughter of his major distributor 1893 Rudolf Diesel built successful CI engine which was 26% efficient (double the efficiency of any other engine of its time) G P SRINAGAR Mahesh 8 Complementary Technologies for IC Engine-powered Automobiles Pneumatic tires (1888, Dunlop) Cheap liquid fuels (Oil industry born in PA 1859) Venturi effect carburetor (1892, Willi Maybach) Variable mechanical transmission (primitive type by Levassor, 1891) Electric starter (Kettering 1912) G P SRINAGAR Mahesh 9 G P SRINAGAR Mahesh 10 1860 One-cylinder engine, kerosene- fuel. 1864 Two-cylinder gasoline engine 1876 Otto built four-stroke gas engine 2-stroke engines accomplish the same steps, but less efficiently & with more exhaust emissions. 1885 Gasoline-powered engine mounted onto bicycle- motorcycle & 1887 First car- included steering tiller & 4- speed gearbox - Daimler & Maybach In 1885 German engineer Gottlieb Daimler mounted an engine of his own design into a wood-framed vehicle. The vehicle had 4 wheels, including 2 round stabilizing wheels. World’s first motorcycle. G P SRINAGAR Mahesh 11 CLASSIFICATION OF INTERNAL COMBUSTION ENGINES G P SRINAGAR Mahesh 12 1. Application 2. Basic Engine Design 3. Operating Cycle 4. Working Cycle 5. Valve/Port Design and Location 6. Fuel 7. Mixture Preparation 8. Ignition 9. Stratification of Charge 10. Combustion Chamber Design 11. Method of Load Control 12. Cooling G P SRINAGAR Mahesh 13 Operating Cycle Otto (For the Conventional SI Engine) Atkinson (For Complete Expansion SI Engine) Miller (For Early or Late Inlet Valve Closing type SI Engine) Diesel (For the Ideal Diesel Engine) Dual (For the Actual Diesel Engine) G P SRINAGAR Mahesh 14 CLASSIFICATION OF INTERNAL COMBUSTION ENGINES G P SRINAGAR Mahesh 15 In Line (Automobile) V (Automobile) Horizontally Opposed (Subaru) Opposed Piston (crankshafts geared Radial (Aircraft) together) G P SRINAGAR Mahesh 16 G P SRINAGAR Mahesh 17 Numbering and Firing Order G P SRINAGAR Cylinder Configurations Straight Configuration V Configuration Displacement refers to the volume inside each piston Flat chamber. For example: a 3.0 Configuration Liter engine with 6 cylinders will have 0.5 liters per G P SRINAGARcylinder. Mahesh 19 ENGINE NOMENCLATURE G P SRINAGAR Mahesh 20 Cylinder head Parts of an Air cleaner Breather cap IC Engine Rocker arm Choke Valve spring Valve guide Throttle Pushrod Intake manifold Sparkplug Exhaust manifold Combustion chamber Tappet Piston rings Dipstick Piston Cam Wrist pin Camshaft Cylinder block Connecting rod Water jacket Oil gallery to piston Wet liner Oil gallery to head Connecting rod bearing Crankcase Crankpin Crankshaft Main bearing Oil pan or sump G P SRINAGAR Mahesh 21 Displacement / Clearance Volumes G P SRINAGAR Mahesh 22 Valve Location G P SRINAGAR Mahesh 23 Basic Engine Definitions Clearance volume Displaced volume Compression ratio G P SRINAGAR Mahesh 24 Engine Cutaway G P SRINAGAR Mahesh 25 Torque G PTorque SRINAGAR= F x b Mahesh 26 Power Power = Torque x Angular Speed P = 2NT N(rev / min)T(lb ft) P(hp) F 5252 P(kw) = N(rev / min)T(N m) G P SRINAGAR7045 Mahesh 27 Gallery of Engines G P SRINAGAR Mahesh 28 G P SRINAGAR Mahesh 29 G P SRINAGAR Mahesh 30 Intake Exhaust valve valve Top Dead Center (TDC) : Upper most position Bottom Dead Center (BDC) : Lower most position TDC Stroke : Length of piston travel Bore : Diameter of the cylinder Stroke Bore Clearance Volume (Vc) : V where piston is at TDC Displacement Volume (V ) :Swept Volume (V -V ) BDC d max min Compression Ratio (rv) = (Vmax/Vmin) = (VBDC/VTDC) Mean Effective Pressure (MEP) : Wnet = (MEP) x (Displacement Volume) Diesel engine, Compression Ignition • Only air is drawn into the cylinder during intake stroke • fuel is injected into the cylinder after the air is compressed and the piston reaches TDC • And continue injecting until reaches “Cut Off Volume, V3” • Cut off ratio rc = V3/V2 = v3/v2 • Fuel is self ignited as a result of compression. • Therefore, the Compression Ratio, rv , must be high enough, Typical rv ~12 – 24 • During the combustion PRESSURE remains constant . • Others processes are the same as Otto Cycle • Thermal efficiencyG of actual P Diesel SRINAGAR engine ~ 30-40% Mahesh 31 4 Cycle Process Exhaust Valve 1 Intake Valve 2 4 Intake Exhaust 3 Manifold Manifold Spark Cylinder Plug Piston Connecting Rod Crank Crankcase Power Stroke Intake Stroke Compression Stroke Exhaust Stroke Both valves closed, Fuel-air mixture burns, Exhaust valve open, Intake valve opens, increasing temperature admitting fuel and air. Fuel/air mixture is exhaust