Rotary valve
A rotary valve is a type of valve in which the rotation of a passage or passages in a transverse plug regulates the flow of liquid or gas through the attached pipes. The common stopcock is the simplest form of rotary valve. Rotary valves have been applied in numerous applications, including:
- Changing the pitch of brass instruments.
- Controlling the steam and exhaust ports of steam engines, most notably in the Corliss steam engine.
- Periodically reversing the flow of air and fuel across the open hearth furnace.
- Loading sample on chromatography columns.
- Certain types of 2-stroke gasoline engines.
Use in brass instruments
In the context of brass instruments, rotary valves are found on horns, trumpets, trombones, flugelhorns, and tubas. Many European trumpet players tend to favor rotary valves.[citation needed]
Trombone F-attachment valves are usually rotary, with several variations on the basic design also in use, such as the Thayer axial-flow valve and Hagmann valve.
Joseph Riedlin is credited with the first use of rotary valves on brass instruments in 1832.
Use in industry
In industry, a rotary valve (which can also be called airlock) is often used to enter or extract material from two chambers with different pressure level.
As part of the material exchange process, the valve is often used as a measuring or metering device.
Use in engine design
The rotary valve combustion engine possesses several significant advantages over the conventional assemblies, including significantly higher compression ratios and reduced complexity.
Rotary valves have been used in several different engine designs. In Britain, the National Engine Company Ltd advertised its rotary valve engine for use in early aircraft, at a time when poppet valves were prone to failure by sticking or burning. [1]
From the 1930s, Frank Aspin developed a design with a rotary valve that rotated on the same axis as the cylinder bore, but with limited success.[2]
Kawasaki and others have also used rotary valves in two-stroke motorcycle engines, where the arrangement helps to prevent reverse flow back into the intake port during the compression stroke.[3]
A US company has developed a spherical rotary valve for internal combustion engines which replaces the poppet valve system. This particular design is four-stroke, with the rotary valves operated by overhead shafts in lieu of overhead camshafts (i.e. in line with a bank of cylinders). The first sale of such an engine was part of a natural gas engine-generator. [4]
Use in chromatography
Rotary valves are used for loading samples on columns used for liquid or gas chromatography. The valves used in these methods are usually 6-port, 2-position rotary valves.
See also
References
- ^ Flight magazine, April 1911
- ^ Aspin Rotary Valve Engine Accessed on 18th Oct 2010
- ^ Free engine info Accessed on 18th Oct 2010
- ^ Coates International Accessed on 3rd Mar 2011
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