DESIGN AND FABRICATION OF WATT AND PORTER GOVERNOR A PROJECT REPORT Submitted by B.JAGADISH S.KAUSHIK RAJALINGAM J.KENNETH R.PRASANTH In partial fulfillment for the award of the degree Of
BACHELOR OF ENGINEERING In MECHANICAL ENGINEERING
SRI SAIRAM ENGINEERING COLLEGE
ANNA UNIVERSITY: CHENNAI 600025 April 2011
ANNA UNIVERSITY: CHENNAI 600 025 BONAFIDE CERTIFICATE Certified that this project report “DESIGN AND FABRICATION OF WATT AND PORTER GOVERNOR “ is the bonafide work of “B.JAGADISH (41908114032), S.KAUSHIK RAJALINGAM (41908114039), J.KENNETH (41908114040), R.PRASANTH (41908114059)”, who carried out the project work under my supervision.
SIGNATURE
SIGNATURE
Dr. A. RAJENDRA PRASAD
V.M.MANICKAVASAGAM
HEAD OF THE DEPARTMENT,
SUPERVISOR,
Department of Mechanical Engineering,
Assistant Professor,
Sri Sairam Engineering College,
Department of Mechanical Engineering,
Chennai: 600 044.
Sri Sairam Engineering College, Chennai: 600 044.
INTERNAL EXAMINER
EXTERNAL EXAMINER
ACKNOWLEDGEMENT
We here by acknowledge our sincere gratitude to our beloved Chairman Thiru. MJF.Ln.LEO MUTHU for the help and advice he has shared upon us and providing us with large facilities. We are thankful to our beloved CEO, Mr.J.SAI PRAKASH and our Secretary Mr.M.VASU for providing the opportunity to showcase our skills and knowledge. We express our sincere thanks to our Director and Professor Mr.V.R.RAJAMANICKAM, and our Principal Dr. C.V. JAYAKUMAR for having given us spontaneous and whole hearted support for completing the project. We are grateful to Dr.A.RAJENDRA PRASAD, Head of the Department, Dean-R&D for his constant support and his valuable guidance during the entire course of our project. We are greatly indebted to Mr. V.M. MANICKAVASAGAM, our project guide, Assistant Professor, Department of Mechanical Engineering, for his valuable guidance in this endeavor. We are thankful to all non-teaching staffs for their help in manufacturing and Fabrication of the components. We express our gratitude to all other faculty members, seniors and our classmates who have constantly encouraged and helped us in completing this project successfully. We thank all persons who have directly or indirectly made their contribution in this project.
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ABSTRACT The aim of our project is to develop prototype of a product “watt and porter governor”. The function of the governor is to maintain the speed of an engine within specified limits whenever there is a variation of load. It is a dynamic device done in the field of manufacturing technology. It's rather inexpensive and can be used in almost all vehicles. The governor generally consists of a sleeve which is attached to a throttle valve. When the sleeve reaches its lowest position, the engine should develop maximum power. On the sudden removal of load its sleeve should reach the top most position at once. Its sleeve should float at some intermediate position under normal operating conditions. When the load on an engine increases or decreases, obviously its speed will respectively decrease or increase to the extent of variation of load. This variation of speed has to be controlled by the governor, within small limits of the mean speed. This necessities that when the load increases and consequently the speed decreases, the supply of fuel to one engine has to be increased accordingly, to compensate for the loss of the speed, so as to bring back the speed close to the mean speed. Conversely when the load decreases, and the speed increase, the supply of fuel has to be reduced. This implies that the governor should have its mechanism working in such a way, that the supply of fuel is automatically regulated according to the load requirement for maintaining approximately a constant speed.
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LIST OF CONTENTS CHAPTER
TITLE
No.
PAGE NO.
ACKNOWLDGEMENT
i
ABSTRACT
ii
TABLE OF CONTENTS
iii
LIST OF FIGURES
v
1.
INTRODUCTION
1
2.
