OPTICAL LEVEL GAUGE

Description

Field of the invention

[0001] The invention relates to fill level measurement. In particular, the invention relates to an optical fill level measuring device configured for measuring a fill level of a medium through the container wall of a plastic container, multiple uses of an optical distance sensor, a fill level measuring arrangement for measuring a fill level of a medium through the container wall of a plastic container, a method for measuring a fill level of a medium through the wall of a plastic container, a program element, and a computer-readable medium. Technical area

[0002] Non-contact level sensors are often used to detect the level or limit of a medium in a container, particularly for process automation in industrial environments. These are typically radar level sensors installed in an opening in the container. These level sensors transmit measurement signals toward the product surface or the container bottom, which are then reflected and received by the product surface and / or the container bottom. The level can be calculated based on the travel time of the measurement signal from the level sensor to the product surface and back.

[0003] The installation of the level sensor usually requires an opening in the container into which the sensor can be screwed or otherwise fastened.

[0004] WO 2019 / 115996 A1 describes a transmission measuring system for measuring transmission through a container wall.

[0005] DE 10 2018 102 366 A1 describes a level measuring device with a radar module for emitting a radar signal in the direction of the filling material to determine a distance to the surface of the filling material based on the reflected radar signal and a 3D camera for recording at least one area of ​​the surface of the filling material. Summary

[0006] It is an object of the present invention to provide a level measuring device which can be used in a simple manner for different containers and which provides reliable, accurate measuring results.

[0007] This object is achieved by the features of the independent patent claims. Further developments of the invention emerge from the subclaims and the following description of embodiments.

[0008] A first aspect of the invention relates to a level measuring device, in particular an optical level measuring device, which is designed to measure a level of a medium or filling material through the container wall of a plastic container.

[0009] The level gauge comprises an optical distance sensor configured to emit a light signal through the container wall toward the product surface and to receive the light signal reflected from the product surface, also through the container wall. In other words, the optical level gauge is configured to measure the fill level or limit level through the container wall. Therefore, it does not need to be installed in an opening of the container or inside the container. In particular, the container does not need to have an opening.

[0010] The level measuring device has an evaluation device which is designed to determine the fill level or the limit level of the medium in the plastic container by evaluating the received light signal (which has passed through the container wall twice, once on the outward path and once on the return path).

[0011] The level gauge is designed specifically for use with small plastic containers and process automation in industrial environments. It measures through the wall of the plastic container. In particular, it is capable of clearly detecting the limiting cases "container completely full" and "container completely empty."

[0012] According to a further embodiment, the level measuring device comprises a radar sensor configured to transmit a radar signal through the container wall toward the product surface and to receive the radar signal reflected from the product surface, also through the container wall. The evaluation device is configured to determine the fill level or limit level of the medium in the plastic container by evaluating the received radar signal and / or evaluating the received light signal.

[0013] In particular, it can be provided that the received light signal is used to interpret the measurement result of the radar sensor, for example to verify whether the measurement has produced a correct result or to decide whether the container is completely full or completely empty.

[0014] According to a further embodiment, the evaluation device is configured to first evaluate the received radar signal and, if this evaluation is ambiguous, to evaluate the received light signal.

[0015] Such ambiguity can arise when the container is completely full or empty. In this case, the radar sensor only detects the bottom echo and, if applicable, an echo from the upper container wall through which the radar signal is transmitted. The optical distance sensor provides additional information that makes it possible to clearly determine whether the container is empty or full.

[0016] According to a further embodiment of the present disclosure, the evaluation device is configured to first carry out the evaluation of the received radar signal and, only if this evaluation is ambiguous, to carry out a measurement with the optical distance sensor and to carry out the evaluation of the received light signal.

[0017] This saves energy and computing power because the optical distance sensor is only activated and used under certain circumstances.

[0018] According to a further embodiment, the light signal of the optical distance sensor is a laser signal.

[0019] According to a further embodiment, the optical level measuring device has a housing in which both the optical distance sensor and the radar sensor are housed. It is thus a single, integrated measuring device. The housing can, for example, be a plastic housing made of a similar material to the plastic container.

[0020] According to a further embodiment, the optical level measuring device has a radio communication interface (wireless interface) configured to transmit the measured value and / or other data to an external computing unit, for example, a cloud or a mobile user device such as a smartphone. The radio communication interface can be the sole interface for external communication. However, a wired or additional radio communication interface can also be provided, for example, to use a different transmission protocol.

[0021] According to a further embodiment, the optical level measuring device is configured as a self-sufficient level measuring device, without external power supply.

[0022] According to a further embodiment, the optical level gauge is designed to be glued to the outside of the plastic container, for example, using an adhesive film or a magnetic connection. In the latter case, a magnetic plate can be glued to the outside of the plastic container.

[0023] Another aspect of the present disclosure relates to the use of an optical distance sensor for interpreting the measurement result of a radar sensor.

[0024] Another aspect of the present disclosure relates to the use of an optical distance sensor in a radar level gauge.

