Overspeed (engine)
Overspeed is a condition in which an engine is allowed or forced to turn beyond its design limit. The consequences of running an engine too fast vary by engine type and model and depend upon several factors, chief amongst them the duration of the overspeed and by the speed attained. With some engines even a momentary overspeed can result in greatly reduced engine life or even catastrophic failure. The speed of an engine is ordinarily measured in revolutions per minute (RPM).
Examples of overspeed
* In aircraft an engine overspeed will occur should the propeller – ordinarily connected directly to the engine – be forced to turn too fast by high speed airflow while the aircraft is in a dive.
* In jet aircraft an overspeed results when the axial compressor exceeds its maximum operating RPM – this often leads to the mechanical failure of turbine blades, flameout and complete destruction of the engine.
* In vehicles an engine can be forced to turn too quickly by changing to an inappropriately low gear.
* Most unregulated engines will overspeed should there be no or little load while power is applied.
Overspeed protection
Sometimes a regulator or governor is fitted to make engine overspeed impossible or less likely. For example:
* Many steam engines use a centrifugal governor which centrifugally close a throttle to restrict steam flow as engine speed increases.
* In motor vehicles automatic gearboxes will change gear to prevent the engine from turning too quickly.
* Some aircraft have constant speed units which automatically change propeller pitch to keep the engine running at the optimum speed.
Large diesel engines are sometimes fitted with a secondary protection device which operates if the governor fails. This consists of a flap valve in the air intake. If the engine overspeeds, the air flow through the intake will rise to an abnormal level. This causes the flap valve to snap shut, starving the engine of air and shutting it down.
Corliss Orville Burandt
Corliss Orville Burandt is an American engineer who invented a system of variable valve timing in automobile engines. Working through a 1965 Corvair, he designed a system of putting a sensor into the cylinder to optimize the fuel-air mixture during combustion. He claims that the hybrid autos which are on the market today use technology from his patents.
Burandt assigned the rights to his most cherished invention to Investment Rarities, a venture capital company which specialized in gold trading. When Investment Rarities had financial and tax setbacks in the late 1980s, it ceased paying the maintenance fees on Burandt’s patents. Thus the patents fell into the public domain.
After his patents came to naught, Burandt fell upon hard times. Suffering from obsessive-compulsive disorder, he says “I mean, I lost everything. I lost my house, I lost all my cars. I lost everything. I was fricking homeless. I lived in that goddamn car for a while. I mean, how many inventors live in their prototypes? I mean, is that ridiculous or what? It was just…I ruined my family with the deal. But in terms of what happened to me: basically, I was left to rot for eight years.”
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