TRANSDUCER AND MEASURING DEVICE

Description

[0001] The invention relates to a measuring sensor of a measuring device for detecting a mass flow or a density of a medium flowing through at least one measuring tube of the measuring sensor. An exciter is configured to excite the at least one measuring tube to vibrate, and at least two sensors are configured to detect the measuring tube vibrations. The invention further relates to a measuring device comprising such a measuring sensor.

[0002] The aforementioned exciter and / or sensors typically comprise a coil device with a coil arranged on or in a circuit board, see, for example, DE102015120087A1. The coil devices, in turn, are attached to a measuring tube or a support body of the sensor via a holder. In high-temperature applications, necessary mechanical contact between the circuit board and a circuit board holder can lead to destruction of the circuit board after repeated temperature changes or when exposed to high temperatures.

[0003] EP1105700A1 describes a Coriolis mass flowmeter with a conventional sensor coil device with a coil holder and a winding coil.

[0004] The object of the invention is therefore to propose a high-temperature stable measuring sensor and a measuring device comprising such a measuring sensor.

[0005] The object is achieved by a measuring sensor according to claim 1 and a measuring device according to claim 10.

[0006] A measuring sensor according to the invention of a measuring device for detecting a mass flow or a density of a medium flowing through at least one measuring tube of the measuring sensor comprises: the at least one measuring tube with an inlet and an outlet, which is configured to guide the medium between the inlet and the outlet; at least one exciter, which is configured to excite the at least one measuring tube to oscillate; at least two sensors, which are configured to detect the deflection of the oscillations of at least one measuring tube; wherein at least one exciter and the sensors each have a coil device, each with at least one coil, and each have a magnetic device, wherein the magnetic devices are movable relative to the respective coil device, and wherein the magnetic device and the coil device of an exciter or sensor interact with each other by means of magnetic fields, wherein the coil device has a printed circuit board with at least one printed circuit board layer, wherein the coil is arranged on and / or in at least one printed circuit board layer,wherein the circuit board has a first coefficient of thermal expansion, wherein the measuring sensor has a carrier body which is configured to hold the measuring tube, wherein at least one coil device of the sensors and / or the coil device of the exciter is each fastened to the carrier body or to a measuring tube by means of a holding device, wherein the holding device is configured to clamp the circuit board in order to hold the circuit board by means of lateral frictional engagement, wherein the circuit board is mechanically contacted with the holding device by means of at least one holding element of the holding device, wherein the holding element has a second coefficient of thermal expansion, wherein the first coefficient of thermal expansion and the second coefficient of thermal expansion differ from each other by less than 3*10 -6< / Kelvin, and in particular less than less than 2*10 -6< / Kelvin and preferably less than less than 1.5*10 -6< / Kelvin,wherein the printed circuit board is produced by a sintering process, wherein the printed circuit board comprises, for example, a ceramic material, wherein the ceramic material is in particular a low-temperature single-fired ceramic. ,

[0007] Low-temperature cofired ceramics (LTCC) are particularly suitable as a basis for the production of coil devices due to their excellent properties with regard to minimal disruption of coil properties and the good applicability of electrically conductive traces, which can be used to form coils. However, a disadvantage of such ceramics is their greater brittleness compared to metals and thus increased sensitivity to mechanical stress. However, this disadvantage can be overcome by adapting the first and second thermal expansion coefficients according to the invention.

[0008] In one embodiment, the holding element comprises at least one of the following materials: zirconium, titanium, tantalum.

[0009] Particularly in combination with low-temperature single-fired ceramic as a circuit board, there are small differences between the thermal expansion coefficients.

[0010] In one embodiment, the first thermal expansion coefficient is less than 9*10 -6< / Kelvin, and in particular less than 8*10 -6< / Kelvin, and preferably less than 7*10 -6< / Kelvin.

[0011] A high thermal expansion coefficient of the circuit board can have a negative impact on the magnetic properties of a coil, since, for example, the inductance of a coil depends, among other things, on its geometric dimensions, which would therefore also change with temperature changes. This should be avoided, for example, with regard to measurement signal evaluation.

[0012] In one embodiment, the circuit board is held by means of a screw, clamp, or by means of at least one rivet or at least one bolt.

[0013] In one embodiment, the holding element is attached to a holding device body.

[0014] The holding device body can be arranged on the measuring tube or on the carrier body.

[0015] In one embodiment, the circuit board has a bore in which a screw is arranged, which engages in a thread of a bore of the holding device, wherein pressure is exerted on the circuit board by means of the screw.

