Torque-limiter coupling for valve actuator

Patent metadata

Field	Value
Publication number	US-12372165-B2
Application number	US-202318341628-A
Country	US
Kind code	B2
Filing date	Jun 26, 2023
Priority date	Jun 26, 2023
Publication date	Jul 29, 2025
Grant date	Jul 29, 2025

Abstract

A valve actuator system includes a gearbox assembly including an output gear for coupling to a valve stem, an input gear operably coupled to the output gear to drive rotation of the output gear and an input shaft operably coupled to the input gear to drive rotation of the input gear, a torque-limiter coupling having a solid body defining a proximal end and a distal end, the proximal end including a recessed interior accepting the input shaft of the gearbox assembly, a retainer extending between the torque-limiter coupling and the input shaft to transmit torque therebetween, the retainer operable to disengage the torque-limiter coupling from the input shaft in response to a torque applied to the torque limiter-coupling exceeding a critical torque predetermined to prevent damage to the gearbox assembly, and an actuator operatively coupled to the proximal end of the torque-limiter coupling to provide torque to the torque-limiter coupling.

First claim

The invention claimed is:

1. A valve actuator system comprising:
a gearbox assembly including an output gear for coupling to a valve stem, an input gear operably coupled to the output gear to drive rotation of the output gear and an input shaft operably coupled to the input gear to drive rotation of the input gear;
a torque-limiter coupling defining a proximal end and a distal end, the proximal end including a recessed interior accepting the input shaft of the gearbox assembly therein;
a retainer operatively coupling the torque-limiter coupling and the input shaft to transmit torque therebetween, the retainer operable to disengage the torque-limiter coupling from the input shaft in response to a torque applied to the torque limiter-coupling exceeding a predetermined shear limit to prevent damage to the gearbox assembly; and
an operatively detachably coupled to the distal end of the torque-limiter coupling with one or more fasteners to provide torque to the torque-limiter coupling.

2. The valve actuator system of claim 1 , wherein the actuator comprises a handwheel for manual provision of torque by an operator.

3. The valve actuator system of claim 1 , wherein the retainer is operable to fracture at the critical torque to thereby disengage the torque-limiter coupling from the input shaft and prevents further torque transmission from the actuator to the gearbox assembly.

4. The valve actuator system of claim 3 , wherein the retainer comprises a cotter pin inserted into aligned holes defined through both the input shaft and the torque-limiter coupling.

5. The valve actuator system of claim 1 , wherein the gearbox assembly includes a worm drive, wherein the output gear is a worm gear, and the input gear is a worm shaft with a helical gear defined on the input shaft.

6. The valve actuator system of claim 1 , wherein the torque-limiter coupling further comprises a transitional section with tapered or rounded geometry defined between the proximal end and the distal end.

7. The valve actuator system of claim 1 , wherein the gearbox assembly includes a gearbox housing and first and second bearings supporting the input shaft in the gearbox housing.

8. A method, comprising:
locating a gearbox assembly including an output gear coupled to a valve stem of a valve, wherein the gearbox assembly includes an input gear operably coupled to the output gear to drive rotation of the output gear and an input shaft operably coupled to the input gear to drive rotation of the input gear;
securing a torque-limiter coupling to the input shaft of the gearbox assembly such that the torque-limiter coupling freely rotates about the input shaft;
installing a retainer to extend between the torque-limiter coupling and the input shaft to transmit torque therebetween, the retainer operable to disengage the torque-limiter coupling from the input shaft in response to a torque applied to the torque limiter-coupling exceeding a critical torque predetermined to prevent damage to the gearbox assembly; and
detachably coupling an actuator onto the torque-limiter coupling with one or more fasteners such that the actuator is operatively coupled to the input shaft to transmit torque thereto.

9. The method of claim 8 , further comprising:
dismantling the gearbox assembly to remove the input shaft from a gearbox housing of the gearbox assembly;
drilling a hole through the torque-limiter coupling and into the input shaft; and
rebuilding the gearbox assembly to re-couple the input shaft to the gearbox housing.

10. The method of claim 9 , wherein rebuilding the gearbox assembly further comprises:
mating a helical gear defined on the input shaft with a worm gear of the gearbox assembly to form a drive mechanism; and
securing the drive mechanism within the gearbox housing.

11. The method of claim 8 , wherein the torque-limiter coupling defines a recessed interior, and wherein securing the torque-limiter coupling to the input shaft comprises receiving the input shaft within the recessed interior and thereby coupling the actuator to the torque-limiter coupling.

12. The method of claim 8 , further comprising:
selecting the retainer to have a fracture strength such that the retainer fractures at the critical torque to thereby disengage the torque-limiter coupling from the input shaft.

13. The method of claim 12 , further comprising:
applying a torque greater than the critical torque to the torque-limiter coupling with the actuator; and
fracturing the retainer to disengage the torque-limiter coupling from the input shaft of the gearbox assembly.

14. The method of claim 13 , further comprising:
removing the actuator from the torque-limiter coupling; and
removing the fractured retainer from the torque-limiter coupling and the input shaft.

15. The method of claim 14 , further comprising:
installing a subsequent retainer onto the torque-limiter coupling and the input shaft;
re-installing a side cover of the gearbox assembly; and
re-installing the actuator on to the torque-limiter coupling.

16. The valve actuator system of claim 6 , wherein the proximal end of the torque-limiter coupling includes a cross-sectional diameter greater than a cross-sectional diameter of the distal end.

17. The valve actuator system of claim 6 , wherein the transitional section is defined circumferentially around the torque-limiter coupling.

18. The method of claim 14 , wherein removing the actuator from the torque-limiter coupling includes removing a threaded fastener from a threaded recess in the torque-limiter coupling.

19. The method of claim 15 , wherein re-installing the actuator on to the torque-limiter coupling includes:
aligning a threaded recess of the torque-limiter coupling with an actuator hole of the actuator; and
inserting a threaded fastener through the actuator hole and into the threaded recess to detachably couple the actuator to the torque-limiter coupling.

20. A torque-limiter coupling comprising:
a cylindrical body, the body including:
a proximal end including a recessed interior for accepting an input shaft of a gearbox assembly therein and a coupling hole defined laterally through the proximal end and recessed interior;
a distal end defining a threaded recess for detachably coupling with an actuator and a key slot for receiving a key of the actuator; and
a transitional section with tapered or rounded geometry extending between a larger cross-sectional area diameter of the proximal end and a smaller cross-sectional diameter of the distal end; and

a retainer receivable within the coupling hole to operatively couple the torque-limiter coupling to the input shaft of the gearbox assembly, the retainer operable to disengage the torque-limiter coupling from the input shaft in response to a torque applied to the torque limiter-coupling exceeding a predetermined shear limit.

Assignees

• Saudi Arabian Oil Co

Inventors

• Dobaisi Mahdi Y
• Moqdad Hamzah M

Classifications

• Y10T137/1669

  Tensile or sheer pin or bolt · CPC title

• F16D9/10

  having a part movable after disconnection so as to provide reconnection, e.g. advanceable shear pins · CPC title

• F16H35/10

  Arrangements or devices for absorbing overload or preventing damage by overload · CPC title

• F16K31/53

  with toothed gearing · CPC title

• F16K31/535 Primary

  for rotating valves (F16K31/54 takes precedence) · CPC title