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.. Diesel Engine

The diesel engine is a type of internal combustion engine that operates through a diesel cycle (named

after Dr. Rudolf Diesel). The main feature of the diesel engine is the use of compressed air to burn the

fuel, which is injected into the combustion chamber during the end of the compression stroke

[compression stroke]. It is contrary to the gasoline engine, in which air fuel-air mixture is ignited by the

spark plug.

Diesel engines produced in the form of 2-stroke and 4-stroke. Originally it was built as a replacement

for stationary steam engines more efficient. Since the 1910s it was used in ships and submarines. Soon the

diesel engine is also used in railroad locomotives, large trucks and electric generators. In the 1930s, it

began to be used in a number of car models. As of 2007, approximately 50 percent of new cars in Europe

using diesel engines.

Rudolf Diesel

Rudolf Diesel, a German national, was born in 1858 in Paris where her parents were immigrants

from Bavaria. He received his education at Politaknik munich. After graduate, he worked as an engineer

in the refrigerator, but his main desire is the engine designs. Diesel designing various types of heat

engines, including solar power air engine problem. In 1893, he published a paper on an internal

combustion engine. In 1894, he filed a patent for a new invention of the diesel engine. Diesel-Syariah

nearly killed when the engine exploded attempt however. The engine proves that the fuel can be burned

without the need for spark plugs. He operates a successful first engine built in 1897.

In 1998, Diesel awarded US Patent 608.845 to "internal combustion engine"

In Augsburg. On August 10, 1893, Rudolf Diesel's prime model, a single iron cylinder engine of 3.0 m

with a flywheel at its base, moving on its own for the first time, Diesel menghabislan within 2 years

improving the engine and in 1896 purchased a demonstration model of both the theoretical efficiency

75%, unlike a steam engine, which produces only 10% efficiency. By the year 1898, Diesel has become a

millionaire. The engine used in electric power plants and water, cars and trucks, as well as water vessels.

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It is also used in mines, oil exploration plants, factories and large ships.

What is a Diesel Engine

Diesel engine differs from the gasoline engine compression ratio through the use of higher air to burn

fuel than gasoline engines use spark plugs ("compression ignition" rather than "combustion ignition").

In addition tinggisehingga compression ratio allows combustion to occur without a separate ignition

system, a high compression ratio also increases the efficiency of the engine. In gasoline engines, the

compression ratio can not be too high to avoid engine damage due to ignition or knocking.

In a diesel engine, air is compressed with a compression ratio typically between 15: 1 to 22: 1,

increase the temperature to 532 ºC. The air temperature in the combustion chamber to burn the air fuel-air

mixture. There are fuel injected into the combustion chamber ignites by itself, generate power to the

engine.

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Four Stroke Cycle of a Diesel Engine

1. Suction Stroke – With pistons moving downwards and opening of the inlet valve creates suction of

clean air into the cylinders.

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2. Compression Stroke – With closing of Inlet valve the area above the piston gets closed. The piston

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moves up resulting in compression of the air in a confined space under higher compression-ratio.

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3. Combustion Process – At this stage the injector sprays the diesel into the combustion chamber. The

rise in temperature of the air caused by its compression; results in instantaneous burning of diesel

with in an explosion. This causes heat to release resulting in generation of expanding forces known

as power.

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4. Power Stroke – These forces again push the pistons downwards resulting in their reciprocating

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motion.

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5. Exhaust Stroke – On their way up, the pistons push the exhaust gases above them through the

exhaust valve which opens during exhaust stroke.

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6. This cycle repeats itself until the engine is turned off, resulting in continuance of engine’s running.

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...Diesel engine fuel system

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1. Gear pump sucks the fuel from the fuel tank. Before getting to the fuel pump switch in strained by

the main filter.

2. Then, move the pump to pump fuel to the injector pump. Prior to the injector pump, fuel is filtered in

two stages, filtered by secondary filter and then filtered by the filter end.

