Fluid flow measuring device and armature comprising a fluid flow measuring device

1. An armature, comprising:

a housing having an inlet for receiving a fluid flow, an outlet and a flow channel extending between the inlet and the outlet;

a fluid flow measuring device comprising:

a rotatable magnetic element positioned in the flow channel and thereby within the fluid flow, wherein the rotation of the rotatable magnetic element depends on the fluid flow through the flow channel, and wherein the rotatable magnetic element has a positive pole and a negative pole and generates a magnetic field;

at least one sensing coil pair each having a first sensing coil and a second sensing coil;

wherein the respective sensing coils of each of the at least one sensing coil pair are arranged in such a way that the magnetic field generated by the fluid flow dependent rotation of the rotatable magnetic element has a first phase in the region of the respective first sensing coil and a second phase in the region of the respective second sensing coil, wherein said first phase and second phase differ from each other by more than 135 degrees but less than 225 degrees; and

wherein the respective first and second sensing coils of each of the at least one sensing coil pairs are connected in series to provide a subtraction of their signals thereby reducing noise caused by a disturbing magnetic field.

2. The armature of claim 1 , wherein:

the respective first sensing coil of each of the at least one sensing coil pairs is positioned around a respective first ferromagnetic core, wherein the first ferromagnetic core guides the magnetic field generated by the rotatable magnetic element to the first sensing coil;

the respective second sensing coil of each of the at least one sensing coil pairs is positioned around a respective second ferromagnetic core, wherein the second ferromagnetic core guides the magnetic field generated by the rotatable magnetic element to the second sensing coil; and

wherein the respective ferromagnetic cores are positioned within recesses of the housing outside of the flow channel and thereby outside the fluid flow.

3. The armature of claim 1 , wherein the armature is one of a water treatment armature, a back flow preventer armature, a pressure regulator armature, or a control valve armature.

4. The armature of claim 1 , wherein said first phase and second phase of the respective first and second coils of each of the at least one sensing coil pairs differ from each other by an angle that is within the range of 180°±5°.

5. A fluid flow measuring device, comprising:

a rotatable magnetic element positioned in a fluid flow, wherein the rotation of the rotatable magnetic element depends on the fluid flow, and wherein the rotatable magnetic element has a positive pole and a negative pole and generates a magnetic field;

at least one sensing coil pair each having a first sensing coil and a second sensing coil;

wherein the respective sensing coils of each of the at least one sensing coil pairs are arranged in such a way that the magnetic field generated by the fluid flow dependent rotation of the rotatable magnetic element has a first phase in the region of the respective first sensing coil and a second phase in the region of the respective second sensing coil, wherein said first phase and second phase differ from each other;

wherein, for each of the at least one sensing coil pairs, the first sensing coil is positioned at a first circumferential position relative to the rotatable magnetic element and the second sensing coil is positioned at a second circumferential position relative to the rotatable magnetic element, wherein an angle between the first circumferential position and the second circumferential position is in the range of 180°±5°; and

wherein for each of the at least one sensing coil pairs, the first sensing coil and the second sensing coil are connected in series to provide a subtraction of their signals thereby reducing noise caused by a disturbing magnetic field.

6. The fluid flow measuring device of claim 5 , wherein:

the respective first sensing coil of each of the at least one sensing coil pairs is positioned around a respective first ferromagnetic core, wherein the first ferromagnetic core guides the magnetic field generated by the rotatable magnetic element to the respective first sensing coil; and

the respective second sensing coil of each of the at least one sensing coil pairs is positioned around a respective second ferromagnetic core, wherein the respective second ferromagnetic core guides the magnetic field generated by the rotatable magnetic element to the respective second sensing coil.

7. The fluid flow measuring device of claim 6 , wherein:

the respective first sensing coil of each of the at least one sensing coil pairs is wound around the respective first ferromagnetic core, wherein a longitudinal axis of the respective first ferromagnetic core, which corresponds to a winding axis of the respective first sensing coil around the respective first ferromagnetic core, runs parallel to a rotation axis of the rotatable magnetic element; and

the respective second sensing coil of each of the at least one sensing coil pairs is wound around the respective second ferromagnetic core, wherein a longitudinal axis of the respective second ferromagnetic core, which corresponds to the winding axis of the respective second sensing coil around the respective second ferromagnetic core, runs parallel to the rotation axis of the rotatable magnetic element and parallel to the longitudinal axis of the respective first ferromagnetic core.

