Level gauge with a movable antenna carrier

Abstract

Level measuring device for measuring the level of a fill level in a container, with which, in measuring operation, electromagnetic signals are sent into the container by means of an antenna (2) and their echo signals reflected at a fill level surface of the fill level are received after a transit time dependent on the fill level, comprising - a rod-shaped antenna support (3), wherein the antenna (2) is arranged at a first end of the antenna support (3), - a measuring electronics (4) which is arranged at a second end of the antenna carrier (3), wherein inside the antenna carrier (3) a signal line (5) is provided, via which the antenna (2) is supplied with transmitting signals from the measuring electronics (4) during measurement operation and via which the echo signals received by the antenna (3) are supplied to the measuring electronics (4), wherein the antenna support (3) has a spherical segment-shaped section (7) between the antenna (2) and the measuring electronics (4), wherein the spherical segment-shaped section (7) rotatably rests on a counter bearing (6), wherein the counter bearing (6) serves to mount the level measuring device on the container, so that the transmission direction of the antenna (2) can be changed by moving the antenna support (3), characterized by that the antenna support (3) has a flange (8) which is arranged between the measuring electronics (4) and the spherical segment-shaped section (7), and that a fixing device is provided which fixes the flange (8) of the antenna support (3) against the counter bearing (6) so that the antenna support (3) is immovable relative to the counter bearing (6).

Description

[0001] The invention relates to a level measuring device according to the preamble of claim 1.

[0002] Measuring devices for determining the fill level or limit level of a medium in a container are available in a wide variety of different designs. For example, non-contact level measuring devices are available that are based on the ultrasonic and / or radar and / or microwave principles. The level measuring devices are mounted on, in, or in the lid of the container and above the maximum expected fill level of the medium in the container. These non-contact level measuring devices send measuring signals from inside the container to the medium, at whose surface the measuring signals are reflected and returned to the measuring device. From the reflected signals and their propagation time, the distance between the medium surface and the measuring device can be determined. This, taking the geometry of the container into account, then results in the desired fill level of the medium.

[0003] A particular challenge arises with the aforementioned measuring devices for determining fill or limit levels, which are mounted on the outside of the container and whose sensors or transducers extend into the interior of the container. In order to achieve the desired measurement accuracy even with an unfavorable container shape or an unfavorable mounting position, e.g., when the measuring device is mounted on a nozzle that is tilted or obliquely arranged on the container, it is necessary to align the measuring device or measuring probe using an alignment device. This requires, particularly with liquid media, to align or position the measuring device or measuring probe in such a way that the measurement signals hit the surface of the medium to be measured as vertically or perpendicularly as possible.

[0004] In contrast, the focus, especially when measuring the level of non-liquid media such as bulk materials, is less on the extreme accuracy of the measurement and more on ensuring that the measurement signals illuminate the entire container, which is usually tapered, in order to measure the level across the entire container contents. To achieve maximum accuracy of the measuring device in containers, alignment devices are used to align the measuring device accordingly.

[0005] The utility model DE 29 622 974 U1 shows a fixing device for a rotatable antenna reflector, which is based on corresponding fixing elements.

[0006] The publications DE 10 2007 061 571 A1 and DE 10 2004 060 117 A1 each describe counter bearings for spherical segment-shaped sections on an antenna carrier, whereby the counter bearings are used to mount the level measuring device on the container with a variable transmission direction of the antenna.

[0007] DE 10 2007 061 571 A1 describes a level gauge for measuring the level of a medium in a container. During measuring operation, electromagnetic signals are transmitted into the container via an antenna, and the echo signals reflected from the surface of the medium are received after a transit time dependent on the level. The level gauge comprises an antenna carrier having a rod-shaped section. A signal line is provided inside the antenna carrier, via which the antenna is fed with transmission signals during measuring operation, and via which echo signals received by the antenna are fed to the measuring device's electronics. The rod-shaped antenna carrier has a spherical segment-shaped section that rests rotatably on a counterbearing. The counterbearing is firmly connected to a fastening device with which the level gauge is mounted on the container.The antenna is aligned by rotating the antenna support relative to the counter bearing.

