| 摘要 |
1529587 Measuring pressure FISCHER & PORTER CO 25 March 1976 [21 May 1975] 12137/76 Heading G1N A differential pressure transducer includes meter body M having force beam 10 extending, below its pivot, into a chamber of body M and being outside body M above its pivot F, diaphragm means 11A, 12A, 14 responsive to the difference of high and low pressures to produce a force applied by means 14 to the lower end of beam 10, at least one restraining spring, as 18, 19, attached between the upper part of beam 10 and a fixed point, and, attached to the beam top, detector 20 producing an electrical signal corresponding to beam motion. In the detector embodiment of Fig. 2, magnetostrictive wire 22 is attached to beam 10 and meter body 23. Arcuate sections 22A and 22B are connected to the primary of transformer 24 and the secondary of transformer 25 respectively. The transformers are connected by feedback amplifier 28, so that the switching on pulse causes twisting of section 22B due to interaction with the field of magnet 27. This results in the system oscillating at a frequency varied by the motion of beam 10 to cause convecter F/V to give a D.C. voltage output. A pair of such magnetostrictive wires may be attached on either side of beam 10, each having an associated amplifier connected to a common mixer giveing the beat frequency resulting from beam movement. Other embodiments use (a) a differential transformer with its armature attached to beam 10, or (b) a variable reluctance device with its armature linked to beam 10 to vary the inductance of a coil so as to alter the amplitude of an A.C. voltage applied to an amplifier, the output of which is rectified, or (c) a variable capacitor, or (d) a strain gauge which may be mounted on the sealing diaphragm 15, which acts as the pivot, or on a range spring extending between a tap plate fixed to the top of beam 10 and a bottom plate fixed to body M. There may be a second range spring diametrically opposite the first. |
