Jam-Tolerant Rotary Control Motor for Hydraulic Actuator Valve

Abstract

According to one embodiment, a linear control motor includes a first permanent magnet, a coil, a shaft, a first non-magnetic material, and a joint coupled between the shaft and a spool operable to convert rotations of the shaft into axial movements of the spool. The first non-magnetic material is disposed between at least one of the movable components and at least one of the static components and operable to prevent physical contact between at least one of the movable components and at least one of the static components.

What is claimed is: 
     
         1 . A control motor, comprising:
 a first permanent magnet operable to generate a first magnetic flux path;   a coil operable to selectively add magnetic flux to and subtract magnetic flux from the magnetic flux flowing in the first magnetic flux path, wherein one of the first permanent magnet and the coil comprises a movable component and the other one of the first permanent magnet and the coil comprises a static component, the movable component operable to rotate relative to the static component in response to variations in flux flowing in the first magnetic flux path;   an output shaft coupled to the movable component such that the output shaft is operable to rotate in response to variations in flux flowing in the first magnetic flux path;   a first non-magnetic material disposed between the movable component and the static component and operable to prevent physical contact between the movable component and the static component; and   a joint coupled between the output shaft and a second shaft and operable to convert rotations of the output shaft into axial movements of a second shaft.   
     
     
         2 . The control motor of  claim 1 , wherein the first non-magnetic material is at least partially movable relative to both the movable component and the static component. 
     
     
         3 . The control motor of  claim 1 , wherein a spring couples the first non-magnetic material to the movable component. 
     
     
         4 . The control motor of  claim 1 , wherein a spring couples the first non-magnetic material to the static component. 
     
     
         5 . The control motor of  claim 1 , the joint comprising:
 a pin comprising a detent portion;   a detent member adjacent to the pin and sized to fit at least partially within the detent portion;   a spring configured to apply a force against the detent member towards the pin, the detent member positioned between the spring and the pin; and   a substantially spherical member adjacent the pin and partially disposed within a recess of the second shaft, the substantially spherical member operable to reposition the pin such that the detent portion is positioned to at least partially receive the detent member.   
     
     
         6 . The control motor of  claim 1 , further comprising:
 a bearing separating the output shaft from the static component; and   a break wire adjacent to the bearing, the break wire configured to sever in response to a failure of the bearing.   
     
     
         7 . The control motor of  claim 1 , further comprising:
 a metal tube positioned around the output shaft;   an electrical transmission line connected to the metal tube;   a bearing separating the metal tube from the static component; and   a jam member disposed between the bearing and the metal tube, the jam member configured to deform the metal tube in response to a failure of the bearing such that the deformation closes an electrical circuit.   
     
     
         8 . The control motor of  claim 1 , further comprising:
 a spring-biased detent pin connected to the output shaft;   an electrical transmission line connected to the spring-biased detent pin;   a bearing separating the output shaft from the static component; and   a detent member disposed between the bearing and the output shaft, the detent member configured to allow movement of the spring-biased detent pin in response to a failure of the bearing such that the movement closes an electrical circuit.   
     
     
         9 . The control motor of  claim 1 , wherein the permanent magnet is a movable component operable to rotate relative to the static component. 
     
     
         10 . The control motor of  claim 1 , wherein the movable component is operable to rotate within the static component. 
     
     
         11 . A method of actuating a device, comprising:
 generating a first magnetic flux path;   providing a static magnetic component at least partially disposed in the first magnetic flux path;   providing a movable magnetic component at least partially disposed in the first magnetic flux path and coupled to an output shaft, the movable magnetic component operable to rotate relative to the static magnetic component in response to variations in flux flowing in the first magnetic flux path;   preventing physical contact between the movable magnetic component and the static magnetic component;   rotating the output shaft by varying the flux flowing in the first magnetic flux path; and   converting rotations of the output shaft into axial movements of a second shaft.   
     
     
         12 . The method of  claim 11 , wherein preventing physical contact comprises providing a first non-magnetic material between the movable magnetic component and the static magnetic component. 
     
     
         13 . The method of  claim 12 , wherein preventing physical contact further comprises allowing restricted movement of the first non-magnetic material relative to both the movable magnetic component and the static magnetic component. 
     
     
         14 . The method of  claim 11 , further comprising:
 providing a bearing separating the output shaft from the static magnetic component;   providing a break wire adjacent to the bearing; and   detecting severing of the break wire in response to a failure of the bearing.   
     
     
         15 . The method of  claim 11 , further comprising:
 providing a metal tube positioned around the output shaft and an electrical transmission line connected to the metal tube;   providing a bearing separating the metal tube from the static magnetic component;   providing a jam member adjacent to the bearing, the jam member configured to deform the metal tube in response to a failure of the bearing such that the deformation closes an electrical circuit; and   detecting closure of the electrical circuit in response to a failure of the bearing.   
     
     
         16 . The method of  claim 11 , further comprising:
 providing a spring-biased detent pin connected to the output shaft and an electrical transmission line connected to the spring-biased detent pin;   providing a bearing separating the output shaft from the static magnetic component;   providing a detent member adjacent to the bearing, the detent member configured to allow movement of the spring-biased detent pin in response to a failure of the bearing such that the movement closes an electrical circuit; and   detecting closure of the electrical circuit in response to a failure of the bearing.   
     
     
         17 . The method of  claim 11 , wherein the movable magnetic component comprises a permanent magnet operable to generate the first magnetic flux path. 
     
     
         18 . The method of  claim 11 , wherein the movable magnetic component is operable to rotate within the static magnetic component.