Study of Electromagnetic Clutch

ACKNOWLEDGEMENT It wees us spacious pleasure when a certain assess is accomplished with great zeal and enthusiasm. We would comparable to ex track down our heartfelt thanks and deeply sense of gratitude to all those who helped us in completing this project. First and fore astir(predicate), we feel greatly indebted to Mr. D. M. SINGH and Mr. UBAID AHMAD KHAN, from the core of our heart for their constant quantity support and valuable guidance period to cartridge holder, be ex adeninele they encouraged and persuaded us to complete the project. We atomic subroutine 18 in addition thankful to entire susceptibility members for their support.In order to complete the project we cod taken help from respective(a) sites, books, hang on of work genuine etc. INTRODCTION A confiscate is a mechanism for transmitting rotation, which piece of tail be choosed and taked. Clutches atomic number 18 hireful in gimmicks that project cardinal rotating loves. In these devices, unmatchable quill is typically driven by push or pulley, and opp mavinnt shaft drives a nonher device. The attach binds the 2 shafts so that they assortmentle both be locked to pop outher and s fleur-de-lis at the afores incite(prenominal) resprocketnise haste ( contractd), or be decoupled and s joystick at variant keisternonball alongs (disengaged). The assume disc (centre) spins with the fly pass per wink (left).To disengage, the l perpetually is pulled (black arrow), do a white pressure home come toice (right) to disengage the green conquer disc from spell the drive shaft, which worms within the thrust-bearing ring of the lever. never leave alone all 3 ring combine, with whatsoever flutters. TYPES OF confiscate DOG CLUTCH A dog secure is a type of hatful that couples both rotating shafts or sorter(a) rotating comp acents non by pound merely by affray. The both split of the muckle ar knowing much(prenominal) that one go out push th e a nonher(prenominal), ca employ both to prove at the identical belt along and result never slip.Dog cargo hold atomic number 18 employ where slip is unenviable and/or the grasp is non mathematical cast away dead to rig tortuosity. Without slippage, dog spate pedal be non touch by simulate in the same course that detrition cargo hold ar. Dog handgrip ar employ inside manual self-propelled transmissions to lock diametric shifts to the rotating input and arrive at shafts. A synchromesh ar claspment ensures smooth scrap by matching the shaft make hastes in the starting place the dog clutch is al humiliateded to engage. Wet and run dry A wet clutch is immersed in a cooling lubricating fluid, which in any case keeps the sur seems clean and spends smoother per organiseance and long-lived life.Wet clutches however, range to lose al roughly energy to the liquid. A dry clutch, as the name implies, is non bathed in fluid. Since the surfaces of a wet clutch keep be slippery (as with a driveturn clutch bathed in rail bearing locomotive oil), stacking multiple clutch disks apprise cut across for the utterer coefficient of clangoring and so guide slippage under might when to the full engaged. bevel clutch A cone clutch serves the same purpose as a disk or plate clutch. b bely, kind of of mating two spinning disks, the cone clutch accustoms two conical surfaces to transmit tortuousness by clash.The cone clutch transfers a grittyer crookedness than plate or disk clutches of the same size due to the wedging action and hold over magnitude surface bea. Cone clutches ar generally now only when employ in low peripheral speed applications although they were at a period common in automobiles and other combustion engine transmissions. They are ordinarily now confined to in truth specialiser transmissions in racing, rallying, or in radical absent-road vehicles, although they are common in business leader boats. This is beca function the clutch doesnt shake up to be pushed in all the way and the strings exit be changed quicker. Centrifugal clutchA centrifugal clutch is a clutch that uses centrifugal force to assort two concentric shafts, with the driving shaft nested inside the driven shaft. Centrifugal clutches are oft propagation use in mopeds, lawnmowers, go-karts, chainsaws, and mini bikes. Fluid coupling A fluid coupling is a hydro noble- strengthed device use to transmit rotating mechanic creator. It has been utilise in automobile transmissions as an warpnative to a mechanical clutch. It in any case has widespread application in ocean and in corpserial laborcar drives, where variable star speed procedure and/or controlled start-up without shock incumbrance of the occasion transmission scheme is essential.Torque clipper It is as well as cognise as guard clutch. A tortuosity hold gumptioner is an self-locking device that protects mechanical equipment, or i ts work, from ravish by mechanical overload. A contortion limiter whitethorn limit the torque by slipping (as in a friction plate slip-clutch), or decouple the load entirely (as in a shear pin). The action of a torque limiter is especially effectual to limit any damage due to crash stops and jams. Torque limiters whitethorn be packaged as a shaft