초록 ▼

A measuring device (1) is provided for measuring the flow rate of a medium (5) flowing through measuring tube (3). The measuring device (1) contains means for generating a constant magnetic field (B) perpendicular to the flow direction (v) of the medium (5) and at least two decoupling regions (7, 7′

A measuring device (1) is provided for measuring the flow rate of a medium (5) flowing through measuring tube (3). The measuring device (1) contains means for generating a constant magnetic field (B) perpendicular to the flow direction (v) of the medium (5) and at least two decoupling regions (7, 7′) which are disposed in a plane (E) perpendicular to the flow direction (v) of the medium (5) on the wall (9) of the measuring tube (3). Each decoupling region (7, 7′) comprises an electrode (13, 13′) which has a non-metal porous layer (11) on the side facing the medium (5) and a measuring unit (19) for detecting a measuring signal. In the measuring device (1), the porous layer (11, 11′) comprises an oxidic and/or non-oxidic ceramic material.

대표청구항 ▼

1. A measuring device (1) for measuring a flow velocity of a medium (5) flowing through a measuring tube (3), the measuring device (1) comprising: means for generating a constant magnetic field (B) perpendicular to a flow direction (v) of the medium (5);at least two decoupling regions (7, 7′) dispos

1. A measuring device (1) for measuring a flow velocity of a medium (5) flowing through a measuring tube (3), the measuring device (1) comprising: means for generating a constant magnetic field (B) perpendicular to a flow direction (v) of the medium (5);at least two decoupling regions (7, 7′) disposed on a wall (9) of the measuring tube (3) in a plane (E) perpendicular to the flow direction (v) of the medium (5), wherein each decoupling region (7, 7′) comprises a respective electrode (13, 13′) having a porous layer (11, 11′) on a side facing the medium; anda measuring unit (19) for detecting a measurement signal, wherein the porous layer (11, 11′) comprises an oxidic and/or non-oxidic ceramic material, completely covers the side of the electrode facing the medium, and electrically insulates the electrode from the medium. 2. The measuring device (1) according to claim 1, wherein the measuring unit (19) has an input resistance of at least 100 gigaohm. 3. The measuring device (1) according to claim 1, wherein the means for generating a magnetic field (B) generates a flow density of at least 0.1 tesla within the measuring tube (5). 4. The measuring device according to claim 1, wherein the means for generating a magnetic field (B) includes a permanent magnet comprising a material selected from the group consisting of rare earths, preferably SmCo and NdFe. 5. The measuring device according to claim 1, wherein the porous layer (11, 11′) comprises a metal oxide. 6. The measuring device according to claim 1, wherein the porous layer (11, 11′) comprises a metal nitride. 7. The measuring device according to claim 1, wherein the porous layer (11, 11′) comprises a metal carbide. 8. The measuring device according to claim 1, wherein the porous layer (11, 11′) comprises plastic. 9. The measuring device according to claim 1, wherein the porous layer (11, 11′) has a pore structure or a fractal structure. 10. The measuring device according to claim 1, wherein a thickness of the porous layer (11, 11′) essentially corresponds to a wall thickness of the measuring tube (3). 11. The measuring device according to claim 1, wherein the porous layer (11, 11′) is applied to the electrode (13, 13′) in situ. 12. The measuring device according to claim 1, wherein the decoupling region (7, 7′) is mounted in the measuring device (1) as a constructional element. 13. The measuring device according to claim 1, wherein the porous layer (11, 11′) is integrated into the wall (9) of the measuring tube (3). 14. The measuring device according to claim 1, wherein the porous layers (11, 11′) are symmetrically arranged, and wherein the measurement signal is decoupled via the two symmetrically arranged porous layers (11, 11′) such that interference signals of both decoupling regions (7, 7′) largely compensate the difference, and wherein the usable signal (U0) is a full-level signal and is the sum of the signals from each respective half amplitude of the two decoupling regions (7, 7′). 15. The measuring device according to claim 1, wherein the porous layer (11, 11′) exhibits low pass characteristics due to a coordinated selection of its specific electric resistance and electric coefficient. 16. A method for measuring flow velocity of a medium (5) flowing in a measuring tube (3), the method comprising: causing the medium (5) to be penetrated by a constant magnetic field (B) perpendicular to a flow direction of the medium (5); anddetecting electric voltage (U0) building up in the medium (5) via an electrode (13, 13′) disposed on a wall (9) of the measuring tube (3) in a plane (E) perpendicular to the flow direction, wherein the electrode (13, 13′) is covered in the flow direction of the medium (5) by a porous layer (11, 11′) which comprises an oxide and/or non-oxidic ceramic material, completely covers a side of the electrode facing the medium, and electrically insulates the electrode from the medium, andwherein a measurement signal is supplied to a measuring unit (19) having an input resistance of at least 100 gigaohm.