Re: Difference Between Flywheel And Governor Pdf Download
Eliane Lebouf
The main difference between the two is that the flywheel is always under operation when the engine is running and the operation is continuous from cycle to cycle, whereas the operation is intermittent in case of the governor, which means it only operates when the engine does not run at its mean speed.
A flywheel is a heavy rotating wheel attached to a revolving shaft that smooths out the delivery of power of a reciprocating engine due to the difference between the driving torque and the active torque over the cycle of operation.
Both are mechanical devices used for speed regulation/control to compensate for speed variations but with different point of impact. A flywheel maintains a constant speed under different load conditions for each thermodynamic cycle. A governor, on the other hand, also controls the engine operation and its main speed but the means is different from that of a flywheel.
Flywheel is a heavy rotating metal wheel that resists changes in rotational speed providing energy when the energy source is discontinuous. The momentum of inertia is what drives the flywheel and it rotates at a varying angular speed. Despite energy variations, the crankshaft runs at constant speed in each stroke of the cycle. Governor, on the other hand, controls and maintains the speed of the engine by regulating the amount of fuel supply to the engine.
A flywheel rotates at a varying angular speed which increases when storing energy and decreases when releasing the same. It absorbs mechanical energy by increasing its angular velocity and releases the energy by decreasing the angular velocity. A governor, on the other hand, minimizes fluctuations within the mean speed which occurs due to load variation. It increases the fuel flow to keep the mean speed constant.
A centrifugal governor is a specific type of governor with a feedback system that controls the speed of an engine by regulating the flow of fuel or working fluid, so as to maintain a near-constant speed. It uses the principle of proportional control.
Centrifugal governors, also known as "centrifugal regulators" and "fly-ball governors", were invented by Christiaan Huygens and used to regulate the distance and pressure between millstones in windmills in the 17th century.[1][2] In 1788, James Watt adapted one to control his steam engine where it regulates the admission of steam into the cylinder(s),[3] a development that proved so important he is sometimes called the inventor. Centrifugal governors' widest use was on steam engines during the Steam Age in the 19th century. They are also found on stationary internal combustion engines and variously fueled turbines, and in some modern striking clocks.
The devices shown are on steam engines. Power is supplied to the governor from the engine's output shaft by a belt or chain connected to the lower belt wheel. The governor is connected to a throttle valve that regulates the flow of working fluid (steam) supplying the prime mover. As the speed of the prime mover increases, the central spindle of the governor rotates at a faster rate, and the kinetic energy of the balls increases. This allows the two masses on lever arms to move outwards and upwards against gravity. If the motion goes far enough, this motion causes the lever arms to pull down on a thrust bearing, which moves a beam linkage, which reduces the aperture of a throttle valve. The rate of working-fluid entering the cylinder is thus reduced and the speed of the prime mover is controlled, preventing over-speeding.
A limitation of the two-arm, two-ball governor is its reliance on gravity, and that the governor must stay upright relative to the surface of the Earth for gravity to retract the balls when the governor slows down.
Governors can be built that do not use gravitational force, by using a single straight arm with weights on both ends, a center pivot attached to a spinning axle, and a spring that tries to force the weights towards the center of the spinning axle. The two weights on opposite ends of the pivot arm counterbalance any gravitational effects, but both weights use centrifugal force to work against the spring and attempt to rotate the pivot arm towards a perpendicular axis relative to the spinning axle.
Spring-retracted non-gravitational governors are commonly used in single-phase alternating current (AC) induction motors to turn off the starting field coil when the motor's rotational speed is high enough.
They are also commonly used in snowmobile and all-terrain vehicle (ATV) continuously variable transmissions (CVT), both to engage/disengage vehicle motion and to vary the transmission's pulley diameter ratio in relation to the engine revolutions per minute.
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. A giant statue of Watt's governor stands at Smethwick in the English West Midlands.
Centrifugal governors' widest use was on steam engines during the Steam Age in the 19th century. They are also found on stationary internal combustion engines and variously fueled turbines, and in some modern striking clocks.
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 centrifugal clutch or a drum brake. This is used in a spring-loaded record player and a spring-loaded telephone dial to limit the speed.
The centrifugal governor is often used in the cognitive sciences as an example of a dynamic system, in which the representation of information cannot be clearly separated from the operations being applied to the representation. And, because the governor is a servomechanism, its analysis in a dynamic system is not trivial. In 1868, James Clerk Maxwell wrote a famous paper "On Governors"[6] that is widely considered a classic in feedback control theory. Maxwell distinguishes moderators (a centrifugal brake) and governors which control motive power input. He considers devices by James Watt, Professor James Thomson, Fleeming Jenkin, William Thomson, Lon Foucault and Carl Wilhelm Siemens (a liquid governor).
The action of this principle is exactly like that of the centrifugal governor of the steam engine, which checks and corrects any irregularities almost before they become evident; and in like manner no unbalanced deficiency in the animal kingdom can ever reach any conspicuous magnitude, because it would make itself felt at the very first step, by rendering existence difficult and extinction almost sure soon to follow.[7]
The centrifugal flywheel governor system is a device for automatically adjusting and controlling the speed of the engine. It has opened the precedent of modern automatic control, marked the birth of modern automatic control technology, and been widely used in modern industry. When the centrifugal flywheel governor system is disturbed, the velocity of the system will change suddenly and the chaotic vibration will be produced [1, 2]. In order to make the centrifugal governor system run stably and play a good role in practical application, it is necessary to study the chaotic dynamics law when the system is disturbed and how to control the chaotic motion to the stable state.
In this paper, chaos and its adaptive control of the fractional-order centrifugal flywheel governor system are studied. The outline of this paper is given as follows. In Section 2, the fractional-order centrifugal flywheel governor system is introduced. In Section 3, dynamics of the integer-order centrifugal flywheel governor system are investigated numerically by the bifurcation diagram, LEs, the phase portrait, and the basins of attraction. In Section 4, the adaptive control formula is derived and the chaos control of the system is realized by simulation. In Section 5, the results are summarized.
The mechanics model of the centrifugal flywheel governor with external disturbance is depicted in Figure 1, where l, m, r, and ϕ represent the length of the rod, the mass of the fly ball, the distance between the rotational axis and the suspension joint, and the angle between the rotational axis and the rod, respectively. The motor drives the flywheel to rotate with angular velocity ω. The flywheel is joined to the axis through a gear box, so the axis rotates with angular velocity nω. n is the proportional coefficient, k is the stubborn coefficient of the spring, and is the gravitational acceleration. Ignoring the mass of the pipe and casing and assuming that the damping coefficient at the joint of the rod head and the ball is c, the motion equation of the system is given by [10, 14]
In this paper, the method used is presented. For the proposed system, there are four state variables x, y, z, and . Thus, four time series are obtained, and they can be defined as , where N is the length of the time series. Then, the position of the attractor is defined bywhere the mean values of each time series are used. The size of the attractor is given bywhere , , , and . Suppose that there are two chaotic attractors, and their time series are defined by and . The error between the positions of the two attractors is given bywhile the error regarding the size of the attractors is defined by
The process of controlling a chaotic system to a stable state is called chaotic control. At present, the main method of controlling fractional-order chaotic systems is to extend the control method used in integer-order chaotic systems to fractional-order chaotic systems. The main methods of chaos control include: parameter perturbation method [33], feedback control method [34], adaptive control method [35], and neural network method [36]. In this section, the chaos control of the fractional-order centrifugal flywheel governor system is realized by using the adaptive control method. The adaptive chaos control formula is derived, and the numerical simulation of chaos control effect is shown.
7fc3f7cf58