DETAILED DISCUSSION
2
2.1 CLASSIFICATION OF GOVERNORS
3
COMPONENTS
4
3.1 MAJOR COMPONENTS
4
3.2 KEY COMPONENTS
4
WATT GOVERNOR
6
4.1 SPECIFICATIONS
7
4.2 PRINCIPLE AND WORKING
8
4.3 DESIGN OF WATT GOVERNOR
10
4.4 FABRICATION
13
PORTER GOVERNOR
19
5.1 SPECIFICATIONS
20
5.2 PRINCIPLE AND WORKING
21
5.3 DESIGN OF PORTER GOVERNOR
23
5.4 FABRICATION
26
3.
4.
5.
iii
6.
BEARING
28
6.1 PRINCIPLE AND WORKING
28
6.2 SPECIFICATIONS
29
6.3 DESIGN OF BEARING
30
MOTOR
32
7.1 SPECIFICATIONS
32
7.2 WORKING
32
8.
COST OF FABRICATION
34
9.
APPLICATIONS
37
10.
HURDLES FACED
36
11.
CONCLUSION
37
12.
REFERENCE
38
7.
iv
LIST OF FIGURES FIGURE NO.
TITLE
PAGE NO.
2.1
Classification of governors
3
4.2
Watt governor
6
4.3
Watt governor-line diagram
9
4.4
Fabrication of watt governor
14
5.2
Porter governor
19
5.3
Porter governor-line diagram
21
5.4
Fabrication of porter governor
27
6.2
Roller ball bearing
28
7.1
FHP motor
33
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CHAPTER 1 INTRODUCTION
A governor, or speed limiter, is a device used to measure and regulate the speed of a machine, such as an engine. A classic example is the centrifugal governor, also known as the watt or fly-ball governor, which uses weights mounted on spring-loaded arms to determine how fast a shaft is spinning, and then uses proportional control to regulate the shaft speed. Centrifugal governors were used to regulate the distance and pressure between millstones in windmills since the 17th century. Early steam engines employed a purely reciprocating motion, and were used for pumping water – an application that could tolerate variations in the working speed. It was not until the Scottish engineer James Watt introduced the rotative steam engine, for driving factory machinery, that a constant operating speed became necessary. Between the years 1775 and 1800, Watt, in partnership with industrialist Matthew Bolton, produced some 500 rotati-ve beam engines. At the heart of these engines was Watt‟s self-designed "conical pendulum" governor: a set of revolving steel balls attached to a vertical spindle by link arms, where the controlling force consists of the weight of the balls. Building on Watt‟s design was American engineer Willard Gibbs who in 1872 theoretically analyzed Watt‟s conical pendulum governor from a mathematical energy balance perspective. During his graduate school years at Yale University, Gibbs observed that the operation of the device in practice was beset with the disadvantages of sluggishness and a tendency to overcorrect for the changes in speed it was supposed to control.
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CHAPTER 2 CLASSIFICATION (i) A governor, or speed limiter, is a device used to measure and regulate the speed of a machine, such as an engine. A classic example is the centrifugal governor, also known as the Watt governor, which uses weights mounted on loaded arms to determine how fast a shaft is spinning, and then uses proportional control to regulate the shaft speed. The watt governor is named after James Watt who used it for steam engines. James Watt designed his first governor in 1788 following a suggestion from his business partner Matthew Boulton. It was a conical pendulum governor and one of the final series of innovations Watt had employed for steam engines. James Watt never claimed the centrifugal governor to be an invention of his own. Centrifugal governors were used to regulate the distance and pressure between millstones in windmills since the 17th century. It is therefore a misunderstanding that James Watt is the inventor of this device. (ii)A giant statue of Watt's governor stands at Smethwick in the English West Midlands. It is known as the fly ball governor. (iii)Another kind of centrifugal governor consists of a pair of masses on a spindle inside a cylinder, the masses or the cylinder being coated with pads, somewhat like a drum brake. This is used in a spring-loaded record player and a spring-loaded telephone dial to limit the speed. (iv)The major advantage of the governors is rather inexpensive and highly efficient.
