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EPO 220 Diesel Engineering I

Fuel Injection & Combustion Chamber Design

Material Compiled by Robert Jackson

Diesel Engine Combustion Chambers

Combustion chambers are designed to promote air turbulence which helps atomize the fuel in preparation for combustion.

Modern diesel engines typically utilize an openopen type combustion chamber.

Though not commonly used today, the following chamber designs were utilized in the past to promote complete combustion: Turbulence Chambers Precombustion Chambers Energy Cell or Air Cell Chambers

Air Turbulence in the Combustion ChamberA- Intake Stroke; B-Compression Stroke;

C-Power Stroke; Exhaust Stroke

Diesel Engine With Open Combustion Chamber

Typical Open Combustion Chamber Design

Hemispherical Type Open Combustion Chamber

M Type Open Combustion Chamber

Precombustion Chamber

Precombustion Chamber The precombustion chamber is connected to the

piston clearance volume by one or more passages.

This chamber may be located in the head or cylinder wall.

A precombustion chamber will hold 25 to 40 percent of the total clearance volume.

Because of the larger surface area of the combustion chamber, heat losses are increased and thermal efficiency decreases.

The precombustion chamber promotes smooth combustion and improves engine performance at low loads.

Mercedes Diesel

With Precombustion Chamber

& Glow Plug

Removable Injector plus Precombustion Chamber Combination

(Caterpillar Tractor Co.)

SEMT Pielstick Variable Geometry Combustion Chamber

Turbulence Chamber

Turbulence Chamber The turbulence chamber is very similar in design to the

precombustion chamber. The principal difference between the two designs is the amount of chamber volume compared to the clearance volume of the main combustion chamber.

Engines utilizing turbulence chambers have very small clearance volumes.

When the piston reaches TDC virtually all of the available air has been compressed in the turbulence chamber.

The chambers are usually spherical in shape and are incorporated into either the head or cylinder.

The opening through which the air must pass becomes smaller as the piston reaches the top of the stroke, thereby increasing the velocity of the air in the chamber.

Waukesha Engine Turbulence Chamber

Lanova Energy Cell

The Lanova Energy Cell The energy cell is a combination of the

precombustion chamber and turbulence chamber designs.

The Lanova system has two rounded combustion spaces shaped like a figure 8.

The fuel is injected in a pencil stream, passing directly across the narrow throat of the combustion chamber so most of the fuel enters the energy cell.

Most of the fuel entering the energy cell is trapped in the small inner cell, but a small portion passes into the outer cell where it meets with a sufficient quantity of super-heated air to explode violently.

Combustion Sequence in the Lanova Energy Cell

System

The nozzle injects fuel in a pencil stream which penetrates into the

energy cell. Partial combustion takes place inside the energy cell radically raising cell pressure. High pressure

gasses exiting the energy cell through the venturi throat cause high turbulence levels in the main combustion chamber

promoting good combustion.

Pintle & Hole Type Fuel Injector Nozzle

Operation Of Fuel Injection Nozzle

Angular Difference Between Needle Face & Injector Seat

Fuel Injectors

Fuel Line Pressure (lower line) & Needle Lift Diagrams

a) At high load

b) At low load

Injector Nozzle Tip for the Mak

Mak Fuel Injector With Oil Cooling

Sulzer RND-M InjectorNon-Recirculating Type, Water Cooled

Fuel Injector Hold Down Bolt

Tensioning Washer Disk Stack

Sulzer Fuel Injectors

Low Sac Volume Fuel Injection Nozzle Tip

Injector Tip Advances To Minimize Sac Volume

Port & HelixHigh-Pressure

Fuel Pump

Effective Stroke of the Port & Helix Pump

Port & Helix High-Pressure

Fuel Pump

Illustration showing pump plunger, barrel,

delivery valve, & control rack for

adjustment of pump effective stroke

Exploded View of the

Port & Helix Fuel Pump

High-Pressure Fuel Pump &

Camshaft Follower For

Mak 6M 322 Diesel Engine

High-Pressure Fuel Pump Timing

Balance Delivery Valve Utilized on

Mak 6M 322 Diesel Engine

MAN B&W K98MC Slow-Speed

Crosshead Diesel Engine

Bore 980mmStroke 2660mm

94 Rpm Maximum6 to 12 Cylinders

5,720 kW Per Cylinder

12 Cylinder Engine Produces 68,640 kW

(93,360 BHP)

MAN B&WSlow-Speed Diesel Engine

High-Pressure Fuel Pump

MAN B&W Fuel Pumps

B&W Slow-Speed Diesel Engine High-Pressure Fuel

Pump With Variable Injection Timing

B&W High-Pressure Fuel

Pump

B&W High-Pressure

Fuel Pump

Fuel Pump Shock

Absorber

The Modern Slow Speed Diesel Engine

Sulzer RTA84C

Diesel Engine

Sulzer Fuel Pump Placement

Sulzer RTA84T High-Pressure Fuel

Pump

RTA Camshaft, Valve Actuators, & High Pressure

Fuel Pumps

Sulzer Valve Controlled

High-Pressure Fuel Pump

Spill Valve Cut-away Illustration

Sulzer High-Pressure Fuel Pump Block1 Cover

2 Cylinder

3 Piston

4 Slide Ring

5 Viton-ring

6 Conical Clamp Ring

7 Spring

8 Spring Plate

9 Spindle

10 Guide Bush

11 Rubber “O” Ring

12 Suction Valve

13 Rubber “O” Ring

14 Yoke

D Delivery Valve

U Spill Valve

S Suction Valve

D –Delivery ValveD –Delivery Valve

U -Spill ValveU -Spill Valve

S -Suction ValveS -Suction Valve

10 –Connecting 10 –Connecting piece for high piece for high pressure fuel pipepressure fuel pipe

11 –Tension Bolt11 –Tension Bolt

30 –Cover for 30 –Cover for suction & Spill Valvesuction & Spill Valve

31 –Rubber Ring31 –Rubber Ring

32 –Relief Valve32 –Relief Valve

33 –Guide Bush33 –Guide Bush

34 –Push Rod34 –Push Rod

35 –Spring35 –Spring

36 –Locking Wire36 –Locking Wire

37 –Pressing Nipple37 –Pressing Nipple

Fuel Pump Effective Stroke Without Variable

Injection Timing

Sulzer Safety Cut-Out Device

Constant Volume or “OTTO” Cycle

Dual Cycle

The Stroke Based Indicator Card

Typical Indicator Diagram (crank-angle based)

Indicator Card Showing Retarded Ignition Due to Low

Quality Fuel

Example of Retarded Ignition

Variable Injection Timing

Characteristics

Fuel Pump Effective Stroke With Variable

Injection Timing

Fuel Pump Linkage

Port & Helix High-Pressure

Fuel PumpWith Variable

Injection Timing

MAN B&W Fuel Pumps

MAN B&WHigh-Pressure

Fuel Pump

MAN B&WMedium Speed Diesel Engine

L32/40

Variable Injection Timing Used On L32/40 Medium-Speed Diesel Engine

Wartsila Split High-Pressure Fuel Pump

Wartsila Split Pump Operation

For description of pump operation see “Wartsila 64 Technical Review” pp 14

Typical Heavy

Fuel Oil

System

Nozzle Tip Fuel Circulation

Nozzle Fuel Circulation

Sulzer Circulating Type

Injectors

B&W Circulating Type Fuel Injector

B&W Cylinder Cover

Showing High-Pressure

Pipes & Fuel Injectors

Unit Type

Fuel Injector

Distributor Type Fuel Injector System