1 Agricultural Power Systems Identifying Engine Systems and Their Components

Engine Systems What are the major systems involved with small engine operation? 2

3 Engine Systems Compression system – creates the engine compression and converts the energy of combustion to mechanical energy Governor system Fuel System Cooling and lubrication system Ignition system

4 Purpose of a compression system To efficiently compress air to increase the potential energy resulting from the combustion of the fuel

Compression Problems Inadequate Compression (Leaks) Excessive Compression (Preignition/Detonation) 5

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7 Combustion is usually lost in one of three places: Fit of the piston to the cylinder Head gasket Valves Decrease pressure of charge (unwanted air) Increase exhaust gas temperature (wear and degradation)

Pre-Assessment Quick Write- Which parts make up the compression system of an engine? 8

9 Components of the compression system Piston – machined from lightweight alloys Piston Rings – made of cast iron and/or steel Compression rings Oil rings

Piston Rings 10

11 Components (continued) Head gaskets – provide a seal between the cylinder head and the cylinder block Cylinder head – forms the top of the combustion chamber Cylinder block – houses the cylinders and crankshaft

Cylinder Block 12

13 Components (continued) Valves – Intake valves – open and seal the intake ports Exhaust valves – open and seal the exhaust ports Valve springs – both close the valves and hold them open Spring retainers – hold the springs on the end of the valves

14 Components (continued) Valves – Valve guides – support the valve stem as the valve moves back and forth CamshaftsCamshafts – open and close the valves PushrodsPushrods – transfer the rotating movement of the camshaft to the linear movement of the valves

Parts of an engine valve 15

Engine Disassembly 16 In pairs, you will disassemble a small engine. Please follow the directions in the packet given and use proper tools for precise measurements. Today we will complete questions #1-8. When you have completed #8 please come see me!

17 Operating System Components Air intake system – provides a source of clean air necessary for combustion Fuel system – delivers clean and adequate amounts of fuel to the cylinder Exhaust system – removes the exhaust gases and particles from the combustion chamber

18 Air intake system Air must first be cleaned by passing through the air cleaner – a filtering device Fuel and air are mixed in the carburetor – provides fuel and air to the engine in correct proportions and volume Fuel-air mixture enters the engine cylinder through intake valves

Parts of an air intake system 20

Fuel system Fuel tank stores fuel Fuel filter cleans the fuel that passes through it Fuel injection system inject fuel into the combustion chamber Mechanical fuel injection systems Electronic fuel injection systems

21 Exhaust system Exhaust manifold – collects gasses from one or more individual cylinders Exhaust pipe connects exhaust manifold to the muffler Muffler is the sound deadening device used to quite engine operations

Parts of an exhaust system 23

Material beyond this slide will not be included in the quiz on Monday September 28 th.

24 Operating System Components (continued) Engine cooling system – manages the heat produced by the combustion of the air-fuel mixture Lubrication system – keeps internal engine parts coated with oil to reduce friction, enhance cooling, seal internal engine components, and clean internal parts

25 Engine cooling system Liquid cooling system – uses a liquid to transfer heat from engine components to the surrounding air Air-cooled system – transfers the heat of the engine components directly to the surrounding air

Air-cooled system 26

27 Components of a liquid cooling system Radiator – a heat transfer device Water pump – forces the coolant to flow thorough the system Thermostat – a flow control valve Water Jacket- a series of interconnected cavities cast into the engine block & cylinder head for circulation of coolant. Additional components: radiator cap, fan, fan belt, and temperature gauge

Parts of a liquid cooling system 26

Liquid Cooled System 29 Pressurized system- boiling point of liquid raised significantly How an engine cooling system works

Lubrication System Purpose- maintain proper operation by reducing friction and cooling internal engine components. How it works Splash Lubrication Pressure Lubrication Full Pressure Lubrication 30

31 Lubrication system Oil filter – removes dirt particles from oil Pressure regulator – maintains the operating pressure of the system Sump – a reservoir for the engine oil Oil pump – circulates oil through the engine

Oil Characteristics Viscosity- the internal resistance of flow of a fluid. (thickness) SAE viscosity rating-number based on the volume of a base oil that flows through a specific orifice at a specified temp, atm pressure, time period. High rating- small volume flow caused by high resistance. Low rating- large volume of oil flowing caused by low resistance. Multi-viscosity- characteristics of 2 viscosity ratings. Offers low viscosity in cold. High in hot. Ex: SAE 10W-30 32

33 Operating System Components (continued) Ignition System – starts the combustion of the air-fuel mixture Starting system – used to turn the engine crankshaft until the engine starts

34 Ignition system Compression ignition system – does not consist of any unique parts Spark Ignition systems – uses high voltage electrical spark to ignite the compressed air and fuel mixture

35 Spark ignition systems Magneto–type ignition systems – use magnets and coils to generate electrical pressure to ark the spark plug Battery-type ignition systems - use the energy from a battery and/or alternator to create the ignition spark

36 Battery-type ignition systems Breaker point-type battery system – an ignition switch begins the process Ignition coil – converts low battery voltage to high voltage Distributor – sends the high voltage current to the correct spark plug Condenser – function as a capacitor which stores electrical energy

37 Battery-type ignition systems (continued) Breaker points – provide a switch to initiate the spark in the engine Distributor cam –controls the opening and closing of the breaker points, and regulates through the distributor rotor the timing of the engine spark

Breaker point-type battery ignition system 31

39 Starting system Manual – manually turning the crankshaft – rope starter Electrical – solenoid-type switch controls the voltage going to the starter Flywheel – a gear which is attached to the crankshaft

40 Review/Summary What are the three categories of internal combustion engine systems? Identify the components of the primary or compression system What components make up an engine’s operating system?

41 Terms Accessory systems Air cleaner Air cooled system Air intake system Battery-type ignition systems Breaker point-type battery system Breaker points Camshafts Carburetor Compression ignition system Condenser Cylinder head Distributor

42 Terms (continued) Distributor cam Electronic fuel injection systems Engine cooling system Exhaust manifold Exhaust system Exhaust valves Flywheel Fuel filter Fuel injection systems Fuel system Head gaskets Ignition coil

43 Terms (continued) Ignition system Intake valves Liquid cooling system Lubrication system Magneto-type ignition systems Mechanical fuel injection systems Operating systems Piston rings Primary system Pushrods

44 Terms (continued) Radiator Spark ignition systems Spring retainers Starting system Thermostat Valve guides Valve springs Water pump