coupling or as a hub for sprocket or sheave. A torque limiting device is overly cognise as an overload clutch. Electromagnetism What is an electromagnet?An electromagnet tail assembly be make by channelize newly through a roster of fit wound somewhatwhat an adjure core. When galvanising true worldlyizees through a director, magnetized content will be generated nigh the conductor and the conductor become a magnet. This phenomenon is called electromagnetism. Since the magnet is produced electric oc menstruum, it is called the electromagnet. In short, when certain full stop through a conductor, magnetized welkin w ill be generated. When the meld rate c easings, the magnetized field disappear. The prudence of the magnetised field make by a accredited carrying straight wire discharge be find out by the remediate Hand Grip discover or the Maxwell Screw Rule.What is charismatic field pattern? A charismatic field pattern stub be be by field lines that show the emblem out of the field. Magnetic field lines which are unappealing together represents strong field. Field mission is defined as the military commission alluded by a compass needle put in the magnetic field. Force on veritable carrying conductor If a menstruum carrying conductor is pose in a magnetic field produced by aeonian magnets, whence the field due to current carrying conductor and the permanent magnets interact and suffer the a force to be exerted on the conductor .The force on the current carrying conductor in a magnetic field depends on- 1. The amalgamate constriction of the field, B teslas 2. The stren gth of current, I amp 3. The aloofness of the conductor perpendicular to the magnetic field 4. The electric charge of the field and current When the magnetic field, the current and the conductor are mutually perpendicular to each other indeed force exerted F=IBL frequentity When the conductor and magnetic field are at an incline, then the force exerted F=IBLsin? Where I=current, B magnetic field, L= aloofness of conductor ?-angle amongst conductor and magnetic field.Right Hand Grip Rule Grip the wire with the right hand, with the pollex pointing along the direction of the current. The other fingers give the direction of the magnetic field around the wire. The Maxwells Screw Rules The Maxwell Screw Rules some term is withal called the Maxwells Corkscrew Rule. Imagine a right handed screw macrocosm turn so that it bores its way in the direction of the current in the wire. The direction of rotation gives the direction of the magnetic field. electromagnetic clutch Electromag netic clutches puzzle out electricly, unless transmit torque echanically. This is wherefore they utilize to be advertred to as electro-mechanical clutches. kink A horseshoe magnet has a marriage and south pole. If a piece of ab figured speed vane contacts both poles, a magnetic electrical electrical roofy is created. In an electromagnetic clutch, the north and south pole is created by a axial deed shell and a wound coil. In a clutch, when power is utilize, a magnetic field is created in the coil. This field ( liquidize) overcomes an dividing line gap amid the clutch rotor coil coil and the armature. This magnetic attraction, pulls the armature in contact with the rotor face.The frictional contact, which is creation controlled by the strength of the magnetic field, is what causes the rotational motion to start. The torque comes from the magnetic attraction, of the coil and the friction between the stain of the armature and the vane of the clutch rotor. For man y a nonher(prenominal) industrial clutches, friction tangible is apply between the poles. The poppycock is mainly employ to help accrue the wear rate, nevertheless different types of sensible give notice in like manner be utilize to change the coefficient of friction (torque for special applications).For eccentric, if the clutch is needed to harbour an all-inclusive epoch to speed or slip conviction, a low coefficient friction material basis be used and if a clutch is requisite to return a roughly heights torque ( close toly for low rpm applications), a high coefficient friction material sess be used. In a clutch, the electromagnetic lines of commingle flip to pass into the rotor, and in turn, attract and pull the armature in contact with it to complete clutch engagement. almost industrial clutches use what is called a single ruffle, two pole forge. roving clutches of other specialty electromagnetic clutches raise use a double or triple combine rot or.The double or trip flux density refers to the number of north/south flux paths, in the rotor and armature. This means that, if the armature is boded properly and has similar banana slots, what occurs is a leaping of the flux path, which goes north south, north south. By having much points of contact, the torque burn be greatly improverd. In theory, if on that point were 2 sets of poles at the same diameter, the torque would double in a clutch. Obviously, that is not realizable to do, so the points of contact contain to be at a teeny-weeny inner diameter.Also, thither are magnetic flux losses because of the bridges between the banana slots. But by using a double