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

Fluid flow measuring device for measuring a fluid flow, comprising a rotatable, magnetic element, wherein the rotatable, magnetic element is positioned in the fluid flow, wherein the rotation of the rotatable, magnetic element depends from the fluid flow, wherein the rotation of the rotatable, magnetic element generates a magnetic field; further comprising at least one sensing coil pair having a first sensing coil and a second sensing coil, wherein the respective sensing coils of each sensing coil pair are arranged in such a way that the magnetic field generated by the fluid flow dependent rotation of the rotatable element has a first polarity and a first phase in the region of the respective first sensing coil and a second polarity and a second phase in the region of the respective second sensing coil, wherein at least said polarities differ from each other.

This application claims priority to European Patent Application Serial No. 15 173 754.1, filed Jun. 25, 2015, which is incorporated herein by reference.

The present patent application relates to a fluid flow measuring device and to an armature for a fluid system comprising such a fluid flow measuring device.

In fluid systems like potable water systems it is desired to measure the fluid flow through the fluid system or through components of fluid system like through armatures. For the time being such a fluid flow measurement is provided by separate devices. Such devices use for the fluid flow measurement a rotatable element positioned in the fluid flow, whereby the number of rotations per time unit or the rotation speed of the rotatable element is used to measure the fluid flow.

It is known that such fluid flow measuring devices make use of a magnetic rotatable element, wherein the rotation of the rotatable, magnetic element generates a magnetic field which is detected by a sensing coil. The magnetic field induces an electrical current signal in the sensing coil, namely an alternate current signal, which frequency is determined. The frequency of the electrical current signal depends from the fluid flow. If the magnetic strength of the rotatable, magnetic element is too weak and/or if the sensing distance between the rotatable, magnetic element and the sensing coil is too big, than the signal induced in the sensing coil can be disturbed by noise caused by the magnetic field generated by electrical devices like the motors, transformers and the like. The frequency of the noise signal induced by such magnetic disturbance is in the range of the frequency induced by the rotatable, magnetic element. This results in an inaccurate fluid flow measurement. This is also the reason why fluid flow measuring is provided by separate devices and not as integral function of armatures.

It is desired to provide a fluid flow measuring device which can provide a more reliable fluid flow measuring being less effected by noise caused by the magnetic field generated from electrical devices and which can be an integral element of armatures.

Against this background, a novel fluid flow measuring device according to claim1is provided.

The novel fluid flow measuring device comprises a rotatable, magnetic element, namely a magnetic turbine wheel or a paddle wheel having at least one pair of magnetic paddles, wherein the rotatable, magnetic element is positioned in the fluid flow, wherein the rotation of the rotatable, magnetic element depends from the fluid flow, and wherein the rotation of the rotatable, magnetic element generates a magnetic field.

The novel fluid flow measuring device further comprises at least one sensing coil pair having a first sensing coil and a second sensing coil, wherein the respective sensing coils of each sensing coil pair are arranged in such a way that the magnetic field generated by the fluid flow dependent rotation of the rotatable element has a first polarity and a first phase in the region of the respective first sensing coil and a second polarity and a second phase in the region of the respective second sensing coil, wherein at least said phases and preferably also said polarities differ from each other.

The novel fluid flow measuring device can provide a more reliable fluid flow measuring being less effected by noise caused by the magnetic field generated from disturbing electrical devices.

Further, the novel fluid flow measuring device can be an integral element of armatures.

According to a preferred embodiment of the invention, the respective first sensing coil of each sensing coil pair is positioned around, namely wound around, a first ferromagnetic core that is positioned at a first circumferential position of the rotatable, magnetic element, and the respective second sensing coil of each sensing coil pair is positioned around, namely wound around, a second ferromagnetic core that is positioned at a second, different circumferential position of the rotatable, magnetic element. The first ferromagnetic core guides the magnetic field generated by rotation of the rotatable element to the respective first sensing coil, wherein the second ferromagnetic core guides the magnetic field generated by rotation of the rotatable element to the respective second sensing coil. A longitudinal axis of the respective first ferromagnetic core which corresponds to the winding axis of the respective first sensing coil around the respective first ferromagnetic core runs parallel to the rotation axis of the rotatable, magnetic element and has a first distance from the rotation axis of the rotatable element, 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 also parallel to the rotation axis of the rotatable, magnetic element and has a second distance from the rotation axis of the rotatable element. Said first distance and said second distance are preferably identical or almost identical. This allows a beneficial integration of the fluid flow measurement device in an armature and at the same time a reliable fluid flow measuring being less effected by noise caused by a disturbing magnetic field.

