Electromagnetic flowmeter

Claim 2

An electromagnetic flowmeter comprising: A a flow tube having a pair of diametrically-opposed electrodes mounted thereon, and B an electromagnet assembly for establishing a magnetic field in the tube which is intercepted by the fluid to be metered to induce a signal in said electrodes which depends on flow rate, X being the diametrical axis connecting the electrodes, Z being the longitudinal axis of the tube and Y being a transverse axis mutually perpendicular to axes X and Z, said assembly being constituted by two pairs of electromagnets, each pair being disposed at diametrically-opposed positions on the tube exterior to produce a magnetic field whose lines of flux are substantially parallel to the Y-axis, the two pairs being disposed on either side of a plane defined by the X and Y axes to create a combined magnetic field having a magnetic flux component whose magnitude in said plane is relatively weak and increases as one moves in either direction along said Z-axis and then decreases, thereby defining a flux magnitude pattern having a saddle-shaped formation.

Claim 3

An electromagnetic flowmeter for measuring the flow rate of a fluid in a manner rendering the meter substantially immune to disturbances in the flow profile of the fluid; said flowmeter comprising: A a flow tube through which the fluid to be metered is conducted, said tube having a diameter D, a longitudinal flow axis Z, and a transverse axis Y intersecting axis Z; B a pair of electrodes mounted at opposed positions on said tube on a diametrical axis X which is mutually perpendicular to said Y and Z axes, the X, Y and Z axes intersecting at a point of origin; and C an electromagnet assembly for generating a magnetic field in the region of the electrodes whose lines of flux are substantially parallel to said Y axis and perpendicular to an X-Z plane which includes the X and Z axes, said magnetic field having a magnetic flux component in the direction of the Y axis which in a curve representing the magnitude of this component with respect to a base line extending along the Z axis has a double-humped saddle-shaped formation whose midpoint trough lies in an electrode plane which includes the X and Y axes, the magnitude of this component increasing in either direction on the Z axis from said point of origin to a maximum value and then decreasing to define the humps of the saddle-shaped formation, the magnitude of this component decreasing in either direction on the X axis from said point of origin.

Claim 4

An electromagnetic flowmeter for measuring the flow rate of a fluid in a manner rendering the meter substantially immune to disturbances in the flow profile of the fluid; said flowmeter comprising: A a flow tube through which the fluid to be metered is conducted, said tube having a diameter D, a longitudinal flow axis Z, and a transverse axis Y intersecting axis Z; B a pair of electrodes mounted at opposed positions on said tube on a diametrical axis X which is mutually perpendicular to said Y and Z axes, the X, Y and Z axes intersecting at a point of origin; and C an electromagnet assembly for generating a magnetic field in the region of the electrodes whose lines of flux are substantially parallel to said Y axis and perpendicular to an X-Z plane which includes the X and Z axes, said magnetic field having a magnetic flux component in the direction of the Y axis which in a curve representing the magnitude of this component with respect to a base line extending along the Z axis has a double-humped saddle-shaped formation whose midpoint trough lies in an electrode plane which includes the X and Y axes, the magnitude of this component increasing in either direction on the Z axis from said point of origin to a maximum value and then decreasing to define the humps of the saddle-shaped formation, the magnitude of this component decreasing in either direction on the X axis from said point of origin.

Claim 5

An electromagnetic flowmeter as set forth in claim 2, wherein said electromagnet assembly includes a pair of pole faces located on either side of said electrode plane, the center lines of the pole faces being substantially parallel to the Y axis.

Claim 6

An electromagnetic flowmeter as set forth in claim 3, in which the faces of the pole pieces are curved to conform to the circumference of the flow tube.

Claim 7

An electromagnetic flowmeter as set forth in claim 4, wherein the pole pieces each have a width dimension in the direction of the Z axis which is between about 0.15 D and 0.8 D.

Claim 8

An electromagnetic flowmeter as set forth in claim 5, wherein the faces of the pole pieces have an included angle of between about 90° and 150°.