Maintenance & Operation of Deisel Engines

by

Asif Ali Rajput

Contents

History of Deisel Engine Working Principles Main Parts and function Operating Parameters Trouble Shooting Preventive Maintenance

History Rudolf Diesel, a German national designed first IC engine in 1897 and named it Deisel engine. He was born in 1858 in Paris, and educated at Munich Polytechnic. After graduation he was employed as a refrigerator engineer but his true love lay in engine design. Diesel designed many heat engines, including a solar-powered air engine. In 1893, he published a paper describing an engine with combustion within a cylinder, the internal combustion engine. In 1894, he filed for a patent for his new invention, dubbed the diesel engine. His engine was the first to prove that fuel could be ignited without a spark. He operated his first successful engine in 1897.In 1898, Rudolf Diesel was granted U.S. Patent 608,845 for an "internal combustion engine".

Patent1893: Rudolf Deisel obtains patent on his engine design1897: On August 10 Diesel builds his first working prototype in Augsburg

1899: Diesel licenses his engine to builders

1906: A diesel engine built by MAN AG

Principles of Diesel Operation In diesel engine, air is introduced into the combustion chamber. The air is then

compressed by piston in the cylinder with a compression ratio typically between 15 and 22 resulting a 40 bar / 600 psi pressure. This high compression heats the air up to 550 °C / 1000 °F. At this moment, fuel is injected through fuel injector directly into the compressed air in combustion chamber. The fuel injector ensures that fuel is broken down into small droplets, and that the fuel is distributed as evenly as possible.

The heat of the compressed air vaporizes fuel from the surface of the droplets. The vapour is then ignited by the heat of compressed air in the combustion chamber. Fuel droplets continue to vaporize from their surfaces and burn, getting smaller & smaller, until all the fuel in the droplets has been burnt.

The start of vaporization causes a delay period during ignition, and the characteristic diesel knocking sound is produced as the vapour reaches ignition temperature and causes an abrupt increase in pressure above the piston. The rapid expansion of combustion gases then drives the piston downward, supplying power to the crankshaft.

Deisel Engine Parts & FunctionEach engine part has its own particular function to perform and in

conjunction with other parts, equally important, comprises the assembly called the internal-combustion engine or, in short, combustion engine.

An understanding of the operation or functions of the individual parts is necessary for a better understanding of the whole engine.

A person who intends to work in the field of diesel-engines, must have know how to recognize the engine parts by sight and must learn their correct names and also their particular functions as well.

Let us see a cross sectional views of basic diesel engineIn Figs. 1 and 2 are showing cross-sectional views of a diesel engine

of the heavier type.

Ship Diesel Engine

Marine Diesel Engine

Ship Deisel Engine Generator

Figure 1The section of cylinder head is taken through the injector, or spray nozzle, and starting-air valve,

Main parts of the engine are visible here and

Figure 2The section through the center line of the engine and in the cylinder head shows the intake and exhaust valves.

Engine Parts & Their Function

For understanding of the component parts used in the diesel engine, let us see the function of individual engine parts shown in the x-sectional drawings fig 1 & 2:

Engine Parts & Their FunctionAir filter: A device for filtering the air, to prevent particles of dust from entering the engine.

Air injection: The system of injecting fuel into the combustion chamber of a diesel engine by means of a blast of highly compressed air.

Air starter: A system to turn the engine by admitting compressed air into the cylinders in order to initiate firing.

Atomizer: Breaks up fuel into extremely fine particles for burning inside the cylinder.

Bedplate: The lower part of the engine resting on the foundation.

Bore: The interior diameter of an engine or compressor cylinder.

Crank Shaft: To transmits power to alternator or any driven machine.

Cam: A disk-like piece attached to a shaft, a portion of which is circular, and remainder is oval protruding beyond the circle. Cams are used to impart a desired motion to poppet valves.

Camshaft: The shaft which carries the various cams required for the operation of inlet, exhaust, fuel, and starting-air valves.

Cam follower: That part of the push rod that is in contact with the cam.

Engine Parts & Their FunctionCompression Rings: Piston rings placed in the upper part of a piston to seal against loss of compression pressure and against gas blowing.

Combustion chamber. The space above the piston in which the fuel-air mixture starts to burn.