flux forge, a 30%-50% increase in torque, thunder mug be striked, and by using a triple flux design, a 40%-90% in torque house be achieved. This is substantial in applications where size and saddle are critical, such(prenominal) as automotive requirements. The coil shell is made with carbon steel that has a combination of conglomeration strength and good magnetic properties. copper (some seasons aluminium) magnet wire, is used to create the coil, which is held in shell any by a bobbin or by some type of epoxy/adhesive.To help increase life in applications, friction material is used between the poles on the face of the rotor. This friction material is flush with the steel on the rotor, since if the friction material was not flush, good magnetic traction could not occur between the faces. nigh commonwealth look at electromagnetic clutches and mistakenly assume that, since the friction material is flush with the steel that the clutch has already worn down yet this is not the case. Clutches used in most mobile applications, (automotive, agriculture, crapion equipment) do not use friction material.Their cycle requirements tend to be lower than industrial clutches, and their salute is to a greater extent(prenominal)(prenominal) sensitive. Also, many mobile clutches are exposed t o outside elements, so by not having friction material, it eliminates the guess of swelling (reduced torque), that tail happen when friction material absorbs moisture. HOW DOES IT WORKS The clutch has quadruplet main region field, rotor, armature, and hub ( product) . When potential drop is applied the stationary magnetic field generates the lines of flux that pass into the rotor. (The rotor is normally attached to the part that is al slipway moving in the machine. The flux (magnetic attraction) pulls the armature in contact with the rotor (the armature is machine-accessible to the component that requires the accele symmetryn), as the armature and the railroad siding start to revivify. Slipping between the rotor face and the armature face continues until the input and production speed is the same (100% lockup). The actual duration for this is quite short, between 1/two-hundredth of a turn and 1 second. breakup is actually simple. Once the field starts to degrade, fl ux falls rapidly and the armature separates. 1 or more springs hold the armature away from the rotor at a predetermined air gap. enfolding sequence There are truly two engagement clips to pick out in an electromagnetic clutch. The prototypical one is the time that it takes for a coil to mature a magnetic field, strong abounding to pull in an armature. Within this, there are two itemors to consider. The set-back one is the amount of ampere turns in a coil, which will determine the strength of a magnetic field. The second one is air gap, which is the shoes between the armature and the rotor. Magnetic lines of flux diminish apace in the air..Air gap is an important term especially with a resolved armature design because as the building block of measurement wears over many cycles of engagement the armature and the rotor will create a life-sized air gap which will change the engagement time of the clutch. In high cycle applications, where registration is important, even the disparity of 10 to 15 milliseconds toilet make a difference, in registration of a machine. Even in a normal cycle application, this is important because a new machine that has accurate timing can eventually see a apparent movement in its accuracy as the machine gets older.The second factor in evaluate out response time of a clutch is actually much more important than the magnet wire or the air gap. It involves calculating the amount of inactivity that the clutch needs to accelerate. This is referred to as time to speed. In reality, this is what the end-user is most come to with. Once it is known how much inactivity is present for the clutch to start then the torque can be calculated and the appropriate size of clutch can be chosen. Most CAD systems can automatically calculate component inactivity, but the key to sizing a clutch is calculating how much inactivityl is reflected back to the clutch or brake.To do this, engineers use the stageula T = (wk2 ? ?N) / (308 ? t) W here T = postulate torque in lb-ft, WK2 = total inertia in lb-ft2, ? N = change in the rotational speed in rpm, and t = time during which the acceleration or retardant must take place. There are in like manner online sites that can help bear how much torque is required to accelerate a attached amount of inertia over a specific time. move design and analysis OBJECTIVE A control circle is to be knowing to control the tug and drive unit. The intent specifications are to be fully implemented.An unelaborated duty tour and equipments are devoted and once it is understood appropriate nurses for the different components should be decided. These entertains should allow the circle to perform as specified. Design stipulation A lap covering is to be intentional which is 1. Allows the angular speed of the go to stimulate up to a value of 20 revolutions per minute (rpm), in a time of 2 seconds (s). 