[0016] In one embodiment, the holding device is attached to the carrier body.

[0017] This is advantageous because the carrier body is largely acoustically decoupled from the measuring tube, and the coil assembly is virtually unaffected by measuring tube movements. This increases the durability of the coil assembly.

[0018] In one embodiment, the measuring sensor has two collectors, wherein a first collector on an upstream side of the measuring sensor is designed to receive a medium flowing into the measuring sensor from a pipeline and to guide it to the inlet of the at least one measuring tube, wherein a second collector is designed to receive the medium emerging from the outlet of the at least one measuring tube and to guide it into the pipeline.

[0019] In one embodiment, the measuring sensor has two process connections, in particular flanges, which are designed to connect the measuring sensor to a pipeline.

[0020] A measuring device according to the invention comprises: A measuring sensor according to one of the preceding claims; an electronic measuring / operating circuit, wherein the electronic measuring / operating circuit is configured to operate the sensors and the exciter and is connected to them by means of electrical connecting lines, wherein the at least one electrical connection is guided to the electronic measuring / operating circuit by means of a cable guide, wherein the electronic measuring / operating circuit is further configured to determine and provide mass flow measured values and / or density measured values, wherein the measuring device in particular has an electronics housing for accommodating the electronic measuring / operating circuit.

[0021] In the following, the invention is described using exemplary embodiments. Fig. 1 outlines a measuring device with a measuring sensor according to the invention. Fig. 2 outlines a coil device. Fig. 3 outlines two holding devices for coil devices according to the invention. Fig. 4 outlines an arrangement of vibration sensors of a measuring transducer with respect to a measuring tube.

[0022] Fig. 1outlines a measuring device 200 with a measuring sensor 100, wherein the measuring sensor has two measuring tubes 110 which are held by a carrier body 120 of the measuring sensor. The measuring tubes open on the inlet side into a first collector 141 and on the outlet side into a second collector 142, wherein the collectors 140 are designed to receive a medium flowing into the measuring sensor from a pipeline (not shown) and to distribute it evenly among the measuring tubes. Accordingly, the second collector is designed to receive the medium flowing out of the measuring tubes and transfer it into the pipeline. The measuring sensor is connected to the pipeline via process connections 150, in particular flanges 151. The measuring sensor has a vibration exciter 11 which is designed to excite the measuring tubes to vibrate.The measuring sensor additionally has two vibration sensors 10, which are designed to detect the vibrations of the measuring tubes.

[0023] The skilled person is not limited to the number of measuring tubes, vibration exciters, and vibration sensors mentioned here. The design shown here is exemplary in these aspects.

[0024] The measuring device comprises an electronic measuring / operating circuit 210, which is configured to operate the vibration exciter and the vibration sensors, and to calculate and output mass flow and / or density measured values of the medium. The electronic measuring / operating circuit is connected to the vibration sensors and the vibration exciter via electrical connections 230. The measuring device comprises an electronics housing 220 in which the electronic measuring / operating circuit is arranged. To determine the mass flow, the measuring device utilizes the Coriolis effect, which acts on the flowing medium due to measuring tube vibrations, with the flow characteristically influencing the measuring tube vibrations.

[0025] Fig. 2shows a plan view of a coil device 1 with a printed circuit board 2, a first side surface 3.1 and a second side surface 3.2. A coil 4 with a first coil end 4.1 and a second coil end 4.2 is applied to the first side surface 3.1 in the form of an electrically conductive conductor track 4.3, as shown here. The coil device has contacting elements 5 with a first contacting element 5.1 and a second contacting element 5.2. The first contacting element is connected to the first coil end 4.1, and the second contacting element is connected to the second coil end 4.2. The contacting elements are designed to be contacted with electrical connecting lines 230, by means of which the coil device can be connected to the electronic measuring / operating circuit.The circuit board can be a multilayer circuit board and have a coil on each of the multiple circuit board layers, with adjacent coils being connectable, for example, by means of vias. Those skilled in the art will select coil devices according to their needs. The coil devices shown in . Fig. 2 The coil device outlined is purely exemplary and not intended to be restrictive. The circuit board may have a hole 6 for receiving a screw, bolt, or rivet, as shown here.

[0026] Figs. 3 a) and 3 b ) each outline an exemplary holding device 131 according to the invention for a circuit board 2 of a coil device. The holding device has a holding device body 136, which is connected, for example, to a measuring tube or to the carrier body. The geometric design of the holding device is subject to the choice of the person skilled in the art.

