FLOW METER

Abstract

A flow meter for determining the flow velocity of a fluid in a media line, having a sensor base having a bluff body and a sensor body, an electronics unit and a signal interface. The bluff body is arranged substantially upstream of the sensor body in the direction of flow. The sensor body has a carrier part and a substrate arrangement having at least one ceramic substrate, and an anemometer sensor unit and a vortex meter sensor unit are arranged on the substrate arrangement.

Claims

1. A flow meter for determining a flow velocity of a fluid in a media line, the flow meter comprising: a sensor base comprising a bluff body and a sensor body, the bluff body being arranged at least substantially upstream of the sensor body in a direction of flow, the sensor body comprising a carrier part and a substrate arrangement having at least one ceramic substrate; an electronics unit; a signal interface; an anemometer sensor unit arranged on the substrate arrangement; and a vortex meter sensor unit arranged on the substrate arrangement.

2. The flow meter according to claim 1, wherein the anemometer sensor unit comprises: a first thick-film resistor for determining a medium temperature of the fluid; and a heated thick-film resistor for determining a flow-dependent power output, and wherein the first thick-film resistor and the heated thick-film resistor are arranged at a first distance from each other with respect to a vertical longitudinal axis of the sensor body.

3. The flow meter according to claim 2, wherein the vortex meter sensor unit and the anemometer sensor unit are arranged at a second distance from each other with respect to a vertical longitudinal axis of the sensor body, and wherein the vortex meter sensor unit is arranged at an end section of the sensor body that is remote from the sensor base.

4. The flow meter according to claim 3, wherein the heated thick-film resistor is arranged on a ceramic substrate which has cross-sectional reductions, wherein the cross-sectional reductions are arranged with respect to a vertical longitudinal axis of the sensor body in the region of the first distance and/or in the region of the second distance.

5. The flow meter according to claim 1, wherein the vortex meter sensor unit comprises a pressure sensor, wherein the pressure sensor is formed as a MEMS chip or as a membrane integrated in the ceramic substrate, on which membrane at least one strain-sensitive measuring element is arranged.

6. The flow meter according to claim 5, wherein the pressure sensor is arranged on a ceramic substrate which has a through-opening, wherein the pressure sensor is arranged above this through-opening, and/or wherein the sensor body has a clearance so that the pressure sensor acquires a pressure of the flowing fluid through the clearance, and wherein the through-opening and/or the clearance are/is sealed with a flexible filling compound.

7. The flow meter according to claim 2, wherein the substrate arrangement comprises a first ceramic substrate and a second ceramic substrate, wherein the heated thick-film resistor is disposed on the first ceramic substrate, wherein the first thick-film resistor and the vortex meter sensor unit are disposed on the second ceramic substrate, wherein the ceramic substrates are arranged substantially parallel to each other, and/or wherein the carrier part is arranged between the ceramic substrates.

8. The flow meter according to claim 1, wherein ceramic substrates and elements arranged thereon are coated with a protective layer, wherein the protective layer is a thick-film glaze and/or wherein the protective layer is applied by the sol-gel method.

9. The flow meter according to claim 1, wherein the carrier part has recesses on its side surfaces, the side surfaces being aligned at least substantially orthogonally to the flow direction, and wherein ceramic substrates are inserted or pushed into the recesses.

10. The flow meter according to claim 1, wherein the sensor base and/or the bluff body and/or the carrier part is/are made of a plastic by injection molding, wherein the plastic is designed to be thermally and electrically insulating and/or is selected from the material class of fiber composites.

11. The flow meter according to claim 1, wherein the sensor body has, at least in sections, an oval cross-sectional contour at least on the side which faces the flow, and wherein the cross-sectional contour is elliptical or circular.

12. The flow meter according to claim 1, wherein the sensor base, the bluff body and the sensor body are integrally formed or integrally formed in an injection molding process.

13. The flow meter according to claim 1, wherein the sensor base has sockets for receiving and holding the bluff body and/or the sensor body, and wherein the sockets are sealed by seals or by a form fit with respect to the bluff body and/or sensor body.

14. The flow meter according to claim 13, wherein the bluff body and/or the sensor body is or are displaceably mounted in the sockets relative to the sensor base and at least substantially orthogonally to the flow direction and at least substantially parallel to a longitudinal axis of the sensor body, and wherein the flow meter comprises a fixing device which rigidly connects the bluff body and/or the sensor body to the sensor base.

