High pressure, low flow rate fluid flow control

Abstract

An adjustable high pressure, low flow metering valve provides a sleeve extending about a restrictor shaft, the sleeve having a narrow helical groove formed in the inside diameter. A restrictor shaft within the sleeve encloses the groove and forms a sealed helical flow channel. The length of the flow channel is varied by withdrawing the restrictor shaft in the sleeve, whereby only a selected axial extent of the groove is enclosed by the sleeve to form a confined flow path. The shaft is provided with a threaded engagement in the body of the metering valve, so that rotation of an adjustment knob provides extremely fine control of the length of the flow path, and thus highly accurate selection of the flow resistance.

1 . An adjustable resistance device for high pressure, low flow rate liquids, including: 
 a sleeve having an internal surface;    a groove extending into said internal surface of said sleeve;    a restrictor shaft disposed within said sleeve, said restrictor shaft having an outer circumferential surface impinging on said internal surface of said sleeve and forming a seal with said groove to define a flow path within said groove;    means for translating said restrictor shaft within said sleeve to selectively unseal portions of said groove and change the length of said flow path within said groove.    
     
     
         2 . The adjustable resistance device of  claim 1 , wherein said sleeve is a tubular member.  
     
     
         3 . The adjustable resistance device of  claim 2 , wherein said groove extends generally helically in said internal surface.  
     
     
         4 . The adjustable resistance device of  claim 1 , wherein said restrictor shaft is press fit into said sleeve.  
     
     
         5 . The adjustable resistance device of  claim 1 , wherein said restrictor shaft is formed of a ceramic material.  
     
     
         6 . The adjustable resistance device of  claim 1 , wherein said means for translating includes threaded means connected to one end of said restrictor shaft.  
     
     
         7 . The adjustable resistance device of  claim 6 , further including means for preventing rotation of said restrictor shaft while permitting axial translation of said restrictor shaft.  
     
     
         8 . The adjustable resistance device of  claim 6 , wherein said threaded means includes a threaded drive shaft connected to said restrictor shaft, and further including a rotatable collar connected to said sleeve, said collar having internal threads to engage said threaded drive shaft.  
     
     
         9 . The adjustable resistance device of  claim 8 , further including a manual adjustment knob connected to said rotatable collar.  
     
     
         10 . The adjustable resistance device of  claim 8 , further including motor drive means for rotating said rotatable collar.  
     
     
         11 . The adjustable resistance device of  claim 1 , further including a sealed first flow space disposed at a first end of said groove.  
     
     
         12 . The adjustable resistance device of  claim 11 , further including a high pressure input fitting connected to said first flow space.  
     
     
         13 . The adjustable resistance device of  claim 12 , further including a low flow output fitting connected to said first flow space.  
     
     
         14 . The adjustable resistance device of  claim 13 , wherein said low flow output fitting includes a fixed fluid resistance therein.  
     
     
         15 . The adjustable resistance device of  claim 14 , further including a plurality of interchangeable low flow output fittings, each having a different fixed fluid resistance.  
     
     
         16 . The adjustable resistance device of  claim 11 , further including a sealed second flow space disposed at a second end of said groove.  
     
     
         17 . The adjustable resistance device of  claim 16 , further including a high flow output fitting connected to said second flow space.  
     
     
         18 . The adjustable resistance device of  claim 14 , further including a sealed second flow space disposed at a second end of said groove, a high flow output fitting connected to said second flow space, said fixed fluid resistance having a flow resistance greater than the flow resistance of said flow path through said groove.  
     
     
         19 . The adjustable resistance device of  claim 18 , further including an indicator shaft extending outwardly from said restrictor shaft to indicate the ratio of flow rate through said fixed flow resistance compared to flow rate through said flow path.  
     
     
         20 . A fluid flow meter arrangement, including: 
 a high pressure fluid source connected to first and second parallel flow paths;    said first flow path having a known fixed flow resistance connected in series to a first pressure sensor and thence to an unknown flow resistance;    said second flow path having a second fixed flow resistance in series with a second pressure sensor and an adjustable fluid flow resistance.    
     
     
         21 . The fluid flow meter arrangement of  claim 20 , wherein said pressure sensors generate pressure signals, and means for digitally computing flow rates through said first and second flow paths.  
     
     
         22 . The fluid flow meter arrangement of  claim 21 , wherein said means for digitally computing includes a signal condition and A/D converter connected to each pressure sensor.  
     
     
         23 . The fluid flow meter arrangement of  claim 22 , wherein said means for digitally computing includes servo means for automatically varying said adjustable fluid flow resistance in response to said computed flow rates.