[0027] Fig. 3 a)shows a holding device 131 with a holding device body 136, two holding elements 132, and a screw 133, wherein the circuit board is clamped by means of the screw between a screw head and the holding device body. A holding element is arranged between the circuit board 2 and the screw head or the holding device body 136, which are in mechanical contact with the circuit board. The screw runs through openings, for example bores, in the holding elements and the circuit board and engages in a thread 135 of a bore in the holding device 134. The bore in the circuit board 6 and the openings of the holding elements each have a diameter that can accommodate changes in the diameter of the screw due to temperature fluctuations. The person skilled in the art will base this on known thermal expansion coefficients of the materials used.The circuit board is therefore attached to the holding device body 136 by a screw connection.

[0028] Fig. 3 b) shows a holding device 131 with a holding device body 136 with a holding element 132, which holding element partially encompasses the circuit board 2 and holds it by means of a clamp. A person skilled in the art will configure a clamp according to his or her needs.

[0029] The Figs. 3 a) and 3 b The holding device body shown in Figure 1 serves to illustrate the invention. The holding device body may comprise one or more body elements; the person skilled in the art will configure the holding device according to his or her needs.

[0030] According to the invention, the circuit board has a first coefficient of thermal expansion and the at least one holding element has a second coefficient of thermal expansion, wherein the first coefficient of thermal expansion and the second coefficient of thermal expansion differ from one another by less than 3*10 -6< / Kelvin, and in particular less than less than 2*10 -6< / Kelvin and preferably less than less than 1.5*10 -6< / Kelvin. In this way, it is ensured that the circuit board 2 is held by means of lateral frictional engagement, and that lateral stresses caused by temperature changes remain so low that the circuit board remains intact. This is particularly advantageous for brittle circuit board materials such as ceramic.

[0031] The printed circuit board is preferably produced by a sintering process, wherein the printed circuit board comprises, for example, a ceramic material, wherein the ceramic material is in particular a low-temperature cofired ceramic. Low-temperature cofired ceramic, also known as low-temperature cofired ceramic (LTCC), is particularly suitable as a basis for the production of coil devices due to its good properties with regard to minimal disruption of coil properties and the good applicability of electrically conductive conductor tracks, which can be used to form coils. A disadvantage of such ceramics, however, is their greater brittleness compared to metals and thus increased sensitivity to mechanical stress. However, this disadvantage can be avoided by adapting the first thermal expansion coefficient and the second thermal expansion coefficient according to the invention.

[0032] Fig. 4schematically outlines a side view of a measuring tube 110 of a measuring device with two vibration sensors 10 each comprising a coil device 1 according to the invention from a side view SA, see Fig. 2, wherein the vibration sensors are each connected to the measuring tube 110 by means of a holding device 131 according to the invention (see left vibration sensor) and are configured to follow its vibration movements, or are mechanically connected to the carrier body 120 by means of a holding device 131 according to the invention (see right coil device). Magnetic devices 7, which, as sketched here, are mounted on a second measuring tube concealed by the measuring tube shown and are configured to follow its vibration movements, interact with the associated coil devices via electromagnetic fields during measuring operation. In the case of opposing measuring tube vibrations, vibrations can thus be detected by means of electrical voltages induced in the coil.

[0033] If the coil devices are attached to the measuring tube, as sketched for the left-hand coil device, the electrical connecting lines 230 can be routed along the measuring tube. If the coil devices are attached to the support body, as sketched for the right-hand coil device, the electrical connecting lines can be routed along the support body past the measuring tube.

[0034] Alternatively, the measuring sensor may, for example, have only one measuring tube, wherein a magnetic device of a respective sensor is attached, for example, to the measuring tube, and the associated coil device to the carrier body or vice versa.

[0035] If the coils are attached to the carrier body, each measuring tube per vibration sensor has a magnetic device with at least one magnet each.