[0025] A further aspect of the present disclosure relates to a fill level measuring arrangement for measuring a fill level of a medium through the container wall of a plastic container. The fill level measuring arrangement comprises an optical fill level measuring device, as described above and below, with an optical distance sensor, as well as an evaluation device, as described above and below, configured to determine a fill level or to detect a limit level of the medium in the plastic container by evaluating the received light signal from the optical fill level measuring device. Furthermore, the fill level measuring arrangement comprises a plastic container, to the outside of which the optical fill level measuring device is attached.

[0026] A further aspect of the present disclosure relates to a method for measuring the fill level of a medium through the container wall of a plastic container, in which a light signal is first emitted through the container wall toward the filling material surface or the container bottom, and the reflected light signal is received again. It has thus passed through the container wall twice. The fill level or limit level of the medium in the plastic container is then determined by evaluating the received light signal. In particular, the received light signal can be used to decide whether the container is completely full or completely empty.

[0027] A further aspect of the present disclosure relates to a program element which, when executed on an evaluation device of a level measuring arrangement, instructs the level measuring arrangement to carry out the method steps described above and below.

[0028] Another aspect of the present disclosure relates to a computer-readable medium on which a program element described above is stored.

[0029] The term "process automation in industrial environments" can be understood as a branch of technology that involves measures for operating machines and systems without human intervention. One goal of process automation is to automate the interaction of individual components of a plant in the chemical, food, pharmaceutical, petroleum, paper, cement, shipping, or mining industries. A variety of sensors can be used for this purpose, each of which is specifically adapted to the specific requirements of the process industry, such as mechanical stability, resistance to contamination, extreme temperatures, and extreme pressures. Measured values ​​from these sensors are typically transmitted to a control room, where process parameters such as fill level, limit level, flow, pressure, or density are monitored, and settings for the entire plant can be changed manually or automatically.

[0030] One sub-area of ​​process automation in the industrial environment concerns logistics automation. With the help of distance and angle sensors, processes inside or outside a building or within a single logistics facility are automated in the field of logistics automation. Typical applications for logistics automation systems include baggage and freight handling at airports, traffic monitoring (toll systems), retail, parcel distribution, and building security (access control). What the above examples have in common is that the respective application requires presence detection in combination with precise measurement of the size and position of an object. Sensors based on optical measuring methods using lasers, LEDs, 2D cameras, or 3D cameras that measure distances according to the time-of-flight (ToF) principle can be used for this purpose.

[0031] Another sub-area of ​​process automation in the industrial environment concerns factory / production automation. Applications for this can be found in a wide variety of industries, such as automotive manufacturing, food production, the pharmaceutical industry, and packaging in general. The goal of factory automation is to automate the production of goods using machines, production lines, and / or robots, i.e., to run it without human intervention. The sensors used here and the specific requirements regarding measurement accuracy for detecting the position and size of an object are comparable to those in the previous example of logistics automation.

[0032] Embodiments of the present disclosure are described below with reference to the figures. Where the same reference numerals are used in the following description of the figures, they denote identical or similar elements. The representations in the figures are schematic and not to scale. Short description of the characters

[0033] Fig. 1 shows an optical level measuring device according to one embodiment. Fig. 2A, Fig. 2B and Fig. 2C show three measurement curves at different fill levels. Fig. 3 shows a flowchart of a method according to an embodiment. Detailed description of embodiments

[0034] Fig. 1shows an optical level measuring device 100, which can determine the fill level or limit level of a medium in a plastic container from the outside by sending the radar signal of the radar sensor 103 and the light signal of the optical distance sensor 101 through the wall of the plastic container, being reflected by the filling material and then running through the wall back into the measuring device, where they are detected.

[0035] The optical distance sensor 101 and the radar sensor 103 are located within the same housing 104, for example, a plastic housing. They are both connected to the evaluation unit 102. The electronics within the measuring device are powered by the energy storage unit 110.

[0036] A radio communication interface 105 is provided, via which measurement data can be transmitted to the external device 106. The external device 106 can send parameterization data or control data to the measuring device 100. The external device 106 can be an external control unit, a mobile device such as a smartphone, or a cloud-based system.

[0037] The autonomous radar sensor 103 measures through the wall of the plastic container, and the measuring device can transmit the measured value to the cloud. Particularly with low containers, typically less than 1 m high and a low dielectric constant of the medium, such as oil, the echo curves obtained from the radar measurement may not provide a clear fill level. Depending on the configuration, it may no longer be possible to distinguish between the states "container completely empty" and "container completely full." In addition to the radar sensor 103, an optical distance sensor 101, for example, a laser rangefinder, is integrated into the level measuring device 100. This optical distance sensor also measures through the plastic container. This is possible because the plastic container is, for example, a semi-transparent IBC container made of HDPE material.Although the measurement result of the optical distance sensor 101 can be distorted by the container wall, the fill level is detected with sufficient accuracy to achieve a clear measurement result in combination with the radar measurement.