3. Next, injector pumps will pump high-pressure fuel to the injectors through the high-pressure pipe.

4. Finally, fuel is sprayed into the combustion chamber by the injector. Excess fuel is injected will flow

back into the fuel tank through an overflow pipe.

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.. Inline-type Diesel Injection Pump

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Injector pump type series includes a line of private plunger. That is one plunger for each cylinder,

which is powered by an internal cam shaft. High pressure tubing to connect each injector plunger. The

spring return valve plunger acts like a 'pop-off' and open their own when a certain pressure is reached.

This type of fuel injector pumps are widely used in marine engines. it is a simple equipment and easy to

maintain. But not widely used because of the 'jerk pump' that commonly affects this type of pump.

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Fuel enters through the intake port 'on the right side of the pump through the valve forwarding

(delivery valve). Pieces / external helical groove on the plunger serves as a conveyor of fuel while the

plunger is at KBS. Fuel enters the helical groove is then filled the space available on the top of the

plunger. Fuel is also included under the head of the plunger through the helical groove. When it moves up

(by the camshaft) it will cover the fuel inlet port and compresses the fuel. pressure will cause the fuel

valve lift and valve spring opens. The fuel will be pushed towards the injector (injector) through the high

pressure line. And when the plunger moves up again, the helix on the plunger that opens the fuel inlet port

causes the pressure to be low. An enclosed conveyor valve because the valve spring pressure is higher

than the fuel pressure causes the fuel delivery ends.

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Injection Pump Repair

1. Adjusting the plunger head

a) Using a dial indicator, remove the valve and spring passes. Replace the valve with a brass rod of

the same size. Combine the rod with a dial indicator and ensure an upright position 90 degrees.

Rotate the cam until the pump position no.1 adjust the dial indicator to zero. Lift tappet as high

as possible and note the dial indicator must be between 2-20 Thau.

Installation of dial indicator to measure the relief plunger head.

b) Using the cam. No need to remove the valve and spring conductor. Adjust the tappet so that the

valve plunger touching the transmitter. Lower plunger of ½ rounds.

2. Hand Phasing

a) Remove the valve transmitter, then adjust the control rod in the maximum position. Connect the

fuel at the pump and remove the air. Install the rotor and the plate is marked with the hand pump

coupler and adjust pointer.

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Installation of dial indicator to measure the displacement of the fuel control rack.

Determine the direction of rotation of the pump shaft and adjust the pointer. Adjust pump to KBS

dizziness no.1 coupler until the termination of the overflow length by using pipe goose neck. Install

all valves and springs back to the pump and do so according to the rules no.2 and burning.

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.. Distributer-type Diesel Injection Pump

A pump driven by the engine which supply fuel at high pressure for injection reciprocating engine,

where it is atomized and turned as it leaves the nozzle injection. Injection pump is a device that pumps

fuel into the cylinder diesel engine. Traditionally, the pump is driven directly from the crankshaft by a

gear, chain or toothed belt (often timing belt) which is also driving the camshaft. It rotates at half

crankshaft conventional four-stroke engine. Time is such that the fuel is injected with a little time before

the dead center of the compression stroke of the cylinder. It is also common for the pump belt on the

engine-driven fuel directly from camshaft. In some systems may be as high injection pressure of 200

MPa. Because of the need for positive injection into an environment of very high pressure pumps,

pressure typically develop large 15,000 psi (100 MPa) or more on the new system. This is a good reason

to take great care when working on the diesel system; escape of fuel at this pressure can easily penetrate

skin and clothing, and will be injected into the tissues of the body with medical effects serious enough to

warrant amputation.

Distributor-type Diesel Injection Pump is the pump used in cars and light trucks, rotary pump or

distributor pump has been developed. It uses a single injection cylinder driven from the axis of the cam

plate, which is injected into the fuel line of the individual through a rotating distribution valves. Later

incarnations such as Bosch VE pump change injection time with a crank speed to allow greater power at

high crankshaft speeds, and smooth, economical running at slow revs. Some variants of the VE has a

pressure-based system that allows the injection volume to increase more than usual to allow the engine is

equipped with a turbocharger or supercharger to develop more power under the terms of boost.

