DE10051025A1 - Device for determining container fill material level antenna positioned in side wall opening so measurement signals are radiated towards fill medium and reflected signals pass to antenna - Google Patents

Abstract

The device has a signal generating unit, at least one antenna that emits measurement signals towards the fill medium and receives reflected signals and a regulation/evaluation unit that determines the level from the signal transition time. The container side wall has an opening in which the antenna is positioned so the measurement signals are essentially radiated towards the fill medium and signals reflected from the medium pass to the antenna. The device has a signal generating unit, at least one antenna (8,9) that emits measurement signals towards the fill medium (3) and receives reflected signals and a regulation/evaluation unit that determines the level from the signal transition time. The upper region of the container side wall (5) has an opening (6) in which the antenna is positioned so that the measurement signals are essentially radiated towards the fill medium and signals reflected from the fill medium pass to the antenna.

Description

The invention relates to a device for determining the Filling level of a filling material in a container with a signal generation unit, generates the measurement signals with at least one antenna, which the measurement signals in Direction of the surface of the filling material and that on the Surface of the product receives reflected measurement signals, and with a Control / evaluation unit, which based on the duration of the measurement signals Level of the filling in the container determined. With the measurement signals it is preferably ultrasonic signals or microwave signals.

Runtime procedures take advantage of the physical law, according to which the Running distance equal to the product of running time and speed of propagation is. In the case of level measurement, the running distance corresponds to that twice the distance between the antenna and the surface of the product. The Useful echo signal, i.e. the signal reflected on the surface of the product, and its duration are based on the so-called echo function or digitized envelope determined, the envelope the amplitudes of the Echo signals as a function of the distance "antenna - surface of the product" reproduces. The fill level itself results from the difference between the known distance of the antenna to the bottom of the container and the distance of the surface of the filling material determined by the measurement Antenna.

All known methods can be used which make it possible to relatively short distances by means of reflected measurement signals determine. If the measurement signals are microwaves, it can both the pulse radar and the frequency modulation continuous wave radar (FMCW radar) are used. Microwave measuring devices, the pulse radar are used by the applicant, for example, under the Designation "MICROPILOT" distributed. A type of device that uses ultrasound signals works, is for example under the Description "PROSONIC" offered.  

Both in the known ultrasonic measuring devices and in microwaves measuring devices are the antennas, over which the measuring signals in the direction of Surface of the filling material is emitted or via which on the surface of the Filling material reflected measurement signals are received in the lid area of the To find a container. This arrangement is necessary so that the measurement signals impinge essentially perpendicularly on the surface of the filling material. before an antenna is positioned in a nozzle that is already in the cover of the container is present. In cases where there is no opening, it must be created especially for the attachment of the antenna. The The measuring device is fastened in the nozzle opening of the cover in simplest case about a flange.

The assembly and maintenance of a measuring device in the lid area of a container turns out to be particularly cumbersome and difficult when there no opening is provided and an opening is created beforehand got to. Installation and maintenance of the are particularly problematic Measuring device for containers with large geometric dimensions - that is usual case in industrial process and measurement technology.

In many cases, however, there are also openings in the side wall of the Container in which the contents are stored. These openings can for example to accommodate a so-called bypass, i.e. a pipe section, which is arranged parallel to the outer wall of the container, serve. You can but also be provided for attaching a differential pressure sensor. In Both variants must refer to both the lower and the upper Area of the side wall of the container each have an opening. Furthermore, there may be an opening in the side wall around a receiving opening for a pressure or temperature sensor or for a limit switch for determining and / or monitoring the act maximum fill level of a product in the container. What for? this opening was always intended. It is in the upper one Area of the side wall of the container, so it is related to the device according to the invention can be used.

The object of the invention is to propose a device, an inexpensive and simple installation of a level measuring device, that works on the runtime principle, enables on a container.  

