Load measurement method and device
A device for axial load measurement on a mechanical control device ( 10 ) having rotating shaft ( 30 ) maybe used to derive a torque measurement. A mechanical control device ( 10 ) may comprise a valve actuator for fluid flow control devices. The load measurement device may include a beam ( 65 a ) operatively connected to a rotatable shaft and configured to deform under axial displacement of the shaft. A sensor ( 80 ) maybe coupled with the at least one beam ( 65 a ) and configured to produce an output signal related to the axial displacement of the shaft. The beam may be retained between two bearings ( 74 ) of the rotatable shaft at a first end, and fixed to the housing ( 120 ) of the mechanical control device at a second end. The first end of the beam ( 65 a ) may displace axially with the rotatable shaft. The beam ( 65 a ) may comprise a discrete segment of a uniform width and thickness.
1. A mechanical control device comprising:
a shaft configured for rotation;
at least one beam operatively connected to the shaft and configured to deflect under axial displacement of the shaft; and
a sensor coupled with the at least one beam and configured to produce an output signal proportional to the axial displacement of the shaft.
2. The mechanical control device of claim 1 , wherein the at least one beam has a substantially uniform cross-section through an entire length of the at least one beam.
3. The mechanical control device of claim 1 , further comprising bearings for translating the axial displacement of the shaft to the at least one beam.
4. The mechanical control device of claim 3 , wherein the bearings comprise an annular bearing disposed about the shaft and contacting a first surface of the at least one beam, and another annular bearing disposed about the shaft and contacting a second, opposing surface of the at least one beam.
5. The mechanical control device of claim 1 , further comprising:
an annular body encircling the shaft, the at least one beam extending outwardly from the shaft toward the annular body, and a portion of the at least one beam fixed to the annular body; and
a housing fixed to the annular body, the housing configured for axial movement of the shaft relative to the housing.
6. The mechanical control device of claim 1 , wherein the output signal relates any misalignment of the shaft.
7. The mechanical control device of claim 1 , wherein the sensor comprises at least one strain gauge.
8. The mechanical control device of claim 1 , wherein the at least one beam comprises a metal.
9. The mechanical control device of claim 1 , wherein the at least one beam comprises an array of discrete beams arranged in a spoke formation about the shaft.
10. A load sensor for measuring the axial load on a rotatable shaft, comprising:
at least one deflection beam having a first end portion thereof retained between two bearings, each bearing operatively connected to the rotatable shaft for translating axial movement of the shaft to a deflection of the at least one deflection beam; and
a sensor operatively connected to the at least one deflection beam and configured for measuring the deflection of the at least one deflection beam.
11. The load sensor of claim 10 , wherein the sensor comprises at least one strain gauge.
12. The load sensor of claim 10 , wherein the at least one deflection beam comprises a discrete segment of a substantially uniform width and thickness therethrough.
13. The load sensor of claim 10 , wherein the at least one deflection beam comprises a metal.
14. The load sensor of claim 10 , wherein the at least one deflection beam includes a second end portion fixed to a housing for the load sensor, the housing configured to enable relative axial displacement of the rotating shaft with respect thereto.
15. The load sensor of claim 10 , further comprising:
an annular body encircling the rotatable shaft, the at least one deflection beam comprising an array of deflection beams arranged in a spoke formation about the shaft, extending outwardly from the shaft toward the annular body, wherein a second portion of each deflection beam is fixed to the annular body; and
a housing fixed to the annular body, the shaft configured for axial movement relative to the housing.
16. The load sensor of claim 15 , wherein each deflection beam of the array of deflection beams includes a sensor operatively connected thereto, each sensor in communication with an output device.
17. A mechanical control device comprising:
a shaft configured for rotation;
an annular plate operatively connected to the shaft and configured to deflect under axial displacement of the shaft; and
a sensor coupled with the annular plate and configured to produce an output signal proportional to the axial displacement of the shaft.
18. The mechanical control device of claim 17 , further comprising:
a central passageway through the annular plate; and
at least one circumferentially positioned aperture through the annular plate.
19. The mechanical control device of claim 18 , wherein the sensor is positioned on the annular plate radially between the central passageway and the at least one circumferentially positioned aperture.