Mechanical pump gradually phased in to comply with the international emissions, and to improve the

performance and economy. Alternatives include common rail diesel system and direct injection system

electronics unit. This allows for higher pressures to be developed, and for finer control of injection

compared with mechanical systems. The main function of a diesel injection pump is to maintain fuel

pressure, supply regulated fuel and sends fuel to each cylinder according to the firing order.

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Distributor-type Diesel Injection Pump Component

External components

Internal components

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Distributor-type Diesel Injection Pump Images

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.. Glow plug / Heater Plug

A glow plug is a heating device used to aid starting diesel engines . In cold weather, high speed

diesel engines can be difficult to start because the mass of the cylinder block and cylinder head absorb the

heat of compression, preventing ignition due to the higher surface-to-volume ratio. Glow plug is

temporarily activated to add a hot spot within the combustion chamber until the residual temperature of

the combustion chamber achieves the level required to support self-combustion.

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Indirect Injection Direct Injection

For that reason indirect injected diesel engines aremanufactured with glow-plugs in each pre-

chamber, and direct injected diesel engines are manufactured with glow-plugs in each combustion

chamber.

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The glowplug is a pencil-shaped piece of metal with a heating element at the tip. This heating

element, when electrified, heats due to its electrical resistance and begins to emit light in the visible

spectrum, hence the term "glow"-plug. The visual effect is similar to a toaster . The fuel injector spray

pattern then impinges directly upon the hot tip of the glow plug during the injection of fuel at top dead

center. This enables the fuel to ignite even when the engine is insufficiently hot for normal operation. This

reduces the cranking time needed to start the diesel engine.

Operation

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"Wait-to-Start" light (glow plug indicator light) in a diesel car.

In older generation diesel-engine vehicles, unlike in a gasoline-engine vehicle, the operator did not

simply turn the key to the "start" position and have the engine immediately start. Instead, the operator

turned the key to the "on" position for a long duration; the glowplug relay switches the glowplugs on, and

a light (see picture at right) on the instrument cluster illuminates. This process is called "pre-heating" or

"glowing".

This is a glow plug being heated up whilst outside an engine as a test.

Starting

When a pre-set time has elapsed, the glow plug relay switches off the "wait-to-start" light. A pre-

heating cycle usually lasts for 2 to 5 seconds. The operator then proceeds to turn the key to the "start"

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position. The relay switches off the glow plugs after the engine is running (or,in older cars, at the same

time the "wait to start" light goes out). In some cars, glow plugs continue to operate for up to 180 seconds

after engine start to keep the engine within emissions regulations, as combustion efficiency is greatly

reduced when the engine is very cold.

Warm Engine Start

If the car had been running very recently, or if the ambient temperature was hot, the "wait to start"

light might not come on. In this case, the operator may proceed to turn the key to the "start" position and

start the engine without having to wait.

Construction

A glow plug resembles a short metal pencil . The heating filament is fitted into its tip. Glow plug

filaments must be made of certain materials, such as platinum and iridium , that are resistant to both

oxidation and high temperature.

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.. Injector Nozzle

Function

Injector is very important part in the fuel system. It serves to prevent the fuel from inject into the

combustion chamber at the inappropriate time. Injector atomizes the fuel for better combustion. Injector

will inject fuel in the form of a fine, misty spray into the combustion chamber and preads the fuel spray to

fully mix with air into the cylinder. It is also designed so that the fuel can withstand high pressure into the

combustion chamber, so as to achieve the desired pressure limit.

Types

1. C.A.V Injector

C.A.V injector consist 2 major parts. One part is the body and the other part is the needle

valve and the nozzle. Between these 2 parts there is only small gap. When these 2 major

parts is fastened by cap nut, the needle may only lifted as far as “0.004- 0.008” from there

seat.

C.A.V injector has a spring where you can differentiate their tension and their end there is a

push rod and adjusting screw to adjust the atmospheric pressure.