8. The fluid flow measuring device of one of claim 6 , wherein:

a longitudinal axis of the first ferromagnetic core is spaced a first distance (a) from a rotation axis of the rotatable magnetic element; and

a longitudinal axis of the second ferromagnetic core is spaced a second distance (b) from the rotation axis of the rotatable magnetic element.

9. The fluid flow measuring device of claim 8 , wherein said first distance (a) and said second distance (b) have a ratio a/b that is in the range of 0.95≤a/b≤1.05.

10. The fluid flow measuring device of claim 5 , wherein:

the respective first sensing coil of each of the at least one sensing coil pairs is an air coil, wherein a winding axis of the respective first sensing coil runs perpendicular to a rotation axis of the rotatable magnetic element; and

the respective second sensing coil of each of the at least one sensing coil pairs is an air coil, wherein a winding axis of the respective second sensing coil runs perpendicular to the rotation axis of the rotatable magnetic element.

11. The fluid flow measuring device of one of claim 10 , wherein:

the respective first sensing coil is spaced a first distance (a) from the rotation axis of the rotatable magnetic element; and

the respective second sensing coil is spaced a second distance (b) from the rotation axis of the rotatable magnetic element.

12. The fluid flow measuring device of claim 11 , wherein the first distance (a) and the second distance (b) have a ratio a/b that is in the range of 0.95≤a/b≤1.05.

13. The fluid flow measuring device of claim 5 , wherein:

the respective first sensing coil of each of the at least one sensing coil pairs is wound around a respective first ferromagnetic core, wherein the respective first ferromagnetic core guides the magnetic field generated by the rotatable magnetic element to the respective first sensing coil, and wherein a longitudinal axis of the respective first ferromagnetic core runs perpendicular to a rotation axis of the rotatable magnetic element; and

the respective second sensing coil of each of the at least one sensing coil pairs is wound around a respective second ferromagnetic core, wherein the respective second ferromagnetic core guides the magnetic field generated by the rotatable magnetic element to the respective second sensing coil, and wherein a longitudinal axis of the respective second ferromagnetic core runs perpendicular to the rotation axis of the rotatable magnetic element and parallel to the longitudinal axis of the respective first ferromagnetic core.

14. The armature of claim 5 , wherein the rotatable magnetic element comprises a plurality of positive and negative pole pairs.

15. The armature of claim 14 , wherein the rotatable magnetic element comprises a paddle wheel with a plurality of paddle wheel pairs, wherein each paddle wheel pair forms one of the plurality of positive and negative pole pairs.

16. A fluid flow measuring device, comprising:

a rotatable magnetic element positioned in a fluid channel and thus in a fluid flow, wherein the rotation of the rotatable magnetic element depends on the fluid flow, and wherein the rotatable magnetic element has a positive pole and a negative pole and generates a magnetic field;

at least one sensing coil pair each having a first sensing coil and a second sensing coil;

wherein the respective sensing coils of each of the at least one sensing coil pair are arranged in such a way that the magnetic field generated by the fluid flow dependent rotation of the rotatable magnetic element has a first phase in the region of the respective first sensing coil and a second phase in the region of the respective second sensing coil, wherein said first phase and second phase differ from each other;

the respective first sensing coil of each of the at least one sensing coil pairs is positioned around a respective first ferromagnetic core that is positioned at a first circumferential position relative to the rotatable magnetic element, wherein the first ferromagnetic core guides the magnetic field generated by the rotatable magnetic element to the first sensing coil;

the respective second sensing coil of each of the at least one sensing coil pair is positioned around a respective second ferromagnetic core that is positioned at a second circumferential position relative to the rotatable magnetic element, wherein the second ferromagnetic core guides the magnetic field generated by the rotatable magnetic element to the second sensing coil;

wherein an angle between the corresponding first circumferential position and the corresponding second circumferential position is 180°±5° and wherein the respective first sensing coil and the respective second sensing coil are connected in series to provide a subtraction of their signals thereby reducing noise caused by a common mode magnetic field; and

wherein the respective ferromagnetic cores are positioned within corresponding recesses in the housing outside of the flow channel and thereby outside the fluid flow.