Q4-19.
An open combustion chamber requires which
the chamber. The fuel injection is timed to occur when
of the following properties to obtain the
the turbulence in the chamber is greatest. This ensures a
proper fuel and air mixture?
thorough mixing of the fuel and air, causing the greater
part of combustion to take place in the turbulence
1. Higher air pressure entering the cylinder
chamber. The pressure created by the expansion of the
2. Higher injection pressure to obtain proper
burning gases is the force that drives the piston
atomization
downward on the power stroke.
3. Less air turbulence inside the cylinder
4. Less fuel-to-air ratio to produce combus-
Q4-14.
Which of the following descriptions best de-
tion
scribes a diesel engine?
1. It is known as a compression-ignition en-
GOVERNORS
gine
LEARNING OBJECTIVES: Recognize the
2. It is known as a spark-ignition engine
purpose of governors. Identify the components
3. It is known as a suction-pressure engine
of selected types of governors.
4. It is known as an injection-compression
The speed and the power output of an engine are
engine
determined by the combustion process in the cylinders.
Q4-15.
Which of the following conditions is NOT the
Since combustion depends upon air and fuel, the speed
result of a poor or an improper fuel grade
and the output of an engine can be controlled by
being used?
regulating the amounts of air and fuel supplied for the
1.
Loss of torque
combustion process.
2.
Smoky exhaust
In diesel engines, a varying amount of fuel is mixed
3.
Hard starting
with a constant amount of compressed air inside the
4.
Engine knocks
cylinder. A full charge of air enters the cylinder during
each intake event. Since the quantity of air admitted is
Q4-16.
Which of the following factors is very im-
constant, combustion and, in turn, speed and power
portant when dealing with diesel fuel?
output are controlled by regulating the amount of fuel
1.
Viscosity
injected into the cylinders.
2.
Volatility
Even though it is not a part of the fuel system, a
3.
Combustion
governor is directly related to this system since it
4.
Cleanliness
functions to regulate speed by control of the fuel or of
the fuel-air mixture, depending upon the type of engine.
Q4-17.
The viscosity of a diesel fuel must be low
In diesel engines, governors are connected in the
enough to perform which of the following
linkage between the throttle and the fuel injectors. The
functions?
governor acts, through the fuel injection equipment, to
1.
Ignite at low temperatures
regulate the amount of fuel delivered to the cylinders.
2.
Prevent knocking of the engine
As a result, the governor holds engine speeds
3.
Flow freely at low temperatures
reasonably constant during fluctuations in load. Since
4.
Ignite at high temperatures
the speed and output of a gasoline engine depend on the
amount of fuel-air mixture available, governors, when
Q4-18.
Which of the following types of combustion
used on these engines, are so connected that they
chambers are most commonly used in support
control the amount of the mixture flowing from the
equipment?
carburetor to the intake manifold.
1. Open combustion chamber and pre-
Governors, like carburetors and fuel injection
combustion chamber
equipment, seem somewhat complicated unless you
2. Open combustion chamber and turbu-
have a thorough understanding of the construction and
lence combustion chamber
operating principles of the equipment. As you progress
3. Turbulence combustion chamber and
through the AS rating, you will acquire, through
closed combustion chamber
practical experience and study, the knowledge
4. Turbulence combustion chamber and pre-
necessary to understand the factors that may seem
combustion chamber
complicated at the present. For the time being, it is
enough to understand the relationship of speed-control
devices to the fuel system of an engine.
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