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李坪山制动器的英文版及翻译

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来源:https://www.bjmy2z.cn/gaokao
2021-01-19 15:28
tags:

如丧考妣是什么意思-驾驶证记分

2021年1月19日发(作者:项朝宗)


The Brakes





The brakes function by absorbing in friction the energy possessed by the moving car. In so
doing they convert the energy into hear. There are tow types of brakes, the drum brake and the
disc brake. Either or both types may be fitted. But where both types are used it is usual for the disc
brakes to be fitted to the front wheels. In both drum and disc brakes, a hydraulic system applies
the brakes. The hydraulic system connects the brake pedal to the brake parts at each wheel.
1


Drum

Brakes



The drum brake consists of a pair of semicircular brake shoes mounted on a fixed back plate
and situated inside a drum. This drum is fixed to the road wheel and rotates with it .One end of
each shoe is on a pivot and a spring holds the other end in contact with the piston of a hydraulic
cylinder.(In front brakes it is usual to use two hydraulic cylinders in order to equalize the pressures
exerted
by
the
shoes,
as
shown
in
Fig.7.1)Each
shoe
is
faced
with
material
,known
as
brake
lining ,which produces high frictio
nal resistance.















1















The
hydraulic
system
comprises
a
master
cylinder
and
the
slave
cylinders
which
are
the
cylinders on the road wheels. The slave cylinders are connected to the master cylinder by tubing
and the whole system is filled with hydraulic fluid .A piston in the master cylinder is connected to
the brake pedal, so that when the driver depresses the pedal the fluid is forced out to each slave
cylinder and operates their pistons. The fluid pushes the pistons out of their cylinders. They

in
turn,
push
against
the
inner
ends
of
the
brake
shoes
and
force
them
against
the
drums
in
each
wheel. We say that the brakes are on. This friction of the shoes against the drums, which are fixed
to the road wheels, slows down or stops the car.




As the brake pedal is allowed to come up, the hydraulic fluid returns to its original position,
the pistons retract, and a spring attached to each brake shoe returns it also to its original position.

Free of the brake drum. Now we say that the brakes are off.(Fig.7.2)




The brakes may also be operated by mechanical linkages from the foot pedal and hand brake
lever.
Common
practice
is
to
operate
both
front
and
rear
brakes hydraulically
with
a
secondary
mechanical system operating the rear brakes only from the hand lever. One of the great advantages
of hydraulic operation is that the system is self-balancing, which means that the same pressure is
automatically produced at all four brakes, whereas mechanical linkages have to be very carefully
adjusted for balance. Of course, if more pressure is put on one of the brakes than on the others
there is a danger that the car will skid.




The
mechanical
linkage
on
the
rear
brakes
is
a
system
of
rods
or
cables
connecting
the
handbrake lever to the brake-shoe mechanism, which work entirely independently of the hydraulic
system.
Drum brakes are prone to a reduction in the braking effort, known as “fade”, caused by
the overheating of the brake linings and the drum. Fade can affect all or only some of the brakes at
a time, but it is not permanent, and full efficiency returns as soon as the brakes have cooled down.
However, fading is unlikely to occur except after the brakes have been used repeatedly in slowing
the car from a high speed or after braking continuously down a steep hill. Descending such a hill,
it would have been preferable to use engine braking by changing down into a lower gear. Drum
brakes can be made less prone to fade by improving the cooling arrangements, by arranging for
more air to be deflected over them, for example.

2

2


Disc Brakes
The disc brake consists of a steel disc with friction pads operated by slave hydraulic cylinders.
The steel disc is attached to the road wheel and rotates with it. Part of this steel disc is enclosed in
a caliper. This caliper contains two friction pads

one on each side of the disc, and two hydraulic
cylinders, one outside each pad. The pads are normally held apart by a spring, but when the driver
depresses the brake pedal, pistons from the hydraulic cylinders force the pads against the sides of
the disc. Because the disc is not enclosed all the way round, the heat generated when the brakes
are applied is dissipated very much more quickly than it is from brake shoes which are entirely
enclosed
inside
a
drum.
This
means
that
disc
brakes
are
less
prone
to
fade
than
drum
brakes.(Fig.7.3)


















3

Anti-lock Brake System (ABS)



The function of an anti-lock, or anti-skid, braking system is to prevent the wheels from locking
under
hard
braking.
Maximum
braking
force
is
obtained
just
before
the
wheels
lock
and
skid.
Such anti-skid system ate useful on slippery surfaces, such as ice and snow, where the wheels may
lock easily. Locked wheels are dangerous because the car needs a much longer distance to stop.
Locked wheels also can cause the driver to lose control.





