GB579451A - Improvements in or relating to apparatus for indicating or measuring the thrust of a shaft - Google Patents

Abstract

579,451. Electric indicating systems. SHEPHERD, G. R. (Westinghouse Electric International Co.). April 13, 1944, No. 6854. [Class 40 (i)] [Also in Groups XIX and XXXVI] Apparatus for indicating or measuring the thrust of a shaft comprises a rotor assembly secured to said shaft, a stationary member, coil means secured to said stationary member for inducing a flow of magnetic flux in said stationary member and said rotor assembly, and a source of alternating current for energizing said coil means, characterized by means included in the rotor assembly responsive to the axial deformation of the shaft for altering the value of the magnetic flux thereby changing the value of a voltage in the electrical coil means by an amount indicative of the thrust of said shaft. The rotor assembly 3, Fig. 1, comprises a pair of axially displaced rings 7 and 9 secured to rotate with the shaft 1 on non- magnetic bushings 11 and 13 and having inwardly formed flange portions in close proximity forming air-gaps 14. The stationary member 5 has annular rings 17 and 19 forming two circular air gaps 21 and 23 with the peripheries of the rings 7 and 9 respectively. A coil 25 is secured within an annular recess of the stationary member 5 and is connected as one leg in a conventional impedance bridge circuit 27 which is supplied from a suitable source of alternating current and is adjusted to a balanced condition when the shaft is subject to zero thrust so no voltage will appear across the terminals of an indicating meter 29. When the coil 25 is energized a magnetic flux will flow in the path shown across the air gaps 14, 21 and 23, if the shaft 1 is not subjected to load this flux will remain at a constant value. If however there is axial deformation due to thrust the air gap 14 will be altered, the magnetic flux will change and so correspondingly change the voltage in the coil 25 by an amount indicative of the thrust on the shaft, this amount being indicated on the meter 29. The confronting faces of the rings 7 and 9 are provided with radial grooves 15 to compensate for any variations due to torque on the shaft 1. In another embodiment, Fig. 2, not shown, two coils are used and the arrangement of the air gaps is slightly different. Fig. 5 shows the invention applied to a shaft of large diameter, the rotor assembly being inside the shaft in this case.