15. The flow meter according to claim 14, wherein the fixing device comprises reservoirs which are filled with a potting compound or with a two-component potting compound, and wherein the reservoirs are arranged such that the potting compound flows into the sockets when the reservoirs are broken open and solidifies therein in a sealing manner.

16. The flow meter according to claim 1, wherein the electronics unit is set up to detect the sensor signals of the anemometer sensor unit and the vortex meter sensor unit and, as a function of the sensor signals, to assign them to a low velocity measuring range or to an overlap measuring range or to a high velocity measuring range.

17. The flow meter according to claim 16, wherein the electronics unit is set up to evaluate the sensor signal of the anemometer sensor unit in the low velocity measuring range and provide it as a measured value signal via the signal interface and to evaluate the sensor signal of the vortex meter sensor unit in the high velocity measuring range and provide it as a measured value signal via the signal interface.

18. The flow meter according to claim 16, wherein the electronics unit is set up to evaluate the sensor signals of the anemometer sensor unit and the vortex meter sensor unit together in the overlap measuring range and to provide them as a resulting measured value signal via the signal interface.

19. The flow meter according to claim 16, wherein the electronics unit is set up to evaluate the sensor signals of the anemometer sensor unit and the vortex meter sensor unit together in the overlap measuring range, and to align the sensor signal of the anemometer sensor unit with the sensor signal of the vortex meter sensor unit and/or to adaptively adjust signal deviations of the anemometer sensor unit to the vortex meter sensor unit in the overlap measuring range for the low velocity measuring range.

20. The flow meter according to claim 1, wherein the electronics unit is set up to evaluate the sensor signals of the anemometer sensor unit and the vortex meter sensor unit together and to determine, with the aid of plausibility data stored in the electronics unit that the anemometer sensor unit is defective or the vortex meter sensor unit is defective, and to output an error signal via the signal interface.

21. The flow meter according to claim 1, wherein the electronics unit is set up to evaluate the sensor signals of the anemometer sensor unit and the vortex meter sensor unit together, to receive information about the flow velocity of the fluid via the signal interface, and to calculate a fluid property from the sensor signals and the information and output it via the signal interface, and wherein the property is a density, a viscosity or a thermal conductivity of the fluid.

22. The flow meter according to claim 2, wherein the electronics unit is set up to temporarily increase a heating power at the heated thick-film resistor such that the sensor body is at least partially freed from organic deposits.

23. A method for installing a flow meter according to claim 1 in a media line, the method comprising: arranging the sensor base at a measuring point of the media line; inserting a bluff body through a socket, wherein an immersion depth of the bluff body corresponds at least substantially to a diameter of the media line; inserting the sensor body through a socket, wherein an immersion depth of the sensor body corresponds at least substantially to a radius of the media line; and fixing the bluff body and the sensor body to the sensor base by a fixing device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0109] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0110] FIG. 1 shows a schematic view of a flow meter in a media line,

[0111] FIG. 2 shows a schematic view of ceramic substrates,

[0112] FIG. 3A to 3C show a schematic view of a carrier part and cross-sections through a sensor body,

[0113] FIG. 4A to 4C show a schematic view of three sub-steps of a method for installing a flow meter,

[0114] FIG. 5 shows a schematic view of two graphs, and

[0115] FIG. 6 shows a schematic cross-sectional view of a second ceramic substrate of a substrate arrangement.

DETAILED DESCRIPTION

[0116] FIG. 1 shows an exemplary embodiment of a flow meter 100, which combines features of several of the possible further developments of the flow meter 100 according to the invention described above.

[0117] The flow meter 100 is arranged at a measuring point 201 of a media line 200. A flow velocity profile of the fluid in the media line 200 is schematically indicated by arrows on the left side of the media line 200.

[0118] The flow meter 100 comprises a sensor base 101, a bluff body 102, the immersion depth of which corresponds substantially to the diameter D of the media line 200, and a sensor body 103 with a carrier part 110, a substrate arrangement 111, an anemometer sensor unit 104 and a vortex meter sensor unit 105. The vortex meter sensor unit 105 is arranged in the region of an end section 131 of the sensor body 103. An immersion depth of the sensor body 103 corresponds at least substantially to half the diameter D of the media line 200, wherein the sensor body 103 is arranged downstream of the bluff body 102 in the flow direction. A vertical longitudinal axis 500 of the sensor body 103 is shown as a dashed arrow.