C.A.V injector has an angle between the needle and the nozzle which is 60 ° and 59 °27’

during the fuel sprayed into the cylinder.

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a) Single-Hole Nozzle -150 ATS Pressure

b) Multi-Hole Nozzle – 180 ATS Pressure

c) Pintle Nozzle – 100 ATS Pressure

d) Pintaux Nozzle – 105 ATS Pressure

2. Gardner Injector

Gardner injector’s needle attached to the push rod and has a big gap in between the needle

and the nozzle that act as a pressure chamber.

Gardner injector’s needle can be lifted as far as “0.008”.

Gardner injector can be adjusted by adding or reducing the number of shim.

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a) Gardner injector “LW”

b) Gardner injector “E”

c) Gardner injector “EL”

d) Gardner injector “ELS”

e) Gardner injector “K”

Components

1. Needle valve

2. Nozzle body

3. Nozzle holder

4. Thrust pin

5. Injection nozzle holder “lower part”

6. Compression spring

7. Injection nozzle holder “upper part”

8. Leak – off connection

9. Fuel inlet

10. Steel shim

11. Inlet port

12. Pressure chamber nozzle body

13. Filter

14. Cross hole

15. Center hole

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Operation

1. High pressure fuel from the injector/ nozzle will go through the inlet pipes and straight to the

pressure chamber located in injector nozzle.

2. When the pressure is greater than the spring pressure, it will cause the spring to be pushed and the

needle valve will be lifted and the nozzle hole will be open.

3. When the nozzle hole is opened, the high pressure fuel will be spray in form of mist.

Nozzle Failure

Symptoms problem: Cause of problem:

Opening Pressure too high - Faulty/rusty needle valve.

- Blocked nozzle.

Spraying brailing pressure too low - Broken valve spring.

Crooked needle valve & Spray not in mist form. - Broken needle valve.

- Nozzle carbonaceous.

Nozzle does not making “ Hiss sound” while fuel

injection

- Needle valve fastened too tight.

- Cap nut crooked/ band.

- Spring attached.

Fuel dripping - Seat damaged.

- Dirty nozzle.

End of nozzle turned blue - Wrong nozzle installation.

- Cooling system problem.

Excessive pressure dropped. - Needle valve wear.

- Nozzle cap loose.

- There grime between nozzle and nozzle body.

Diesel Injector Tester

Diesel injector test components:

1. Reading meter (Psi,Bar,Kg/Cm2 & Etc)

2. Fuel pipe line

3. Flare nut

4. Pressure adjuster knob

5. Handle pump

6. Diesel fuel reservoir

1. Opening Pressure test

To test the spring force, when will the needle valve will be lifted.

Operation:

i. You need a spanner sets to perform this test.

ii. A container.

iii. Connect the injector/nozzle to the diesel injector tester using spanner “17 & 19”

depends on what size is the injector bolt.

iv. Fill the diesel fuel in fuel reservoir.

v. Grab the handle, and pump it until the injector spray.

vi. Check the pressure readings from the reading meter (New nozzle 115-125kg/cm2

(1,636psi – 1,778 psi) (Used nozzle 105-125kg/cm2 (1,493psi – 1,778psi)

2. Spray pattern test

To examine the spray pattern whether it can produce a mist form spray.

Operation:

i. You need a spanner sets to perform this test.

ii. A container.

iii. Connect the injector/nozzle to the diesel injector tester using spanner “17 & 19”

depends on what size is the injector bolt.

iv. Fill the diesel fuel in fuel reservoir.

v. Grab the handle, and pump it until the injector spray.

vi. A good injector will produce a spray which is a mist form.

3. Drip test

Determine whether there is a fuel dripping, if in 60 seconds there is not more than 2

drips, that means the injector are in a good shape.