The respective sensing coils of the respective sensing coil pair are preferably connected in series. Further, an angle between said first circumferential position and said second circumferential position at which the respective ferromagnetic cores are positioned is preferably 180° or almost 180°. Almost 180° covers an angular deviation of maximum 5° from 180°. This allows a very reliable fluid flow measuring being less effected by noise caused by the magnetic field generated from electrical devices.

Preferred developments of the invention are provided by the dependent claims and the description which follows. Exemplary embodiments are explained in more detail on the basis of the drawing, in which:

The present application relates to a fluid flow measuring device and to an armature for a fluid systems like a potable water system comprising such a fluid flow measuring device.

FIGS. 1 to 4illustrate details of an armature10for a fluid system having as an integral element a fluid flow measuring device11.

The armature10can be a water treatment armature like a water filter or back flow preventer armature or pressure regulator armature or control valve armature or the like.

The armature10comprises a housing12that provides an inlet13for the fluid, an outlet14for the fluid and a flow channel15for the fluid, wherein said flow channel15extends between the inlet13and the outlet14.

The fluid flow measuring device11which is preferably an integral element of the armature comprises a rotatable, magnetic element16. The rotatable, magnetic element16is positioned in the fluid flow, namely in the flow channel15.

The rotation of the rotatable, magnetic element16depends from the fluid flow through the flow channel15. The rotation of the rotatable, magnetic element16generates an alternating magnetic field.

The rotatable, magnetic element16can be provided by magnetic turbine wheel or a paddle wheel having at least one pair of magnetic paddles.

In the embodiment ofFIGS. 1 to 4, the rotatable, magnetic element16is provided by a magnetic turbine wheel providing on the first half a south pole S and on the opposite second half a north pole N (seeFIG. 4), wherein a separation plane17between the south pole S and the north pole N runs parallel to a rotation axis18of the rotatable, magnetic element16.

The fluid flow measuring device11which is preferably an integral element of the armature10further comprises at least one sensing coil pair19having a first sensing coil19aand a second sensing coil19b.

The respective sensing coils19a,19bof each respective sensing coil pair19are arranged in such a way that the magnetic field generated by the fluid flow dependent rotation of the rotatable element16has a first polarity and a first phase in the region of the respective first sensing coil19aand a second polarity and a second phase in the region of the respective first sensing coil19b, wherein at least said first and second phases and preferably in addition said first and second polarities differ from each other.

By using at least one such coil pair19with sensing coils19a,19bthat make use of the magnetic field with different phases and preferably different polarities in the region of the sensing coils19a,19bof the respective coil pair19, the influence of noise caused by a disturbing magnetic field generated from electrical devices can be eliminated, especially when the source of the disturbing magnetic field has a distance from the sensing coils19a,19bbeing at least 5 times the distance between the sensing coils19a,19b.

Further, such a fluid flow measuring device11can be integrated in a fluid armature like a water armature and can provide an accurate and reliable flow measurement.

The first sensing coil19aof respective sensing coil pair19is positioned around, namely wound around, a first ferromagnetic core20a. The second sensing coil19bof respective sensing coil pair19is positioned around, namely wound around, a second ferromagnetic core20b. A longitudinal axis21aof the first ferromagnetic core20awhich corresponds to the winding axis22aof the first sensing coil19aaround the first ferromagnetic core20aruns parallel to the rotation axis18of the rotatable, magnetic element16. A longitudinal axis21bof the second ferromagnetic core20bwhich corresponds to the winding axis22bof the first sensing coil19baround the first ferromagnetic core20bruns also parallel to the rotation axis18of the rotatable, magnetic element16and therefore parallel to the longitudinal axis21aof the first ferromagnetic core20a.

Said first ferromagnetic core20aguides the magnetic field generated by the rotation of the rotatable element16with the first polarity and the first phase to the first sensing coil19aof respective sensing coil pair19. Said second ferromagnetic core20bguides the magnetic field generated by the rotation of the rotatable element16with the second polarity and the second phase to the second sensing coil19bof respective sensing coil pair19.

