Abstract:
A pressure-controlled valve comprising an elastic-walled conductor, such as a tube, with a flow-obstructing body within the conductor. Fluid flow through the conductor is controlled by expanding the elastic wall away from the flow-obstructing body to provide fluid flow paths and by contracting the elastic-wall of the conductor toward the body to close the flow paths. Expansion and contraction of the elastic-wall of the conductor is in response to the differential pressure between the inside and the outside of the conductor.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a pressure-controlled valve, that is a valve whose flow path is closed when a predetermined static fluid pressure is applied to the control chamber of the valve or a valve where a predetermined differential pressure is employed to cause the valve to operate. Further, the invention relates to a pressure-controlled valve wherein the control is accomplished with a small volume of both control and controlled fluids. 
     2. Background of the Invention 
     Prior art pressure-controlled valves which are used to perform a function contemplated by the present invention have required a relatively large &#34;hold-up volume&#34; of the controlled fluid within the pressure-controlled valve. In such valves the valve body itself holds a substantial volume both upstream and downstream from the valve closure point. Such valves require too much &#34;approach volume&#34; and &#34;discharge volume&#34; to be useful in a system wherein the volume of controlled fluid is quite small. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, flow of fluid stream is controlled by constricting the flow path of the fluid stream. The constriction is accomplished when the differential pressure between the controlled fluid and the controlling fluid causes compression of a circumferential member about the flow path of the controlled fluid. The circumferential member effectively closes the flow path without enclosing a volume of the controlled fluid within the valve and, when the circumferential member is relaxed the flow path is opened to pass controlled fluid without a surge discharge of controlled fluid trapped within the valve. 
     The valve of the present invention is substantially unlimited in operating pressure in that the control is accomplished within a control chamber where the relative pressure between the controlled fluid and the controlling fluid can be contained by as large or as small a valve body as will be needed to withstand the differential pressure between ambient pressure and the controlled fluid pressure. 
     In a preferred embodiment of the invention a compressible tube of flexible material provides a flow path surrounding a spreader which functions as a flow obstructing body within the tube. The spreader has a generally oval cross-sectional configuration and a cross-sectional area slightly larger than the internal cross-sectional area of the tube when the tube is in a relaxed state. The tube is stretched about the spreader and is compressible to completely close the flow path through the annular region between the spreader and the tube when a pressure is applied to the exterior of the tube which exceeds the pressure of the fluid flowing within the inside of the tube. The cross-section of the spreader has a smooth circumference so as to avoid creasing of the interior surface of the tube. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an assembly drawing in longitudinal-section illustrating the preferred embodiment of the present invention. 
     FIG. 2 is a partial sectional view of the valve closure portion of the present invention. 
     FIG. 3 is a sectional view along the line A--A of FIG. 2 illustrating the valve closure portion in closed position. 
     FIG. 4 is a sectional view along the line A--A of FIG. 2 illustrating the valve closure portion in open position. 
     FIG. 5 is a sectional view through the end seal member. 
     FIG. 6 is a sectional view along the lines B--B of FIG. 5. 
     FIG. 7 is an elevational view of one part of the valve insert. 
     FIG. 8 is an end view of FIG. 7. 
     FIG. 9 is a sectional view along line C--C of FIG. 7. 
     FIG. 10 is a side elevational view of the tube spreader flow obstructing body. 
     FIG. 11 is a sectional view along the lines E--E of FIG. 10. 
     FIG. 12 is a sectional view along the lines D--D of FIG. 10 illustrating an alternative form of the shaft of the spreader element. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention is particularly applicable to the rapid control of very small quantities of a fluid material in a broad range of pressure conditions, for example when the quantity of one fluid material to be added to another system is substantially instantaneously and in minute quantities. The desired speed is accomplished by substantially instantaneous closing off of the flow path of the controlled fluid and the desired small volume of controlled fluid is accomplished by providing a very small flow path with the substantially instantaneous control. 
     The valve of the present invention is illustrated in assembled form in FIG. 1 wherein a valve body 11 is shown having a threaded inlet port 12, a threaded outlet port 13, and a threaded control inlet port 14. The threads in the ports may be tapered pipe threads or machine threads for cooperation with input and output piping elements. The elements threaded into the input and output ports function to hold the functioning valve elements within the valve body 11 while maintaining a pressure seal within the valve. The valve body 11 is bored between the threaded inlet port 12 and outlet port 13 to provide an internal cylindrical channel 15. The control conduit 16 is machined through the valve body 11 from the bottom of the control inlet port 14 to the channel 15. 
     The internal cylindrical channel 15 confines the valve operating elements constituting a pair of end seals 17 and 18, an insert 19 comprising a pair of complimentary half members 21 and 22, an elastic-walled tube 23, and a tube spreader flow obstructing body 24. Each of these elements is shown in more detail in other figures of these drawings. 
