Stepper motor operated balanced flow control valve

Abstract

A flow control valve includes a body having a body bore oriented coaxially with a longitudinal axis of the body and a seat member extending into the bore. A valve member is slidably disposed in the bore and oriented coaxially with the longitudinal axis of the body. The valve member includes a non-circular geometrically shaped head having a bore. A drive adapter includes a head receiving cavity slidingly receiving the geometrically shaped head of the valve member and preventing axial rotation of the valve member. A stepper motor is connected to the drive adapter, the stepper motor incrementally rotating a shaft engaged with the bore of the valve member. First and second equal diameter pistons of the valve member provide pressure balanced valve member operating positions.

What is claimed is: 
     
         1 . A flow control valve, comprising:
 a body having a longitudinal axis, the body defining a body bore oriented coaxially with the longitudinal axis and a seat member that extends into the body bore, the body bore having a bore diameter;   a valve member slidably disposed in the body bore and oriented coaxially with the longitudinal axis, the valve member including:
 a valve head having a geometric shape defined by at least one anti-spin feature disposed along an otherwise cylindrical surface; 
 a valve member having a cylindrical shape, the valve member being disposed in the body bore adjacent the valve head and having a seat engagement member that extends radially outwardly to selectively engage the seat member of the body during sliding motion of the valve member in the body bore; and 
 a threaded bore extending into the valve head; 
   a drive adapter connected to the body, the drive adapter including a head receiving cavity that is shaped to match the geometric shape of the valve head and that slidingly receives the valve head while preventing axial rotation of the valve head relative to the drive adapter and the body;   a stepper motor connected to the drive adapter, the stepper motor operating to axially rotate a shaft threadably engaged with the threaded bore of the valve head to axially displace the valve member; and   an inlet port and an outlet port extending through the body from the body bore to a ported face of the body, the inlet port and the outlet port being disposed on opposite sides of the seat member.   
     
     
         2 . The flow control valve of  claim 1 , wherein the at least one anti-spin feature forming part of the geometric shape of the valve head includes a flat longitudinal face disposed along the otherwise cylindrical surface of the valve head. 
     
     
         3 . The flow control valve of  claim 2 , wherein the head receiving cavity includes a cavity face that abuts the flat longitudinal face of the valve head to prevent axial rotation of the valve head. 
     
     
         4 . The flow control valve of  claim 1 , wherein the geometric shape of the valve head includes two flat longitudinal faces disposed on opposite sides of the otherwise cylindrical surface of the valve head. 
     
     
         5 . The flow control valve of  claim 4 , wherein the head receiving cavity includes two cavity faces that abut the two flat longitudinal faces of the valve head to prevent axial rotation of the valve head. 
     
     
         6 . The flow control valve of  claim 1 , wherein the at least one anti-spin feature includes a groove disposed along the otherwise cylindrical surface of the valve head that engages the drive adapter to prevent rotation of the valve head relative to the drive adapter. 
     
     
         7 . The flow control valve of  claim 1 , wherein the at least one anti-spin feature includes a concave face disposed along the otherwise cylindrical surface of the valve head that abuts a complimentary cavity face of the head receiving cavity to prevent rotation of the valve head relative to the drive adapter. 
     
     
         8 . The flow control valve of  claim 1 , wherein the seat engagement member engages the seat member to define a closed position of the flow control valve. 
     
     
         9 . The flow control valve of  claim 8 , wherein rotation of the shaft in a first direction longitudinally displaces the valve member in the body bore from the closed position to an open position of the flow control valve, and rotation of the shaft in an opposite second direction returns the valve member from the open position to the valve closed position. 
     
     
         10 . The flow control valve of  claim 1 , wherein the valve member further includes:
 a first piston positioned at an opposite end of the valve member from the valve head; and   a second piston positioned between the seat engagement member and the at least one anti-spin feature of the valve head, the first and second pistons operating to seal against cylinder walls of the body as the valve member slidably moves in the body bore.   
     
     
         11 . The flow control valve of  claim 10 , wherein the first and second pistons have substantially equal diameters such that a pressurized fluid acting oppositely against the first and second pistons results in balanced pressure forces acting on the valve member. 
     
     
         12 . The flow control valve of  claim 1 , further comprising an electronic interface device receiving a command signal and converted by the electronic interface device to an output for operation of stepper motor. 
     
     
         13 . The flow control valve of  claim 12 , further including an electronic interface housing having the electronic interface device disposed therein and an electrical connector sealing the electronic interface housing from the atmosphere and providing electrical connection for the flow control valve. 
     
