Multiple channel RVDT with dual load path and fail-safe mechanism

1. An angular displacement sensor, comprising a primary gear coupled to an input shaft, a plurality of secondary gears arranged around and coupled to the primary gear, and a plurality of displacement sensors integrally coupled with the secondary gears, wherein each secondary gear is coupled to a shaft of one of the angular displacement sensors in a manner that permits breakaway in case of a jam, such that the remaining angular displacement sensors continue sensing if one of the secondary gears breaks away from the corresponding shaft.

2. A sensor as in claim 1 , further comprising a shear notch formed on the input shaft.

3. The angular displacement sensor of claim 1 wherein the secondary gears are coupled to the shafts of the angular displacement sensors by a controlled penetration laser weld, and wherein the laser weld breaks if the secondary gear becomes jammed.

4. The angular displacement sensor of claim 1 comprising at least four secondary gears arranged around and coupled to the primary gear, and at least four displacement sensors integrally coupled with the secondary gears.

5. A displacement sensor, comprising:

an input shaft adapted to have one end thereof coupled to a load of interest;

a main gear affixed to another end of the input shaft;

a plurality of secondary gears arranged to mesh with the main gear and each affixed to a of displacement sensor; and

a cover having a top portion and cylindrical portion that at least partially surrounds the main gear and secondary gears, wherein the top portion includes a plurality of cylinders integral therewith for respectively receiving and containing the plurality of secondary gears, such that if a secondary gear comes loose it will be contained.

6. A sensor as in claim 5 , further comprising a shear notch formed on the input shaft.

7. A sensor as in claim 5 , wherein each secondary gear is coupled to a sensor in a manner that permits breakaway in the event of a jam.

8. A sensor as in claim 5 , further comprising:

a main cylindrical housing, wherein the shaft housing is formed coaxially inside the main housing;

a cover plate enclosing one end of the main housing and having a central opening and a plurality of secondary openings distributed around the central opening, wherein the shaft housing is affixed proximate to the central opening and the input shaft extends through the central opening, wherein the main gear is affixed to the input shaft outside of the main housing, wherein the angular displacement sensors are affixed in corresponding secondary openings with the sensor shafts extending through the openings, wherein the secondary gears are affixed to corresponding sensor shafts outside the main housing.

9. A sensor as in claim 8 , wherein each secondary gear is fixed to its corresponding sensor shaft by a controlled penetration laser weld.

10. A sensor as in claim 5 , further comprising a self-null mechanism coupled to the main gear, wherein the self null mechanism comprises a null plate, a torsion spring and a retainer plate.

11. A method of sensing angular displacement, the method comprising the steps of:

(a) providing an angular displacement sensor that includes

an input shaft having one end thereof coupled to a load of interest;

a shaft housing including bearings supporting the input shaft;

a main gear affixed to another end of the input shaft;

a plurality of secondary gears mounted so as to mesh with the main gear; and

a plurality of angular displacement sensors each having a shaft wherein each of the secondary gears is affixed to the corresponding shaft;

(b) sensing angular displacement using all of the angular displacement sensors;

(c) jamming one of the secondary gears;

(d) breaking the jammed secondary gear away from the corresponding shaft such that the secondary gear is no longer coupled with the shaft; and

(e) sensing angular displacement with the angular displacement sensors that are still coupled to their corresponding shafts.