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2.1 CLASSIFICATION OF GOVERNORS The governors may, broadly, be classified as 1. Centrifugal governor 2. Inertia governor Governors may further be classified as follows: 1. Pendulum type (Watt governor) 2. Loaded type
Figure 2.1
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CHAPTER 3 COMPONENTS 3.1 MAJOR COMPONENTS: Frame: A frame is a structural system that supports other components of a physical construction. Shaft/Spindle: A spindle is a rotating axis of the machine, which often has a shaft at its heart. The shaft itself is called a spindle, but also, in shop-floor practice, the word often is used metonymically to refer to the entire rotary unit, including not only the shaft itself, but its bearings and anything attached to it. Motor: An electric motor converts electrical energy into mechanical energy. Most electric motors operate through interacting magnetic fields and currentcarrying conductors to generate force, although electrostatic motors use electrostatic forces. 3.2 KEY COMPONENTS: SLEEVE: The sleeve valve is a type of valve mechanism for piston engines, distinct from the more common poppet valve.
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BEARING: A bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can handle. RULER: A ruler, sometimes called a rule or line gauge, is an instrument used in geometry, technical drawing, printing and engineering/building to measure distances and/or to rule straight lines.
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CHAPTER 4 WATT GOVERNOR The Watt governor is a simple governor but is not terribly accurate where very fine control of speeds in needed and so was super ceded in many applications by more specialized and accurate governors, however for many agricultural end pumping engines where absolute speed was not essential it survived and can still be seen on numerous preserved engines.
Figure 4
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4.1 SPECIFICATIONS: Basic specifications: (i) Power supply (ii) 230 V AC, Single phase, Variac. Materials: (i) Spindle: Stainless Steel (ii) Fly balls: Cast Iron (iii) Arms: Stainless steel (iv) Frame: Mild steel Governor Mechanism: Watt Governor
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4.1 Principle: The function of the governor is to regulate the mean speed of an engine, when there are variations in the load .e.g. when the load on an engine increases, its speed decreases therefore it becomes necessary to increases the supply of working fluid .On the other hand, when the load on the engine decreases, its speed increases and thus less working fluid is required. The governor automatically controls the supply of the working fluid to the engine with the varying load conditions and keeps the mean speed within certain limits. A little consideration will show ,that when the load increases ,the configuration of the governor changes and a valve is moved to increase the supply of the working fluid ; conversely , when the load decreases , the engine speed increases and the governor decreases the supply of working fluid. Working: Probably the most widely used governor in the early days; it is named the watt governor because James Watt applied it to his early beam engines. He did not however invent it as it had been in use on wind and water mills many years before this. A belt or gearing from the engine crankshaft drives the input shaft 'm' causing the bevel gears 'l' to revolve and in turn rotate the vertical shaft 'a'. The bracket 'b' at the top of 'a' supports two arms 'c' which are pivoted at the top, at the end of the arms are two very heavy metal weights 'B' partway along the arms 'c' are fixed two pivoted link arms‟d‟ which link to a collar 'c' which rotates with them but is able to slide up and down shaft „a‟.
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figure 4.1 The up and down motion of this collar is followed by a pair of pins 'f' which move a bell crank 'g' which is in turn linked to a throttle actuating rod 'I' linked to a throttle or butterfly valve in the supply of steam to the engines cylinder which can allow more or less steam through. At rest the governor weights are held in the lowest position by gravity, the throttle will be in its most open position. As the engine speed increases these weights rotate faster until centrifugal force exceeds that of gravity and they fly further outwards and as a result of the linkages, upwards, this movement is transmitted to the throttle valve which begins to close. The faster the governor is driven the further out the weights move and the more the throttle is closed, until the amount of steam it lets through balances the demand and the engine speed stabilizes. 9
4.2 DESIGN OF WATT GOVERNOR: The Design of Watt Governor involves determining the Minimum and maximum speed of the Governor. The minimum speed occurs when the sleeve is at its rest or initial position.
figure.4.2 Here, AB- length of the arm (cm) BC = r = Radius of rotation (cm) AC =h = Height of the Governor (cm) 30° = α = Angle of inclination. 10
Length AB =41cm; BC= 146mm; α= 30º •
Height of governor: „h‟
WKT
hı = AB * cosα = 14.6 * cos30º = 12.64 cm or .126 m
But hı= 895/Nı² Nı²= 895/.126 Minimum speed,
Nı=84.2 rpm.
