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US 4,741,365 AGranted
Compound pneumatic valve
AssigneeMcDonnell Douglas Corporation
InventorCharles A. Van Ornum
Life of this patent
Estimating the term…
Abstract
A compound pneumatic valve of the bang-bang, spool type; electro-mechanically driven by a pair of face type opposing solenoids which in turn are driven by a pulse width modulator signal. First and second cylinder parts are alternately pressurized and vented through asymmetrical slot style ports to function in the two horsepower range having bandwidths of 30 to 45 Hz.
Claims11
A high power, compound, pneumatic, bang-bang, spool type valve with a closed center position and very fast opening and closing time, adapted to be electro mechanically driven by a pulse width modulated command signal, for driving a balanced piston actuator with high bandwidth comprising:
- a valve body having a thru bore, a pressure inlet port, an external vent, and first and second cylinder ports formed by at least one asymmetrical slot,;
- a valve spool slideably oriented in said valve body bore and having at least two enlarged first and second lands oriented to cover said first and second cylinder ports when said spool is in said center position and displacement of said spool in one direction connects said pressure port with said first cylinder port and said vent to said second cylinder port and displacement of said spool in the opposite direction connects said pressure port with said second cylinder port and said vent to said first cylinder port;
- said asymmetrical slots forming said first and second cylinder ports oriented so that when said spool is displaced to vent said cylinder port, the area of said cylinder port is greater than the area of said cylinder port when said spool is displaced to connect said pressure port to said cylinder port;
- first and second solenoids having a flat faced armature and a core assembly with said armatures attached to the respective ends of said spool and spaced from said core assembly;
- means to bias said spool in said closed center position in the absence of said pulsed command signal, said biasing means applying essentially no force when said spool is in said closed center position and an essentially constant force with spool displacement so that said solenoids produce a force which when algebraically summed with all other forces acting on said spool produce a high net force authority which increases as the spool stroke increases so as to produce a fast opening and closing valve.
2 more elements
A compound pneumatic, bang-bang, spool type, electro-mechanically driven valve, comprising:
- a valve body having a thru bore, a pressure inlet port, an external vent, and first and second cylinder ports formed by at least one asymmetrical slot;
- a valve spool slideably oriented in said valve body bore and having at least two enlarged first and second lands oriented to cover said first and second cylinder ports when said spool is in said center position and displacement of said spool in one direction connects said pressure port with said first cylinder port and said vent to said second cylinder port and displacement of said spool in the opposite direction connects said pressure port with said second cylinder port and said vent to said first cylinder port;
- said asymmetrical slots forming said first and second cylinder ports oriented so that when said spool is displaced to vent said cylinder port, the area of said cylinder port is greater than the area of said cylinder port when said spool is displaced to connect said pressure port to said cylinder port;
- first and second solenoids having a flat face type armature and a core assembly with said armature attached to the respective ends of said spool and spaced from said core assembly;
- means to bias said spool in said closed center position in the absence of power to said solenoids, said biasing means applying essentially no force when said spool is in said closed center position and an essentially constant force with spool displacement so that said solenoids produce a force which when algebraically summed with all other forces acting on said spool produce a high net force authority which increases as the spool stroke increases so as to produce a fast opening and closing valve;
- and
- means to drive said solenoids by varying the width of a high frequency electrical pulse producing a period greater than the response time to move said spool from close to open and maintaining said open duration during each pulse width cycle proportional to said commanded flow and thereby establish a linear relationship between commanded signal and actual valve flow.
4 more elements
Dependencies are inferred from the claim text.