190203c Basic Mechanical Fuel Injection Systems Flashcards
What is injection timing?
Injecting the fuel at the correct time
several degrees BTDC.
All diesel fuel injection systems must perform what three functions
The inject proper amount of fuel at correct time and rate, they atomize the fuel, they inject the fuel at pressure high enough to penetrate the combustion chamber
Two types of basic fuel injection?
Multi plunger injection and unit injection
Rate of injection can be explained as
Time it takes to inject fuel into the cylinder
A controlled injection rate is important because?
It alows for even pressure rise and for proper combustion.
If fuel pressure rises to high to quickly what noise will you hear
You should hear a combustion knock
BOI refers to
Beginning of injection
True or false
if fuel is injected to late. And maximum combustion pressure develops after optimum crank angle power is gained.
False power is lost.
fuel must be inject at the correct time for max hp and least amount of east emissons.
True or false. Rate of injection is adjustable by a technician
False. Rate of injection is controlled by fuel injection system design
What are the two methods of varying fuel injection timing advance used on diesel engines that must respond to continual changes in speed
Mechanical or electronic
What are the two ways to duration can be expressed
Degrees of crankshaft rotation, time for example 1/1000 of a second
What two factors control Atomization of fuel
Injection pressure ( set by fuel injection system design) and fuel injection nozzle design (number and size of nozzle spray holes)
All fuel injection systems must supply exactly the right quantity of fuel for all engine speed and loads. This is referred to as
Metering
What’s the definition of penetration
Penetration is the ability of the fuel spray to reach all areas of the combustion chamber
Timing of injections must be how accurate to ensure engine produces maximum power, maximum fuel economy and minimum exhaust emissions?
Timing of injections must be accurate within + or -1° of crankshaft rotation
What is metering?
Supply of the correct amount of fuel for all vehicle speeds and loads.
How accurate must the metering of fuel be?
The metering must be within 5%
Timing of the injections must be accurate to within how many degrees of crankshaft rotation?
+/- 1 degree of crank rotation.
Name the two basic types of fuel injection systems.
- Multi-plunger injection pumps
2. Unit injection system
Basic fuel injection systems consist of what 2 sections?
Fuel supply (low psi) and the injection (high psi)
Explain how the fuel supply section prepares the fuel for the high pressure section.
It cleans the fuel of contaminants such as dirt and water, removes air trapped in the system and also regulates temperature.
True or false, Water separators are combined with primary fuel filters
True, Water separators are often combined with primary fuel filter or installed up stream as a separate unit.
What is the function of a transfer pump ?
Move fuel from the tank to the injection pump or unit injection pump.
Multi-plunger injection pump would supply what kind of fuel injectors with high pressure fuel
Hydraulic Injection Nozzles
