Fill level measuring device

Abstract

The invention relates to a modular radar level measurement device (1) which can be produced compact. For this purpose, the high-frequency modules (11, 12, 120) of the radar level measurement device according to the invention are biased within the device housing (131) by means of spring elements (130, 133) such that the waveguide sections (120) of the high-frequency modules (11, 12, 120) press against corresponding high-frequency connections (100) of the antenna arrangement (10) with a corresponding force. Thereby, a gap-free and thus low-interference connection of the high-frequency modules (11, 12, 120) to the antenna arrangement (10) by means of the waveguide sections (100, 120) is ensured. This simplifies the modular design of the level measurement device (1). In this case, in particular in the case that the high-frequency modules (11, 12, 120) are accommodated towards the antenna arrangement (10) into a measurement device neck (131) of the device housing (13), the level measurement device (1) can be produced very compact.

Description

Technical Field

[0001] This invention relates to a compact, modular material level measuring device. Background Technology

[0002] In process automation, corresponding field devices are used to capture relevant process parameters. To obtain these parameters, appropriate measurement principles are implemented in the field devices to acquire information such as fill level, flow rate, pressure, temperature, pH value, redox potential, or conductivity as process parameters. Endress+Hauser manufactures and sells a variety of such field devices.

[0003] Non-contact measurement methods have been developed for measuring the fill level of materials in containers because they are robust and require minimal maintenance. Another advantage of non-contact measurement methods is their ability to measure fill level quasi-continuously. Therefore, radar-based measurement methods are primarily used in the field of continuous fill level measurement (in the context of this patent application, the term "radar" refers to signals or electromagnetic waves with frequencies between 0.03 GHz and 300 GHz). One established measurement method is FMCW ("Frequency Modulated Continuous Wave"). For example, an FMCW-based fill level measurement method is described in published patent application DE 10 2013 108 490 A1.

[0004] In principle, the antenna of a radar-based level measurement device will be attached to the container interior in direct contact, as there is no radar-impenetrable barrier between the antenna and the packing material. In contrast, the electronic modules of the level measurement device—such as a dedicated high-frequency radar module for high-frequency signal generation—and other units for data processing and transmission are housed in a separate enclosure outside the container. This is because spatial separation between the active module—i.e., the powered module—and the passive antenna is typically required primarily for explosion protection purposes. For this purpose, the enclosure includes a neck through which the antenna is mechanically connected. In this case, a corresponding explosion-proof barrier facing the antenna is arranged in the neck. In addition to or as an alternative to explosion protection requirements, the neck may need to provide further protective functions. Depending on the application, high temperature, high pressure, or hazardous gases may dominate inside the container. Therefore, depending on the application, the neck must act as a pressure seal, temperature barrier, and / or media seal.

[0005] To enable the device housing and its embedded (interface) module to function not only in level measurement equipment but also as a platform for other types of field equipment, and to allow for a more compact overall design, a high-frequency module specifically designed for radar-based level measurement equipment could be housed within the neck of the measuring device. However, due to specific thermal insulation and explosion-proof requirements, the space constraints in the neck of the measuring device are extremely limited. Therefore, it is difficult to accommodate a radar-specific high-frequency module within the neck. Especially in the case of a modular design, the connection from the high-frequency module to the antenna assembly is also challenging, as the connection must be designed to be releasable, and any plug connections between corresponding waveguide sections increase the risk of high-frequency interference. Summary of the Invention

[0006] Therefore, the object of the present invention is to provide a compact, modular material level measuring device.

[0007] This invention achieves this objective by means of a radar-based level measuring device for determining the filling level in a container, and includes the following components:

[0008] - An antenna device, controllable via a high-frequency connector, by means of which radar signals can be transmitted toward the filling material in each case, and by means of which the corresponding received signal can be received in each case after the radar signal is reflected from the surface of the filling material.

[0009] - High-frequency module, which includes:

[0010] The o-transmitter / receiver unit is designed to generate radar signals according to a defined measurement principle, and after the radar signals are reflected off the surface of the filling material, to determine the filling level based on the corresponding received signal according to the implemented measurement principle. It also includes:

[0011] An electronic package containing a transmitting / receiving unit, wherein the transmitting / receiving unit and a second waveguide section are enclosed within the electronic package for explosion protection by potting up to the feedthrough section, and includes:

[0012] The second waveguide section, for transmitting radar signals, is connected to the transmit / receive unit, thus guiding the second waveguide section out of the electronic package.

