Valves and valve actuation – Fluid actuated or retarded – Pilot or servo type motor
Patent
1998-01-21
2000-05-16
Lee, Kevin
Valves and valve actuation
Fluid actuated or retarded
Pilot or servo type motor
251 28, 251 3001, 137244, F16K 31383, F16K 3134
Patent
active
060625309
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to valves for controlling fluid flows. In particular, this invention relates to a technique which makes it extremely feasible to achieve minute, yet highly consistent fluid flow rates. Making use of this technique will open the way to making fluid valves having low manufacturing and maintenance costs, improved operating characteristics and very weak forces to operate. That is, the solution to the persistent problems other valve manufacturers are trying to ameliorate, is only one part of what this technique offers.
DESCRIPTION OF THE PRIOR ART
Conventional valves have a valve seat and a movable valve member which bears against the valve seat to control the fluid flow. An actuator acts directly on the valve member to cause movement of the valve member. In large valves the forces required to move the valve member may be large, making manual actuation difficult or impossible, in which case a mechanical actuator is required. The present invention aims to at least ameliorate some of the above disadvantages.
Basically at least part of the valve member is exposed to a pressure in a chamber. By altering the pressure in the chamber the direction of the net force applied to the valve member may be changed.
In particular this specification details improved valve structure to those described in the Applicant's earlier Australian Patent Application No. 24554/92.
Conventional pilot operated valves are primarily designed to replace direct acting valves in situations where it is not possible to provide strong forces nor consume high power for controlling said direct acting valves. However, said conventional pilot operated valves have disadvantages and limitations which valve manufacturers are constantly searching for feasible ways to ameliorate.
It appears that these limitations will persist unless the elevated flow rates through the by pass circuit of these pilot operated valves are significantly lowered. These flow rates, however, could not be lowered below a relatively high limit without facing serious flow consistency problems, thereby making it impossible to improve the situation.
SUMMARY OF THE INVENTION
The invention seeks to enable fluid passageways capable of providing minute, yet highly consistent flow rates, and also capable of filtering the fluid, that passes through them, from particles which may block downstream passageways. Said fluid passageways have the properties of firstly, ultra high fluid flow resistance, secondly, self-cleaning, and, thirdly, filtering capabilities (strainer).
The ultra-high flow resistance is achieved by being able to simultaneously reduce the cross-section of the passageway and increase the surface area of its internal walls independently from the flow-path length of said passageway. That is, the cross-section of said passageway will effectively have an elongated shape or a series of elongated shapes.
The self-cleaning is achieved by allowing or by forcing the walls forming the passageway to make the necessary relative movements to each other and by the high speed at which the fluid flows through the passageway. Solid particles and slime may be shaken loose and forced out of said passageway by said wall movements and fluid flow. This process diminishes the effect of slime and solid particles on the flow resistance of said passageway.
The filtering is achieved due to solid particles having effective diameters larger than the width of the cross-section of the said passageway will obviously not enter said passageway, they will rather be allowed to precipitate and/or get washed away from the inlet of said passageway.
In one broad form the invention provides a valve device comprising: first port to said second port; position and a lifted position; first port; second port; fluid flow therethrough, and to thereby urge said valve member into either said seated or lifted position; and, restrict the flow of fluid through said passageways, and, to prevent the ingress of particles which might otherwise clog said passageways and/or flow p
REFERENCES:
patent: 2712325 (1955-07-01), Andrus
patent: 4785842 (1988-11-01), Johnson, Jr.
patent: 5042775 (1991-08-01), Williamson et al.
E.S.H. Consulting Engineers Pty Limited
Lee Kevin
LandOfFree
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