3








The
system
uses
a
sensor
that
knows
when
one
wheel
(or
a
pair
of
wheel)
is
skidding.
(Fig.7.4) The sensor sends a signal to a computer, which signals a modulator valve. The modulator
connects into the hydraulic system and can momentarily release the brake pressure and prevent the
wheels from locking.(The pressure release is so fast that a driver is seldom aware of it.) pressure is
then reapplied until the sensor again senses that the wheel is about to lock up. Thus, this system
keeps the wheels as close to lock up as possible, without actually allowing the wheels to lock up
and skid. This is called incipient lock up. Maximum braking occurs at that point. If any part of the
system should fail to work, the system goes into a “fail
-
safe” mode. The brakes operate normally,
as they would on a car that is not equipped with ABS. Today , ABS is an optional or standard
feature that typically is found on expensive luxury cars and sports cars. In the future, ABS may be
available for all cars.
3.1

ABS overview




Anti-lock braking system is using the body of a rubber balloon, while hitting the brakes, will
give brake oil pressure, feeding through to the ABS body, using of the air in the middle of the air
layer to return the pressure, make wheels evade the locked points. When the wheel will arrive next
locked point, brake oil pressure makes balloon in a repeat function, so can function eight to thirty
times in one second equivalent constantly brake, relax, namely, similar to the


s
lateral
sliding
coming
up
and
the
wheels
rubbing
on
one
point
with
the
ground
without
being
locked in the emergency brake

so it can make the brake friction efficiency achieves ninety percent.
It also can reduce the braking consumption and prolong the brake wheel drum, disc and tire twice
with the service life of the vehicle in the ABS. On the dry tarmac road or on snowy or on rainy
days,
the
slippery
performance
reached
80%
-
90%,
30%
-10%,
15%
-
20%.
Ordinary
braking
system on a wet road surface brake, or in the emergency brake, it

s easy for wheels to be locked
owing to the braking force exceeds the friction force of the tires and ground. In recent years, the
consumers of the vehicle emphasis on the safety , so most of the cars have ABS listed as standard.
Without
ABS,
emergency
brake
usually
cause
tire
locked,
then,
the
rolling
friction
becomes
sliding friction, as a result, braking force dramatically decreased. And if front wheels are locked
first, the vehicle will lose the steering ability; if the rear tires are first locked, the vehicle is easy to
slide laterally , so the direction becomes impossible to control. Through electronic or mechanical
control,
the
ABS
system
controls
the
braking
fluid
pressure
at
a
fast
speed
to
avoid
the
wheels
4

locked. Insure the tire have the biggest braking force and the turning ability when braking, and
make
the
vehicle
have
the
ability
to
evade
the
obstacles
in
emergency
braking.
With
the
rapid
development
of
the
automotive
industry,
safety
increasingly
become
the
important
basis
of
that
people choose and buy cars. At present the widespread adoption of holding brake system (ABS)
that people can fully meet the safety of requirements. Automobile brake prevent embrace system,
referred to as the ABS, is to improve the car an important device passive safety. Someone said
brake
prevent
embrace
system
is
auto
safety
measures
relay
belts
after
another
major
progress.
Automobile braking system is the bus passengers safety is the most important relationship to one
of the second systems. With the rapid development of the automotive industry, automobile safety
for people appeals more and more attention. Automobile brake prevent embrace system, is another
major progress to improve the safety.




ABS braking system is controlled by automobile microcomputer, when braking, it can keep
the wheel rotating to help driver control vehicle parking safely. The anti-locked braking system
detects wheel speed by speed sensor, and then send the wheel speed signals to the microcomputer.
The
microcomputer
controls
wheel
slipping
rate
by
increasing
or
decreasing
the
brake
pressure
repeatedly according to the input wheel speed to keep wheel rotate. In braking process, keeping
wheel rotate not only ensures the ability of controlling driving direction, but also provides higher
brake force than the locked wheel in most circumstances, .
3.2