The object is achieved in that in the upper region of a side wall an opening of the container is provided and that the at least one Antenna is positioned in this opening, the antenna being arranged or is designed such that the measurement signals essentially in the direction of Fill material are emitted or that on the surface of the fill material reflected measurement signals are received by the antenna. Selbstver Of course, the sending and receiving unit can also be used as separate units be formed, it is quite possible to use both antennas in one to arrange integral unit trained device.

As already mentioned above, openings in the upper region of the side wall of the container are preferably used on the one hand for the assembly of the fill level measuring device, the openings on the other hand already being present there. Both measures can of course considerably simplify assembly and maintenance of the level measuring device. In many cases, the customer would also like to replace the existing differential pressure measurement technology with a measurement technology that works with electromagnetic measurement signals. Replacing a differential pressure sensor with a measuring device that works with freely emitted measuring signals offers several advantages:

• - Reduction of installation effort: with differential pressure measurement two variables must be recorded, namely the static one Pressure of a liquid and z. B. the pressure of a gas cushion. to Capture of the two sizes must be in the outer wall of the container at least two openings may be provided. In addition, one is the pipeline connecting both measuring points required. With such Pipelines are at risk of clogging, especially if the Pressure is measured in viscous products.
• - Danger of product leakage: openings in the lower area of the Containers are always a risk, of course, especially when in toxic containers are stored in the container.
• - Workload when maintaining and replacing a Differential pressure sensor: To a device that is in the lower area of the In principle, it is necessary to replace the container Empty containers beforehand.

As already said, it is within the scope of the device according to the invention very simple way possible, one in the side wall of the container mounted differential pressure sensor by a microwave or To replace ultrasonic sensor.

According to a favorable development of the device according to the invention the antenna is essentially an elongated element, whose outer dimensions are larger in the longitudinal direction and in the transverse direction are smaller than the inside dimensions of the opening. Because of this staltung it is possible to the antenna from the outside through the side wall Introduce the interior of the container and adjust it so that the measuring signals emitted essentially in the direction of the surface of the filling material become. In the simplest case, the antenna is adjusted by a corresponding rotation of the elongated element about the longitudinal axis. at the antenna can be, for example, a leaky waveguide, a Bridge waveguide or a Yagi antenna. Furthermore it is possible to use the antenna as a horn with symmetrical or asymmetrical to design the horn, the horn preferably in the elongated Element is integrated.

Alternatively, a separate rod antenna or a separate horn antenna may be provided. The rod antenna or the Horn antenna is then preferably foldable in the area of the front of the elongated element arranged. To the antenna through the opening in the To be able to bring the container wall into the interior of the container is Rod or horn antenna in the direction of the longitudinal axis of the elongated element oriented, the antenna is dimensioned in this position so that it can be pushed from the outside through the opening. Is that elongated Element and in particular the antenna in the interior of the container arranged, the rod or horn antenna is pivoted by 90 °, so that the measurement signals now in the direction of the surface of the filling material emit or receive the measurement signals reflected on the surface can.  

An advantageous embodiment provides an additional sensor that determines at least one process variable in the container. This additional Sensor is with the antenna, which the level over the life of Measurement signals determined, connected. The additional sensor is preferably in Attached to the longitudinal axis of the antenna. With the additional sensor can be, for example, a vibration detector, i.e. a limit switch for determining and / or monitoring the level in the Act a container, a pressure sensor or a temperature sensor. One before partial development of the device according to the invention proposes that in or two antennas are arranged on the elongated element, the measuring signals of different frequencies in the direction of the surface of the product emit or the measurement reflected on the surface of the product received signals. In addition - as in the previous section described - provided that two in and / or on the elongated element Antennas are arranged, one as a transmitting unit and the other used as a receiving unit for measurement signals of a predetermined frequency is. In the latter case, it is a level sensor with separate transmitter and receiver unit.

According to a particularly advantageous development of the invention Device is proposed that at least the additional Sensor is a sensor that meets a given security standard corresponds. The following security standards can include: B. from that Sensor must be fulfilled: Water Resources Act, regulation regarding flammable liquids, Safety Integrity Level (SIL). The advantage for the Users of such a device can be seen in that when in use of a sensor that corresponds to at least one safety standard Insurance premiums are incurred, which makes operating costs significant can degrade.

