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EP-4374143-B1 - ELECTROMAGNETIC FLOW METER

EP4374143B1EP 4374143 B1EP4374143 B1EP 4374143B1EP-4374143-B1

Inventors

  • FRISO, Ermanno

Dates

Publication Date
20260506
Application Date
20220725

Claims (11)

  1. Electromagnetic flow meter (10) comprising a sensor element (11) which comprises a duct (12) for the flow of a fluid, a device (13) for generating a magnetic induction field (B), comprising at least two coils (14) and a magnetic core comprising a plurality of metal elements (24, 25), and a detection element comprising a plurality of electrodes (15, 16), wherein said duct (12) is made of high resistance thermoplastic material and wherein it has, in correspondence with a measurement plane, a rectangular cross section (S0) that has a smaller area than the area of respective inlet and outlet circular cross sections (S1), characterized in that it comprises a container (20) for housing said sensor element (11) which has a cylindrical shape, in that it comprises a structural matrix (R) disposed between said sensor element (11) and said housing container (20) completely filling the space present between them, and in that said structural matrix (R) is a resin.
  2. Flow meter (10) as in claim 1, characterized in that said thermoplastic material is reinforced with glass fiber and has very high stiffness with elastic modulus comprised between 10 and 45 GPa.
  3. Flow meter (10) as in claim 1, characterized in that it comprises at least one stiffening element (32) disposed between said sensor element (11) and said housing container (20), embedded in said structural matrix (R).
  4. Flow meter (10) as in claim 3, characterized in that said at least one stiffening element (32) is a cylindrical component (32a) coaxial to said housing container (20).
  5. Flow meter (10) as in claim 3, characterized in that said at least one stiffening element (32) is a flat component (32b) that has undulated contact surfaces.
  6. Flow meter (10) as in any claim hereinbefore, characterized in that the ratio between the area of the circular cross sections (S1) and the area of the rectangular cross section (S0) is comprised between 1.5 and 3.5.
  7. Flow meter (10) as in any claim hereinbefore, characterized in that the proportionality ratio between the height (L1) and the width (L2) of said rectangular cross section (S0) is comprised between 0.3 and 0.7, preferably between 0.5 and 0.6.
  8. Flow meter (10) as in any claim hereinbefore, characterized in that said coils (14) are flat coils or coils of the solenoid type.
  9. Flow meter (10) as in any claim hereinbefore, characterized in that said plurality of electrodes (15, 16) comprises at least two measurement electrodes (15) and at least one reference electrode (16), and in that said electrodes (15) are each positioned on one of the shorter sides (30) of said duct (12).
  10. Flow meter (10) as in any claim hereinbefore, characterized in that said electrodes (15, 16) are made entirely of metal material and are incorporated into the thermoplastic material which constitutes said duct (12) by means of co-molding techniques during the production process by means of injection molding of the duct (12).
  11. Flow meter (10) as in any claim hereinbefore, characterized in that it comprises, disposed in said housing container (20), an integrated electrical energy supply source (27) and a supply circuit (27a) which is able to be interfaced directly both with an external electrical energy supply source and also with said integrated electrical energy supply source (27) without any drop in performance.

Description

FIELD OF THE INVENTION The present invention concerns a flow meter for fluids, in particular a meter of the electromagnetic type. The invention can be used to measure the flow rate of water, conductive liquids in general and suchlike. It is particularly indicated, but not restrictively, for use in applications such as irrigation, low-cost industrial markets and suchlike, in which it may be of interest to reduce the cost of the meter while keeping unchanged its metrological performance and its insensitivity to fluid dynamic disturbances, especially when the flow rates are relatively low. It is also indicated, but not restrictively, for use in applications where better characteristics in terms of bulk and weight may be of interest. BACKGROUND OF THE INVENTION Electromagnetic flow meters are known, with a circular or rectangular cross section, typically made of metal materials using traditional metallurgical techniques. Due to the cost of these materials and construction methods, the final cost of the meters that can be made is unsustainable for many applications. Another disadvantage of electromagnetic flow meters made of metal material is that they require a coating process. In fact, due to the metal structure, the flow tube of the meter has to be coated to achieve the insulation required by the functional principle of the instrument. Moreover, some of the materials, such as for example carbon steel - a preferred metal alloy to keep construction costs down - have to be coated for protection against corrosion. Coating is an expensive process, and its qualitative result can affect the metrological performance of the meter. Economical coating processes usually result in the production of very thin coatings, which can be subject to abrasion by solid bodies present in the fluid, especially in electromagnetic flow meters with a small cross section. Electromagnetic flow meters made of polymeric materials are also known. In these cases, the choice of a circular cross section is obligatory, since polymeric materials have a significant limitation with respect to the dimensional stability of cross sections with high pressure and high temperature. Current ducts with a non-circular cross section are not in fact able to withstand the high pressures that the fluid can exert. For example, given the same area, a duct with a rectangular cross section is less resistant to high pressures than a duct with a circular cross section, in particular on its longer sides. In particular, the increase in the cross section area due to the deformation of the duct can cause errors in measurement: the deformation can therefore affect the metrological performance of the flow meter. One disadvantage in terms of cost of electromagnetic flow meters with a circular cross section in the size range of interest is that they typically use saddle coils to generate the magnetic induction field, because they optimize the distribution of the field in the ducts of the flow meter. However, the production of saddle coils is difficult to industrialize compared to more common coils, such as solenoid coils, or in any case of the flat type with a circular or quadrangular cross section. The alternative use of solenoid coils 102 in flow meters 100 with a duct that has a circular cross section 101, as shown in fig. 1, can however lead to a deterioration of the metrological performance. Another disadvantage is that flanges are often used in electromagnetic flow meters in the size range of interest. Flanged type flow meters are very flexible, but the different flange standards available complicate the supply chain and production processes of the product, contributing to increased costs. Furthermore, the metal flanges are very heavy and bulky, in particular during the shipping and transport steps. The costs and bulk are also increased by the need, often felt, to have external accessories for connection to external supply sources for the electromagnetic meter. Examples of known flow meters subject to one or more of the disadvantages as above are described in documents US2021/0116273 A1 and US 2015/168188 A1. There is therefore a need to perfect a flow meter which can overcome at least one of the disadvantages of the state of the art. In order to do this, it is necessary to solve the technical problem of developing an electromagnetic flow meter with a low cost but high performance. In particular, one purpose of the present invention is to provide an electromagnetic flow meter which has a low cost, comparable for example to that of mechanical flow meters, and which has high performance in terms of measurement accuracy, in particular in the case of low flow rates. Another purpose of the present invention is to reduce the bulk and weight of the flow meter as much as possible. Another purpose of the invention is to provide an electromagnetic flow meter which allows versatility of use and electrical power supply. The Applicant has devised, tested and embodied the present in