The working principle of ABS



It includes control devices and ABS warning lights, in different ABS system, the structure of
brake
pressure
adjusting
device
and
working
principle
of
electronic
control
devices
are
often
different, the internal structure and control logic of ABS system usually includes the wheel speed
sensors, brake pressure adjusting device, electronic identical and so on. In common ABS system,
each wheel is installed a rotational speed sensor on the wheel speed, input the signal to electronic
control device. The electronic control unit states monitoring and determination according to each
wheel
speed
sensors’
sign
al
about
each
wheel
movement,
and
has
formed
the
corresponding
control
instruction.
Brake
pressure
adjusting
device
is
mainly
composed
by
pressure
regulating
solenoid
valves,
electric
pump
composition
and
liquid
container
components
compose
an
independent whole, braking main cylinder and the cylinder brake wheel connected by the brake
pipe. Brake pressure adjusting device is controlled by the electronic unit to control all brake wheel
cylinders
’ brake pressure.
The working process of ABS can be divided into general braking, brake
pressure kept brake pressure decrease and brake pressure increase stage. In general braking phase,
ABS doesn't intervene brake pressure control, pressure regulating electromagnetic valve assembly
in various into liquid solenoid valves are no electricity and is open, each produced liquid are no
electricity and electromagnetic valve is in the closed position, electric pump also operates without
electricity, and brake main cylinder to each brake wheel cylinder brake lines are in communication
condition,
and
the
brake
wheel
cylinder
to
liquid
brake
lines
are
in
close
condition,
the
brake
wheel cylinder brake pressure change with the output pressure brake master cylinder, the braking
5

process at this time is completely the same with conventional braking system braking process.




In
braking
process,
when
the
electronic
control
detects
that
the
wheels
primarily
tend
to
embrace dies according to the wheel speed sensors of the wheel speed signal input, ABS came into
the braking anti-lock process. For example, when the electronic control unit judges the front-right
wheel tends to embrace, the electronic control unit will make control scrape the dynamic pressure
front-right
wheel
failure
into
liquid
solenoid
valves
electricity,
make
the
fluid
electromagnetic
valve
closed,
brake
main
cylinder
output
brake
fluid
no
longer
enter
into
brake
wheel
cylinder,
right
now,
right
at
the
end
of
a
fluid
electromagnetic
valve
still
energized
and
closed,
the
right
brake
wheel
cylinder
brake
fluid
also
won't
outflow,
the
right
brake
wheel
cylinder
scraping
dynamic
pressure
stays
certain,
and
other
arms
tend
to
be
dead
wheel
with
still
brake
pressure
braking
main
cylinder
and
the
increase
of
output
pressure
increases;
If
the
right
brake
wheel
cylinder brake pressure keep certain, the electronic control unit front-right wheel failure still tend
to judge lock, the electronic control unit and move out liquid solenoid valves also electrify into a
state
of
opening,
the
part
right
brake
wheel
cylinder
brake
wave
will
pass
is
open
from
fluid
electromagnetic
valve
flow
back
to
liquid
container,
make
right
brake
wheel
cylinder
brake
pressure holding diminishes quickly front-right wheel failure will start to eliminate death trend,
with
the
right
brake
wheel
cylinder
brake
pressure
decreases,
the
front-right
wheel
under
the
action of inertia force will speed up gradually; accelerate gradually When the electronic control
device
determines
the
lock
front-right
wheel
failure
to
completely
eliminate
according
to
the
wheel
speed
sensors
input
signal,
the
electronic
control
unit
makes
right
into
the
fluid
electromagnetic
valve
and
a
liquid
solenoid
valves
are
without
electricity,
make
into
fluid
electromagnetic
valve
to
open,
use
liquid
into
closed
electromagnetic
valve,
also
make
electric
pump
operation,
energized
to
brake
wheel
cylinder
pump
brake
fluid,
output
by
brake
main
cylinder brake fluid electromagnetic valve into the right brake wheel cylinders, make right brake
wheel cylinder brake pressure increased rapidly, opening up a front-right wheel failure and slow
rotation. ABS control the sliding rate of wheels which tend to be locked through holding the brake
force of wheels that tends to be locked repeatedly ,adhesion coefficient is in peak within the scope
of
the
sliding
rate,
until
the
bus
speed
reduced
to
very
low
or
brake
main
cylinder
pressure
no
longer tend to be locked. Brake pressure to adjust cycle of frequency can reach 3 ~ 20HZ. In the
ABS
each
has
on
the
fluid
and
the
fluid
electromagnetic
valve
in
corresponding
at
each
brake
wheel cylinder, but by the electronic control device to control, therefore, respectively, the brake
wheel cylinder brake pressure can be independently adjustment so that four wheels are not occur
braking
lock
phenomenon.
Although
various
ABS
structure
form
and
working
process
is
not
exactly
the
same,
are
based
on
the
brake
holding
pressure
adaptive
cycle
adjustment
of
wheel
which tends to be locked, to prevent the controlled wheels holding in death occurred when brake.
6

如丧考妣是什么意思-驾驶证记分


如丧考妣是什么意思-驾驶证记分


如丧考妣是什么意思-驾驶证记分


如丧考妣是什么意思-驾驶证记分


如丧考妣是什么意思-驾驶证记分


如丧考妣是什么意思-驾驶证记分


如丧考妣是什么意思-驾驶证记分


如丧考妣是什么意思-驾驶证记分



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