Common rail: A pipe or header from which branch lines lead to each of the fuel valves in the different cylinder heads of a diesel engine and in which fuel is carried at high pressure, ready for delivery to each separate cylinder when the fuel valve is opened by a cam.

Connecting rod: The engine part which connects the piston to the crankshaft. It changes reciprocating motion of the piston into rotary motion of the crankshaft or vice versa.

Connecting rod bearin:. The bearing located in the large end of the connecting rod by which it is attached to the crankshaft.

Crankcase: The middle part of the engine structure surrounding the working parts.

Crankshaft: That part of the engine which transmits the reciprocating motion of the pistons to the driven unit in the form of rotary motion. That part to which the connecting rods are attached.

Crankshaft cheek: The part J the crankshaft that connects the crankpin to the main crankshaft journal. Also called crank shaft web.

Crankshaft journal: The part of the crankshaft which rotates in the main bearings and transmits the torque developed by the engine.

Crosshead: The part of an engine to which are attached the piston pin with the connecting rod and the piston rod and which is supported on guides.

Engine Parts & Their FunctionCylinder: The cylindrical part of the engine in which the piston moves.

Cylinder head. The part which covers and seals the end of the cylinder and usually contains the valves.

Exhaust manifold. The pipe that collects the burnt gases as they are expelled from the cylinders.

Flywheel. The wheel on the end of the crankshaft that gives the crankshaft momentum to carry the pistons through the compression stroke.

Fuel injector. The device which sprays the fuel into the cylinder.

Fuel pump. The pump that delivers the fuel to the injector Governor. A mechanism used to control the speed of an engine.

Muffler. A device used to diminish noise of the intake or exhaust. Also called as a silencer.

Oil-control rings. The piston ring, usually located at the lower part of the piston, that prevents an excessive amount of lubricating oil from being drawn up into the combustion space during the suction stroke. Also called simply oil ring and oil scrapper ring.

Piston. A cylindrical part which reciprocates in the cylinder bore of an engine and transmits the force of the gas pressure through the connecting rod to tine crankshaft.

Engine Parts & Their FunctionPiston Ring: A split ring placed in a groove of the piston to form a leak proof joint between the piston and the cylinder wall.

Super charger: Supplying of combustion air to an engine at higher than atmospheric pressure, usually 2 to 4 psig, in some engines up to 30 psig.

Tachometer. An instrument indicating instantaneous rotary speed of a shaft in rpm.

Water jacket: The outer casing forming a space around an engine cylinder to permit circulation of cooling water.

Intercooler: It is a simply a heat exchanger mounted between the turbo-charger, or super-charger and the inlet side of the engine. Cold air is blown through it to cool down the hot, compressed air inside; this makes it denser and gives maybe another 10% more power.

Operating Parameters

Operating Parameters There are many parameters to monitor, but following are

the most important in continuing safe operations:1. Engine Temperature2. Lube Oil Pressure3. Speed or Frequency4. Vibrations5. Exhaust Conditions If above parameters are under control, the engine is

safe to operate.

Checks Duration Operations

Check Every 8 HoursOperation of pre-lube pump.

Operation of starting air compressors or battery charger. Batteries are charged. Control power is available to the control system and all controls are

in the proper position to allow automatic starting of the engines. Look for fuel oil, lube oil and coolant leaks.Check Day Tank area for leaks. Check lube oil level add if required.

Trouble Shooting

Trouble Shooting

Trouble Shooting

Trouble Shooting

Trouble Shooting

Preventive MaintenanceDiesel Engines are most efficient and durable than any other engines. So, it’s maintenance

requirement is preventive in nature. Diesel Engine PM consists of the following operations:

• General inspection • Lubrication service • Cooling system service • Fuel system service • Servicing and testing starting batteries • Regular engine exercise

It is generally a good idea to establish and adhere to a schedule of maintenance and service based on the specific power application and the severity of the environment. Let us see a preventive maintenance schedule for our DEGs

PM Schedule for Diesel Engine Generators

Conclusion

Preventive Maintenance for diesel engine generators plays a critical role in maximizing reliability, minimizing repairs and reducing long term costs by following

generally recognized diesel engine maintenance procedures and OEM recommendations.

Thank You