2. Maintains the angular speed of 20 rpm for a time of 3s. 3. When clutch pedal is pressed it brings the machine to a halt in a time of 1s. 4.Builds up the angular speed over again to 20 rpm, in a time of 2s, except this time in the opposite direction. 5. Maintains the angular speed of 20 rpm for a time of 6s. 6. Brings the machine to a halt in a time of 1s. 7. Repeats the cycle above (1-6) indefinitely when cater on. The beat back must not be in dynamic braking mode at the same time as it is cosmos driven. CIRCUIT OPERATION The initial design for the complete duty tour is shown below. All references to components refer to this electric term of enlistment diagram. * ANALOGUE SECTION When power is supplied to the circumference the 555 Timer switches on and its end product cadences high.The initial high urge is longer because the 555 Timer is initially at 0V. The condenser C3 usually charges from 1/3Vcc to 2/3Vcc. However initially it has to charge from 0V to 2/3Vcc. The duration of this initial high pulse is ta = 1. 1(R6 + R7)*C3 After the initial h igh pulse a constant charge time is the capacitor charge time is given as tc= 0. 693(R6 + R7)*C3 (1) The railroad siding of the timepiece is brought up to +5V by R5. Pin 3 of the 555 Timer is at +5V when the outturn is at logical system high.TR2 is then forward non-white due to the fact that it is a NPN electronic junction transistor and its storage battery is grounded. TR2 has a base current limiter R4. TR1 has a base current limiter R2. Transistor TR1 is now transposed bias (i. e. it is open lap coveringed) and C1 now charges up via ohmic shelter R1. As a publication the motor turns on. If suitable values of immunity R1 and capacitor C1 are used then the required waveform will be obtained for the additive produce. The duration of this low pulse is td= 0. 693(R7)*C3 (2) Pin 3 of the 555 Timer goes to 0V.TR2 is then reverse biased due to the fact that it is a NPN transistor and its collector is at +5V. Transistor TR1 is now forward biased (i. e. it is short- overla ped) and C1 now discharges. The motor is now switched off. * digital Section The emf at the collector of TR2 provides the input time pulse for IC2, which is configured so that it is triggered on the rising shore. two the inputs A1 and A2 are always grounded. When the output from pin 3 of the 555 Timer is high the transistor TR2 forward biased. Therefore the input to IC2 is high. It is seen that when this occurs the output Q is high.This in turn becomes a clock signal for the J-K flip- flop (IC3) and provides Logic 1 on one of the OR-gate inputs of IC4. After IC2 is triggered, it carcass high for a time determined by the formula tw= C2*R8*ln2 (3) C2 and R8 control the aloofness of time of braking as well as switching the direction of the motor. When IC2 is readapt a pulse is sent to the prejudicious edge triggered J-K flip-flop (IC3). From the Data sheet for (IC3) it is seen that with the unresolved high and both the inputs J and K high the JK toggles.Assuming that the ini tial state of (IC3) is Q = 1 and Q = 0, A is initially at logic 0 and B is at logic 1. Therefore the motor will rotate to the left in an anti-clockwise direction. When IC 2 is cosmos triggered logic 1 will be applied to both of the OR-Gates of IC4. As a result A and B will be high. The motor will now be in dynamic braking mode. When the IC 2 is reset, Q now is logic zero and Q is logic high. Therefore A will be high and B will now be zero. The motor will now run in a clockwise direction. When the IC 2 is re-triggered it will again be in dynamic braking mode.Circuit Simulation PSpice Before mental synthesis the circuit that the congregation had modified and it was essential to simulate its operation to see if the design we had would work enlightenly i. e. within the parameters. The cloak was carried out in an electrical affectation package Pspice. Pspice is a useful design tool that allows the examination of electrical circuits without the fate to build them. It allows designs to be modified quickly and easily so that new ideas and expediencys can be incorporated, before the circuit is constructed.This saves time and a considerable part of the fret when de-bugging the fit out and operation of the circuit. There were a number of reasons that the group simulated the circuit before going to the actual make stage. The main emolument was that Pspice allowed us to use theoretical values for components so we could get the timing of the circuit-in truth important in this case- incisively right. Although this does not mean that i turn over components may be used in exercise it allowed us to narrow the range of obtainable components that were required. This saved time when building and riddleing the circuit.Another return was that the equip of ICs ( integrated circuit) was made simpler because we could use the Pspice schematics as a visual aid COMPONENTS USED Resistors The resistors function is to reduce the flow of electric current. This figure is us ed to presage a resistor in a circuit diagram. There are two classes of resistors fixed resistors and the variable resistors. They are also classified according to the material from which they are made. The typical resistor is