[0008] The disadvantage of this type of level gauge is that the spherical segment and the counter bearing are only frictionally connected. If the measuring device electronics or antenna are heavy, or if vibration occurs, the antenna mount rotates relative to the counter bearing. This changes the antenna's preset alignment, distorting the level readings.

[0009] The invention is based on the object of specifying a radar-based level measuring device that provides reliable measurement values ​​for the level.

[0010] The object is achieved by the subject matter of the invention. The subject matter of the invention is a level measuring device for measuring the level of a filling material in a container, with which, during measuring operation, electromagnetic signals are transmitted into the container by means of an antenna and their echo signals reflected from a filling material surface are received after a propagation time dependent on the filling level, comprising - a rod-shaped antenna support, wherein the antenna is arranged at a first end of the antenna support, - a measuring electronics unit arranged at a second end of the antenna support, wherein a signal line is provided inside the antenna support, via which the antenna is fed with transmission signals from the measuring electronics unit during measuring operation, and via which echo signals received by the antenna are fed to the measuring electronics unit, wherein the antenna carrier has a spherical segment-shaped section between the antenna and the measuring device electronics, wherein the spherical segment-shaped section rests rotatably on a counter bearing, wherein the counter bearing serves to mount the level measuring device on the container so that a transmission direction of the antenna can be changed by moving the antenna carrier.

[0011] According to the invention, the antenna carrier has a flange which is arranged between the measuring device electronics and the spherical segment-shaped section, and a fixing device is provided which fixes the flange of the antenna carrier against the counter bearing, so that the antenna carrier is immovable relative to the counter bearing.

[0012] A fixing device that secures the flange of the antenna support against the counterbearing creates a force-locking connection between the antenna support and the counterbearing in addition to the frictional connection. This restricts the antenna support in all of its remaining degrees of freedom.

[0013] According to a favorable embodiment, the fixing device comprises at least three separate fixing elements. The fixing elements can be screws, spacers, or other elements suitable for fixing the flange to the counterbearing.

[0014] According to an advantageous embodiment, at least one of the fixing elements and the counter-bearing have, at least in part, such a high surface roughness on their contact surfaces that a positive connection is created at the contact surface. Preferably, the fixing devices and the counter-bearing are made of the same material.

[0015] According to an advantageous development, a sealing element, in particular an O-ring, is arranged between the spherical segment-shaped section and the counterbearing. The sealing element can be made of metal or plastic.

[0016] The object of the invention is also achieved by the subject matter of a method. The subject matter of the method is a method for adjusting a level measuring device according to at least one of the preceding claims, wherein the antenna carrier is aligned with respect to the counter support such that a transmission direction of the antenna is arranged perpendicular to the surface of the filling material.

[0017] The invention is explained in more detail with reference to the following drawings. It shows: Fig. 1: a side view of a level measuring device according to the invention, and Fig. 2: a longitudinal section of a level measuring device according to the invention corresponding Fig. 1.

[0018] Fig. Figure 1 shows a side view of a level measuring device 1 according to the invention. The level measuring device 1 has a rod-shaped antenna support 3. An antenna 2 is arranged at a first end of the rod-shaped antenna support 3, wherein the antenna 2 is a radar antenna. Measuring device electronics 4 are arranged at a second end of the rod-shaped antenna support 3, wherein the measuring device electronics 4 is suitable for determining the level.

[0019] Between the measuring device electronics 4 and the antenna 2, the level measuring device 1 has a first disc 10 and a second annular disc 13. The first disc 10 and the second disc 13 are arranged side by side, with the first disc 10 having a plurality of holes 11 through which the level measuring device 1 can be attached to a container (not shown).

[0020] Between the first disc 10 and the measuring device electronics 4, the antenna carrier 3 has a flange 8. Three fixing elements 12, which are designed as screws, fix the flange 8 of the antenna carrier 3 against the second disc 13 of the level measuring device 1. The screws each have a screw nut 15, which firmly fastens the respective screw against the flange 8.