[0013] - The equipment housing, adjacent to the antenna assembly, and the high-frequency module is arranged within the equipment housing, or the high-frequency module is arranged within the measuring equipment neck of the equipment housing, and

[0014] - A spring element that biases the high-frequency module or electronic package against the device housing or neck of the measuring device, such that the guided second waveguide segment presses against the high-frequency connector with a corresponding force in the direction of the common waveguide axis.

[0015] The spring element according to the invention ensures a gapless and therefore low-interference connection between the high-frequency module and the antenna device via the waveguide section or corresponding high-frequency connector, resulting in a simplified modular design of the level measuring equipment. In this case, particularly when the high-frequency connector and waveguide section are designed as hollow conductors, HF interference sensitivity is reduced through compression. In this case, the principle of compressing the waveguide section according to the invention can also be applied if a bidirectional form-fitting electrical isolator is arranged between the high-frequency connector and the waveguide section to electrically decouple the antenna device.

[0016] The compression of the electronic module according to the invention is particularly advantageous when the equipment housing includes the neck of the measuring device as a thermal decoupling towards the antenna device. In this case, the high-frequency module to be connected to the antenna device can be arranged in the neck of the measuring device under the bias according to the invention. On the one hand, this saves space in the actual equipment housing. On the other hand, this design minimizes the length of the high-frequency path between the antenna device and the high-frequency module, thereby further reducing HF interference sensitivity within the filler level measurement range.

[0017] In the context of this invention, there is no fixed specification regarding whether the high-frequency module or its waveguide section is pressed against the high-frequency connector by the spring element under pressure or tension. Therefore, the spring element can be designed as a compression spring or a tension spring. If the spring element is designed as a compression spring, it will be positioned on the outer side of the electronic package opposite the waveguide section for biasing the high-frequency module within the device housing or measurement device neck. If the spring element is designed as a tension spring, it will be positioned on the outer side of the electronic package facing the waveguide section for biasing the high-frequency module within the device housing or measurement device neck. Depending on the design, the spring element can therefore be designed as, for example, one or more wave springs, helical springs, or disc springs.

[0018] To enable simple and safe insertion of high-frequency modules into the equipment housing or measuring device neck during manufacturing, a level measuring device can be designed with at least one such guiding element, allowing the high-frequency module to be guided within the equipment housing or measuring device neck along the common waveguide axis of the high-frequency connector or waveguide section. This ensures that the waveguide section precisely mates with the high-frequency connector during installation.

[0019] Within the scope of this invention, the terms "unit" or "module" are generally understood to mean any electronic circuit suitably designed for its intended purpose—e.g., for high-frequency generation or as an interface. Depending on the need, the corresponding unit may therefore be an analog circuit for generating or processing a corresponding analog signal. However, the unit may also be a digital circuit (such as an FPGA) or a storage medium that interacts with a program. In this case, the program is designed to perform corresponding method steps or apply the necessary computational operations of the corresponding unit. In this context, for the sense of this invention, various electronic units or modules of the measuring device can also potentially access a common physical memory or operate by means of the same physical digital circuitry. Specifically, a transmit / receive unit for controlling an antenna device via a waveguide can be based on, for example, the FMCW method or the pulse propagation time method. Attached Figure Description

[0020] The invention will be explained in more detail with reference to the following figures. In the figures:

[0021] Figure 1 A radar-based level measurement device on a container is shown.

[0022] Figure 2 A cross-sectional view of the material level measuring device according to the present invention is shown, and

[0023] Figure 3 A detailed view of the level measuring device in the waveguide section is shown. Detailed Implementation

[0024] To gain a basic understanding of radar-based filler level measurement, Figure 1 A container 3 with filling material 2 is shown, and its filling level L will be determined. Depending on the type of filling material 2 and the application field, container 3 can reach a height of over 100m. The conditions inside container 3 also depend on the type of filling material 2 and the application field. For example, in the case of an exothermic reaction, high temperature and high pressure loads will occur. In the case of dust or flammable substances, the interior of the container must maintain corresponding explosion-proof conditions.

[0025] To determine the filling level L independently of primary conditions, a radar-based level measuring device 1 is attached to the container 3 at a known mounting height h above the filling material 2. In this case, the level measuring device 1 is fastened to the corresponding (flange) opening of the container 3, or aligned such that the antenna device 10 of the level measuring device 1 is perpendicularly pointed into the container 3 and towards the filling material 2. The remaining housing 13 of the level measuring device 1, which houses the electronic components 11, is arranged outside the container feed passage. Because the electronic components 11 in the housing 13 are separated from the antenna device 10 or the space inside the container via the measuring device neck 131, explosion protection within the container 3 is ensured. Furthermore, the electronic components 10 in the housing 13 or the measuring device neck 131 are protected from temperature and pressure loads from inside the container. Figure 1 and Figure 2 As shown, the neck 131 of the measuring device has corresponding cooling ribs for thermal decoupling of the device housing 13.

