Everything about Centrifugal Governor totally explained
A
centrifugal governor is a specific type of
governor that controls the
speed of an
engine by regulating the amount of
fuel (or
working fluid) admitted, so as to maintain a near constant speed whatever the
load or fuel supply conditions. It uses the principle of
proportional control.
It is most obviously seen on
steam engines where it regulates the admission of steam into the
cylinder(s). It is also found on
internal combustion engines and variously fueled
turbines.
Operation
The device shown is from a steam engine. It is connected to a
throttle valve that regulates the flow of
working fluid (steam) supplying the
prime mover (prime mover not shown). 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.
Mechanical stops may be used to limit the range of throttle motion, as seen near the masses in the image at right.
The direction of the lever arm holding the mass will be along the
vector sum of the
reactive centrifugal force vector and the gravitational force.
History
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.
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. This is used in a spring-loaded
record player and a spring-loaded
telephone dial to limit the speed.
Dynamic systems
The centrifugal governor is often used in the cognitive sciences as an example of a
dynamic system, in which the representation of information can't 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 far from trivial.
James Clerk Maxwell wrote a famous paper "On governors", which is quite frequently considered a classical paper in feedback
control theory, in 1868. Maxwell distinguishes moderators (a centrifugal
brake) and governors which
control motive power input. He considers devices by
Watt, Professor
James Thomson, Mr.
Fleeming Jenkin, Sir
William Thomson, M.
Leon Foucault and Mr
Carl Wilhelm Siemens (a liquid governor).
In a largely overlooked passage of his famous 1858 paper to the
Linnean Society (which led
Darwin to publish his monumental
On the Origin of Species)
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..
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 19
th Century". 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.
References
Further Information
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