Electromagnetic brakes are the brakes working
on the electric power & magnetic power. They works on the principle of
electromagnetism. These are totally friction less. Due to this they are more
durable & have longer life span. Less maintenance is there. These brakes
are an excellent replacement on the convectional brakes due to their many
advantages. The reason for implementing this brake in automobiles is to reduce
wear in brakes as it friction less. Therefore there will also be no heat loss.
It can be used in heavy vehicles as well as in light vehicles.
The electromagnetic brakes are much effective
than conventional brakes & the time taken for application of brakes are
also smaller. There is very few need of lubrication. Electromagnetic brakes
gives such better performance with less cost which is today’s need. There are
also many more advantages of Electromagnetic brakes. That’s why electromagnetic
brakes are an excellent replacement on conventional brakes.
Electromagnetic brakes are of today’s
automobiles. An electromagnetic braking system for automobiles like cars, an effective
braking system. And, by using this electromagnetic brakes, we can increase the
life of the braking unit. The working principle of this system is that when the
magnetic flux passes through and perpendicular to the rotating wheel the eddy
current flows opposite to the rotating wheel/rotor direction. This eddy current
trying to stop the rotating wheel or rotor. This results in the rotating wheel
or rotor comes to rest/ neutral.
HISTORY
It is found that electromagnetic brakes can
develop a negative power which represents nearly twice the maximum power output
of a typical engine, and at least three times the braking power of an exhaust
brake. (Reverdin 1994).
These performance of electromagnetic brakes make them much more competitive
candidate for alternative retardation equipment’s compared with other
retarders. By using by using the electromagnetic brakes are supplementary
retardation equipment, the friction brakes can be used less frequently, and
therefore practically never reach high temperatures. The brake linings would
last considerably longer before requiring maintenance and the potentially
“brake fade” problem could be avoided.
In research conducted by a truck manufacturer,
it was proved that the electromagnetic brake assumed 80% of the duty which
would otherwise have been demanded of the regular service brake (Reverdin 1974).
Furthermore the electromagnetic brakes prevents the danger that can arise from
the prolonged use of brake beyond their capability to dissipate heat.
This is most likely to occur while a vehicle descending a long gradient at high
speed. In A study with a vehicle with 5 axles and weighing 40 tons powered by a
powered by an engine of 310 b.h.p travelling down a gradient of 6% at a steady speed
between 35 and 40 m.h.p, it can be calculated that the braking power necessary
to maintain this speed at the order of 450 hp. The brakes, therefore, would
have to absorb 300 hp, meaning that each brake in the 5 axles must absorb
30 hp, that a friction brake can normally
absorb with self-destruction.
The magnetic brake is well suited to such
conditions since it will independently absorb more than 300 hp (Reverdin 1974). It
therefore can exceed the requirements of continuous uninterrupted braking,
leaving the friction brakes cool and ready for emergency braking in total
safety.
The installation of an electromagnetic brake
is not very difficulty if there is enough space between the gearbox and
the rear axle. If did not need a subsidiary cooling system. It relay on the
efficiency of engine components for its use, so do exhaust and hydrokinetic
brakes. The exhaust brake is an on/off device and hydrokinetic brakes have very
complex control system. The electromagnetic brake control system is an electric
switching system which gives it superior controllability.
CONSTRUCTION
The construction of the electromagnetic
braking system is very simple. The parts needed for the construction are
electromagnetic, rheostat, sensors and magnetic insulator. A cylindrical ring
shaped electromagnet with winding is placed parallel to rotating wheel disc/
rotor. The electro magnet is fixed, like as stator and coils are wounded along
the electromagnet. These coils are connected with electrical circuit containing
one rheostat which is connected with brake pedal. And the rheostat is used to
control the current flowing is used to control the magnetic flux. And also it
is used to prevent the magnetization of other parts like axle and it act as a
support frame for the electromagnet. The sensor used to indicate the disconnection
in the whole circuit. If there is any error it gives an alert, so we can avoid
accident.
WORKING PRINCIPLE
The working principle of the electric retarder
is based on the electric retarder is based on the creation of eddy currents
within a metal discs rotating between two electro magnets, which set up a force
opposing the rotation of the discs. If the electromagnet is not energized, the
rotation of the disc free and accelerates uniformly under the action of the
weight to which its shaft is connected.
When the electromagnet is energized, the
rotation of the disc is retarded and the energy absorbed appears as heating of
the discs. If the current exciting the electromagnet is varied by a rheostat,
the raking force varies indirect proportion of the value of the current. The
development of this invention began when the French company Thelma, associated
with Raoul Sarasin, developed and marketed several generations of electric
brake based on the functioning principle described above. A typical retarder
consists of stator and rotor. The stator hold 16 induction coils, energized
separately in group of four. The coils are made up of varnished aluminium wire
mounted in epoxy resin.
The stator assembly is supported resiliently
through anti-vibration mountings on the chasisframe of the vehicle. The rotor is made up of two discs,
which provide the braking force when subjected to the electromagnetic influence
when the coil are excited. Carefully design of the fins, which are integral to
the disc, permit independent cooling of the arrangement.
ADVANTAGES
1. Electromagnetic brakes can develop a
negative power which represents nearly twice the maximum power output of a
typical engine.
2. Electromagnetic brakes work in a
relatively cool condition and satisfy all
The energy requirements of braking at high
speeds, completely without the use of friction. Due to its specific
installation location (transmission line of rigid vehicles), electromagnetic
brakes have better heat dissipation capability to avoid problems that friction
brakes face times the braking power of an exhaust brake.
3. Electromagnetic brakes have been used
as supplementary retardation equipment in addition to the regular friction
brakes on heavy vehicles.
4. Electromagnetic brakes has great
braking efficiency and has the potential to regain energy lost in braking.
5. Its component cost is less.
DISADVANTAGES
1. The installation of an electromagnetic
brake is very difficult if there is
Not enough space between the gearbox and the
rear axle.
2. Need a separate compressor.
3. Maintenance of the equipment components
such as hoses, valves has to done periodically.
4. It cannot use grease or oil.
APPLICATIONS
1. Used in crane control system.
2. Used in winch controlling.
3. Used in lift controlling.
4. Used in automatic purpose.
The lots of new technologies are arriving in
world. They create a lot of effect. Most industries got their new faces due to
this arrival of technologies. Automobile industry is also one of them. There is
a boom in World’s automobile industry. So lots of research is also going here.
As an important part of automobile, there are also innovations in brakes.
Electromagnetic brake is one of them.
A electromagnetic braking for automobiles like cars,
an effective braking system. And, by using this electromagnetic brakes, we can
increase the life of the braking unit. The working principle of this system is
that when the electromagnetic flux passes through and perpendicular to the
rotating wheel the eddy current is induced in the rotating wheel or rotor. This
eddy current flows opposite to the rotating wheel. This eddy current tries to
stop the rotating wheel or rotor. This results in the rotating wheel or rotor
comes to rest.