Operation:

i. You need a spanner sets to perform this test.

ii. A container.

iii. Connect the injector/nozzle to the diesel injector tester using spanner “17 & 19”

depends on what size is the injector bolt.

iv. Fill the diesel fuel in fuel reservoir.

v. Grab the handle, and pump it slowly.

vi. Check at the end of valve whether there is a fuel dripping.

vii. Make sure the place that you are using is dry while you perform this test.

viii. If happen there is a drip at the end of the nozzle, make sure it is not more than 2 drips in

60 seconds.

ix. Measure the drip size using diffuser paper, not more than ½ inch.

4. Leak test

To examine whether there is a leak occur from the injector body.

Operation:

i. You need a spanner sets to perform this test.

ii. A container.

iii. Connect the injector/nozzle to the diesel injector tester using spanner “17 & 19”

depends on what size is the injector bolt.

iv. Fill the diesel fuel in fuel reservoir.

v. Set the pressure to 90kg/cm2 (1280psi).

vi. Grab the handle, and pump.

vii. Check if there is fuel leaks at the nozzle valve seat and at the retaining nut.

Cleaning Injector

1. You need injector cleaning kit.

2. You need wooden stick / wood splinter and wire brushes (Brass brush).

3. Diesel fuel.

How to perform cleaning procedure:

i. Remove nozzle needle from nozzle body.

ii. Hold on the stem needle and remove all the carbon that found in needle tip using

wooden stick.

iii. Warning:

iv. Do Not Use Any Rough Surface Tool to perform this Cleaning procedure, it might

damage the nozzle.

v. To clean on the inside the nozzle body, use the tool that provided on the cleaning kit,

that is grinding compound.

vi. Clean the spray hole using special needle inside the nozzle cleaning kit.

vii. Insert the special needle inside the spray hole.

viii. Check all the nozzle parts if there is sign of wear, crack, scratch, and damaged.

ix. Sliding test.

x. After cleaned all parts of the nozzle using diesel. Inspect with care whether the needle

will slide through the nozzle body by itself.

xi. Repeat this steps if needed.

.. Governor

Operation of a constant speed, hydraulically compensated governor. The principles involved

are common in any mechanical and hydraulic governor.

The speed governor operates the diesel engine fuel racks to ensure a constant engine speed is

maintained at any load. The governor is a mechanical-hydraulic type governor and receives its

supply of oil from the engine lubricating system. This means that a loss of lube oil pressure will

cut off the supply of oil to the governor and cause the governor to shut down the engine. This

provides the engine with a built-in shutdown device to protect the engine in the event of loss of

lubricating oil pressure.

Spark-ignition engines have a built-in governor in the form of a throttle valve that, even wide

open, limits the amount of air passing into the engine. Diesels have no such limitation, since

surplus air is always available for combustion. Engine speed depends solely upon the amount of

fuel delivered. If the same volume of fuel necessary to cope with severe loads were delivered

under no-load conditions, the engine would rev itself to destruction. Consequently, all diesel

engines need some sort of speed-limiting governor.

Most governors also control idle speed, a task that verges on the impossible for human

operators. This is because the miniscule amount of fuel injected during idle exaggerates the

effects of rack movement. Automotive applications are particularly critical in this regard. Idle

speed must be adjusted for sudden loads, as when the airconditioner compressor cycles on and

off, and when the driver turns the wheel and engages the power-steering pump.

In addition to limiting no-load speed and regulating idle speed, many governors function

over the whole rpm band. The operator sets the throttle to the desired speed and the governor

adjusts fuel delivery to maintain that speed under load. The degree of speed stability varies with

the application. No governor acts instantaneously—the engine slows under load before the

governor can react. Course regulation holds speed changes to about 5% over and under the

desired rpm, and is adequate for most applications. Fine regulation, of the kind demanded by AC

generators, cuts the speed variation by half or less.

Centrifugal governors sense engine speed with flyweights and throttle position with spring

tension. Figure 5-28 illustrates the principle: As engine speed increases, the spinning flyweights

open to reduce fuel delivery. As the throttle is opened, the spring applies a restraining force on the

flyweight mechanism to raise engine speed.

Governor Components

.. Diesel system inspection

Change diesel fuel filter

Test diesel fuel injectors