[0026] Due to its arrangement on container 3, the level measuring device 1 can transmit radar signals S vertically in the direction of the surface of the filling material 2 via antenna device 10. HF After being reflected off the surface of the filling material, the level measuring device 1 receives the reflected radar signal R again via the antenna device 10. HF In this situation, the corresponding radar signals S are sent and received. HF R HF The signal transmission time is proportional to the distance d between the level measuring device 1 and the filling material 2, wherein the signal transmission time can be determined by the level measuring device 1, for example, using the FMCW method or the pulse transmission time method. Therefore, the level measuring device 1 can, for example, allocate the measured transmission time to the corresponding distance d based on the corresponding calibration. Thus, provided the installation height h is stored in the level measuring device 1, the level measuring device 1 can again determine the filling level L according to the following formula.

[0027] d = hL

[0028] Typically, the level measuring device 1 is connected to a higher-level unit 4, such as a process control system, via an interface module—such as "PROFIBUS," "HART," or "Wireless HART"—residing in the device housing 13. In this way, the fill level value L can be transmitted, for example, to control the inflow or outflow of the container 3 when necessary. However, other information about the general operating status of the level measuring device 1 can also be transmitted.

[0029] like Figure 2As shown, the antenna device 10 within the level measuring device 1 is controlled by high-frequency modules 11, 12, and 120 via high-frequency technology. In the corresponding transmit / receive units 11 of the high-frequency modules 11, 12, and 120, the FMCW method or pulse propagation time measurement principle is implemented, for example, based on the incoming received signal R. HF To determine the signal transmission time. Furthermore, the transmit / receive unit 11 is used to generate the radar signal S to be transmitted. HF Therefore, in the illustrated embodiment variant, the transmit / receive unit 11 is arranged within the neck 131 of the measuring device on the side of the circuit board facing the antenna assembly 10, for example as a monolithically packaged SMD component.

[0030] The circuit board, together with the transmitter / receiver unit 11, is surrounded by an electronic package 12 of the high-frequency modules 11, 12, 120. The electronic package 12 can be made of plastics such as PC, PE, PP, or PA. This allows for the use of potting compounds (in...) for explosion-proof purposes. Figure 2 (Not explicitly shown) The circuit board is additionally packaged together with the transmit / receive unit 11. On the other hand, according to the invention, coupling from the transmit / receive unit 11 to the antenna device 10 is made possible by means of high-frequency modules 11, 12, 120. For this purpose, in Figure 2 In the illustrated embodiment variant, the antenna device includes a straight hollow conductor section 100 as a high-frequency connector 100, through which high-frequency modules 11, 12, and 120 can contact the antenna device 10 via high-frequency technology.

[0031] In order to transmit radar signal S from or to the transmitter / receiver unit 11 HF R HF Similarly, a straight hollow conductor segment 120 is assigned to the high-frequency modules 11, 12, and 120. This hollow conductor segment 120 extends orthogonally from the transmitter / receiver unit 11 toward the high-frequency connector 100 relative to the circuit board in the fully assembled state of the level measuring device 1. In this case, the hollow conductor segment 120 is fastened to the feedthrough portion 121 of the electronic package 12 via a threaded connector 122, allowing the hollow conductor segment 120 to be guided to the outside through the wall of the electronic package 12. For this purpose, the hollow conductor segment 120 has external threads aligned on the hollow conductor axis a around the cavity, allowing the hollow conductor segment 120 to be fastened to the electronic package 12 from the outside by corresponding nuts, such as... Figure 2 As shown. Instead of Figure 2 The threaded connector 122 shown, and the hollow conductor section 120, can also be correspondingly fastened to the feedthrough of the electronic package 12 by alternative fasteners—for example, by means of a pin.

[0032] Furthermore, the circuit board is mounted on the hollow conductor section 120 by means of at least one fastening device, on which the transmitting / receiving unit 11 is arranged within the electronic package 12. In this case, the fastening device can be an adhesive connector or a pin or threaded connector. Therefore, the circuit board or the transmitting / receiving unit 11 is self-supporting within the electronic package 12. That is, as a result of indirect fixation via the hollow conductor section 120, the transmitting / receiving unit 11 does not need to be directly fixed to the electronic package 12. As a result, the circuit board and therefore the electronic package 12 can be designed to be very compact overall, simplifying the accommodation of the high-frequency modules 11, 12, 120 in the neck 131 of the measuring device.