The first ferromagnetic core20ais positioned at a first circumferential position of the rotatable, magnetic element16. The second ferromagnetic core20bis positioned at a second, different circumferential position of the rotatable, magnetic element16. InFIG. 4an angle α between said circumferential positions is illustrated.

The angle α between said first circumferential position and said second circumferential position is in a range between 45° and 180°, preferably in a range 135° and 180°. Most preferably, the angle α is 180°. When the angle α is 180° the signal based on the magnetic field of the rotatable, magnetic element16is maximal and the noise signal caused by the magnetic field by disturbing electrical devices is minimal.

If the angle α is 180°, the first phase and the second phase differ from each other by a phase shift of 180° which results further in different, namely reversed, polarities.

If the angle α is not 180°, the first phase and the second phase differ from each other by a phase shift, but the performance is still acceptable, especially in the range of angle α down to 135°.

The longitudinal axis21aof the respective first ferromagnetic core20ahas a first distance a from the rotation axis18of the rotatable element16. The longitudinal axis21bof the second ferromagnetic core20bhas a second distance b from the rotation axis18of the rotatable element16. Said first distance a and said second distance b are preferably identical, meaning a=b, or almost identical, meaning 0.95≤a/b≤1.05, to further ensure that signal based on the magnetic field of the rotatable, magnetic element16is maximal.

However, it should be noted that said first distance “a” and said second distance “b” can be significantly different from each other. The ratio a/b can be in the range 0.5≤a/b≤2.0.

As mentioned above, the magnetic field provided by the fluid flow dependent rotation of element16has at least different phases and preferably also different polarities in the region of the sensing coils19a,19bof the respective coil pair19. However, the magnetic field generated from electrical devices has the same phase and same polarity in the region of the sensing coils19a,19bof the respective coil pair19. By subtracting the electrical current signals induced in the sensing coils19a,19bthe influence of the magnetic field generated from the disturbing electrical devices can be eliminated, especially when the source of the disturbing magnetic field has a distance from the sensing coils19a,19bbeing at least 5 times the distance a+b between the sensing coils19a,19b.

Such a subtraction can be provided by an operational amplifier or by a simple series connection of the sensing coils19a,19b.

The rotatable, magnetic element16of the fluid flow measuring device11is positioned within the flow channel15of the armature housing12and thereby within the fluid flow.

The ferromagnetic cores20a,20bof the fluid flow measuring device11are positioned within recesses23a,23bof the armature housing12outside of the flow channel15and thereby outside the fluid flow. The sensing coils19a,19bof the fluid flow measuring device11are positioned on a printed circuit board24outside of the armature housing12. The sensing coils19a,19bcan also be wound directly on the ferromagnetic cores20a,20b. Further, the sensing coils19a,19bcan be bobbin pushed on the ferromagnetic cores20a,20b.

The armature housing12is made from a non-ferromagnetic material like aluminum, brass, non-magnetic stainless steel, plastic and the like.

As mentioned above, the sensing coils19a,19bof the respective sensing coil pair are preferably connected in serious to provide the subtraction of their signals thereby eliminating the noise signal. Other electrical components for processing the electrical current signals of the sensing coils19a,19bmay be provided on the printed circuit board24.

The above details described for the embodiment ofFIGS. 1 to 4are preferred and allow in combination with each other a beneficial integration of the fluid flow measuring device11in an fluid armature10, while the fluid flow measurement is less effected by noise caused by the magnetic field generated from electrical devices so that the fluid flow measurement is accurate and reliable.

FIGS. 5, 6 and 7illustrate other embodiments of a fluid flow measuring devices11′,11″,11′″. However, the embodiment ofFIGS. 1 to 4is preferred.

The fluid flow measuring devices11′,11″,11′″ ofFIGS. 5, 6 and 7also comprise a rotatable, magnetic element16and at least one sensing coil pair19having a first sensing coil19aand a second sensing coil19b. The sensing coils19a,19bof the respective sensing coil pair19are preferably connected in series.