Assume sleeve lift =20mm h2 = hı – 20 mm = 106.4 mm or .1064 m Max speed N2² = 895/h2 => 895/ .335 N2= 91.46 rpm Speed range % = (N1 ≈ N2)/ N2 = (91.77– 84.22) / 84.22 = 8.37 %
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DESIGN OF SHAFT: Diameter of the shaft„d‟ = 13 mm For d< 20 mm; τ = σy / 2
where σy is the yield stress (N/mm^2)
σy = 380 N/mm^2. From DDB. => τ= 190 N /mm² where τ is the shear stress in N/mm^2 W.K.T. T= п/16 * τd³
Where T- torque in the shaft „Nmm‟
= п/16 * 190* 13³ = 81962.18 Nmm => 81.962 Nm Power = 2пNT/60
Max speed N= 91.77 rpm
= 2*п*91.77* 81.962 / 60 =454.94 W The power obtained is less than that of the power rating of a FHP motor which is 746 W and hence the design is safe for 13 mm diameter of shaft.
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4.3 FABRICATION OF WATT GOVERNOR Fabrication as an industrial term refers to building metal structures by cutting, bending and assembling.
The Fabrication of Watt Governor involves: i.
Turning operation in lathe. (spindle)
ii.
Threading operation in lathe machine.( Spindle)
iii.
Drilling holes in watt arms, vertical plate and frame.
iv.
Step turning of sleeve.
v.
Cylindrical grinding for good surface finish.
vi.
Welding operation. (Frame and Arms).
vii.
Gas cutting of frame.
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FABRICATION OF UPPER AND LOWER ARM: i.
The drilling operation can be carried out in both lathe as well as drilling machines.
ii.
For better accuracy, ease and surface finish, drilling machine is preferred.
iii.
Drilling of holes (0.7cm) at the ends of both upper and lower arm.
iv.
The holes are drilled with respect to the bolt diameter and the length of the arm is precisely 14.6 cm fabricated via cutting machine.
v.
Grinding the arms for perfect surface finish.
vi.
The ends of the arms are filleted to avoid any sharp corners.
vii.
To a drill a hole of 0.7cm, standard tool bit “7 mm” is employed.
viii.
For faster and efficient operation drilling machine is employed.
Figure 4.3(a)
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WELDING OPERATIONS: i.
Welding is nothing but the process of joining two materials.
ii.
Here two arms are connected by electric arc welding by butt joint.
iii.
We must make sure that both the materials are of the same material for better bonding.
iv.
The material is immediately cooled after the welding process.
v.
A sphere of diameter 2.2 cm is also welded to the arm by electric arc welding.
vi.
We have considered a Sphere of diameter 2.2 cm and weight 0.4 kg.
Figure 4.3 (b)
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FABRICATION OF SPINDLE: i.
A spindle of any standard length is taken and the length of the material is machined to the required length say 32cm by facing operation.
ii.
The spindle is machined to our required diameter say 13 mm by performing turning operation in the lathe machine.
iii.
The edge of the shaft is threaded to hold the arms rigidly.
iv.
The threading operation at the end of the job is carried out in the lathe for a diameter of 12.58 mm.
v.
Unwanted scraps sticking to the spindle are removed by grinding.
vi.
Since the material of the spindle is stainless steel, necessary cooling procedures must be followed.
Figure 4.3(c)
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FABRICATION OF FRAME i.
The frame has to withstand heavy load of the spindle set up as well as the motor. So the frame must be selected in such a way to withstand heavy load to avoid any disturbance.
ii.
A MS base plate is chosen as the frame to avoid breakage and also prevent noise.
iii.
The frame is cut to the required dimensions using gas cutting process.
iv.
The distance between the spindle setup and motor centre is calibrated with the belt provided.
v.
Two projections are brought out from the base plate, welded, one for the spindle set up and the other for the motor.
vi.
The frame is tightened with the help of bolt and nuts for rigid support.
vii.
Grinding is undertaken for a smooth surface finish.
figure 4.3(d) 17
FABRICATION OF SLEEVE i.
Step turning in lathe machine is undertaken accurately.
ii.
