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Diesel engine maintenance and repair - Automotive Technology Profession For College Level Part 1 - 1

MINISTRY OF LABOR, WAR INVALIDS AND SOCIAL AFFAIRS COLLEGE OF TECHNOLOGY II


COURSE: DIESEL ENGINE MAINTENANCE AND REPAIR


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OCCUPATION: AUTOMOTIVE TECHNOLOGY

(For college level)


HCMC, 2019

INTRODUCTION


The Diesel Engine Maintenance and Repair textbook is compiled to provide learning materials for students in the field of automobile repair. Nowadays, Diesel engine manufacturers have used electronics to control Diesel engines. However, the source of documents on electronic fuel injection systems on the market is very rare. In order to meet the teaching requirements of the Diesel Engine Maintenance and Repair module. The group of teachers of the Faculty of Mechanical Engineering has tried to collect documents from car manufacturers, on websites and other sources, as well as with the existing equipment of the school to compile this textbook.

The course aims to help college students in auto repair have study materials, as well as maintenance and repair of Diesel engines.

Because this subject has only been taught for 3 years, there are still many limitations and the group of authors is trying to complete the curriculum in the near future.


Ho Chi Minh City, date …. month …. year 2019

Participate in editing

Editor: Nguyen Van Ngoc

Le Thanh Nhan

Huynh Diep Ngoc Long

INDEX


Page Item

Lesson 1: Injector (Oil nozzle) 3

Lesson 2: High pressure pump in personal fuel system PF 19

Lesson 3: High pressure pump PE 36

Lesson 4: VE 75 high pressure pump

Lesson 5: EDC 111 Fuel System

Lesson 6: Common Rail Fuel System 134

Lesson 7: Turbocharger control system, EGR 150

References 155

LESSON 1: INJECTOR (OIL NOZZLE)


I. STRUCTURE AND OPERATING PRINCIPLES OF OIL SPRAY NOZZLES.


1. Uses:

Fuel injectors installed in the engine cylinder have the following tasks:

- Spray fuel into the engine's combustion chamber in the form of mist.

- Prevents fuel from directly hitting the cylinder wall and piston top.

- Combined with special forms of combustion chambers so that fuel vapor mixes with air at high pressure and temperature to form a self-igniting mixture, capable of providing the engine with high power and minimum fuel consumption.

2. Classification.

Based on the difference between the needle tip and the jet hole, the output injector is divided into 2 types: closed-end injector and open-end injector.

A. Sealed needle type.

This injector is used in personal fuel systems and high pressure distribution.

a. Structure:

A needle body in which there is a hole for the incoming oil, the return oil (sometimes there is a vent screw) and the oil path to the needle tip. Inside the body there is a push rod, a spring, above the spring there is a nut or screw. The stop nut is used to adjust the spring compression. On top is a cover for the adjusting nut (Depending on the type of needle, the return oil pipe is arranged in the needle body or on this cover).

1. Metal body

2. Connection with high pressure hose

3. Dark and dark

4. Oil hole to

5. Screw the oil pipe back

6. Pusher

7. Spring

8. Spring adjustment screw

9. Shoot

10. Needle punch

11. Seam

12. Needle valve between clearance and body

13. Small cone face of needle valve

14. Jet hole

15. Cover

Figure 2.1: Injector structure

The needle tip (needle head) is connected to the needle body by a connecting link. There is a high-pressure oil line in the needle section. The high-pressure chamber is where the high-pressure oil is stored. At the bottom is the fuel injection hole (jet hole) which is always closed by a spring that compresses through (pusher) to the needle valve.

The needle is cylindrical, one end rests on the push rod in the needle body, the other end has two conical faces. The large conical face is where the high pressure fuel pressure acts to push the needle up. The small conical face at the bottom is to cover the jet hole. Based on the number of jet holes and needle valves, this type is divided into 2 types:

The injector has a jet hole (also known as a sealed injector with a shank or a closed jet hole). With this type, the injector has only one jet hole. Normally when not working, the needle valve closes the jet hole, protruding from a conical shank from the jet hole surface from 0.4 - 0.5 mm. Thanks to the shank, it ensures good fuel injection, with less clogging of the hole due to soot. The fuel jet when sprayed out of the jet hole has a hollow conical shape, the fuel jet angle is from 3 - 6 degrees. This type is often used on engines with separate combustion chambers such as YAMAHA, KUBOTA, ISUDU, MARCH, TOYOTA, with injection pressure from 100 -

120 kg/ cm2 .