An advantageous development of the device according to the invention provides that in the antenna area that in the opening of the side wall of the Container is arranged or that in an antenna area which in arranged in close proximity to the opening in the side wall of the container is to find a metallic shield. Through this configuration can be interference signals caused by reflections in the opening of the container  Wall (the so-called. Doorbell bell), on the container wall or on neighboring Internals caused inside the container, effectively eliminating them. at the shield can be, for example, a metal sleeve.

Around the antenna and / or the sensor of the device according to the invention To protect against the influence of an aggressive product, one suggests Design of the device according to the invention that the additional Sensor and / or that the antenna at least in the area in the Interior of the container protrudes with a protective layer, in particular are / is provided with a dielectric protective layer. This configuration is particularly advantageous if the antenna and / or the additional sensor come / comes into direct contact with the product. Protective layers related to the present invention can be used, for example, from EP 0 669 673 B1 known.

To facilitate maintenance and assembly, according to an advantageous Embodiment of the device according to the invention an outer housing provided that in the opening in the upper region of the side wall of the Container is attached, and that the antenna or the antenna with the additional sensor is positioned in the outer housing. The outside housing is with the container z. B. firmly connected via a flange. The outer housing preferably consists of a dielectric material. However, it is also possible to make the outer case from a conductive To produce material that on the side facing the product Has recess. In this as an outlet and inlet for the measurement Signal-acting recess is an insert made of a dielectric Material provided.

In order to ensure optimal radiation or reception To ensure measurement signals, the antenna can be rotated or swiveled around its longitudinal axis is arranged in the outer housing. An adjustment with regard to the recess described above is therefore easily possible. An adjustment is particularly necessary if the hole pattern of the Customer flange is unknown. A radiation in the direction of the product  is only guaranteed if the direction of radiation is relative to Hole pattern of the flange is variable and adjustable.

According to an advantageous embodiment of the device according to the invention are the measurement signals via a conductive element from the signal generation unit led to the antenna. The conductive element is e.g. B. a coaxial cable, a waveguide or a waveguide. itself understandably it is also possible to use the measurement signals on a circuit board Feed microstrip line directly into the antenna.

The invention is illustrated by the following drawings. It shows:

Fig. 1 shows an embodiment of the inventive device in which the measurement signals are fed via a coaxial cable,

Fig. 2 shows an embodiment of the inventive device in which the measurement signals are fed via a hollow conductor,

Fig. 3 shows an embodiment of the device according to the invention with asymmetrical horn antenna,

Fig. 3a is a cross section along the marking A in Fig. 3,

Fig. 4 shows an embodiment of the inventive device in which the measuring signals are transmitted via a dielectric window or received,

Fig. 5 shows an embodiment of the inventive device with a pivoting rod antenna,

Fig. 6 shows an embodiment of the inventive device with flexibly mounted horn antenna,

Fig. 7 shows an embodiment of the ertindungsgemäßen device is used in the antenna as a Yagi antenna,

Fig. 8 shows an embodiment of the device according to the invention, a slotted waveguide antenna used in an antenna,

Fig. 9 shows an embodiment of the ertindungsgemäßen device with separate transmitting and receiving antenna,

Fig. 10 shows an embodiment of the inventive device with a dielectric protective tube,

Fig. 11 shows an embodiment of the device according to the invention with metal protective tube and a dielectric window,

Fig. 12 shows an embodiment of the inventive apparatus with an additional conductivity sensors,

Fig. 13 shows an embodiment of the inventive apparatus with an additional capacitive sensor,

Fig. 14 shows an embodiment of the inventive apparatus with an additional vibration detector,

Fig. 15 shows an embodiment of the inventive apparatus with an additional ultrasonic sensor and

Fig. 16 shows an embodiment of the device with two ertindungsgemäßen term sensors that operate with measurement signals at different frequencies.