Cylindrical grinding is done for smooth surface finish.
iii.
The smooth surface finishing process is undertaken for the proper effortless movement of the sleeve along the spindle.
Figure 4.3(e)
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CHAPTER 5 PORTER GOVERNOR The porter governor is a modification of a watt‟s governor; with central load attached to the sleeve. This leads to larger centrifugal forces here high speeds are required to bring the fly balls to the same radius.
Figure 5
19
5.1 SPECIFICATIONS: Basic Specifications: (1) Power supply (2) 230 V AC, Single phase, Variac. Materials: (1) Spindle: Stainless Steel (2) Fly balls: Cast Iron (3) Arms: Stainless steel (4) Frame: Mild steel (5) Dead weight: cast Iron Governor Mechanism: (1) Porter Governor
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5.2 PRINCIPLE: The function of the governor is to regulate the mean speed of an engine, when there are variations in the load .e.g. when the load on an engine increases, its speed decreases therefore it becomes necessary to increases the supply of working fluid .On the other hand, when the load on the engine decreases, its speed increases and thus less working fluid is required. The governor automatically controls the supply of the working fluid to the engine with the varying load conditions and keeps the mean speed within certain limits. A little consideration will show ,that when the load increases ,the configuration of the governor changes and a valve is moved to increase the supply of the working fluid ; conversely , when the load decreases , the engine speed increases and the governor decreases the supply of working fluid. Working:
figure 5.1
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The porter governor was the first effective high speed engine governor, designed by the American engineer George Porter. The governor is driven via a pulley (k) through a set of bevel gears (not shown) a vertical shaft (d) is rotated, this in turn drives from above the governor balls (a), through linkages (c) the large and heavy governor deadweight (b) is also rotated, this is free to slide up and down the shaft (d) but rotates at the same speed as the balls. As rotational speed increases centrifugal force acts on the balls and they try to fly outwards, they are restricted by the linkages (c) held by the weight of the dead-weight (b), however, when a speed is reached at which this force exceeds the resistance imposed by the dead-weight they will lift the weight up and be allowed move outwards. This action lifts the collar at the base of the dead-weight at point (f) this lifts the lever (g) which is pivoted at point (e) the lever has a counterbalance weight (a) and a dashpot or oil damper (I) which prevents rapid movements of the governor mechanism which can lead to the engine 'hunting' which is unwanted speed fluctuations due to the sensitivity of the governor. Linkage (l) moves up or down and is connected to the engine this controls the steam allowed into the cylinder either by the amount allowed through a valve or the amount of time a valve is open for, if the engine runs too fast either the quantity of steam allowed in will be reduced or it will be let in for a shorter time, if the engine runs slower than either more steam is let in or it is let in for a longer time.
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5.3 DESIGN PROCEDURE: The design of porter governor involves determining the minimum and maximum speed of the governor. The minimum speed occurs when the sleeve is at its rest or initial position. The only difference between the watt and porter governor is the inclusion of a dead weight as shown in the figure.
figure 5.3 Generally, Speed of rotation, N= (m+M)/m * 895/h Where m – Mass of the ball (kg)
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M – Mass of the dead weight (kg) h – Height of the governor (cm) r – Radius of rotation (cm) α – Angle of inclination Fc – Centrifugal force = m ώ^2 r. Where ώ= 2 π N/ 60. N- Speed of rotation (rpm) Here m= .4 kg i)
M= 1.6 kg
Height Of Governor : h =√ (AB² - BC²) Here the Length of the arms is equal Radius of rotation, r ı = AB sin α = .146 * sin 30º = .534 m Hı = AB cosα = 12.64 cm.
ii)
Speed : N² = (m + M)/m * 895 / h1 = (.4 + 1.4)/.4*895/ .1246 N =179.21 rpm
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Design of Shaft: For solid shaft d= 13 mm, τ = σy/ 2 where τ is the shear stress in N/mm² σy = 380 N/mm^2. From DDB. τ = 380/ 2 = 190 N/mm² iii)
Torque, T = п/ 16 * τ d³ = п/ 16 * 190 * 13³ =81.962 Nm
iv)
Power = 2пNT/60 = 2п*179.21*81.962/60 = 723.26 W
P < [P]
i.e. The power obtained is less than that of the power rating of
a FHP motor which is 746 W and hence the design is safe for 13 mm diameter of shaft. Hence design is safe.
