ME345 Modeling and Simulation
Centrifugal Governor Analysis
In engineering, any device that controls the speed of a machine or engine, usually by
regulating the intake of fuel or steam is called a governor.
A centrifugal governor is a specific type of governor that controls the speed of an
engine by regulating the amount of fuel 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.
The device shown is from a steam engine. It is connected to a throttle valve and to the
prime mover (not shown). The action of the governor is dependent on centrifugal force.
As the speed of the prime mover increases, the central spindle of the governor rotates
at a faster rate and the two masses move outwards, and this motion is translated by the
series of rods and arms to the throttle valve, reducing its aperture. The rate of steam
entering the cylinder is thus reduced and the speed of the prime mover falls. If the
speed of the prime mover falls, the reverse effect occurs and the throttle valve opens
further.
In other words, when the engine speed increases too much, the balls fly out, and cause
the stem valve to close, so the engine slows down. The opposite happens when the
engine speed drops too much.