Magnetically inductive flow rate sensor

Abstract

The invention relates to a flow rate sensor (10), which is designed to measure an electrically conductive fluid that flows in pipework. Said sensor comprises a measuring tube (11), which can be inserted into the run of pipework to conduct the fluid, said measuring tube (11) being electrically non-conductive on at least one inner face that comes into contact with the fluid, an electrode assembly (14) comprising at least two measuring electrodes that are located on the measuring tube and tap an electric voltage that is induced in the fluid, in addition to a magnetic field system that is also located on the measuring tube (11). The magnetic field system of the inventive flow rate sensor is equipped with at least two saddle-shaped field coils (15, 16), for generating a magnetic field that penetrates the fluid when operational, a respective ferromagnetic pole shoe (21, 22) for the field coils, for conducting the magnetic field towards the fluid and at least one ferromagnetic feedback element running around the measuring tube upstream of the two field coils and at least one ferromagnetic feedback element (23, 24) running around the measuring tube downstream of the two field coils, for conducting the magnetic field around said measuring tube. The pole shoes are magnetically coupled to the feedback elements by means of respective ferromagnetic coupling elements (17, 18, 19, 20). Each of said coupling elements, which are preferably configured in a standard manner, comprises at least one substantially gully-type cover segment (17a, 18a, 19a, 20a), which receives a first winding section of the respective field coil, said section essentially lying on a first circumferential segment of the measuring tube, or a second winding section (15a, 15b) of the respective field coil, said section essentially lying on a second circumferential segment of the measuring tube.

Description

technical field [0001] The invention relates to a magnetic induction flow sensor comprising a measuring tube through which a conductive fluid to be measured flows and a saddle coil for generating a magnetic field cutting the fluid. Background technique [0002] For purposes of describing the present invention, "flow sensor" refers to the substantially mechanical portion of a magnetic inductive flow meter without coil current generating circuitry. Such magnetic inductive flow sensors are known to use Faraday's law of induction to generate a measurement voltage. [0003] Various embodiments of magnetically inductive flow sensors for measuring electrically conductive fluids flowing in pipelines are disclosed in DE-A 20 40 682, US-A 46 41 537, US-A 47 74 844 or WO-A91 / 11731. Each flow sensor shown includes: [0004] - measuring tubes, installed in pipes for conducting fluids, the measuring tubes being electrically non-conductive at least on the inner surface in contact with th...

AI Technical Summary

Problems solved by technology

Another possibility to reduce this dependence of the measurement sensitivity on the installation conditions is to make the measuring tube (at least its non-conductive part) axially long enough and / or as shown in US-A 55 40 103, Use of cylindrical field coils, resulting in relatively short field coils and pole pieces in the axial direction, albeit at the expense of operable flow range

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