Stepper motor operated balanced flow control valve

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 having an end cap passage through the end cap in communication with the body bore to vent 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 of the body, the valve member including:
• a rectangular shaped head and a cylindrical shaped body portion that are integrally connected with one another as part of the valve member, both the rectangular shaped head and the cylindrical shaped body 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 rectangular shaped head of the valve member and preventing axial rotation of the valve member;
• 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;
• the flow control valve having a substantially rectangular shape wherein each of the body, the end cap, the drive adapter and the stepper motor have substantially equal widths defining an overall width of the flow control valve;
• and
• the cylindrical shaped body portion of the valve member having a diameter that creates a close tolerance fit with the bore diameter wherein the valve member tapers from the rectangular shaped head to the cylindrical shaped body portion such that the rectangular shaped head of the valve member has a predetermined width that is greater than the diameter of the cylindrical shaped body portion.

A flow control valve, comprising:

• a body having at least one longitudinal face extending parallel to a longitudinal axis of the body, the body defining first and second cylinder walls and a body bore oriented coaxially with the longitudinal axis of the body;
• 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 having a threaded bore coaxially aligned with the longitudinal axis extending through the non-circular geometrically shaped head;
• a first piston positioned at an opposite end of the valve member from the non-circular geometrically shaped head;
• and
• a second piston positioned between the first piston and the non-circular geometrically shaped head and integrally connected to the non-circular geometrically shaped head, having the threaded bore extending into the second piston, the first and second pistons seal against the cylinder walls of the body as the valve member slidably moves in the body bore;
• a drive adapter connected to the body, the 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;
• a stepper motor connected to the drive adapter, the stepper motor rotating a threaded shaft directly threadably engaged within the threaded bore of the valve member;
• a first seat member defined by the body extending between the at least one longitudinal face of the body and the body bore, the first seat member having an outer edge disposed furthest from the drive adapter and a center-line that laterally bi-sects the first seat member;
• a second seat member defined by the body extending between the at least one longitudinal face of the body and the body bore, the second seat member having an outer edge disposed nearest to the drive adapter and a center-line that laterally bi-sects the second seat member;
• an inlet port extending through the body from the body bore to the at least one longitudinal face of the body that is longitudinally positioned between the drive adapter and the second seat member;
• an outlet port extending through the body from the body bore to the at least one longitudinal face of the body that is longitudinally positioned between the first seat member and second seat member;
• an exhaust port extending through the body from the body bore to the at least one longitudinal face of the body that is longitudinally positioned between the end cap and the first seat member;
• the first and second seat members defining an outer spacing equal to the distance between the outer edges of the first and second seat members and a center-line spacing equal to the distance between the center-lines of the first and second seat members;
• and
• the valve body further including a first seat engagement member and a second seat engagement member extending from the valve body that are longitudinally spaced from one another by a set distance that is less than the outer spacing of the first and second seat members and greater than the center-line spacing of the first and second seat members such that the valve body may be moved to one of:
• a valve open position where the first seat engagement member contacts the first seat member and the second seat engagement member is displaced from the second seat member to permit fluid communication between the inlet port and the outlet port and to isolate both the inlet port and the outlet port from the exhaust port;
• a valve closed position where the first seat engagement member contacts the first seat member and the second seat engagement member contacts the second seat member to isolate the inlet port and the outlet port and the exhaust port from one another;
• and
• an exhaust position where the first seat engagement member is displaced from the first seat member and the second seat engagement member contacts the second seat member to permit fluid communication between the outlet port and the exhaust port and isolate both the outlet port and the exhaust port from the inlet port.