[0038] The optical level gauge 100 is mounted on an IBC container, for example. This is shown in the Fig. 2A, 2B and 2C The level measuring device 100 measures through the container wall. Both the light signal from the distance sensor and the radar signal from the radar sensor are reflected by the filling material surface 202 of the filling material 201 and received again in the level measuring device.

[0039] Fig. 2A shows the case of an approximately half-filled container 200. In the echo curve detected by the radar sensor, two peaks 401, 402 are found. Peak 401 corresponds to the reflection at the product surface 202 and peak 402 corresponds to the reflection of the radar signal at the container bottom.

[0040] Both the level echo and the bottom echo are visible in the echo curve.

[0041] However, radar measurement cannot distinguish between minimum and maximum levels. These two cases are described in the Fig. 2B (maximum level) and 2C (minimum level). In both cases, only peak 402 of the bottom echo can be seen in the echo curve detected by the radar sensor.

[0042] If the measurement signal from the optical distance sensor is also evaluated, the unambiguousness can be restored. Although the optical distance signal provides a rather inaccurate measurement signal (for example, with an accuracy of ±50 mm), this is sufficient to distinguish between the maximum and minimum fill levels.

[0043] Fig. 3shows a flowchart of a method according to one embodiment. The method starts in step 301, and a first radar measurement is performed in step 302. In step 303, it is determined whether the radar level measurement has led to a clear measurement result. If this is the case, the level is output by the measuring device in step 306, and the method ends with step 307. If this is not the case, however, an optical measurement 304 is performed by an optical distance sensor. This serves to "plausibility check" the level measurement or to determine whether the container is completely full or completely empty.

[0044] After this plausibility check, the fill level is output in step 306 and the method ends with step 307.

[0045] Additionally, it should be noted that "comprising" and "having" do not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. Furthermore, it should be noted that features or steps described with reference to one of the above embodiments may also be used in combination with other features or steps of other embodiments described above. Reference signs in the claims are not to be considered limitations.

Claims

1. An optical level measuring device (100), configured to measure a level of a medium through the container wall of a plastic container (200), comprising: an optical distance sensor (101), configured to emit a light signal through the container wall in the direction of the product surface and to receive the light signal reflected at the product surface, also through the container wall; an evaluation device (102), configured to determine a fill level or to detect a limit level of the medium in the plastic container by evaluating the received light signal; a radar sensor (103) configured to emit a radar signal through the container wall in the direction of the product surface and to receive the radar signal reflected at the product surface, also through the container wall; wherein the evaluation device (102) is configured to determine the fill level or the limit level of the medium in the plastic container by evaluating the radar signal received.

2. The optical level measuring device (100) according to claim 1, wherein the evaluation device (102) is configured to firstly carry out the evaluation of the received radar signal and, if this evaluation is ambiguous, to carry out the evaluation of the received light signal.

3. The optical level measuring device (100) according to one of the preceding claims, wherein the evaluation device (102) is configured to first carry out the evaluation of the received radar signal and, only if this evaluation is ambiguous, to carry out a measurement with the optical distance sensor (101) and to carry out the evaluation of the received light signal.

4. The optical level measuring device (100) according to one of the preceding claims, wherein the light signal is a laser signal.

5. The optical level measuring device (100) according to one of the preceding claims, further comprising: a housing (104), in which the optical distance sensor (101) and the radar sensor (103) are arranged.

6. The optical level measuring device (100) according to one of the preceding claims, further comprising: a radio communication interface (105), configured for transmitting the measured value to an external computing unit (106).

7. The optical level measuring device (100) according to one of the preceding claims, configured as a self-sufficient level measuring device, without external power supply.

8. The optical level measuring device (100) according to one of the preceding claims, configured to be glued on the outside of the plastic container (200).

9. Use of an optical distance sensor (101) in an optical level meter (100) according to any one of claims 1 to 8 for interpreting the measurement result of a radar sensor (103).

10. Use of a radar sensor (103) in an optical level radar measuring device according to any one of claims 1 to 8.

11. A level measuring arrangement for measuring a level of a medium through the container wall of a plastic container (200), comprising: an optical level meter (100) according to any one of claims 1 to 8; and a plastic container with the optical level gauge attached to its outside.

12. A method for measuring a level of a medium through the container wall of a plastic container (200) using an optical level measuring device (100) according to any one of claims 1 to 8, comprising the steps of: emitting a light signal through the container wall in the direction of the product surface and receiving the light signal reflected on the product surface, also through the container wall; determining a fill level or detecting a limit level of the medium in the plastic container by analysing the received light signal.

13. A programme element which, when executed on an evaluation device (102) of a level measuring arrangement using an optical level measuring device according to any one of claims 1 to 8, instructs the level measuring arrangement to perform the following steps: emitting a light signal through the container wall in the direction of the product surface and receiving the light signal reflected on the product surface, also through the container wall; determining a fill level or detecting a limit level of the medium in the plastic container by analysing the received light signal.

14. A computer-readable medium, on which a programme element according to claim 13 is stored.