Fig. 1 shows a first embodiment of the device according to the invention. The antenna 7 is integrated in the elongated element 8 . The outer dimensions of the elongate element 8 are larger in the longitudinal direction and smaller in the transverse direction than the inner dimensions of the opening 6 , which can be found in the upper region of the side wall 5 of the container 4 . Due to the dimensioning of the elongated element 8 , it is possible to guide the antenna 7 through the opening 6 into the interior of the container 4 and to place it in such a way that the measurement signals strike the surface 3 of the filling material 2 essentially perpendicularly and accordingly into the antenna 7 are reflected back. The antenna 7 , which emits measurement signals in the direction of the surface 3 of the filling material 2 and which receives the measuring signals reflected on the surface 3 of the filling material 2 , is a symmetrical horn antenna 16 with a circular cross section. An asymmetrical horn antenna is the way in which in the figures, Fig. 3 and Fig. 3a embodiment shown on the application. In Fig. 1 the device 1 according to the invention is designed as a compact unit, wherein the electronic part 11, that is, the signal generating unit and the control / evaluation unit, located outside of the container 4. The design as a compact device is of course not mandatory.

In order to avoid undesired reflections of the measurement signals in the area of the opening 6 , a metallic protective layer 35 is provided in the corresponding area of the elongate element 8 . Comparable configurations have already become known in connection with a rod antenna from EP 0 834 722 A2. The key word for embodiments of this type is "inactive length".

While in the embodiment of the device 1 according to the invention shown in FIG. 1, the measurement signals are guided within the elongate element 8 via a coaxial cable 9 , the measurement signals in the case of the embodiment shown in FIG. 2 are routed via a waveguide 12 . A waveguide can also be used. Furthermore, the measurement signals can also be fed directly into the horn antenna 16 via a microstrip line arranged on a circuit board.

Incidentally, in the embodiment shown in FIG. 2, the elongate element 8 is also covered with a dielectric protective layer 36 .

In the embodiment of the device 1 according to the invention shown in FIG. 4, the elongate element 8 is made of a conductive material, in particular a metal. The measuring device is therefore characterized by its high resistance to aggressive filling materials and vapors. If the elongate element 8 is made of a conductive material, the measurement signals are emitted or received via a dielectric window 13 provided in the metallic casing.

In FIG. 5, the antenna is not - as shown in the figures, Fig 1 to Fig. 4 -. Integrated into the elongate element 8. Rather, the measurement signals are emitted or received via a rod antenna 14 which is oriented in a first position, the assembly position, in the longitudinal direction of the elongated element 8 and which is rotated by 90 ° in a second position, the measurement position, via the swivel mechanism 15 , so that the measurement signals are now radiated in the desired direction onto the surface 3 of the filling material 2 or that the measuring signals reflected on the surface 3 of the filling material 2 are received by the rod antenna 14 .

A variant of the device according to the invention is shown in FIG. 6: Here, a horn antenna 16 is arranged in the end region of a flexible waveguide 17 . In the assembly position, the longitudinal axis of the horn antenna 16 virtually forms the continuation of the longitudinal axis of the elongate element 8 or of the flexible waveguide 17 . In the measuring position then - as in the previously described case - the horn antenna 16 is pivoted by 90 °, so that the aperture of the horn antenna 16 is now aligned in the direction of the surface 3 of the filling material 2 .

Another way the design of the antenna 7 7 can be seen in Fig.. Here, a so-called Yagi antenna 18 is used. In FIG. 8, a slot waveguide antenna 19 is used. FIG. 9 shows an embodiment of the device 1 according to the invention with a separate transmission antenna 20 and reception antenna 21 . These and other antenna designs that can be used in connection with the present invention are described in the article "Advanced antenna design for communication modules", Second public Seminar, Ulm, December 9 , 1998 by L. Baggen, W. Simon, J. Borkes described.

