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ABSTACT
• A clutch is a device used to make and brake contact from the transmission. When it engages, then power is transferred from engine to gear box and when it disengage, power flow is stop, hence it is called free running of engine. There is an innovation done in automobile industry, called electro magnetic clutch, which is recently used by Renault Car Company, which uses the basic principle of electrical energy as well as magnetic forces.
• This project revels the manufacturing of electro magnetic clutch. In place of Engine, shaft is directly attached to variance (variable motor) and clutch disc as well as pressure plate is used, in between them friction material called “Asbestos” used to grip between the pressure plate and clutch plate. This project shows, experimental analysis of Electro magnetic clutch, and at last at which speed clutch engage as well as disengage is measured and when clutch disengage, at that time speed of flywheel is also measured.
INTRODUCTION
Definition of clutch:
The clutch is an important part in the transmission system of automobiles. It transmits power from the engine to gear box at various speeds. No shock is caused during this transmission of power.
Purpose:
The function of the clutch is to temporarily disconnect the engine from the gear box unit. When the gear has to be changed from the first to the second ,it should be done after disconnecting the engine from the gear box. If this is not done ,the gear teeth might break. The clutch is thus helpful when starting, shifting gears and idling.
Principle of operation:
The clutch works on the principles of friction. When two friction surfaces are brought in contact with each other and pressed they are united due to the friction between them. If now one is resolved, the other will also revolve. The friction between the two surfaces depends upon the area of the surfaces, pressure applied upon them and co-efficient of friction of the surface materials. The two surfaces can be separated and brought into contact when required. The driving member is kept rotating. When the driven member is brought in contact with the driving member, it also starts rotating. When the driven member is separated from the driving member it does not revolve. This is the principle on which a clutch operates.
COMPLETE DELAILS OF THE ELECTROMAGNETIC CLUTCH:-
Why we used Electromagnetic Clutch?
• Function of clutch is to engage or disengage the engine from the transmission system. Hence it is inserted between the flywheel as well as gear box. It is consists of main important parts like clutch plate, pressure plate, friction disc, operating lever etc. In clutch engage as well as disengage are very important, because due to which clutch is used. But when clutch is applied at that time, some clearance is there in the clutch pedal called clutch pedal play and due to which, proper disengage of clutch is not achieve and clutch will slip or dragged. • There is a need to use some system incorporated in clutch system, to prevent above situation. Hence, if we shift gear and at that time clutch will disengage hence, it is very simple for driver and force require to engage as well as disengage the clutch is also neglected, hence a new type of clutch used in automobile vehicles called “Renault Car” called electromagnetic clutch. • In this clutch system, when gear shift lever is applied at that time, due to MMF clutch will disengage and when release lever, clutch will engage.
Basic operation of electromagnetic clutch:-
• The clutch has four main parts: field, rotor, armature, and hub (output) . When voltage is applied the stationary magnetic field generates the lines of flux that pass into the rotor. (The rotor is normally connected to the part that is always moving in the machine.) The flux (magnetic attraction) pulls the armature in contact with the rotor (the armature is connected to the component that requires the acceleration), as the armature and the output start to accelerate. Slipping between the rotor face and the armature face continues until the input and output speed is the same (100% lockup). The actual time for this is quite short, between 1/200th of a second and 1 second.
ELECTRO MAGNETIC CLUTCH
• Disengagement is very simple. Once the field starts to degrade, flux falls rapidly and the armature separates. One or more springs hold the armature away from the rotor at a predetermined air gap.
• Voltage/current - and the magnetic field.
• If a piece of copper wire was wound, around the nail and then connected to a battery, it would create an electro magnet. The magnetic field that is generated in the wire, from the current, is known as the “right hand thumb rule”. The strength of the magnetic field can be changed by changing both wire size and the amount of wire (turns). EM clutches are similar; they use a copper wire coil (sometimes aluminum) to create a magnetic field.
• The fields of EM clutch can be made to operate at almost any DC voltage, and the torque produced by the clutch or brake will be the same, as long as the correct operating voltage and current is used with the correct clutch. If a 90 V clutch, a 48 V clutch and a 24 V clutch, all being powered with their respective voltages and current, all would produce the same amount of torque. However, if a 90 V clutch had 48 V applied to it, this would get about half of the correct torque output of that clutch. This is because voltage/current is almost linear to torque in DC electromagnetic clutches.
Requirement of a clutch:
1. Torque transmission: - The clutch should be able to transmit maximum torque of the engine.
2. Gradual engagement:- The clutch should engage gradually to avoid sudden jerks.
3. Heat dissipation: - The clutch should be able to dissipate large amount of heat which is generated during the clutch operation due to friction.
4. Dynamic balancing:- The clutch should be dynamically balanced. This is particularly required in the case of high speed engine clutches.
5. Vibrating damping: - The clutch should have suitable mechanism to damp vibrations and to eliminate noise produced during the power transmission.
6. Size:- The clutch should be as small as possible in size so that it will occupy minimum space.
7. 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.
8. Easy in operation: - The clutch should be easy to operate requiring as little exertion as possible on the part of the driver.
9. 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.
ADVANTAGES:
*Eleminate wear and tear of starters and contact points
*Motor need not take heavy currents while starting as it starts ,with no load condition
*Low starting torque and less HP motors can be used
DISADVANTAGES:
*If currents falls the torque or drive transmitted will also tapers
*High initial cost.