Abstract: A magnetic field generating device for an electromagnetic flowmeter of the residual magnetization type which comprises a pair of first yokes having one of their end faces disposed opposite to each other on both sides of a magnetic gap including a fluid conduit of a non-magnetic material, a core disposed between the other end faces of the first yokes, a coil wound around the core, and at least one second yoke in direct contact with at least one of the first yokes and in direct contact with the associated end face of the core. The second yokes are made of a magnetic material having low electrical conductivity and high permeability. The core has an axial length shorter than that of the coil.

Abstract: An electromagnetic flowmeter includes a cylindrical flow path, an even number of magnetic poles disposed on the periphery of the cylindrical flow path by equally dividing the circumference thereof, a plurality of cores having one ends respectively being in contact with the even number of magnetic poles and extending outwardly radially with respect to the cylindrical flow path, a plurality of coils respectively wound about the cores for exciting the cores so that respective adjacent cores exhibit opposite polarities to each other, an outer yoke having a ring shape for connecting the other ends of the cores to form a magnetic circuit, and a plurality of electrodes disposed respectively at intermediate points of respective adjacent magnetic poles and having one ends being in contact with a fluid in the cylindrical fluid path, wherein the even number of magnetic poles are corresponding in number to the cores, to the coils, and to the electrodes, and the number is equal to four or larger.

Abstract: A radial field electromagnetic flow meter includes a radial magnetic flux generator, a magnetic device surrounded by a fluid passage for fluid to be measured and electrically insulated magnetic poles separately positioned on a center line of the fluid passage, a tubular part surrounding a range including the mutually opposite magnetic poles of the magnet device through the fluid passage, and ribs radially crossing portions of the fluid passage between one end of the magnet device and a portion of the tubular part surrounding the one end of the magnet device, respective surfaces of the tubular portions and the ribs which come into contact with the fluid to be measured being electrically insulated, whereby the magnetic reluctance of the magnetic circuit of the magnet device can be reduced and the sensitivity of the electromagnetic flow meter can be improved.

Abstract: An electromagnetic flowmeter has identical exciting coils coupled to portions which exhibit residual magnetism. A control circuit delivers short durations of current to each coil such that the current polarity in each coil determines the polarity of the magnetic flux across the conduit due to each residual magnetic portion. Four states of magnetic flux are repeatedly produced, zero, of one polarity, zero and of the other polarity. Flow note is determined by the difference between sampled voltages in a zero state and a directly succeeding state to eliminate noise components.

Abstract: An electromagnetic flow meter with less power consumption in which an instantaneous pulsate current with alternately changing polarity at given intervals is fed into an exciting coil, and a velocity of flow of fluid is calculated by using a voltage produced between electrodes in accordance with a residual magnetic flux of a magnetic circuit and a flow velocity of the fluid when no exciting current flows.

Abstract: A meter for a liquid, such as water, comprises a measuring circuit (55) for measuring those measuring periods in response to a detection pulse sequence resulting from rotation of a body (30) rotated by the liquid, each of which may be defined either by a period of one complete rotation of the body or a predetermined interval, such as six seconds. The circuit produces measurement signals representative of individual amounts of the liquid used with the individual amounts accompanied by detection errors resulting from a variable flow rate of the liquid. A totalizing circuit (61), which may comprise an ROM or consist of a microcomputer, totalizes the individual amounts with the detection errors reduced.