[0033] like Figure 2 As shown, in addition to the transmitter / receiver unit 11, additional circuit boards 15 can be arranged within the electronic package 12 of the high-frequency modules 11, 12, and 120. As shown, these additional circuit boards can be electrically connected to the circuit board on which the transmitter / receiver unit 11 is arranged, for example, by means of a mechanically flexible cable bundle. In this case, to manufacture the high-frequency modules 11, 12, and 120, the transmitter / receiver unit 11 and any additional circuit board 15 can be inserted from the side of the electronic package 12 away from the feedthrough portion 121 by means of an assembly aid designed as the negative side of the transmitter / receiver unit 11 or the additional circuit board 15.

[0034] In the assembled state, once the high-frequency modules 11, 12, and 120 are inserted into the neck 131 of the measuring device, the high-frequency connector 100, designed as a hollow conductor, and the hollow conductor sections 120 of the high-frequency modules 11, 12, and 120 are adjacent to each other in such a precise fit (or the high-frequency connector 100 and the hollow conductor sections 120 are respectively adjacent to the electrical isolation components 140 arranged between them in such a precise fit), so that the hollow conductor sections 100 and 120 form a common hollow conductor axis a. Therefore, the radar signal S is realized. HF Lossless transmission between antenna device 10 and transmit / receive unit 11. Therefore, in Figure 2 In the illustrated embodiment variant, the high-frequency modules 11, 12, and 120 are designed such that, during insertion into the neck 131 of the measuring device, the electronic package 12 is guided accordingly (from the end region away from the antenna device 10) in the direction of the hollow conductor axis a of the hollow conductor sections 100 and 120. For this purpose, corresponding guiding elements 14 are formed radially symmetrically around the second hollow conductor section 120 in the extension portion of the electronic package 12—corresponding to the inner wall of the neck 131 of the measuring device.

[0035] Made of plastic or ceramic and Figure 2The optional electrical isolator 140 shown is used to electrically decouple the antenna assembly 10 from other electronic components in the transmit / receive unit 11 or the device housing 13. For this purpose, the electrical isolator 140 is arranged in a precise fit between the high-frequency connector 100 and the hollow conductor section 120, wherein the electrical isolator 140 is made of an electrically insulating material such as ceramic or plastic and has a feedthrough corresponding to the internal cross-section of the hollow conductors 100, 120.

[0036] To ensure that the high-frequency connector 100 of the antenna device 10 and the hollow conductor segment 120 of the high-frequency modules 1, 12, 120 are adjacent to each other or adjacent to the electrical isolator 140 without gap when the electronic package 12 is inserted, according to the present invention, the spring element 130, guided by the guide element 14, presses the electronic package from inside the neck 131 of the measuring device toward the antenna device 10, so that the hollow conductor segment 120 is pressed against the hollow conductor of the high-frequency connector 100 with a corresponding spring force. This, in turn, ensures lossless signal transmission. Figure 2 In the illustrated embodiment variant, the spring element 130 is designed as a wave spring. In this case, the wave spring 130 is clamped within the neck 131 of the measuring device between the groove or locking ring 132 and the outer side of the electronic package 12 opposite to the hollow conductor section 120.

[0037] and Figure 2 Compared to the variant of the embodiment shown, alternatively, it is conceivable to design spring elements 130, 133 as tension springs 133 and clamp spring elements 130, 133 in the device neck 131 between the antenna assembly 10 and the electronic package 12, so as to pull the second waveguide segment 120 toward the first waveguide segment 100 with a corresponding spring force. This fixing possibility of the high-frequency modules 11, 12, 120 according to the invention is... Figure 3 As shown in the embodiment therein, the spring ring 133 is positioned on the outside of the electronic package 12 at the feed position of the hollow conductor section 120. In this case, the spring ring 133 is designed to press against the guide element 14 of the electronic package 12 from the inside when the high-frequency modules 11, 12, 120 are inserted into the neck 131 of the measuring device, such that the annular outward rolled edge of the guide element 14 engages outward in the corresponding groove of the neck 131 of the measuring device. In this case, the position of the spring ring 133, the position of the outward rolled edge, and the position of the groove are chosen to be downward so that the hollow conductor section 120 is pressed against the high-frequency connector 100 of the antenna assembly 10 with a defined tensile stress and without gaps.