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5.4 FABRICATION OF PORTER GOVERNOR Fabrication as an industrial term refers to building metal structures by cutting, bending and assembling.
The fabrication of porter governor involves: i.
Turning operation in lathe. (spindle)
ii.
Threading operation in lathe.( Spindle)
iii.
Drilling holes in porter arms, frame and dead weight.
iv.
Step turning of sleeve.
v.
Cylindrical grinding for good surface finish.
vi.
Welding operation. (Frame and Arms).
vii.
Gas cutting of frame.
The fabrication of the components is similar to that of the watt governor. As the Dead weight is the only inclusion to watt governor setup.
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FABRICATION OF DEAD WEIGHT i.
A cylindrical solid shaft is to be taken as the dead weight.
ii.
A hole of 13 mm is drilled in the solid shaft using lathe machine.
iii.
The extra scraps sticking to the dead weight are removed by grinding machine.
iv.
Cylindrical grinding is done to provide a perfect surface finish.
Figure 5.4(a)
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CHAPTER 6 BEARING A bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can handle. 6.1 Roller Bearing: A rolling-element bearing is a bearing which carries a load by placing round elements between the two pieces. The relative motion of the pieces causes the round elements to roll with very little rolling resistance and with little sliding resistance. Ball bearings use balls instead of cylinders. Ball bearings can support both radial (perpendicular to the shaft) and axial loads (parallel to the shaft). For lightly loaded bearings, balls offer lower friction than rollers. Ball bearings can operate when the bearing races are misaligned. Precision balls are typically cheaper to produce than shapes such as rollers; combined with highvolume use, ball bearings are often much cheaper than other bearings of similar dimensions Configuration and Failure: The configuration of the races determines the types of motions and loads that a bearing can best support. A given configuration can serve multiple of the following types of loading:
figure 6 28
6.2 SPECIFICATIONS OF BEARING : A Bearing is a machine element which is mounted on shafts for free and smooth rotation. The bearing facilitates the rotation of the shaft along its axis without any vibration. Generally for this purpose roller ball bearing is chosen and we have done the same. The various stresses acting on a roller ball bearing are (i) (ii)
Radial force acting on the bearing. Axial thrust on the bearing
The design of bearings is done on the basis of the stresses induced, the size of the setup and its specifications.
Figure 6.1(a) (i)The figure shows the dimensions of the bearing chosen. A roller ball bearing of ID 26 mm and OD 52mm. (ii)The ID is chosen as 26mm so as to fix the sleeve rigidly on the bearing.
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6.3 DESIGN PROCEDURE: i)
The design of bearings is done on the basis of the stresses induced and the size of the setup.
ii)
The radial force acting on the governor is given by F = torque / distance. (N) F = 81.951 / .30 Radial force F = 275 N
iii)
For F = 275 N and the inner diameter d = 26 mm, The bearing to be chosen is SKF 6006. SKF 6206 and SKF 6306. Out of which SKF 6206 is highly recommended and chosen by us.
30
ADDITIONAL BEARING: Two more bearings are required for free flow movement of the spindle connected to the motor with the help of a pulley. The bearing of inner diameter 13 mm is required so that the Shaft is rigidly supported by the frame.
Figure 6.1(b) DESIGN: The Radial Force acting on the Governor is given by F = torque / distance. (N) =81.962/ 36 Radial Force F = 216.75 N. For F = 216.75 N and the inner diameter d = 12 mm, The Bearing to be chosen is SKF 6006. SKF 6206 and SKF 6306. Out of which SKF 6206 is highly recommended and chosen by us.