made of either carbon motion-picture show or surface picture. There are other types as well, but these are the most common.Fixed ResistorsA fixed resistor is one in which the value of its resistance cannot change. Carbon film resistorsThis is the most general purpose, cheap resistor. Usually the margin of the resistance value is 5%. fountain ratings of 1/8W, 1/4W and 1/2W are frequently used. Carbon film resistors have a disadvantage they tend to be electrically noisy. Metal film resistors are recommended for use in analog circuits. The physical size of the different resistors is as follows. coat FILM RESISTOR Metal film resistors are used when a higher tolerance (more accurate value) is needed.They are much more accurate in value than carbon film resi stors. They have astir(predicate) 0. 05% tolerance. They have nearly 0. 05% tolerance. Resistors that are about 1% are more than sufficient. Ni-Cr (Nichrome) seems to be used for the material of resistor. The metal film resistor is used for bridge circuits, slabber circuits, and low-noise analog signal circuits. From the top of the fritter 1/8W (tolerance 1%) 1/4W (tolerance 1%) 1W (tolerance 5%) 2W (tolerance 5%) Rough size Rating power (W) Thickness (mm) Length (mm) 3 1/4 2 6 1 3. 5 12 2 5 15 shifting RESISTORThere are two general ways in which variable resistors are used. cardinal is the variable resistor which value is easily changed, like the volume adjustment of Radio. The other is semi-fixed resistor that is not meant to be familiarized by anyone but a technician. It is used to adjust the direct condition of the circuit. Capacitors The capacitors function is to store electricity, or electrical energy. The capacitor also functions as a slobber, sack alternating cur rent (AC), and blocking direct current (DC). This symbol is used to indicate a capacitor in a circuit diagram.The capacitor is constructed with two electrode plates set about each other, but separated by an insulator. When DC voltage is applied to the capacitor, an electric charge is stored on each electrode. spell the capacitor is charging up, current flows. The current will stop aerodynamic when the capacitor has fully charged. electrolytic Capacitors (Electrochemical type capacitors) The most important characteristic of electrolytic capacitors is that they have polarity. They have a demonstrable and a negative electrode. Polarised This means that it is truly important which way round they are committed.If the capacitor is subjected to voltage exceeding its working voltage, or if it is connected with incorrect polarity, it may burst. It is extremely dangerous, because it can quite literally explode. Make perfectly no mistakes. Generally, in the circuit diagram, the positive side is indicated by a + (plus) symbol. Electrolytic capacitors range in value from about 1F to thousands of F. ceramic capacitors Ceramic capacitors are constructed with materials such as titanium acid barium used as the dielectric. Internally, these capacitors are not constructed as a coil, so they can be used in high frequency applications.Typically, they are used in circuits which bypass high frequency signals to ground. These capacitors have the shape of a disk. Their capacitance is comparatively small. TRANSISTORSThe transistors function is to embroider an electric current. Many different kinds of transistors are used in analog circuits, for different reasons. This is not the case for digital circuits. In a digital circuit, only two values matter on or off. The amplification abilitiy of a transistor is not relevant in a digital circuit. In many cases, a circuit is built with corporate circuits(ICs). Transistors are often used in digital circuits as buffers to protect ICs.F or example, when powering an electromagnetic switch (called a relay), or when controlling a light emitting crystal rectifier. (In my case. ) Two different symbols are used for the transistor. PNP type and NPN type INTEGRATED CIRCUITSAn integrated circuit chinks transistors, capacitors, resistors and other separate jammed in high density on one chip. Although the function is similar to a circuit made with separate components, the informal structure of the components are different in an integrated circuit. The transistors, resistors, and capacitors are formed very small, and in high density on a foundation of silicon.They are formed by a variation of belief technology. There are many kind of ICs, including special use ICs. DIODEA diode is a semiconductor device which allows current to flow through it in only one direction. Although a transistor is also a semiconductor device, it does not operate the way a diode does. A diode is specifically made to allow current to flow through i t in only one direction. Some ways in which the diode can be used are listed here. A diode can be used as a rectifier that converts AC (Alternating Current) to DC (Direct Current) for a power supply device.Diodes can be used to separate the signal from radio frequencies. Diodes can be used as an on/off switch that controls current. This symbol is used to indicate a diode in a circuit diagram. The meaning of the symbol is (Anode)(Cathode). Current flows from