Synopsis On Electromagnetic Clutch System

Introduction:

Clutch:

Clutch is basically a mechanism which is being used for transmitting rotation, which can be engaged and disengaged. Clutches are being used particularly in those devices that have two rotating shafts. In these devices, one shaft is typically driven by a motor or pulley, and the second drives the another device. The clutch connects the two shafts so that they can either be locked together and spin at the same speed, or be decoupled and spin at different speeds.

The clutch disc(center) spins with the fly wheel (left). To disengage, the lever is pulled, causing a white pressure plate to disengage the green clutch disc from turning the drive shaft, which turns within the thrust bearing ring of the lever. All the 3 rings will never connect, with any gaps.

Requirement of a clutch:

  • Torque transmission: The clutch should be able to transmit maximum torque of

the engine.

  • Gradual engagement: The clutch should engage gradually to avoid sudden jerks.

  • Heat dissipation: The clutch should be able to dissipate large amount of heat

which is generated during the clutch operation due to friction.

  • Dynamic balancing: The clutch should be dynamically balanced. This is

particularly required in the case of high speed engine clutches.

  • Vibrating damping: The clutch should have suitable mechanism to damp

vibrations and to eliminate noise produced during the power transmission.

  • Size:- The clutch should be as small as possible in size so that it will occupy

minimum space.

  • Free pedal play: The clutch should have free pedal play in order to reduce

effective clamping load on the carbon thrust bearing and wear on it.

  • Easy in operation: The clutch should be easy to operate requiring as little

exertion as possible on the part of the driver.

  • Lightness: The driven member of the clutch should be made as light as possible

so that it will not continue to rotate for any length of time after the clutch has

been disengaged

Main Parts of the clutch:

The main parts of the clutch is divided into three parts :

  • Driving members:

It consist of a fly wheel mounted on the engine crankshaft.

Flywheel couple with clutch

  • Driven members:

The driven members are consist of the disc or plate, called the clutch plate.

Pressure plate and clutch plate

  • Operating members:

Operating members are consist of a foot pedal, linkage, release or throw out bearing, release levers and springs.

Pedal, Bearing and spring

Electromagnetic clutch:

Electromagnetic clutches operate electrically, but transmit torque mechanically. That is why they are called electromechanical clutches. They are most suitable for remote operation since no mechanical linkages are required to control their engagement, providing fast and smoothing operation.

However, because the activation energy dissipates as heat in the electromagnetic actuator when the clutch is engaged, there is a risk of overheating. Consequently, the maximum operating temperature of the clutch is limited by the temperature rating of the insulation of the electromagnet.

  • In this type of clutch, the flywheel consists of winding from the battery or dynamo.

  • When the current passes through the winding. it produced an electromagnetic field which attracts the pressure plate.

  • Thereby engaging the clutch.

  • When the supply is cut-off the clutch is disengaged.

  • The gear lever consists of a clutch release switch.

  • When the driver holds the gear lever to change the gear, the switch is operated

cutting off the current to the winding which causes the clutch disengaged.

  • At low speed when the dynamo output is low, the clutch is not firmly engaged.

  • Therefore, three springs are also provided on the pressure plate which helps the

clutch engaged firmly at low speed also.

Major Parts of the project:

  1. Driving motor

  2. Pressure plate

  3. Clutch plate

  4. Pedal

  5. Steel shaft

  6. bearing

  7. Frame

  8. Gang box

  9. Dc battery

  10. Gen stopper

Working of Electromagnetic clutch:

The main components of EM clutch are a coil shell, an armature, rotor, and hub. The armature plate is lined with friction coating. The coil is placed behind the rotor. When the clutch activated the electric circuit energizes the coil, it generates a magnetic field. The rotor portion of clutch gets magnetized. When the magnetic field exceeds the air gap between rotor and armature and then it pulls the armature toward the rotor. The frictional force generated at the contact surface transfer the torque. Engagement time depends on the strength of magnetic fields, inertia, and air gap. When voltage is removed from the coil, the contact is gone. In most design a spring is used to hold back the armature to provide an air gap when current is removed.

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Application of electromagnetic clutch:

  • They can be used for remote application because they do not require linkage to actuate the clutch. They are used in printing machinery, conveyor drives, copier machines and factory automation. In an automobile, it replaces clutch pedal by a simple switch button. A smaller EM clutch is used to drive the compressor of air conditioning system.

  • The complicated linkage is not required to control clutch.

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