guinot汽车专业英语课文翻译4

2021年1月22日发(作者：了解世界)
Fuel Supply System of Gasoline Engine(UNIT SEVEN)

All
the
gasoline
engines
have
substantially
identical
fuel
systems
and
run
on
a
mixture
consisting of fuel vapor and air. The fuel system comprises the units designed to store, clear and
deliver fuel, the units intended to clean air and a unit for preparing a mixture from fuel vapor and
air.
In a fuel system different components are used to supply fuel from the fuel tank into the
engine cylinder. Some of the important components are fuel tank, fuel pump, fuel filter, carburetor,
intake manifold and fuellines or tubes connecting the tank, pump and the carburetor.
The
fuel
tank
is
a
fuel
container
used
for
storing
fuel.
It
is
made
of
sheet
metal.
It
is
attached to the vehicle frame with metal traps and is located at the rear of the vehicle. They are
mounted in a boot or boot-floor pan in case of front-engined cars and small commercial vehicles.
In
order
to
strengthen
the
tank
as
well
as
to
prevent
surging
of
fuel
when
the
vehicle
rounds
a
curve of suddenly stops, baffle plates are attached to the inside of the tank.
A cap is used to close the filler opening of the tank. The fuel line is attached at or near the
bottom of the tank with a filtering element placed at the connection. The other components of the
fuel tank are the fuel gauge sending unit, a vent pipe, receiving unit. To prevent the dirt and water
from entering the luggage compartment, a sealing strip
is fitted between the fuel tank and boot
floor
pan.
Moreover
to
limit
the
transmission
of
frame
distortion
to
the
tank
giving
rise
to
squeaking as the metal parts get rubbed together, rubber or felt pads are often fitted between the
mountings and the tank. Provision is also made against drumming of the tank by these mountings.
The
tank
may
be
placed
at
the
side
of
the
chassis
frame
for
convenience
in
case
of
large
commercial vehicles. The length of the connecting lines or tubes from the tank to the carburetor is
also restricted by this at the same time.
A porous filter is attached to the outlet lines. By drawing fuel from the tank through the
filter, any water in the bottom of the tank as well as any dirt into the fuel gathers on the surface of
the filter. To keep the fuel always under atmospheric pressure, the filter pipe or tank is vented.
In order to prevent dirt in the fuel from entering the fuel pump or carburetor, fuel filters
and
screens
are
used
in
the
fuel
system.
If
the
dirt
is
not
removed
from
the
fuel,
the
normal
operation of these units will be prevented. The engine performance will also be reduced.

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The
filter
is
either
fitted
inside
the
fuel
tank
and
pump
or
operates
as
a
separate
unit
connected between the fuel tank and pump or between pump and
carburetor into the fuel lines.
Carburetors are also provided filter screens while a filter element is provided in the fuel tank.
The
fuel
filter
used
is
generally
a
sediment
bowl
made
of
glass
or
metal
and
a
strainer
screen. When the fuel drawn from the tank passes through the filter (through the bowl and strainer
screen), particles of dirt and water settle in the bottom of the bowl. In certain vehicles, a separate
filter
either
of
the
disk
or
ceramic
type
is
used.
It
is
either
located
between
the
fuel
pump
and
carburetor or in the fuel line.
For connecting the fuel tank to the fuel pump, metallic tubes or synthetic rubber hose used
are called fuel lines. They are usually positioned with metallic clips along the frame side members.
The tubing or fuel lines are also used to connect fuel pump to the carburetor. In order to absorb
vibration as well as prevent breakage of the fuel lines, a short flexible line is used between the fuel
pump and the tank.
In
order
to
meter
and
caution
the
driver
of
the
motor
vehicle
about
the
quantity
of
fuel
consumed and left in the tank, a fuel gauge is used. It is generally fitted on dash board for easy
reading of the fuel. It is usually a balancing coil type having construction similar to that of an oil
gauge. It is generally electrically operated.
It
consists
of
a
sending
unit
mounted
on
the
fuel
tank
and
a
receiving
unit
having
a
caliberated gauge mounted on the instrument panel.
A sending unit consists of a float controlled thermostat
or variable resistor. With a
float
and the float arm extending into the fuel tank, the whole unit is mounted on it. The level of fuel in
the
tank
varies
the
position
of
the
float.
The
amount
of
electrical
resistance
within
the
variable
resistor
for
controlling
the
amount
of
current
sent
to
receiving
unit
on
the
instrument
panel
is
determined by the float position.
The receiving unit mounted on the dash board indicates the amount of fuel in the tank on a
caliberated gauge by the amount of current received from the sending unit.
On
modern
automobiles,
two
types
of
fuel
gauges;
thermostatic
type
and
an
electromagnetic type are used.
In
order
to
prevent
the
rapid
wear
and
tear
of
engine
operating
components
causing
reduced
performance
air
cleaner
is
fitted
to
the
carburetor
air
intake,
it
is
mounted
on
the

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