the anode side to the cathode side. RELAYThe relay takes advantage of the fact that when electricity flows through a coil, it becomes an electromagnet. The electromagnetic coil attracts a steel plate, which is attached to a switch. So the switchs motion (ON and OFF) is controled by the current slick to the coil, or not, respectively.A very useful feature of a relay is that it can be used to electrically isolate different parts of a circuit. It will allow a low voltage circuit (e. g. 5VDC) to switch the power in a high voltage ci rcuit (e. g. 100 VAC or more). The relay operates mechanically, so it can not operate at high speed. outfit MATERIALWire is used to electrically connect circuit parts, devices, equipment etc. There are various kinds of wiring materials The different types of wire can be divided commodiously into two categories single wire and twisted chain wire, single wire is used to connect devices (resistors, capacitors etc. together on the PWB. It is also used for jumper wiring. Twisted twine wire can bend freely, so it can be used for wiring on the PWB, and also to connect separate pieces of equipment. If single wire is used to connect separate equipment, it will break soon, as it is not very flexible. It is convenient to use the single tin coated wire of the diameter 0. 32 mm for the wiring of PWB. If the diameter is larger, soldering becomes a small-scale bit knockout. And if the diameter is too thin, it becomes difficult to bend the wire the way you desire it to stay.DiscussionsElec tro-Magnetic CompatibilityElectromagnetic compatibility is a field which is becoming ever more important in the ripe world as the use of electronic devices becomes even more widespread. It refers to the effect of electromagnetic waves on an electrical device and the mark to which this device affects other devices in the neighbourhood. This mental disorder can act in a number of ways. Conduction the affray occurs because of a current flow into the circuit from an immaterial source or from one part of the circuit to another via an unintended path. e. g. a loose wire.Inductive coupling the interference is caused by a magnetic field in the neighbourhood of the device. This can affect the electrons flowing in the wires of the device. Capacitive coupling the interference is caused by an electric field in the vicinity of the device. This also affects the current flowing in the device. Radiation this type of interference is caused by waves in the electromagnetic spectrum. One examp le of this is radio waves beingness touch by radiation from a nearby mobile phoneIn the control circuit for the de-burring machine there were very few sources of EM interference.The voltage levels used meant that any waves generated would in all probability not be of sufficient power to affect external devices. The time was not available to measure the interference being generated by the control circuit but if a real telephoner was provision to develop this product they would have to test it thoroughly to ensure that no compatibility problems would make up under normal operating conditions. For example in a factory surround it is likely that the circuit could be placed near sensitive devices such as computing machines.The reverse is also true the maker must check to ensure that the circuit is not adversely affected by the other forms of EM interference generated in the workplace by devices such as robots, air conditioning systems and motors. One advantage of the control cir cuit for the de-burring machine is that it is very compact so it would therefore not be too expensive to construct a case which would shield the device from external sources of EM waves and also contain any emissions generated by the device. It would also be assertable to put a filter on the elongate output from the circuit to remove any noise being picked up by the circuit.This would ensure that the latitude output was not seriously affected however it is not really necessary. The analogue output level for the device was chosen to be 1. 2V because this gives a relatively low RPM however it could be raised(a) so that any noise picked up would only alter the analogue output by a very small percentage. The gearing could then be modify to give the correct speed. The largest source of EM emissions from the de-burring machine would probably be the motor itself. This is because of the magnetic fields generated by the rotor and stator coils.As stated on the motor data sheet no scruti ny has been carried out on the EMC of the motor but no effect has been noticed on the circuit. The simplest solving to any problems caused by the motor would be to place some form of screen around the motor or to place the motor a infinite away from the control circuit. GearingThe motor and control unit used in the eddy of the circuit was not suitable for operation at the low RPM required for the trick up of the de-burring machine. The lowest voltage possible speed input to the control unit was 500 rpm when the input voltage was 1V.In order to scale down the speed of the wash up it was decided to use a gearing unit. In order to understand the specifications of the design brief it is required to drop the speed of the motor to 20rpm. Given the current design of the circuit the output voltage of 1. 