A particularly advantageous embodiment of the device 1 according to the invention is shown in FIG. 10. Here, the elongated element 8 with an integrated antenna 7 is arranged in a protective tube 22 made of a dielectric material. The protective tube 22 is fixedly mounted in the opening 6 via a flange 25 . For the purpose of mounting the elongated element 8 with an integrated antenna 7 , this is positioned in the protective tube 22 and fastened to the connection piece via the flange 10 . In this embodiment, an installation and removal z. B. for maintenance of the device 1 according to the Invention if the contents 2 in the container 4 extends beyond the opening 6 .

If there is an aggressive filling material 2 in the container 4 , it is advantageous to replace the dielectric protective tube 22 by a metallic protective tube 23 or by a metallic sleeve. This configuration is shown in detail in FIG. 11. Thus, the measurement signals are able to penetrate the metallic protective tube 23, in the protective tube 23 a recess 37 is provided in which a dielectric material 24 is inserted.

In the figures, Fig. 12 to Fig. 16 embodiments of the device 1 according to the Invention are presented in which 8, an additional sensor for determining and / or monitoring the filling level is provided on the preferably elongate member. In the case of limit level measurement or monitoring, the additional sensor is, for example, a conductive sensor 26 ( FIG. 12), a capacitive sensor 28 ( FIG. 13) or a vibration detector ( FIG. 13). Should continue z. B. for the purpose of plausibility checks, a further sensor for continuous level measurement or level monitoring can be used, it can either be an ultrasonic sensor 32 ( FIG. 15) or a second microwave sensor 31 ( FIG. 16), which with measurement signals Measuring frequency f2 works, which is different from the measuring frequency f1 of the first microwave sensor 30 . By the way, FIG. 16 also shows the configuration of the device 1 according to the invention, in which the sensor 1 communicates with a remote control point 33 via a bus line 34 . As already mentioned in the previous section, any known transmission standard can be used for communication.

LIST OF REFERENCE NUMBERS

1

device according to the invention

2

filling

3

Surface of the product

4

container

5

Side wall

6

Opening / nozzle

7

antenna

8th

Elongated element

9

Kaoxkabel

10

flange

11

electronics part

12

waveguide

13

Dielectric window

14

rod antenna

15

swivel mechanism

16

horn antenna

17

Flexible waveguide

18

Yagi antenna

19

Slot waveguide antenna

20

transmitting antenna

21

receiving antenna

22

Dielectric protection tube

23

Metallic protective tube

24

Dielectric material

25

flange

26

Conductive sensor

27

management

28

Capacitive sensor

29

vibration detector

30

First microwave sensor

31

Second microwave sensor

32

ultrasonic sensor

33

control Authority

34

bus line

35

Dielectric protective layer

36

Metallic protective layer

37

recess

Claims (17)