[0119] An electronics unit 300 is in communication with the sensor units 104, 105 and a signal interface 400 via electrical lines. The signal interface 400 is shown as a plug-in contact by way of example. The electronics unit 300 and the signal interface 400 are arranged within a dashed housing 127 of the flow meter 100. The bluff body 102 and the sensor body 103 are received and held in sockets 121 of the sensor base 101. The exemplary embodiment, by its features and components, achieves the advantages set forth accordingly in the above description of the invention.

[0120] FIG. 2 shows on the left an exemplary embodiment of a substrate arrangement 111 having a first ceramic substrate 108, and on the right, a front and back side of an exemplary embodiment of a substrate arrangement 111 having a second ceramic substrate 109. The ceramic substrates 108, 109 are shown at the same scale and in relation to a common longitudinal axis 500 of the sensor body 103.

[0121] A heated thick-film resistor 107 is disposed on the first ceramic substrate 108 in the region of a lower end portion 114 of the first ceramic substrate 108. This is connected to contacts 129 at the upper end of the first ceramic substrate 108 via conductive paths 128.

[0122] Above the heated thick-film resistor 107, the first ceramic substrate 108 has cross-sectional reductions 112. These reduce the amount of heat that can propagate upward from the heated thick-film resistor 107. With respect to the drawn vertical longitudinal axis 500 of the sensor body 103, the cross-sectional reductions 112 are disposed in the region of a first distance 501 located between a position of the heated thick-film resistor 107 and a position of the first thick-film resistor 106. A second distance 502 is formed between the position of the heated thick-film resistor 107 and a position of the vortex meter sensor unit 105.

[0123] As shown in the middle figure, on one side the second ceramic substrate 109 carries the vortex meter sensor unit 105, which is an exemplary pressure sensor 113. The pressure sensor 113 is, for example, a MEMS chip. The pressure sensor 113 is bonded to the second ceramic substrate 109 via a through-opening 115 of the second ceramic substrate 109. Bond wires 130 connect the pressure sensor 113 to contacts 129 provided for this purpose. These, in turn, are connected by conductive paths 128 to contacts 129 at the upper edge of the second ceramic substrate 109. These in turn may be connected to the electronics unit 300.

[0124] On its other side, as shown on the right side of the figure, the second ceramic substrate 109 carries the first thick-film resistor 106, which is also electrically conductively connected via conductive paths 128 to contacts 129 at the top of the second ceramic substrate 109. By means of the through-opening 115, the bottom of the pressure sensor 113 is partially exposed so that the pressure sensor 113 can receive pressure from both sides of the second ceramic substrate 109.

[0125] FIG. 3A shows an exemplary embodiment of a carrier part 110 in two perspective views.

[0126] The carrier part 110 forms a side surface 119 of the sensor body 103, which faces the flow of the fluid. The side surface 119 has an oval cross-sectional contour. Both surfaces facing perpendicular to the flow have recesses 120 into which ceramic substrates 108, 109 can be inserted or pushed. Furthermore, the carrier part 110 has a clearance 116.

[0127] FIG. 3B shows a cross-sectional view of an exemplary embodiment of a sensor body 103, perpendicular to a vertical longitudinal axis 500 of the sensor body 103, comprising a carrier part 110 and a substrate arrangement 111.

[0128] The carrier part 110 has a side surface 119 facing the flow, which is designed with an oval cross-sectional contour. Adjacent side surfaces have recesses 120 into which a first ceramic substrate 108 and a second ceramic substrate 109 are inserted or pushed.

[0129] FIG. 3C shows a section X, as indicated in FIG. 3B, through an exemplary embodiment of a sensor body 103, along a vertical longitudinal axis 500 of the sensor body 103.

[0130] A first ceramic substrate 108 and a second ceramic substrate 109 are received or inserted into recesses 120 of a carrier part 110 of the sensor body 103.

[0131] A heated thick-film resistor 107 is disposed on the first ceramic substrate 108. A first thick-film resistor 106 is disposed on the second ceramic substrate 109, on the side of the ceramic substrate 109 facing outwardly toward the fluid.

[0132] A pressure sensor 113 is arranged at an end section 131 of the sensor body 103 in the region of a clearance 116 of the carrier part 110, on the other side of the second ceramic substrate 109. This is connected by bond wires 130 to contacts 129 on the substrate, which are not shown.

[0133] The second ceramic substrate 109 further includes a through-opening 115 within a surface portion on which the pressure sensor 113 is disposed. The clearance 116 and the opening 115 are filled with a flexible filling compound 117 that protects both sides of the pressure sensor 113 from direct contact with the fluid but does not hinder the obtainment of pressure from either side of the sensor body 103.

