Fail safe valve

• US 20040256586A1
• Filed: 06/16/2004
• Published: 12/23/2004
• Est. Priority Date: 06/20/2003
• Status: Active Grant

• Current Assignee: Danfoss A/S
• Original Assignee: Danfoss A/S
• Inventors: Wiwe, Joergen Seindal, Michelsen, Kenneth, Denning, Lars
• Granted Patent: US 6,997,430 B2
• Time in Patent Office: Days
• US Class Current: 251/66
• CPC Class Codes: F16K 31/047 characterised by mechanical means between the motor and the valve, e.g. lost motion means reducing backlash, clutches, brakes or return means F16K31/043 takes precedence
• CPC Class Codes: F16K 31/56 without stable intermediate position, e.g. with snap action
• CPC Class Codes: F16K 39/022 using balancing surfaces

Abstract

The invention concerns a fail-safe valve having a valve element, and a control motor being connected with the valve element via a driveline. It is endeavoured to ensure the tightness of the refrigeration system in a simple manner. For this purpose, it is ensured that the valve element is located inside and the control motor outside a closed valve housing, that the drive line has a magnetic coupling, which acts through the housing, and that the valve element is pressure-released. In addition, a resetting device is provided that causes the valve element to be returned to a predetermined position upon the undesired cessation of control motor operation.

Claims

1. A fail-safe valve comprising:

a valve housing having an inlet and an outlet;

a valve element operably positioned in said valve housing for movement between an open position wherein said inlet is in fluid communication with said outlet and a closed position wherein said valve element engages a valve seat;

equalizing means for minimizing pressure differential between an end of said valve element engageable with said valve seat and a generally opposite end of said valve element, in response to fluid pressure exerted against said valve element;

a displacement member coupled to said valve element;

a spindle, at least a portion of which is rotatably positioned in said valve housing, said spindle being threadably engaged at one end with said displacement member and having at least one first magnet coupled to an opposite end of said spindle;

a drive including a rotatable drive shaft having at least one second magnet coupled thereto, said at least one first magnet and said at least one second magnet cooperating to define a magnetic coupling, such that during operation, rotation of said drive is transferred to said spindle via said magnetic coupling whereby said spindle and said displacement member threadedly cooperate to move said valve element between said open and said closed positions; and

biasing means for urging said valve element toward one of said open and closed positions, thereby causing said spindle to rotate relative to said displacement member and move said valve element to a predetermined position in response to an undesired cessation of operation of said drive.

2. A fail-safe valve as defined by claim 1 wherein said biasing means is a coil spring positioned in said valve housing and surrounding at least a portion of said spindle, said coil spring having one end engaged with said valve element and being one of compressible or tensionable as said valve element moves toward one of said open position and said closed position, so that upon undesired cessation of drive operation said spring exerts force on said valve element and thereby said displacement member to cause said spindle to rotate relative to said displacement member thereby allowing said valve member to move toward said predetermined position.

3. A fail-safe valve as defined by claim 2 wherein said displacement member is polymeric and defines a threaded bore extending there through.

4. A fail-safe valve as defined by claim 3 wherein said displacement member is a nut.

5. A fail-safe valve as defined by claim 1 further comprising an inner magnet holder attached to said spindle, and wherein said at least one first magnet is coupled to said inner magnet holder.

6. A fail-safe valve as defined by claim 5 further comprising an adapter piece coupled to said housing, said inner magnet holder extending into, and being rotatably supported by said adapter piece.

7. A fail-safe valve as defined by claim 6 wherein at least the portion of said adapter piece surrounding said at least one first magnet is made of a non-magnetic material.

8. A fail-safe valve as defined by claim 7 wherein said at least one second magnet is coupled to an outer magnet holder mounted on said drive shaft, said outer magnet holder being located relative to said adapter piece so that said at least one first magnet, and said at least one second magnet are substantially aligned with one another to form said magnetic coupling, and wherein said outer magnet holder is rotatable relative to said adapter piece.

9. A fail-safe valve as defined by claim 8 further comprising an extension coupled to said valve housing, said outer magnet holder and said portion of said adapter piece surrounding said at least one first magnet being positioned in said extension, said outer magnet holder being rotatable relative to said extension, at least a portion of said extension surrounding said outer magnet holder is formed from non-magnetic material, and wherein said drive is mounted on said extension.

10. A fail-safe valve as defined by claim 9 wherein said drive is a stepping motor.

11. A fail-safe valve as defined by claim 1 wherein said equalizing means includes a pressure chamber in fluid communication with said generally opposite end of said valve member, and means for transferring pressure between said pressure chamber and said end of said valve member engageable with said valve seat to thereby minimize pressure differential between opposing ends of said valve member.

12. A fail-safe valve as defined by claim 8 wherein said at least one first magnet includes a plurality of first magnets radially disposed about said inner magnet holder, and said at least one second magnet includes a plurality of second magnets radially disposed about said outer magnet holder.

13. A fail-safe valve as defined by claim 1 wherein said drive is a motor and said biasing means includes a torsion spring coupled to said drive shaft such that rotation thereof causes said valve element, via said magnetic coupling, to move toward a respective one of said open and said closed positions, and also causes a torque to be generated in said torsion spring that, upon undesired cessation of operation of said motor causes said drive shaft and thereby said spindle to rotate and move said valve element to said predetermined position.

14. A fail-safe valve as defined by claim 3 wherein said spindle is formed from stainless steel.