1.Device for determining the filling level of a filling material in a container with a signal generating unit which generates measurement signals, with at least one antenna which emits the measurement signals in the direction of the surface of the filling material and which receives the measuring signals reflected on the surface of the filling material, and with one Control / evaluation unit which determines the filling level of the filling material in the container on the basis of the running time of the measuring signals, characterized in that
that an opening ( 6 ) is provided in the upper region of a side wall ( 5 ) of the container ( 4 ) and
that the at least one antenna ( 7 ) is positioned in this opening ( 6 ), the antenna ( 7 ) being arranged or designed in such a way that the measurement signals are emitted essentially in the direction of the surface ( 3 ) of the filling material ( 2 ) or that the measurement signals reflected on the surface ( 3 ) of the filling material ( 2 ) are received by the at least one antenna ( 7 ). 2. Device according to claim 1, characterized in that an additional sensor ( 26 ; 28 ; 29 ; 31 ; 32 ) is provided which determines at least one process variable in the container ( 4 ), and that the additional sensor ( 26 ; 28 ; 29 ; 31 ; 32 ) is connected to the antenna ( 7 ). 3. Apparatus according to claim 1 or 2, characterized in that the antenna ( 7 ) is essentially an elongated element ( 8 ), the outer dimensions of which are larger in the longitudinal direction and smaller in the transverse direction than the inner dimensions of the opening ( 6 ) , 4. The device according to claim 3, characterized in
that the antenna ( 7 ) is a leaky waveguide ( 19 ), a ridge waveguide, a Yagi antenna ( 18 ) or a horn antenna ( 16 ) with a symmetrical or asymmetrical aperture or
that the antenna ( 7 ) is a rod antenna ( 14 ) or a horn antenna ( 16 ), which is preferably arranged foldable in the region of the end face of the elongate element ( 8 ). 5. The device according to claim 1, 2, 3 or 4, characterized in
that in the antenna area, which is arranged in the opening ( 6 ) of the side wall ( 5 ) of the container ( 4 ) or
that a metallic shield ( 22 ) is provided in an antenna area which is arranged in the immediate vicinity of the opening ( 6 ) in the side wall ( 5 ) of the container ( 4 ). 6. The device according to claim 2, 3, 4 or 5, characterized in that the additional sensor ( 26 ; 28 ; 29 ; 31 ; 32 ) and / or that the antenna ( 7 ) at least in the area which in the interior of the Protrudes container ( 4 ), is provided with a dielectric protective layer ( 35 ) or with a metallic protective layer ( 36 ) with a dielectric window ( 13 ) in the region of the antenna ( 7 ). 7. The device according to claim 1, 2, 3, 4, 5 or 6, characterized in that
that an outer housing ( 22 ; 23 ) is provided which is fastened in the opening ( 6 ) in the side wall ( 5 ) of the container ( 4 ), and
that the antenna ( 7 ) or the antenna ( 7 ) with the additional sensor ( 26 ; 28 ; 29 ; 31 ; 32 ) is arranged in the outer housing ( 22 ; 23 ). 8. The device according to claim 7, characterized in that the outer housing ( 22 ) is made of a dielectric material or that the outer housing ( 23 ) is made of a conductive material which on the side facing the filling material ( 2 ) has a recess ( 37 ) having. 9. The device according to claim 8, characterized in that a dielectric insert ( 24 ) is provided in the recess ( 37 ). 10. The device according to claim 7, 8 or 9, characterized in that the antenna ( 7 ) is arranged rotatably or pivotably about its longitudinal axis in the outer housing ( 22 ; 23 ). 11. The device according to one or more of the preceding claims, characterized in that a conductive element is provided in the antenna ( 7 ), via which the measurement signals are guided. 12. The apparatus according to claim 11, characterized in that it is in the element conducting the measurement signals to a coaxial cable ( 9 ), a waveguide or a waveguide ( 12 ). 13. The apparatus according to claim 1 or 2, characterized in that it is two separate units in the transmitting unit ( 20 ) and in the receiving unit ( 21 ). 14. The apparatus according to claim 2, characterized in that the additional sensor ( 26 ; 28 ; 29 ; 31 ; 32 ) attached in the direction of the longitudinal axis of the antenna ( 7 ). 15. The apparatus of claim 2 or 14, characterized in that it is in the additional sensor ( 26 ; 28 ; 29 ; 31 ; 32 ) is a limit switch for monitoring the level of the filling material ( 2 ) in the container ( 4 ). 16. The apparatus according to claim 2, characterized in
that two antennas ( 30 , 31 ) are arranged in the elongated element ( 8 ), which emit measurement signals of different frequencies in the direction of the surface ( 3 ) of the filling material ( 2 ) or those on the surface ( 3 ) of the filling material ( 2 ) received reflected measurement signals, or
that two antennas ( 20 , 21 ) are arranged in the elongated element ( 8 ), one being used as a transmitting unit ( 20 ) and the other as a receiving unit ( 21 ) for measuring signals of a predetermined frequency. 17. The apparatus of claim 2, 14, 15 or 16, characterized in that it is at least in the additional sensor ( 26 ; 28 ; 29 ; 31 ; 32 ) is a sensor which corresponds to a predetermined security standard.