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Roger C. Montepio WELCOME AGRICULTURAL MACHINERY

Diesel engine

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Page 1: Diesel engine

Roger C. Montepio

WELCOME

AGRICULTURAL MACHINERY

Page 2: Diesel engine

Roger C. Montepio

Page 3: Diesel engine

Roger C. Montepio

LECTURE TOPICS

What is a diesel engine? (comparison between gasoline engine and a diesel engine)

Parts, principles and uses of diesel engineServicing and maintenance of a diesel engineFuel Injector

Page 4: Diesel engine

Roger C. Montepio

Engine Dissection

You are dissecting a 3.5 HP single cylinder, 4 cycle engine, made by Briggs & Stratton in Milwaukee, WI

These engines are typically used in lawn mowers, snow blowers, go-carts, etc

(ref. 2, Used by permission of Briggs and Statton, ©1992, all rights reserved)

Page 5: Diesel engine

Roger C. Montepio

• Engine Terminology• Engine Classifications

- a device which transforms the chemical energy of fuel into thermal energy and uses this energy to produce mechanical work.

What is engine?

ENGINE

Page 6: Diesel engine

Roger C. Montepio

Cylinder volume, V

Clearance volume, Vc

Stroke volume, VS

Top dead center, TDC

Bottom dead center, BDCConnecting rod

Crank

Check

Crank case

Cylinder

Crank pin

Gudgeon or wrist pin

Piston

Suction valve Exhaust valve

Intake of suction manifold

Cylinder head

Exhaust manifold

Crank shaft

ENGINE

Page 7: Diesel engine

Roger C. Montepio

Engine-Review

Convert fuel chemical energy into mechanical powerCombustion of the fuel causes one or more reciprocating pistons, to turn a crankshaft

Transmission of power:Crankshaft via flywheel

Connecting rod

Piston Output shaft

Desired load

Page 8: Diesel engine

Roger C. Montepio

                             Crank Shaft                                      Connecting Rod & Piston

Engine-Review

Page 9: Diesel engine

Roger C. Montepio

Spark vs. Compression Ignition

• Spark ignition (SI) engines– a compressed, homogeneous air-fuel mixture (15:1

ratio of air to fuel by mass) is ignited using a spark• Compression ignition (CI) engines

– rapid compression of air to a high pressure raises the temperature so that fuel, when delivered into combustion chamber, spontaneously ignites without need for a spark

– often referred to as a Diesel engine

Page 10: Diesel engine

Roger C. Montepio

Description SI Engine CI Engine1 Basic cycle Based or Otto cycle. Based on Diesiel cycle.

2 FuelPetrol (gasoline). Hight self-ingintion temperature desirable

Diesel oil. Low self-ignition temperature desirable

3 Introduction of fuel

Fuel and air introduced as agaseous mixture in thesuction stroke. Carburator nessesary to provide themixture. Throtle controls thequantity of mixtureintroduced.

Fuel is injected directly intocombustion chamber at highpressure at of compressionstroke. Carburator is eliminatedbut a fuel pump and injectornecessary. Quality of fuelregulated in pump.

4 IgnitionRequired an ignition system with spark plug in the combustion chamber.

Ignition due to high temperatur, caused by high compression of air, when fuel is injected. Ignition system and spark plug is eleminated.

5Compression ratio rage

6 to 10.5. Upper limit of CR fixed by anti-knock quality of fuel.

14 to 22. Upper limit of CR is limited by the rapidly increasing weight of the engine structure as the compression ratio is further increased.

6 SpeedHigher maximum revolution per minute due to lighter weight.

Maximum r.p.m lower

7 Efficiency Maximum efficiency lower Higher maximum efficiency.

8 Weight Lightrer Heavier due to higher pressures

Page 11: Diesel engine

Roger C. Montepio

DIESEL ENGINE

- a type of internal combustion engine, more specifically, a compression ignition engine, in which the fuel is ignited by the high temperature of compressed gas, rather than a separate source of energy(such as a spark plug).

