GB1271825A - Mass flow-meter apparatus - Google Patents

Abstract

1,271,825. Flowmeters. E. J. DURBIN. Oct.2, 1969, No.48466/69. Heading G1N. In apparatus for measuring the mass flow of a fluid, the fluid is ionized, the ions then imping- ing on a collector, and the displacement of the point of impingement of the ions relative to the position corresponding to no flow conditions is representative of the mass flow. As shown, Fig. 1, the fluid is ionized by a wire 14, the collector 16 being split and the position of the wire under no flow conditions being such that the currents flowing from the two collectors are equal. Under a flow condition U# in the y-axis, the point of impingement of the ions on the collector is shifted to unequalize the currents which are again equalized by shifting the position of the wire by a micrometer to indicate the mass flow. The position of the wire may be adjusted automatically by applying the currents to a reversible motor, via a differential amplifier, the motor also driving the wiper of a potentiometer in a meter circuit which indicates the mass flow, Fig. 5 (not shown). Alternatively, the output of the differential amplifier may adjust a current source to alter a magnetic field or an electrostatic field effecting the point of impingement of the ions on the collector to bring about balance, Figs.7 and 8 (not shown). In a further alternative, Fig.6 (not shown), voltages corresponding to respective collector currents across respective resistors are applied to opposite ends of a galvanometer winding, via respective differential amplifiers, the pointer being connected to the wire whereby the position of the pointer is adjusted to maintain equal currents in the collectors. In Fig. 9, the fluid is ionized by a probe 90, the ions then impinging on a substrate 98 provided with a resistance winding 100 (or coating). The wire 100 is connected in a bridge circuit, the point of impingement of the ions on the substrate forming one corner of the bridge and the wiper 105 of a potentiometer forming the opposite corner of the bridge. Under a flow condition U# in the x-x<SP>1</SP> axis only, the bridge is unbalanced, its output being applied to a reversible motor 126, via a differential amplifier 120, to balance the bridge, the mass flow being indicated on a scale 107. Mass flow in any direction in a plane may be determined by providing two resistance paths at right angles on the substrate and connecting each path in a respective bridge circuit as shown in Fig. 9, Fig. 10 (not shown). In a further embodiment, Fig. 11 (not shown), the fluid is ionized by a disc (200) mounted on a rod coaxially mounted within a cylindrical substrate provided with a resistance winding or coating, which is again connected in a bridge circuit as shown in Fig. 9. The voltage source energizing the ionizing means in any of the embodiments may be adjustable so that the apparatus may be used over a wide range of mass flows.