| 摘要 |
<p>649,030. Automatic control systems for fluid flow. ENGELHARD,Inc.,C. Aug. 7, 1947, No. 21754. Convention date, May 21, 1946. [Class 38 (iv)] [Also in Groups XXIX and XXXVIII] In a flow meter in which the rate of flow is determined using resistance thermometer 58, 59 connected in the arms of a Wheatstone bridge, the rate of flow of the medium (e.g. gasoline) is controlled by a valve 66 controlled by a reversible motor 65 actuated by the out-of-balance of a control galvanometer 62 in the bridge circuit. As shown in Fig. 5, the medium passes through a main conduit with Venturi or orifice 55, and is partially byepassed through a conduit 56 containing a thermallyinsulated heat-conductive section heated by a coil 57 and carrying a resistance thermometer coil 58. Thermo-constant resistors 60, 61 form the remaining arms of the bridge, while the watts input to the coil 57 is controlled by a variable rheostat 63 and indicated on a wattmeter 64 preferably calibrated to give the rate of flow in lb./hr., gall./hr., &c. The desired rate of flow is pre-set by means of the current regulator 63, the bridge being balanced; a change in rate of flow unbalances the bridge whereupon the control galvanometer 62 operates the motor 65 to increase or decrease the valve opening 66 to adjust the flow to the pre-set rate.</p> |