     The valve operating elements are assembled within the valve body with the spreader 24 within the tube 23 and the spreader and tube sealed to an extension of the end seals 17 and 18 by being surrounded by and within the insert 21, 22. Piping connected to the valve body holds the operating elements within the body. 
     As shown in FIG. 5, each end seal, members 17, 18, is formed with a groove at 25 to accommodate an O-ring sealer 26 and has a nipple 27 extending from the surface that will be innermost within the valve body. A hole 28 passes axially through the end seal and the inner face of the nipple 27 at the hole 28 is fluted at 29, as shown in FIG. 6, to prevent the spreader 24 from sealing off the fluid flow. 
     FIGS. 7, 8 and 9 illustrate the formation of the insert 19 assembled from complimentary half members 21 and 22. The half members are formed with an internal rounded end half cylinder void 31 with end bores 32 and 33 at opposite ends passing axially to the exterior of the assembled spreader. A plurality of radial holes 34 pass through the insert body from the exterior to the internal void 31 and a circumferential groove 35 is removed about the center of the insert while leaving half cylinder shoulders 36 and 37 at opposite ends. 
     FIGS. 10 and 11 illustrate a preferred form for the spreader 24 here illustrated as having an elliptical form axially along one radial axis and an oval cross-section. The spreader may be constructed with a solid shaft 41 having the elliptical-oval cross-section material 42 fixed to the shaft. One form for construction of the spreader is to heat-shrink a plastics encapsulating tube, formed from a material such as teflon, of the desired configuration onto the solid shaft 41. 
     The spreader need not have a solid shaft or finger-like extension on the shaft as the spreader may be fixed within the tube at about its center to perform its flow obstructing function. 
     FIG. 1 illustrates the elements in their assembled position. It should be apparent that the relative sizes of the shafts, holes, tubes, nipples and bores are such that the elements when assembled fit securely within the body of the valve. 
     The spreader has a dimension axially at its widest part which is slightly larger than the diameter of the tube 23 and the tube and spreader are enough smaller in overall radial dimension to fit within the void portion 31 of the insert 19. The solid shaft 41 of the spreader fits within the fluted entrance of hole 28 within the nipple 27 on the end seals and the fluting within the hole provides fluid flow passageways around the shaft. The tube 23 fits around the outside of the nipple 27 and the complimentary half members 21 and 22 fit around the mounted tube. The contacting end faces of the assembled insert and end seals hold the insert in place. The O-ring around the end seals and the pressure contact between inlet/outlet piping and the end seals maintains the pressure seal of the valve when in operation. The groove 35 and radial holes 34 place the internal chamber formed by the void 31 in pressure communication with the control inlet port 14. When assembled as illustrated, the inside of tube 23 provides a flow path from inlet port 12 to outlet port 13 at the pressure of the inlet fluid stream and the outside of the tube 23 is at the pressure of the control port 14. 
     FIGS. 2, 3 and 4 illustrate the operation of the control valve of the present invention. FIG. 3 illustrates the tube 23 expanded about the periphery of the spreader 24 as the elements would be positioned when the pressure within the chamber 15 is equal to or greater than the pressure within the tube 23. FIG. 4 illustrates the relative positions of the tube 23 and spreader 24 when the pressure on the inside of the tube is greater than the pressure outside the tube. The tube, having a relaxed cross-section substantially circular, is elongated at the long axis of the oval cross-section of the spreader 24 and expanded outwardly about the short axis of the oval. The space 51 between the spreader 24 and the tube 23 provides a flow path for fluid. 
     The tube 23 is constructed of a flexible compressible material that can be collapsed about the spreader to effect a fluid-tight seal between the tube and spreader. The relative configuration of the spreader cross-section and the interior of the tube provide a means for effecting rapid operation of the valving function. If the differential pressure expands the tube outwardly from the spreader, passageways 51 are opened at the location of the minimum dimension of the spreader. When opened, fluid flow is substantially instantaneous. Any further increase in the differential pressure merely expands the tube about the spreader. When the differential pressure decreases, the tube is relaxed to collapse about the spreader and, when the outside pressure exceeds the inside pressure, flow through the tube is interrupted. 
     The valve of the present invention avoids the disadvantage of prior art valves which require an appreciable approach volume and discharge volume in operating and releasing the valve. The valve, therefore, has particular application to the control of fluid streams where very small quantities of fluid are required. Furthermore, the valve configuration permits the valve to be used throughout a broad range of pressures in that the control is accomplished by the pressure differential between the inside and outside of the fluid flow path. 
     FIG. 12 illustrates an alternate form for assuring there will be passageways for fluid flow through the nipple 27 around the shaft 41 and into the tube. The shaft 41 is provided with external flutings or knurling at 43 to separate the shaft from the interior surface of the nipple. When machined or formed as illustrated, fluid flow paths are provided through the void areas. 
     While certain preferred embodiments of the invention have been specifically disclosed, it should be understood that the invention is not limited thereto as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims.