| 摘要 |
1277403 Measuring fluid density electrically SOLARTRON ELECTRONIC GROUP Ltd 25 Aug 1969 [30 Aug 1968] 41645/68 Heading G1N [Also in Divisions G5 and H4] Apparatus for measuring the density of a fluid comprises a hollow, thin-walled ferromagnetic cylinder located in the fluid with its lower edge clamped, and means for causing the wall to vibrate radially like a bell at its natural resonant frequency, which is indicative of the fluid density. As shown Fig. 1 the cylinder 11 has a stepped flange 19, 20 at its lower end which is clamped to a base member 12, in turn clamped to a base flange 15. Inside the cylinder are drive coil 16 and pick-up coil 17 embedded in perpendicular relationship in a block 27 of epoxy resin and supported on base members 12 so that the coils are located at antinodal positions of the cylinder vibrations. The cylinder 11 has a thickened ring 26 at its upper end to define a nodal position and is surrounded by a magnetic shield 25. The small overlap between flanged parts 19, 20 is basically flexible and forms a circular hinge for the transducer assembly. The test fluid enters via inlet 23, flows over both sides of the wall 18 and exits via outlet 24. The coils 16, 17 are connected via a plug and socket arrangement 29 to a transistor amplifier which maintains oscillation at the natural resonant frequency, measured and indicated on external apparatus. In a modification Fig. 2 (not shown), an inlet and outlet filter are assembled in the fluid-flow path. In another embodiment Fig.5 (not shown) the upper end of the cylinder 11 is closed by a solid plate, enabling the transducer to measure fluid pressure or pressure difference. |
