Usuario:Nava137/Gobernador centrífugo
Un "gobernador centrifugo" es un tipo especifico de gobernador o sistema de retroalimentación que controla la speed de un motor por medio de la regularización de la cantidad de combustible inyectada, para mantener una velocidad casi constante, independientemente de la cantidad o las condiciones de inyección de combustible. Usa el principio de control proporcional.
Fue inventado en 1788 por James Watt para controlar su máquina de vapor donde regulaba la admisión de vapor en el cilindro(s). Su uso mas amplio fue en los motores de vapor durante la Steam Age en los años 1800s. También se puede encontrar en los motores de combustión interna, en varias turbinas y en algunos striking clocks.
Funcionamiento
[editar]El aparato que se muestra proviene de un motor de vapor. La energía es suministrada al gobernador por medio del eje de salida del motor, ambas partes se encuentran conectadas por medio de una banda o una cadena. El gobernador se encuentra conectado a la válvula del acelerador, la cual regula la corriente o la inyección del líquidos de trabajo (vapor) suministrando al motor principal. Mientras que la rapidez del motor principal aumenta, el eje central del gobernador gira a una razón mayor y la energía cinética de las esferas aumenta. Esto permite que ambas masas en los brazos de la palanca se muevan hacia afuera y hacia arriba en contra de la gravedad. Si el movimiento aumenta lo suficiente, causara que los brazos de la palanca bajen hasta el rodamiento, el cual mueve el acoplamiento del eje, el cual reduce la apertura de la válvula del acelerador.El ritmo de entrada del liquido de trabajo al cilindro es reducido y la velocidad del motor principal es controlada , previniendo que se exceda el limite de velocidad.
Frenos mecánicos pueden ser usados para limitar el rango de movimiento del acelerador, como se puede observar cerca de las masas en la imagen de la derecha.
Regulación no-gravitacional
[editar]Una limitante del gobernador de dos brazos, dos masas es su dependencia sobre la gravedad, y es por esto que el gobernador debe estar relativamente perpendicular a la superficie de la Tierra para que la gravedad atraiga las masas cuando el gobernador se ralentiza.
Los gobernadores pueden ser construidos para no depender de la fuerza de la gravedad , utilizando un solo brazo con peso en ambos extremos, un pivote central unido a un eje giratorio, y un eje que trata the forzar a los pesos para que se acerquen al centro del eje giratorio. Ambos pesos en extremos opuestos del brazo del pivote contra-balancean cualquier efecto gravitacional, sin embargo ambos pesos usan la fuerza centrípeta para trabajar en contra del eje
Governors can be built which 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 which 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 centripetal 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 rotations per minute.
History
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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.[1]
A giant statue of Watt's governor stands at Smethwick in the English West Midlands. It is known as the flyball governor.
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.
Dynamic systems
[editar]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"[2] 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, Léon Foucault and Carl Wilhelm Siemens (a liquid governor).
As an influence on cybernetics
[editar]In a largely overlooked passage from his famous 1858 paper to the Linnean Society (which led Darwin to publish On the Origin of Species), Alfred Russel Wallace says of the evolutionary principle:
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.[3]
The cybernetician and anthropologist Gregory Bateson would observe in the 1970s that though seeing it only as an illustration, Wallace had "probably said the most powerful thing that’d been said in the 19th century".[4] Bateson revisited the topic in his 1979 book Mind and Nature: A Necessary Unity, and other scholars have continued to explore the connection between natural selection and systems theory.[5]
See also
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Wikimedia Commons alberga una categoría multimedia sobre
Centrifugal governors.
References
[editar]- ↑ Hills, Richard L (1996), Power From the Wind, Cambridge University Press.
- ↑ Maxwell, James Clerk (1868). «On Governors». Proceedings of the Royal Society of London 16: 270-283. JSTOR 112510. doi:10.1098/rspl.1867.0055.
- ↑ Wallace, Alfred Russel. «On the Tendency of Varieties to Depart Indefinitely From the Original Type». Consultado el 18 de abril de 2009.
- ↑ Brand, Stewart. «For God’s Sake, Margaret». CoEvolutionary Quarterly, June 1976. Archivado desde el original el 11 de noviembre de 2010. Consultado el 11 de noviembre de 2010.
- ↑ Smith, Charles H. «Wallace's Unfinished Business». Complexity (publisher Wiley Periodicals, Inc.) Volume 10, No 2, 2004. Consultado el 11 de mayo de 2007.