[0036] The Fig. 4The different fastenings of the coil devices shown are purely demonstrative; the person skilled in the art will preferably fasten different coil devices with respect to a measuring tube either to the measuring tube or to the support body in order to enable a symmetrical oscillation behavior of the measuring tube. List of reference symbols

[0037] 1 Coil device 2 Circuit board 3 Circuit board layer 4 Coil 4.1 First coil end 4.2 Second coil end 4.3 Electrically conductive track 5 Contacting element 5.1 First contacting element 5.2 Second contacting element 6 Bore 7 Magnetic device 10 Exciter 11 Sensor 100 Measuring sensor 110 Measuring tube 111 Inlet 112 Outlet 120 Support body 131 Holding device 132 Holding element 133 Screw 134 Bore of the holding device 135 Thread of the bore of the holding device 136 Holding device body 140 Collector 141 First collector 142 Second collector 150 Process connection 151 Flange 200 Measuring device 210 Electronic measuring operating circuit 220 Electronics housing 230 Electrical Connecting lines

Claims

1. A measuring sensor (100) of a measuring device for detecting a mass flow or a density of a medium flowing through at least one measuring tube (110) of the measuring sensor, comprising: The at least one measuring tube with an inlet (111) and an outlet (112), said tube being configured to conduct the medium between the inlet and outlet; at least one exciter (10), which is configured to cause the at least one measuring tube to oscillate; at least two sensors (11), which are adapted to detect the deflection of the oscillations of at least one measuring tube; wherein at least one exciter and the sensors each have a coil device (1) with at least one coil (4) and a magnetic device, wherein the magnetic devices can be moved relative to the respective coil device, and wherein the magnetic device and the coil device of an exciter or sensor interact with one another by means of magnetic fields, wherein the coil device has a PCB (2) with at least one PCB layer (3), wherein the coil is arranged on and / or in at least one PCB layer, wherein the PCB has a first coefficient of thermal expansion, wherein the measuring sensor has a support body (120) which is adapted to hold the measuring tube in place, wherein at least one coil device of the sensors and / or the coil device of the exciter is / are in each case attached to the support body or to a measuring tube by means of a fixture (131), characterized in that the fixture is adapted to clamp the PCB in order to hold the PCB in place by means of a lateral frictional connection, wherein the PCB is mechanically connected to the fixture by means of at least one retaining element (132) of the fixture, wherein the retaining element has a second coefficient of thermal expansion, wherein the first coefficient of thermal expansion and the second coefficient of thermal expansion have less than 3*10-6 / Kelvin, and in particular less than 2*10-6 / Kelvin, and preferably less than 1.5*10-6 / Kelvin difference between them, wherein the PCB (2) is produced by a sintering process, wherein the PCB has, for example, a ceramic material, wherein the ceramic material is in particular a low-temperature co-fired ceramic.

2. The measuring sensor as claimed in claim 1, wherein the retaining element comprises at least one of the following materials: Zirconium, titanium, tantalum.

3. The measuring sensor as claimed in one of the preceding claims, wherein the first coefficient of thermal expansion is less than 9*10-6 / Kelvin, and in particular less than 8*10-6 / Kelvin, and preferably less than 7*10-6 / Kelvin.

4. The measuring sensor as claimed in one of the preceding claims, wherein the PCB is held in place by means of a screw or clamp.

5. The measuring sensor as claimed in one of the preceding claims, wherein the retaining element (132) is attached to a fixture body (136).

6. The measuring sensor as claimed in claim 4 or 5, wherein the PCB has a hole (6), in which hole a screw (133) is arranged, which engages in a thread (135) of a hole (134) in the fixture (131), wherein a pressure is exerted on the PCB by means of the screw.

7. The measuring sensor as claimed in one of the preceding claims, wherein the fixture (131) is attached to the support body (120).

8. The measuring sensor as claimed in one of the preceding claims, wherein the measuring sensor has two collectors (140), wherein a first collector (141) on an upstream side of the measuring sensor is designed to receive a medium flowing into the measuring sensor from a pipeline and to conduct it to the inlet of the at least one measuring tube, wherein a second collector (142) is adapted to receive the medium emerging from the outlet of the at least one measuring tube and to conduct it into the pipeline.

9. The measuring sensor as claimed in one of the preceding claims, wherein the measuring sensor has two process connections (150), in particular flanges (151), which are adapted to connect the measuring sensor to a pipeline.

10. A measuring device (200) comprising: A measuring sensor (100) as claimed in one of the preceding claims; an electronic measuring / operating circuit (210), wherein the electronic measuring / operating circuit is adapted to operate the sensors and the exciter and is connected to these by means of electrical connection cables (230), wherein the at least one electrical connection is routed to the electronic measuring / operating circuit by means of a cable guide, wherein the electronic measuring / operating circuit is further adapted to determine and provide measured mass flow values and / or measured density values, wherein the measuring device has, in particular, an electronics enclosure (220) to house the electronic measuring / operating circuit.