products are compressed by rising and pressure, expansion displaced from cylinder. Exhaust valve closed of combustion gases for most of stroke piston. Spark ignites Intake valve opens mixture near end of drives piston down. Both near end of stroke. stroke. valves closed - exhaust G P SRINAGARvalve opens near end Mahesh of stroke 32 G P SRINAGAR Mahesh 33 ANIMATION OF 4 STROKE ENGINE G P SRINAGAR Mahesh 34 G P SRINAGAR Mahesh 35 G P SRINAGAR Mahesh 36 G P SRINAGAR Mahesh 37 G P SRINAGAR Mahesh 38 G P SRINAGAR Mahesh 39 G P SRINAGAR Mahesh 40 G P SRINAGAR Mahesh 41 G P SRINAGAR Mahesh 42 G P SRINAGAR Mahesh 43 G P SRINAGAR Mahesh 44 G P SRINAGAR Mahesh 45 2 Stroke Process Compression Combustion Exhaust Scavenging (ports closed) (ports closed) (intake port closed) and Intake Air Taken Into (ports open) CrankcaseG P AirSRINAGAR compressed in crankcase Mahesh 46 Two Stroke Internal Combustion Engines *How a two stroke engine works *Advantages/Disadvantages G P SRINAGAR Mahesh 47 Introduction to the Two Stroke Engine This type of engine is commonly found in applications such as; lawn and garden equipment dirt bikes small outboard motors G P SRINAGAR Mahesh 48 Introduction to the Two Stroke Engine Two stroke engines have advantages over four stroke: simplified construction (no valves) fire once every revolution for a significant power boost Great power to weight ratio G P SRINAGAR Mahesh 49 The two stroke cycle The two stroke engine ignites every revolution of the crankshaft. These engines overlap operations to reduce parts while maintaining power. G P SRINAGAR Mahesh 50 The two stroke cycle After the fuel air explosion, the piston is driven down. As the piston reached the bottom of it’s stroke, the exhaust port is uncovered. Most of the gases are driven out. G P SRINAGAR Mahesh 51 The two stroke cycle When the piston has bottomed out, the intake port is uncovered. The new fuel enters and is ready for compression and combustion. G P SRINAGAR Mahesh 52 The two stroke cycle When the fuel mixture is being compressed a vacuum is created in the crankcase. The vacuum opens a reed valve and sucks air/fuel/oil in from the carburetor. G P SRINAGAR Mahesh 53 The two stroke cycle Simply put, in a two stroke engine you have only: Compression Combustion Thus, Two Strokes. G P SRINAGAR Mahesh 54 2 stroke compared to 4 stroke In two stroke engines In four stroke engines the crankcase is a the crankcase is pressurization chamber separate from the to force fuel/oil/air into compression chamber. the cylinder. Here you This allows the use of mix oil and gas to heavy oil for lubrication. lubricate internal parts. G P SRINAGAR Mahesh 55 Disadvantages of a two stroke The engines do not last as long due to poor lubrication. You have to mix two cycle engine oil with gasoline. The engines do not use fuel efficiently. These engines produce a lot of pollution. G P SRINAGAR Mahesh 56 Summary Two stroke engines are great for the power to weight ratio and their simple design, however, due to there pollution concerns these engines will be harder to find. G P SRINAGAR Mahesh 57 Two vs. Four-Stroke Engines 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 improves G P SRINAGAR Mahesh 58 Rotary “Wankel” Engine G P SRINAGAR Mahesh 59 ANIMATION OF VALVE MECHANISM G P SRINAGAR Mahesh 60 How do we get the mixture of fuel and air? Venturi-type Carburetor The carburetor of our engine Bernoulli Effect: P+1/2 V2 = Constant Choke Throttle Venturi Higher Pressure Outside Engine G P SRINAGARFuel Mahesh 61 Venturi-type Carburetor in the car Air/Fuel Mixture To Engine Bernoulli Effect: 2 P+1/2 V = Constant Throttle Plate Atomized Fuel Fuel Inlet Valve Stem Float Venturi Bowl Choke Plate Fuel Inlet Air Constant level is Nozzle maintained in bowl -as float moves down, Metering Orifice valve stem moves down, allowing more fuel into bowl, float moves up and G P SRINAGAR Ref. Obert closes valve Mahesh 62 How do we initiate the combustion? Image resource: http://www.nhsnowmobilemuseum.com/burdicksledshed /1974%20Alouette%20Super%20Brute%20440.htm But how do we get the spark plug spark? •Megneto system ( which our engine uses) •Mechanical ignition •Electronic ignition •Engine management system …………….G P SRINAGAR Mahesh 63 Anything else important related to the combustion? Think about following situations: -What will happen if the intake or exhaust valve are not closed during the compression stroke (just before the power stroke)? -What will happen if the intake or exhaust valve open during the power stroke? •Solution? Right timing of the valves.