[0038] Regardless of whether the spring elements 130 and 133 are designed as tension springs 133 or compression springs 130, in addition to the gapless seal between the hollow conductors 100 and 120, clamping also results in the electronic package 12 being fixed within the neck 12 of the measuring device. In this case, according to the invention, if the electronic package 12 is directly housed in the device housing 13, the hollow conductor section 120 can also be pressed against the high-frequency connector 100. This is possible if the device housing 13 of the level measuring device 1 does not include the measuring device neck 131, or if the high-frequency connector 100, in the shape of a hollow conductor, extends through the entire measuring device neck 131. Furthermore, if the individual hollow conductor sections 100 and 120 are not designed as hollow conductors, but rather as dielectric waveguides, for example, the pressing of the individual hollow conductor sections 100 and 120 according to the invention can also be achieved.

[0039] List of reference numerals

[0040] 1. Material level measuring equipment

[0041] 2. Filling material

[0042] 3 containers

[0043] 4. Upper-level unit

[0044] 10-antenna device

[0045] 11 Transmit / Receive Units

[0046] 12 Electronic Packaging

[0047] 13 Equipment casing

[0048] 14. Guiding elements

[0049] 15 Circuit Boards

[0050] 100 High-frequency connectors

[0051] 120 waveguide section

[0052] 121 Feedthrough section in electronic packaging

[0053] 122 Threaded fasteners

[0054] 130 Spring Element

[0055] 131 Measuring equipment neck

[0056] 132 Locking Ring

[0057] 133 Spring Ring

[0058] 140 Electrical Isolation Components

[0059] a waveguide axis

[0060] d Distance

[0061] h Installation height

[0062] L Filling level

[0063] R HF Reflected radar signals

[0064] S HF radar signals

Claims

1. A radar-based level measuring device for determining the level (L) of filler material (2), comprising the following components: - Antenna device (10), said antenna device being controllable via high-frequency connector (100), and o Using the antenna device (10), the radar signal (S) HF ) can be sent toward the filling material (2) in each case, and o Using the antenna device (10), the radar signal (S) HF After being reflected off the surface of the filling material, the received signal (R) HF It can be received in every situation. - High-frequency modules (11, 12, 120), the high-frequency modules comprising: o Transmit / receive unit (11), the transmit / receive unit being designed to generate the radar signal (S HF ), and in the radar signal (S HF After being reflected on the surface of the filling material, the corresponding received signal (R) is used to... HF Determining the filler level (L) includes: o Electronic package (12), in which the transmitting / receiving unit (11) is arranged, and includes: o The second waveguide section (120) is for transmitting radar signals (S HF R HF The second waveguide segment (120) is connected to the transmitting / receiving unit (11), such that the second waveguide segment (120) is guided out of the electronic package (12). - A device housing (13), which is connected to the antenna device (10), and the high-frequency modules (11, 12, 120) are arranged in the device housing (13), and - Spring elements (130, 133), the high-frequency modules (11, 12, 120) are biased against the device housing (13) by means of the spring elements (130, 133), such that the waveguide section (120) presses against the high-frequency connector (100) with a corresponding force in the direction of the common waveguide axis (a).

2. The material level measuring device according to claim 1, wherein, The spring elements (130, 133) are designed as compression springs (130), which are arranged in the device housing (13) on the outer side of the electronic package (12) opposite to the waveguide section (120) for biasing the high-frequency modules (11, 12, 120).

3. The material level measuring device according to claim 1, wherein, The spring elements (130, 133) are designed as tension springs (133), which are arranged inside the device housing (13) on the outer side of the electronic package (12) facing the waveguide section (120) for biasing the high-frequency modules (11, 12, 120).

4. The material level measuring device according to any one of claims 1-3, wherein, The spring elements (130, 133) are designed as wave springs (130), helical springs, disc springs and / or spring rings (133).

5. The material level measuring device according to any one of claims 1-3, wherein, The device housing (13) is connected to the antenna device (10) via the measuring device neck (131), and the high-frequency modules (11, 12, 120) are arranged in the measuring device neck.

6. The material level measuring device according to any one of claims 1-3, wherein, At least the transmitting / receiving unit (11) is encapsulated within the electronic package (12) by means of potting.

7. The material level measuring device according to claim 5, comprising: - At least one guiding element (14) is designed to guide the high-frequency module (11, 12, 120) along the common waveguide axis (a) within the device housing (13) or within the neck (131) of the measuring device.

8. The material level measuring device according to any one of claims 1-3, wherein, The high-frequency connector (100) and the second waveguide segment (120) are designed as hollow conductors.

9. The material level measuring device according to any one of claims 1-3, wherein, A bidirectional form-fitted electrical isolator (140) is disposed between the high-frequency connector (100) and the waveguide section (120).

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