The magnetic element16of the fluid flow measuring devices11″ of the embodiment ofFIGS. 5, 7corresponds to the magnetic element16of the embodiment ofFIGS. 1 to 4, wherein the same is provided by a magnetic turbine wheel providing on the first half a south pole S and on the opposite second half a north pole N.

The magnetic element16fluid flow measuring devices11″ of the embodiment ofFIG. 6is provided by a paddle wheel having at least one, in the shown embodiment three, paddle pairs of paddles25a,25b,25a′,25b′,25a″,25b″, wherein the paddles25a,25a′,25a″ provide south poles S and the paddles25b,25b′,25b″ provide north poles N.

The respective sensing coils19a,19bof the respective sensing coil pair19are arranged in such a way that the magnetic field generated by the fluid flow dependent rotation of the rotatable element16has a first polarity and a first phase in the region of the respective first sensing coil19aand a second polarity and a second phase in the region of the respective second sensing coil19b, wherein at least said phases and preferably also said polarities differ from each other.

In the embodiments ofFIGS. 5 and 6the first sensing coil19aand the respective sensing coil19bof the respective coil pair19are both air coils, meaning that the embodiments ofFIGS. 5 and 6do not make use of the ferromagnetic cores.

In the embodiment ofFIG. 7, which is similar to the embodiment ofFIG. 5, the first sensing coil19aand the respective sensing coil19bof the respective coil pair19are wound around ferromagnetic cores20a,20b. It should be noted that also the embodiment ofFIG. 6can make use of the ferromagnetic cores20a,20b.

The winding axis22a′,22a″,22a′″ of the first sensing coil19aof the respective sensing coil pair19runs perpendicular to the rotation axis18of the rotatable, magnetic element16. Further on, the winding axis22b′,22b″,22b′″ of the second sensing coil19bof the respective sensing coil pair19runs perpendicular to the rotation axis18of the rotatable, magnetic element16.

InFIG. 7, the longitudinal axis21a′″,21b′″ of the ferromagnetic cores20a,20bwhich correspond to the winding axis22a′″,22b′″ of the sensing coils19a,19baround the ferromagnetic cores20a,20brun perpendicular to the rotation axis18of the rotatable, magnetic element16.

The respective first sensing coil19aof the embodiments ofFIGS. 5, 6 and 7is positioned at a first circumferential position of the rotatable, magnetic element16and the respective second sensing coil16bis positioned at a second, different circumferential position of the rotatable, magnetic element. The angle α between said first circumferential position and said second circumferential position is in a range between 45° and 180°, preferably in a range 135° and 180°.

In the all embodiments the angle α is preferably 180°. When the angle α is 180° the signal based on the magnetic field of the rotatable, magnetic element16is maximal and the noise signal caused by the magnetic field by disturbing electrical devices is minimal.

If the angle α is 180°, the first phase and the second phase of the magnetic field in the region of the coils19a,19bdiffer from each other by a phase shift of 180° which results further in different, namely reversed, polarity of the magnetic field in the region of the coils19a,19b.

However, it is also possible to use angles α different from 180°.

In the embodiment ofFIGS. 1 to 4, the angle α is preferably in a range between 45° and 180°. In the embodiment ofFIGS. 1 to 4, with an angle α of 90° the signal based on the magnetic field of the rotatable, magnetic element16is 50% of the maximum signal and the noise signal caused by the magnetic field by disturbing electrical devices is minimal.

In the embodiments ofFIGS. 5, 6 and 7, the angle α is preferably in a range between 135° and 180°. In the embodiment ofFIGS. 5, 6 and 7, with an angle α of 90° the signal based on the magnetic field of the rotatable, magnetic element16is 50% of the maximum signal, however the noise signal caused by the magnetic field by disturbing electrical devices is maximal. So, an angle of 90° should be avoided for the embodiments ofFIGS. 5, 6 and 7.

The respective first sensing coil19ahas a first distance a from the rotation axis18of the rotatable element16and the respective second sensing coil19bhas a second distance b from the rotation axis18of the rotatable element16.

Said first distance “a” and said second distance “b” are preferably identical or almost identical. Almost identical means 0.95≤a/b≤1.05. However, it should be noted that said first distance “a” and said second distance “b” can be significantly different from each other. The ratio a/b can be in the range 0.5≤a/b≤2.0.

LIST OF REFERENCE SIGNS