     
         14 . The flow control valve of  claim 1 , wherein the valve member includes a resilient seal adjacent the valve head that slidably and sealingly engages the bore diameter of the body bore with a close tolerance fit to prevent fluid in the body bore from entering the head receiving cavity. 
     
     
         15 . The flow control valve of  claim 1 , wherein the shaft of the stepper motor is a male threaded shaft that is connected to and extends from the stepper motor such that incremental rotation of the stepper motor rotates the male threaded shaft within the threaded bore of the valve head to incrementally translate the valve member in an axial direction along the longitudinal axis. 
     
     
         16 . The flow control valve of  claim 1 , wherein the otherwise cylindrical surface of the valve head has a diameter that equals a diameter of the valve member adjacent the valve head. 
     
     
         17 . The flow control valve of  claim 1 , wherein the drive adapter is releasably connected to the body. 
     
     
         18 . The flow control valve of  claim 1 , wherein the drive adapter is integrally connected to the body and the valve head is slidably received in the head receiving cavity, the anti-spin feature of the valve head including two flat longitudinal faces on the otherwise cylindrical surface of the valve head and the drive adapter having two cavity faces that mate with the two flat longitudinal faces of the valve head to prevent rotation of the valve head about the longitudinal axis. 
     
     
         19 . The flow control valve of  claim 1 , wherein the seat engagement member is at least partially made of a resilient material. 
     
     
         20 . The flow control valve of  claim 1 , wherein the valve member has a poppet valve shape. 
     
     
         21 . The flow control valve of  claim 1 , wherein the valve member has a spool valve shape. 
     
     
         22 . The flow control valve of  claim 1 , wherein the valve member extends integrally from the valve head such that the valve head and the valve member are integrally connected with one another as part of the valve member. 
     
     
         23 . The flow control valve of  claim 1 , wherein the valve member is detached from the valve head and is held in contact with the valve head by a biasing component that biases the valve member toward the valve head. 
     
     
         24 . The flow control valve of  claim 23 , wherein the biasing component is a spring disposed between the body of the flow control valve and an opposite end of the valve member from the valve head. 
     
     
         25 . A flow control valve, comprising:
 a body having a body bore oriented coaxially with a longitudinal axis of the body, the body bore having a bore diameter;   a valve member slidably disposed in the body bore and oriented coaxially with the longitudinal axis of the body, the valve member including:
 a valve head and a valve body portion that are disposed within the body bore adjacent one another, the valve head having a threaded bore created therein and a geometric shape defined by at least one flat longitudinal face on an otherwise cylindrical surface; and 
 at least one seat engagement member that extends radially outwardly from the valve body portion and first and second pistons that are integrally connected with one another as part of the valve member, the first and second pistons having substantially equal diameters that create a close tolerance fit with the bore diameter such that a pressurized fluid acting oppositely against the first and second pistons is balanced; 
   a drive adapter including a head receiving cavity slidingly receiving the valve head of the valve member, the head receiving cavity having a shape that compliments the geometric shape of the valve head to prevent axial rotation of the valve head within the head receiving cavity;   a stepper motor connected to the drive adapter, the stepper motor rotating a shaft threadably engaged within the threaded bore of the valve head to move the valve member along the longitudinal axis in response to rotation of the shaft of the stepper motor; and   an inlet port and an outlet port extending through the body from the body bore to a ported face of the body that are operably opened and closed by the at least one seat engagement member in response to movement of the valve member along the longitudinal axis.   
     
     
         26 . A flow control valve, comprising:
 a body having a body bore oriented coaxially with a longitudinal axis of the body and an end cap in contact with the body, the body bore having a bore diameter;   a valve member slidably disposed in the body bore and oriented coaxially with the longitudinal axis of the body, the valve member including:
 a non-circular geometrically shaped head and a body portion, the non-circular geometrically shaped head having a threaded bore created therein; and 
 at least one radial outwardly extending seat engagement member and first and second pistons that are integrally connected with one another as part of the valve member, the first and second pistons having substantially equal diameters that create a close tolerance fit with the bore diameter such that a pressurized fluid acting oppositely against the first and second pistons is balanced; 
   a drive adapter including a head receiving cavity slidingly receiving the non-circular geometrically shaped head of the valve member and preventing axial rotation of the valve member; and   a stepper motor connected to the drive adapter, the stepper motor rotating a shaft directly engaged within the threaded bore of the valve member to axially translate the valve member.   
     
     
         27 . The flow control valve of  claim 26 , wherein the body is a 2-way valve body including:
 a seat member extending into the body bore; and   an inlet port and an outlet port disposed on opposite sides of the seat member, the at least one radial outwardly extending seat engagement member contacting the seat member in a valve closed position isolating the inlet port from the outlet port.