基本信息
摘要：1,183,503. Measuring fluid-flow electrically. GEORGE KENT Ltd. June 11, 1968 [June 16, 1967], No.27979/67. Heading G1N . Rotation of a turbine flowmeter, provided with a magnetized disc on its shaft or with magnetized inserts in the turbine blades, is sensed by a semi-conductor detector, e.g. a Hall plate or a magneto-resistive element. As shown, the turbine may be axially aligned with the fluid-flow direction, Fig. 2 and Figs. 1, 3, 4 (not shown), or with its axis on right angles to the flow, Fig.6 and Figs.5, 7, 8 (not shown), and is provided either with a diametically magnetized disc 18, Fig. 2, on the turbine shaft or with magnetized inserts 68 in the blades Fig. 6. One or more Hall plates 24 or magneto-resistive elements are equally spaced round the disc or turbine blades. The Hall plate 24 may be D.C. energized, Fig. 9 (not shown), and its output rectified or it may be A.C. energized, Fig. 10 (not shown), and its output demodulated. Alternatively it may be connected in the feedback circuit of an amplifier, Fig. 11 (not shown), provided with a C.R. circuit, so that the amplifier produces an A.C. output, whose frequency is determined by that of the C.R. circuit, only when the Hall plate emits a positive pulse. In all the above examples the final pulsed output is shaped to provide squarewave pulses which are fed to a counter to provide an indication of flow-rate. If a single magneto-resistive element is employed, it may be connected together with a fixed resistor across an D.C. or A. C. supply, Figs.12, 13 (not shown), the output being rectified or demodulated and shaped as required. For temperature compensation the fixed resistor may be replaced by a second magneto-resistive element, Fig.16 (not shown), which is screened from the magnetic field. If a plurality of magnetoresistive elements are used, Fig.17 (not shown), they may be connected in parallel in series with the fixed resistors. Alternatively, for two magneto-resistive elements positioned 180 degrees or 90 degrees apart, they may be connected in opposite arms of a Wheatstone bridge, Figs.14, 15 (not shown). As before, in each case the pulsed output is shaped to form a squarewave pulse.
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