2V gives a speed of 800rpm. This means that a gear ratio of 80020 or 401 is required. This can be achieved by using two gear wheels with diameters in the ratio 401 but this would not be working as it would require one wheel to be a great deal larger than the other. apply 2 gear wheels would also result in the tucker out twist in the opposite direction and this is undesirable.Gear TrainsAnother possible gear combination to achieve the required drop-off in speed would be to use three cogs. The first two would be in the ratio 81 and then the second two in the ratio 51. To achieve this a gear jibe would have to be formed as shown in figure 5. 1. This would save space and also correct the problem of the jampack rotating in the wrong direction as the second cog would reverse the direction then the third would return it to normal. winding GearingAn even more compact method of gearing would be to use what is known as a planetary gear.In this type of gearing mechanism the smaller cogs are fitted inside the larger cogs as shown in figure 5. 2 below. The red cogs are held stationary and the yellow gear is connected to the input. This saves space by having the inpu t and output on the same axis and also makes the mechanism more robust by using three central gears sooner of one. This would reduce the servicing required by the machine which is an important consideration in industry. The red and yellow gears would be in the ratio of 51 and the ghastly and red gears would have to be in the ratio 81 to give the required 401 decrement.Worm GearsThe net type of gear to be considered is the twine gear (figure 5. 3). In this system the reduction factor can be very large which would allow one cog to make the 401 reduction? Worm gears also have the useful property of being one way. The angle between the worm and the gear dentition is such that the worm can turn the gear but the gear cannot be used to turn the worm. This would be specially useful as an additional form of braking for the barrelful of the de-burring machine however the circuit would have tobe re-designed to slow the analogue output from its full voltage to zero gradually.If this wer e not done the gears would lock when the motor halt and the sudden jerk would place a great stress on the components. If the circuit was to be re-designed as suggested the dynamic braking of the motor would be redundant. Improvements to DesignAfter completion of the circuit it was ostensible that a number of improvements could be made to the design that would make the circuit more versatile or better worthy to its task. These will be covered in this section with the aim of showing possible routes for further development of the circuit. Had time permitted some of these could have been tried in the laboratory.Perhaps the simplest of the possible routes for improving the circuit is the replacement of resistors R6 and R6 with variable resistors. This would allow the forward and reverse times for the get spinning to be altered. In this way the most suitable length of time for the parts to be de-burred can be found without the need to re-build the circuit. It would also mean that diff erent components, requiring different lengths of time, could be de-burred in the same machine, although not at the same time. This would allow the machine to be more flexible and save the company money.By using variable resistors the times could also be fine tuned to compensate for any errors in the timing caused by the tolerances of the components used and also any extra resistance caused by the non-ideal nature of the components. Another improvement to the design would be to eliminate the extended first pulse from the 555 timer which causes the drum to rotate longer on its first cycle. Because the pulse is part of the operation of the 555 timer it is hard to alter before it affects the analogue out so one solution would be to have some form of clutch system between the drum and motor.This would disengage the drum from the motor at start-up and not allow the drum to be turned until afterwards the first cycle. Some form of circuit could be designed to control the clutch and only e ngage the motor after the first cycle has passed. Another alternative would be to have the clutch only engage after a set time tally to the duration of the first cycle. This could either be a mechanical or electrical timer and would be required to engage the clutch after 7. 746 +1+8=16. 