[0134] FIGS. 4A to 4C show three sub-steps of an exemplary embodiment of the method of installing an exemplary embodiment of a flow meter 100 at a measuring point 201 of a media line 200. The media line 200 and the measuring point 201 are not shown for reasons of clarity.

[0135] In FIG. 4A, a sensor base 101 is provided at a measuring point 201. A bluff body 102 and a sensor body 103 are inserted into sockets 121 of the sensor base 101 and vertically displaced therein until they have reached a respective, desired immersion depth. The sockets 121 are provided with seals 122. A fixing device 123 comprises two reservoirs 124 which are filled with a liquid potting compound 125. The potting compound 125 may be, for example, a two-component potting compound, such that each reservoir 124 holds one of the two components.

[0136] Tools 202 are used to break open the reservoirs 124 in FIG. 4B. The potting compound 125 of the fixing device 123 is released and flows into the sockets 121 in which the bluff body 102 and the sensor body 103 are held and sealed by means of the seals 122.

[0137] FIG. 4C illustrates how the potting compound 125 has cured in the sockets 121. Bluff body 102 and sensor body 103 are thus rigidly connected to the sensor base 101, and at the same time the sockets 121 are tightly sealed.

[0138] FIG. 5 shows two graphs. In the upper graph, measurement uncertainties 902, 903 are plotted on the ordinate 901 above an abscissa 900, which shows a flow velocity. In the lower graph, sensor signals are plotted on the ordinate 904 above an abscissa 900, which also shows the flow velocity.

[0139] In the upper graph, the relative measurement uncertainty 902 of an anemometer sensor unit 104 is plotted together with the relative measurement uncertainty 903 of a vortex meter sensor unit 105. The anemometer sensor unit 104 has a constant relative measurement uncertainty 902, i.e., it has the same relative accuracy with respect to the current measured value over its entire measuring range. The vortex meter sensor unit 105, on the other hand, has a constant measurement uncertainty 903 over its entire measuring range, which is related to the end value of the measuring range.

[0140] Accordingly, the relative measurement uncertainty 903 with respect to the respective current measured value becomes smaller and smaller the higher the current measured value, i.e., the flow velocity, is. This shows that it is advantageous to use the sensor signal of the anemometer sensor unit 104 to evaluate a measured value in a first low velocity measuring range 600, while the sensor signal of the vortex meter sensor unit 105 should preferably be selected in a high velocity measuring range 800. In an overlap measuring range 700, the relative measurement uncertainties 902, 903 of both sensor units are approximately equal.

[0141] In the lower graph, a signal characteristic 905 of an anemometer sensor unit 104 and a signal characteristic 906 of a vortex meter sensor unit 105 are plotted.

[0142] In a low velocity measuring range 600, the signal characteristic 905 of the anemometer sensor unit 104 initially rises sharply but flattens out at higher flow velocities. The signal characteristic 906 of the vortex meter sensor unit 105 can only be used reliably above a certain minimum flow velocity. From this point, however, it shows a continuously increasing curve. In an overlap measuring range 700, both signal characteristics 905, 906 still show a usable slope, but in the high velocity measuring range 800, the signal characteristic 905 of the anemometer sensor unit 104 flattens out considerably.

[0143] FIG. 6 shows a sectional view of a possible embodiment of the second ceramic substrate 109 of a substrate arrangement 111, analogous to the sectional view shown in FIG. 3C.

[0144] A first thick-film resistor 106 is disposed at an upper portion of the second ceramic substrate 109. A vortex meter sensor unit 105 is formed on a lower portion of the second ceramic substrate 109.

[0145] In contrast to the embodiment in FIG. 3C in which a pressure sensor 113 is arranged above a through-opening 115 in the ceramic substrate 109, the vortex meter sensor unit 105 in this example is formed by the ceramic substrate 109 itself. In this case, a weakening of the material 133 creates a thin membrane 126 which deforms slightly elastically under the pressure fluctuations caused by the passing vortices. A strain-sensitive measuring element 132 arranged on this membrane 126, for example a bonded strain gauge or a resistor track applied by the thick-film process, serves to convert this deformation into an electrically measurable sensor signal.

[0146] The invention is not limited to the preceding detailed embodiments. It may be modified to the extent set forth in the following claims. Likewise, individual aspects from the dependent claims can be combined with each other.

[0147] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.