Reed valves consist of thin flexible metal or fiberglass strips fixed on one end that open and close upon changing pressures across opposite sides of the valve much like heart valves do. They are intended to restrict flow to a single direction. Bundle of fiberglass Fiberglass or fibreglass is material made from extremely fine fibers of glass. ... Grays Fig. ...

Two-stroke engines

Reed valves (also known as flapper valves) are commonly used in two-stroke engines to control the fuel-air mixture that is admitted to the engine crankcase. As the piston rises in the cylinder the resulting vacuum opens the valve and admits the fuel-air mixture. As the piston descends, it raises the crankcase pressure causing the valve to close to retain the mixture and pressurize it for its eventual transfer through to the combustion chamber. The two-stroke cycle of an internal combustion engine differs from the more common four-stroke cycle by having only two strokes (linear movements of the piston) instead of four, although the same four operations (intake, compression, power, exhaust) still occur. ... Crankshaft Continental engine marine crankshafts, 1942 Crankshaft is also the name of a comic strip about an old, curmudgeonly bus driver. ... A combustion chamber is part of an engine in which fuel is burned. ...

Given the fact that they operate via air pressure alone, reed valves are not as precise as rotary valves since physical inertia causes them to open later than the optimum time. Manufacturers have attempted to address this in part by creating multi-stage reeds with smaller, more responsive reeds within larger ones that provide more volume later in the cycle. It has been suggested that this article or section be merged into brass instrument. ... The principle of inertia is one of the fundamental laws of classical physics which are used to describe the motion of matter and how it is affected by applied forces. ...

The repeated flexing of the valve material eventually causes metal versions to fatigue and fail to seat properly while fiberglass ones will merely snap off and be digested by the engine.

Pulse jets

Reed valves are also used in valved pulse jet engines, such as the Argus engine in the German V-1 flying bomb. Their function is much the same as in a piston engine. They are pulled open by a partial vacuum created by an over-expansion of combustion gasses. The open valves allow a charge of fuel and air into the engine, which explodes, increasing the internal pressure and closing the valves. The cycle then repeats. A pulse jet engine (or pulsejet) is a very simple form of internal combustion engine wherein the combustion occurs in pulses and the propulsive effort is a reaction to the rearward flow of hot gases. ... The Fieseler Fi 103/FZG-76 (Vergeltungswaffe-1, V-1), known as the Flying bomb, Buzz bomb or Doodlebug, was the first modern guided missile used in wartime and the forerunner of todays cruise missile. ... The article on the vacuum cleaner is located elsewhere. ...

See also

• poppet valve