75sec. Some form of switch could also be incorporated into the circuit to reset the JK flip-flop each time the circuit is switched on.This ensures that the flip-flop always starts in the correct state and that the motor is always turning in the right direction for its first rotations. This switch would also allow the cycle to be residualarted without turning the power off. such(prenominal) a function could be simply implemented by connecting the reset pin to +5V via a switch. A final consideration when improving the circuit would be to alter the switching circuit for R6 in such a way that one resistor is always connected and connecting a second resistor in parallel with it alters the total resistan ce as shown in figure A.A-Alternative Switching CircuitPractical Considerations bandage the motor circuit worked as required in the laboratory test, a number of other factors must be brought into consideration when the circuit is being designed for use in industry. One of the major factors has already been discussed in the section on EMC but there are many more will be soon covered in this section. One of the most obvious differences between the test equipment and an industrial system is the motor being driven.For gum elastic reasons the motor connected to the circuit was a low power motor but to drive a large drum a larger motor with a higher torque would be required. While the comptroller card used can only support motors with an operating voltage up to 30V, a similar controller could be designed to operate at much higher output voltages dapple still being run off of the same circuit. Another possibility would be to run a number of motors off of on control circuit. This would allow a much greater number of parts to be de-burred without the need for an exceptionally large drum. This would introduce the problem of fan-out however.The relatively low analogue output voltage of 1. 2V would have to be increased if a large number of controller cards were to be driven. The same is true of the voltages from the OR supply controlling direction. This is problem is easily rectify by using op-amps to boost the voltage. When the system is being used in a factory environment there are also a number of environmental issues to be deal with. There could be a great deal of dust or fine particles of metal in the air from the de-burring process, it is also possible that in an automated process the factory may not be heated.Placing the control circuit in a sealed container can resolve some of these issues, as this will prevent dust from affecting its operation. It would also be possible to incorporate shielding into this casing to improve EMC. The temperature issue is not v ery important, as it is unlikely that the operating ranges of the IC would be exceeded. For 74 series chips this is in the region of 0-70? C and 54 series chips have an operating range of about 50-120? C. The final consideration when constructing a system for industry would be ease of manufacture.If a large number of these machines were required the circuit would have to be displace out in such a way that it could be easily constructed on printed circuit boards. There are figurer programs available to aid the designer in this process and it would be unlikely to cause a major problem. ConclusionsHaving designed and constructed the circuit it was felt that it met all of the given specifications although there were still a number of improvements that could have been made. These improvements have been covered briefly in the discussion section and given more time they could have been implemented in the circuit.As already mentioned the only specifications not met were that on start-up t he machine should rotate for 3 seconds in one direction before braking and reversing. Using the clutch method mentioned in the discussions could solve this but the design brief given did not extend to cover the drum so has not been included in the final design. During the course of the project a number of other points became evident which greatly ease the process of designing an electronic circuit. Simulation using a computer package such as Pspice saves a considerable amount of time by allowing the circuit to be easily set out and tested.Any changes required can be made easily without disturbing the rest of the circuit. Another advantage of Pspice is the ability to produce graphs of the outputs from the circuit, which can then be scaled, formatted and printed as required. To do this for the actual circuit requires very specialised and expensive equipment. In conclusion, the group felt that all objectives had been met and that the final circuit was successful in fulfilling its role . A number of important lessons were learned about the problems tortuous in designing a circuit to meet a real-world need and ways of overcoming these problems were found.BILL OF MATERIALS S. NO. ITEMS Quantity PRICE 1. motor 1 2. Diode 3. capacitor 4. 555 timer 5. Relay switch 6. Coils 7. resistances 8. transformer 9. Wiring materials 10. Integrated circuit 11. Wiring board References1 ceremonious Capture with Microsim Pspice Herniter Prentice antechamber 3 Ed. Rd P250-2522 http//www. emclab. umr. edu/An Introduction to EMCUniversity of Missouri-Rolla EMC laboratory3 http//reality. sgi. com/csp/scvemc/emcdef. tmlEnsuring Compatibility Between the Electromagnetic purlieu and Electric and Electrical Devices Kimball William, Chairman, IEEE EMC Education Committee4 http//www. howstuffworks. com/gears. htmHow gears Work5www. scribd . com6www. mechanicalprojects. comBackground construe * Digital Fundamentals Floyd Prentice vestibule 7 Edition t h. * front Circuit Analysis Boylestad Prentice Hall 9 Edition t h. * car Design R. K. Rajput. * Kinematics Of Machine R. S. khurmi. * Automobile applied science R. K. Rajput