What is a diesel engine?

Page 12: Diesel engine

Roger C. Montepio

DIESEL ENGINE

Page 13: Diesel engine

Roger C. Montepio

DIESEL ENGINE

Page 14: Diesel engine

Roger C. Montepio

How it works?

When gas is compressed its temperature rises. A diesel engine exploits this property in order to ignite the fuel. Air is drawn into the cylinder of a diesel engine, and compressed by the rising piston. This happens at a much higher compression rate than in a spark-ignition engine. At the top of the piston stroke diesel fuel is injected into the combustion chamber at high pressure through an atomising nozzle. It mixes with the hot, pressurised air. The resulting mixture ignites and burns very rapidly. This contained explosion causes the gas in the chamber to expand, driving the piston down with considerable force, and creating power in a vertical direction.

The connecting rod transmits this motion to the crankshaft which is forced to turn, delivering rotary power at the output end of the crankshaft. ‘Scavenging’ - pushing the exhausted gas-charge out of the cylinder and drawing in a fresh draught of air - is done through ports or valves.

Page 15: Diesel engine

Roger C. Montepio

Working Principles

Suction StrokeCompression Stroke,Power Stroke,Exhaust Stroke

Diesel working principles

Page 16: Diesel engine

Roger C. Montepio

Fuel Characteristics

Diesel Fuel Diesel fuel is a product of crude oil, although other oils can be burned inside

an adapted engine. Good quality diesel fuel can be synthesized from vegetable fat and alcohol.

Diesel engines can work on thicker, heavier oil, or oil with higher viscosity, as long as it is heated in order to ease pumping and injection. These fuels are cheaper but dirtier than clean, refined diesel oil.

Diesel fuel is more difficult to ignite than gasoline because of its higher flash point, but once burning, a diesel fire can be extremely fierce.The use of low-grade fuels can lead to serious maintenance problems.

Page 17: Diesel engine

Roger C. Montepio

Supporting Systems

Intake and Exhaust SystemStarting SystemFuel System,Cooling System,Lubricating System

Diesel Supporting Systems

Page 18: Diesel engine

Roger C. Montepio

Intake System

The function of this system is to allow the purified air to the cylinder

Air Cleaner,Intake Manifold,Intake Valve,Supercharger, etc.

Page 19: Diesel engine

Roger C. Montepio

Intake System

1. Wing nut2. Washer3. Air Filter cover4. Rubber Packing5. Air Filter cartridge6. Rubber packing7. Air Filter body8. Rubber packing9. Air Filter flange10. Air Filter leeve11. Intake pipe

Page 20: Diesel engine

Roger C. Montepio

Faults and Remedies

Faults and remedies1) Air cleaner jammed with dirt -Change 2) Internal manifold cracked -Change 3) Cage --- and bent stem of intake valve -Repair or change 4) Super charger not working properly -Repair or change

Page 21: Diesel engine

Roger C. Montepio

Exhaust System

The function of this system is to take out burnt gas from the cylinder

Silencer pipe,Silencer box andTail pipe,

Page 22: Diesel engine

Roger C. Montepio

Faults and Remedies

Faults and remedies1) Exhaust manifold broken/cracked -Change2) Silencer pipe cracked -Repair or change3) Silencer box jammed due to burnt or leaked carbon -Repair or change4) Tail pipe leaked or cracked -Repair or change

Page 23: Diesel engine

Roger C. Montepio

Starting System

The system starts the engine by providing initial rotations via:

Hand-starting system,Self-starting system,Rope-starting system andPedal-starting system

Page 24: Diesel engine

Roger C. Montepio

Starting System

Hand-starting system is generally used in one cylinder diesel engine.There is no fault in this system, one handle is used for starting.( Water,lubricant and fuel must be checked before starting)

Page 25: Diesel engine

Roger C. Montepio

Fuel System

Engine fuel system is very important through which the fuel is taken out of the fuel tank for combustion.

