GB963965A - Improvements in or relating to pressure transducers - Google Patents

Abstract

963,965. Measuring pressure electrically. INTERNATIONAL RESISTANCE CO. Feb. 19, 1963, No. 6655/63. Heading G1N. A transducer for measuring fluid pressure comprises a differential transformer whose core is subjected in part to the test pressure, whereby the permeability of their part is changed, to produce an output voltage from normally balanced winding. As shown (Fig. 1), two primary windings 28, 30 and two secondary windings 32, 34 are symmetrically wound and core 12 having equal central passages 14, 16 separated by a wall 18. The primary windings are connected in series aiding, and the secondary windings in series opposition, or vice versa, whereby the resultant output voltage from the secondary windings is zero. A fluid pressure to be measured is presented to the passage 14 so that the part core surrounding it is stressed, altering its permeability and producing an output signal from the secondary windings indicative of the magnitude of the test pressure relative to the pressure in passage 16. Annular grooves 24, 26 in the core 12 round the passages 14, 16 respectively improve the linearity of the relationship between output voltage and pressure change. A reference pressure may be applied to passage 16. In another embodiment (Fig. 4), the primary winding 60<1> and secondary winding 62<1>, 64<1> are wound on a bobbin 52<1>, fixed to the core 44<1> by an annular rib 52a, and covered by a sleeve 66<1> of magnetic material. A nut 68 is screwed on to the core at each end, with spring fingers gripping the sleeve 66<1>, so that rotation of a nut stresses that part of the core to produce zero output from the transducer at a predetermined pressure difference.