[0021] Fig. 2 shows a longitudinal section of a level measuring device according to the invention according to Fig.1. A signal line 5 is arranged inside the antenna carrier 3, which electrically connects the antenna 2 and the measuring device electronics 4. Between the antenna 2 and the measuring device electronics 4, the antenna carrier 3 has a spherical segment-shaped section 7. Furthermore, the second disc 13 is fastened to the first disc 10 by means of fastening screws 14. The first and second discs 10, 13 are hollowed out centrally to match the surface of the spherical segment-shaped section 7, so that they form a counter-bearing 6 for the spherical segment-shaped section 7.

[0022] A sealing element, which is designed as an O-ring 16, is arranged between the counter bearing 6 and the spherical segment-shaped section 7 of the antenna carrier 3 so that the filling material cannot escape from the container.

[0023] The screw-shaped fixing elements 12 each have a screw head 17. The end faces of the fixing elements 12 facing away from the screw heads 17 have a surface roughness that corresponds to the surface roughness of the second disk 13. This results in a force-locking connection between the fixing elements 12 and the second disk 13, whereby the antenna support 3 and thus the antenna 2 are better protected against misalignment.

[0024] The spherical segment-shaped section 7 of the antenna support 3 and the counter bearing 6 together form a ball joint, which means that the antenna support 3 can be rotated about a specific point. The level gauge is adjusted by aligning the antenna support 3 such that a transmission direction of the antenna 2 is perpendicular to the surface of the filling material in the container (not shown). By attaching the fixing elements 12, a force-locking connection is created between the flange 8 of the antenna support 3 and the second disk 13, whereby the transmission direction of the antenna 2 no longer changes. Furthermore, the fixing elements 12 can be used to finely adjust the transmission direction of the antenna 2. List of reference symbols 1 level measuring device 2 antenna 3 antenna supports 4 Measuring device electronics 5 Signal line 6 counter bearings 7 spherical segment-shaped section 8 Flange 9 Fixing device 10 First Disc 11 holes 12 Fixing element 13 Second disc 14 fastening screws 15 screw nuts 16 O-ring 17 Screw head

Claims

[1] Level measuring device for measuring a filling level of a filling material in a container, with which, in measuring operation, electromagnetic signals are sent into the container by means of an antenna (2) and their echo signals reflected on a filling material surface of the filling material are received after a running time dependent on the filling level, comprising - a rod-shaped antenna support (3), wherein the antenna (2) is arranged at a first end of the antenna support (3), - a measuring electronics unit (4) arranged at a second end of the antenna carrier (3), wherein a signal line (5) is provided inside the antenna carrier (3), via which the antenna (2) is fed with transmission signals from the measuring device electronics (4) during measuring operation and via which the echo signals received by the antenna (3) are fed to the measuring device electronics (4), wherein the antenna carrier (3) has a spherical segment-shaped section (7) between the antenna (2) and the measuring device electronics (4), wherein the spherical segment-shaped section (7) rests rotatably on a counter bearing (6), wherein the counter bearing (6) serves to mount the level measuring device on the container, so that a transmission direction of the antenna (2) can be changed by moving the antenna carrier (3), characterized by , that the antenna carrier (3) has a flange (8) which is arranged between the measuring device electronics (4) and the spherical segment-shaped section (7), and that a fixing device is provided which fixes the flange (8) of the antenna support (3) against the counter bearing (6) so that the antenna support (3) is immovable relative to the counter bearing (6). [2] Level measuring device according to claim 1, wherein the fixing device comprises at least three separate fixing elements (12). [3] Level measuring device according to claim 2, wherein at least one of the fixing elements (12) and the counter bearing (6) have at least partially on their contact surfaces such a great surface roughness that a positive connection is created on the contact surface. [4] Level measuring device according to at least one of the preceding claims, wherein a sealing element, in particular an O-ring (16), is arranged between the spherical segment-shaped section (7) and the counter bearing (6). [5] Method for adjusting a level measuring device according to at least one of the preceding claims, wherein the antenna carrier (3) is aligned with respect to the counter support (6) such that a transmission direction of the antenna (2) is arranged perpendicular to the filling material surface of the filling material.

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