Fuel tank,Fuel line,Fuel filter,Low pressure feed pump,High pressure fuel pump andInjector or atomizer

Page 26: Diesel engine

Roger C. Montepio

Faults and Remedies

Faults and remedies1) Fuel tank leaked/cracked -Repair or change2) Fuel line leaked/cracked -Change3) Filter jammed due to dirt -Change4) Low pressure/feed pump faulty -Repair or change after checking5) High pressure fuel pump faulty -Repair or change after checking6) Injector faulty -Repair or change after checking

Page 27: Diesel engine

Roger C. Montepio

Cooling System

Engine cooling system enables the engine to maintain a constant operating temperature.

Water cooling system andAir cooling system

Page 28: Diesel engine

Roger C. Montepio

Cooling System

Page 29: Diesel engine

Roger C. Montepio

Lubricating System

Using lubricant, the lubrication system prevents wear and tear of moving components and enables components to move faster and more efficiently.

Three functions (Cooling, Sealing and Cleaning)Strainer,Oil pump,Oil filter,Oil pressure gaugeOil passage

Page 30: Diesel engine

Roger C. Montepio

Faults and Remedies

Faults and remedies1) Strainer may be damaged -Change2) Pump may not work -Repair or change3) Oil filter jammed due to dirt -Change4) Oil pressure gauge faulty -Repair or change (after checking)5) Oil passage jammed -Clean

Page 31: Diesel engine

Roger C. Montepio

Engine Faults

Five common faults are faced during engine operation :1. Over-heating2. Excessive engine vibrations3. Excessive fuel consumption4. Excessive lubrication consumption5. Excessive noise during operation

Page 32: Diesel engine

Roger C. Montepio

Engine Faults

Possible reasons for over-heating of engine :1. Low water quantity in radiator or water tank2. Ignition starts after specified time3.Fan belt lose or torn4. Water jacket jammed5. Faulty water pump6.Low quantity of lubricating oil7. Faulty lube oil pump8. Broken fan blade9.Engine operates over load10. Engine operates at a high speed for a long time

Page 33: Diesel engine

Roger C. Montepio

Engine Faults

Possible reasons for engine vibration :1. Vibration damper or engine counter-weight are not working2. Detonation and auto-ignition3. Main engine bearing, the smaller end bearing of connecting rod, or the thrust bearing, have become loose.

Page 34: Diesel engine

Roger C. Montepio

Engine Faults

Possible reasons for excessive fuel consumption :1. Frequent starting and stopping uses a lot of fuel2. Leak in fuel delivery line3. Leak in fuel tank4. Air cleaner jammed5. Engine left in operation unneccessarily6. Improper valve timing7. Over loaded engine

Page 35: Diesel engine

Roger C. Montepio

Engine Faults

Possible reasons of excessive lubrication consumption :1. Piston wrongly fitted 2. Piston and connecting rod misaligned3. Oil ring not placed exactly in oil ring grove4. Too large a gap between piston and cylinder5. Low tension of oil ring6. Excessive wear of big-end bearing7. Main oil seal cracked or damaged8. Intake valve guide wrongly fitted9. Excessive wear of cylinder taper and out / round10. Engine head gasket cracked and damaged

Page 36: Diesel engine

Roger C. Montepio

Engine Faults

Possible reasons for excessive noise during operation :1. Wear and improper adjustment of engine parts2. Abnormal condition due to detonation and auto-ignition3. Poor quality fuel4. Loose connecting rod

Page 37: Diesel engine

Roger C. Montepio

Engine Faults

Wearable and breakable parts of a fuel pump :• Wear of plunger• Wear of plunger bush• Plunger retaining spring can lose tension• Plunger-retaining spring can break• Wear of bush and ball bearing• Wear above tappet and bottom of plunger• Wear of roller and fan