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CHAPTER 7 MOTOR 7.1 SPECIFICATIONS: Motor Specifications: 230 V, 0.32 Amps, Variable speed, Standard Make FHP Motor. Control Panel For speed control of motor. 7.2 WORKING: A motor uses electrical energy to produce mechanical energy, usually through the interaction of magnetic fields and current-carrying conductors. The reverse process, producing electrical energy from mechanical energy, is accomplished by a generator or dynamo. Electric motors can be run as generators and vice versa, although this is not always practical. Electric motors are ubiquitous, being found in applications as diverse as industrial fans, blowers and pumps, machine tools, household appliances, power tools, and disk drives. They may be powered by direct current or by alternating current from a central electrical distribution grid. The smallest motors may be found in electric wristwatches. Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses. The very largest electric motors are used for propulsion of large ships, and for such purposes as pipeline compressors, with ratings in the thousands of kilowatts. Electric motors may be classified by the source of electric power, by their internal construction, and by their application. The physical principle of production of mechanical force by the interactions of an electric current and a magnetic field was known as early as 32
1821. Electric motors of increasing efficiency were constructed throughout the 19th century, but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks. .Here the watt and porter governor employ a standard FHP motor whose top end is connected to spindle with the help of a belt provided on the pulleys supported on both sides. The motor is mounted to a steel frame and fitted properly with the help of screws.
figure 7.1
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CHAPTER 8 COST OF FABRICATION Components
Cost (Rs)
Motor
900
Regulator
350
Frame
600
Spindle
60
Bearings
150
Sleeve, Pipe and Arms
150
Extras
310
Grand Total
2560
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CHAPTER 9 APPLICATIONS (i) On aircraft propellers the governor senses shaft rpm, and adjusts or controls the angle of the blades to vary the torque load on the engine. Thus as the aircraft speeds up (as in a dive) or slows (in climb) the RPM is held constant. (ii) Centrifugal flyweight mechanism driven by the engine is linked to the throttle and works against a spring in a fashion similar to that of the pneumatic governor, resulting in essentially identical operation. A centrifugal governor is more complex to design and produce than a (iii) Pneumatic governor. However, the centrifugal design is more sensitive to speed changes and hence is better suited to engines that experience large fluctuations in loading. (iv) Electronic servo motor is linked to the throttle and controlled by an electronic module that senses engine speed by counting electrical pulses emitted by the ignition system or a magnetic pickup. The frequency of these pulses varies directly with engine speed, allowing the control module to apply a proportional voltage to the servo to regulate engine speed. Due to their sensitivity and rapid response to speed changes, electronic governors are often fitted to engine-driven generators designed to power computer hardware, as the generator's output frequency must be held within narrow limits to avoid malfunction.
35
CHAPTER 10 HURDLES FACED i)
We experienced bending the spindle while trying to fix the bearing in position which later led to wobbling of the spindle. Hence we changed a new one later.
ii)
Due to irregular speed control the arms bent while rotating which we replaced later with a new arm of more harder material to overcome that problem.
iii)
We also experienced turbulence of the entire setup while operating due to less weight of frame for which we added some extra weight for stability.
iv)
Fixing the bearing in position caused failure of bearings because of hard impact by hammer for which we replaced the faulty bearing later.
36
CHAPTER 11 CONCLUSION (i) Thus governor plays an important role in speed control. (ii) It ensures regulation of speed at any conditions. (ii)
Obtaining the governor characteristics.
(iii)
To study the effect of varying the mass of the center sleeve in porter governor SCOPE
(i)
The governors extend their scope in all kind of vehicles. They can be employed in hydro plants assessment.
(ii)
They can also be used in speed sensing devices which employ digital speed governors.
(iii)
The introduction of analog and digital speed governors have created a rage among the automobile industries.
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CHAPTER 12 REFERENCE (i)Wheeler, Lynder Phelps (1947), "The Gibbs Governor for Steam Engines", in Wheeler, Lynder Phelps; Waters, Everett Oyler; (ii) Dudley, Samuel William, The Early Work of Willard Gibbs in Applied Mechanics, New York: Henry Schuman, pp. 63–78 (iii)Wheeler, L. (1951). Josiah Willard Gibbs - the History of a Great Mind. Woodbridge, CT: Ox Bow Press. (iv)Harris, Tedric A. (2000, 4th edition). Rolling Bearing Analysis. Wiley-Interscience. ISBN 0-471-35457-0. (v)Machine Design (2007), Did You Know: Bud Wisecarver, Machine Design, p. 1.
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