Figure 2.2: Short-handled metal wick

A: When closed B: When fully open


Multi-jet injector (also known as closed-end injector or open-end injector).

This type has a convex protrusion at the tip of the needle. On the protrusion, there are inclined jet holes. The number and diameter of jet holes also depends on the type of engine and the type of combustion chamber. There are usually 2-10 jet holes, with a diameter of 0.1-0.35 mm. The jet angle is usually 120-150 degrees.

Figure 2.3: Types of needle tips

A: Type with shank with auxiliary bolt hole

B: Closed-hole, open-hole, multi-hole type C: Closed-hole, open-hole, 1-hole type

There is a type of needle that is longer than the normal type to reduce the effect of temperature causing the needle to get stuck in the needle.

This type of needle is used on engines with unified or combined combustion chambers in many types of cars such as REO I, REO II, REO III, IFA, CAROSA, KAMAZ... with injection pressure from 120 - 200 kg/ cm2 .

In both types of needles above, sometimes the manufacturer also designs an additional ear hole to run at idle speed or start up.

b. Working principle:

When the engine is running, fuel from the high pressure pump flows through the high pressure oil pipe into the injector, down to the needle tip located in the high pressure oil reservoir. Normally, the spring always presses the needle valve to close the jet holes. When fuel is supplied, the high pressure pump increases the fuel pressure and acts on the large cone face of the needle valve. This pressure gradually increases until it is greater than the compression force of the spring, the needle valve is lifted by the oil pressure, opening the jet holes to spray fuel into the engine cylinder in the form of mist.


Figure 2.4: Long-handled metal wick

A: When closed B: When just opened C: When fully opened

When the injection stops, the fuel pressure is less than the spring compression. The spring pushes the needle valve to close (the small cone surface contacts the needle tip). No fuel is sprayed. The fuel injection process ends. The lift of the needle jet is usually from 0.3 - 1.1 mm and is controlled between the needle tip and the needle body.

A small amount of fuel will leak through the gap between the needle valve and the needle pin and up the oil return line to the tank. This amount of oil is very important because it is necessary for cooling and cleaning the injector.

Fuel injection pressure can be adjusted by adjusting the spring screw or changing the shim when there is no adjusting screw. If the spring compression pressure is increased, the fuel injection pressure increases and vice versa. The increased spring pressure makes the fuel jet longer and more misty. However, the injection pressure cannot be increased arbitrarily because it also depends on the high pressure pump condition and the type of combustion chamber.

B. Open type

This type does not have a needle that seals the tip of the needle. That is, the fuel line in the injector is always connected to the combustion chamber and the fuel is sprayed when there is a pressure difference between the engine combustion chamber and the fuel pressure. Therefore, at the time when there is no injection, the fuel is not sprayed because the combustion chamber pressure is higher than the fuel pressure. This type has the disadvantage of being easy to spray and drip, and spraying without mist at low rpm. Therefore, this type is rarely used (except for the GM Cummin SPT type which will be presented in the next chapter).


3. INJECTOR CHARACTERISTICS

a. Characteristics recorded on the body of the needle.

Example: AKB 50SD54

A - American needle pump AMERICAN BOSCH KB – method of attaching the needle to the engine.

B – fasten with retaining wall. C – fasten with screws.

K – no push rod.

50 – height from contact surface (50 mm) S – needle body size.

D – spare needle body type can be used for long shank type. 54 – features for replacing parts depending on engine type.

a. Features recorded at the tip of the needle.



Figure 2.5 : Needle tip characteristics.

Example 1: ADL 120 T52

A American type AMERICAN BOSH. DL Open-hole closed needle type.

120 Fuel beam angle.

52 Replacement features depending on engine type. T Needle size.

Example 2: AND 4S12.

DN Type of closed-hole needle point.

4 Fuel jet angle.

S Needle holder for long shank type. 12 Features of replacement parts.

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