Page 38: Diesel engine

Roger C. Montepio

Others

COMPLAINT POSSIBLE CAUSE REMEDYEngine Lacks Power * Incorrect grade of oil * Use recommended type and

SAE number of oil* Wrong type of fuel * Change* Insufficient air * Clean or change element* Engine overcooled * Use radiator cover, replace

parts* Valve clearance incorrect * Readjust* Injection pump defective * Readjust or replace* Injection nozzles defective * Readjust or replace* Injection timing incorrect * Readjust* Compression pressure low * Disassemble and replace

parts

Page 39: Diesel engine

Roger C. Montepio

Others

COMPLAINT POSSIBLE CAUSE REMEDYWhite or blue exhaust smoke * Too much oil in crankcase * Fill only to correct level on

gauge* Oil viscosity too low * Refill with correct viscosity

of oil* Engine overcooled * Use radiator cover, or

clean, test and replace thermostat

* Injection timing incorrect * readjust* Compression pressure low * Diassemble and replace

parts* Poor fuel spray from injection nozzles

* Readjust or replace

Page 40: Diesel engine

Roger C. Montepio

Others

COMPLAINT POSSIBLE CAUSE REMEDYBlack or gray exhaust * Wrong type of fuel * Refill with correct type of

fuel* Valve clearance incorrect * Readjust* Injection pump defective * Readjust or replace* Compression pressure low * Disassemble and replace

parts* Insufficient air * Clean or change element

Page 41: Diesel engine

Roger C. Montepio

Others

COMPLAINT POSSIBLE CAUSES REMEDYHigh fuel consumption * Injection pump defective * Readjust or replace

* Injection nozzles defective * Readjust or replace* Wrong type of fuel * Refill with correct type of

fuel* Compression pressure low * Disassemble and replace

parts* Insufficient air * Clean or change air

cleaner element. Check turbocharger

* Injection timing incorrect * readjust

Page 42: Diesel engine

Roger C. Montepio

Others

COMPLAINT POSSIBLE CAUSES REMEDYHigh oil consumption * Too high oil level in

crankcase* Maintain oil level in operating range on gauge

* Incorrect grade of oil * Use recommended type and SAE number of oil

* Oil leaks * Retighten or replace

* Cylinders and piston rings worn

* Disassemble and replace parts

Page 43: Diesel engine

Roger C. Montepio

Others

COMPLAIN POSSIBLE CAUSE REMEDYEngine overheats * Fan belt house * readjust

* Lack of coolant * refill* Too low oil level * Maintain oil level in

operating range on gauge* Water pump defective * Replace* Thermostat defective * Replace

Page 44: Diesel engine

Roger C. Montepio

Others

COMPLAINT POSSIBLE CAUSE REMEDYLow oil pressure * Lack of oil * Refill up to level

* Oil viscosity too low * Refill with correct viscosity of oil

* Oil filter clogged * Replace element* Oil pump defective * Readjust or replace* Oil pressure regulating valve defective

* Readjust or replace

Page 45: Diesel engine

Roger C. Montepio

Nozzle Servicing

Page 46: Diesel engine

Roger C. Montepio

Nozzle Servicing

• Open faulty nozzle and clean away soot (carbon); then check whether nozzlemoves freely.• Check delicate parts.• Check nozzle valve and body.• Immerse nozzle valve and body in clear diesel oil in order to remove carbon.• Use copper wire brush - not a steel brush – to clean off soot (carbon).• Fuel bore should be cleaned with a fine drill.

Page 47: Diesel engine

Roger C. Montepio

Air Bleeding

The correct method of air bleeding the fuel system :• Fill up the fuel tank with new diesel oil.• Open valve of the tank.• Loosen bleeding plug of the fuel filter and pump till fuel flow is continuous.• Tighten the plug.• Loosen injection line nut and crank the engine till fuel is flowing without foam.• Close the injection line and check for leaks.