DE102007042043A1 - Level measuring instrument for determining and monitoring level of filling material provided in container with run time measuring method of sent signals, has transducer unit and sensor unit having ultrasonic sensor - Google Patents

Abstract

The level measuring instrument (1) has a transducer unit (2) and a sensor unit (3). The sensor unit has an ultrasonic sensor for sending ultrasonic signals and a microwave sensor for sending of microwave signals, and is built in common sensor housing. The microwave sensor and the ultrasonic sensor are arranged concentrically or rotationally symmetrical in the sensor housing.

Description

The The present invention relates to a device for detection and monitoring the level of a product in a container according to a transit time measurement method of emitted Signals, consisting of a transmitter unit and a sensor unit.

such Devices for detecting and monitoring the level in a container are common in the measuring instruments used the automation and process control technology. Of the Applicants are for example measuring devices under the name Prosonic, Micropilot or Levelflex produced and distributed which work according to the transit time measurement method and serve a level of a product in a container and / or monitor. At the term measurement method will be For example, ultrasonic waves via a transducer or radiated microwave or radar waves via an antenna; and the echo signals reflected at the medium surface are received again after the distance-dependent runtime. From the duration of the signals can be with the help, for example an echo curve representing the amplitudes of all reflected echo signal components depending on the running time, and the known Propagation speed of the signals of the level of the Calculate medium in a container.

at All known physical measuring principles usually have to be compromised in terms of accuracy of measurement and reliability the measurement will be received. Therefore, based on the environmental conditions and medium properties of the corresponding application the most expedient selected physical measuring principle, its advantages over its disadvantages predominate. Become fundamental in the Process measuring technology as freely radiating measuring methods different physical measuring principles, such as the microwave transit time measurement, the ultrasonic transit time measurement and the gamma ray absorbance measurement, and occasionally the laser light transit time measurement used. Medium-contacting measuring methods are in process measuring technology including the solder measuring method, the capacitive measuring method, the conductive measuring method and the measuring method with the guided Microwave known. All of these measurement methods are appropriate the measuring principle, the measuring medium, the measuring situation, the process conditions and the measurement performance certain advantages over one other measuring methods.

Of the direct comparison of the different physical measuring principles shows that the selection of the current application suitable measuring principle in most cases very difficult is. However, a variety of applications can already be done today due to the highly developed, freely radiating measuring devices in the microwave and ultrasound range.

It The object of the invention is a level gauge with a compact, inexpensive sensor unit, which has optimized measurement accuracy and optimized reliability.

These The object is achieved according to the invention the sensor unit has at least one ultrasonic sensor for emitting of ultrasonic signals and at least one microwave sensor for Emission of microwave signals includes that in a common Sensor housing are installed.

A advantageous embodiment of the invention Solution is to see that the microwave sensor and the ultrasonic sensor in the sensor housing concentric with each other and / or rotationally symmetrical to a radiation direction of the signals are arranged.

A further advantageous embodiment of the invention Solution is to be seen in that the ultrasonic sensor a has continuous, central bore, in which the microwave sensor Concentric in the ultrasonic sensor fixed or detachable is inserted.

In a particularly preferred embodiment of the invention it is provided that the ultrasonic sensor at least one annular or annularly arranged ultrasonic transducer.

According to one advantageous embodiment of the invention Device is provided that the microwave sensor at least comprises a waveguide with at least one coupling element, the generates and / or receives the microwave signals.

A advantageous embodiment of the invention Device is to be seen in that the waveguide as a metallic Hollow cylinder with a packing of a dielectric Material is designed.

A very advantageous variant of the invention Device is to be seen in that the waveguide of a a cylindrical element formed filler constructed of a microwave permeable, dielectric material and that on the outer surface at least partially an electrically conductive coating having.

According to one advantageous variant of the device according to the invention is provided that a conical, frusto-conical or pyramidal configuration of the packing is provided in the emission direction as a matching element.

A further advantageous variant of the invention Device is that at least one decoupling element in an annular gap of the bore between the ultrasonic sensor and the inserted microwave sensor is inserted.

A advantageous embodiment of the invention Device is to be seen in that the annular or annularly arranged ultrasonic transducer of the ultrasonic sensor is divided into individual, separately controllable segments.

In a particularly preferred embodiment of the invention Device is provided that between the annular or the annularly arranged ultrasonic transducer and a formed on the sensor housing in the direction of radiation, annular or annularly arranged ultrasound membrane at least an annular or annular matching layer is arranged.

A very advantageous variant of the invention Device is to be seen in that the ultrasonic sensor and / or the microwave sensor by a damping casting attenuating the ultrasonic waves are shed in the sensor housing.

In a particularly advantageous variant of the invention Device is adjacent to the sensor housing of the ultrasonic sensor and / or the microwave sensor at least one antenna horn in the emission direction intended.

A extended advantageous variant of the invention Device arises from the fact that the antenna horn by separating elements is divided and / or that the antenna horn by separating elements according to the segments of the annular or annular subdivided arranged ultrasonic transducer of the ultrasonic sensor is.

object The present invention is a concept for a multi-sensor consisting of an ultrasonic sensor with a microwave sensor, to improve reliability and accuracy the distance measurement of the meter leads. To one increased accuracy and reliability of the measurement to ensure the level in the Process measuring technology redundant measuring instruments for plausibility analysis and calibration of the measurement used. This is when a multivariate Redundanzbetrachtung the measurement sought, the redundant measuring instruments to realize as different as possible. For example can to determine the content in a big oil tank a pressure sensor in the tank bottom area, which indicates the level determined by hydrostatic level measurement, and in addition a radar in the tank lid area, the Level determined using the transit time measurement method become. By using different physical measuring methods the probability that a systematic error in the different measuring devices are the same and at the same time affects, extremely low. This is the diversified redundancy used by ultrasonic and microwave signals in that on the one hand the main disturbances in the propagation path different on electromagnetic and ultrasonic waves on the other hand, however, the useful signals although the different principle of action are redundant. The useful signals can thus without complex and usually lossy feature transformations linked at the signal level and in particular the weaknesses the various individual sensors are overcome.

The ultrasonic and microwave sensors work almost independently of difficult environmental conditions, such. As extreme humidity and / or heavy pollution, with a high linearity and long-term stability. The generally high dynamics of the received signals ensure a good differentiation of DUTs, the relatively small amount of data enables easy data acquisition and fast signal processing. With their simple design and low price, ultrasonic sensors have long been established in process measurement technology. Due to advances in the development of microwave components and the construction technique and microwave sensors are increasingly inexpensive to produce. A disadvantage of measuring devices that work with ultrasonic waves, but that they are subject to various influences: temperature gradients, air movements or material changes of the medium are reflected in amplitude and phase fluctuations of the received signals noticeable. In addition, strong interference sources, such as internals or agitators, can mask or simulate useful echo signals in the detection area. In contrast, level measuring devices that work with microwaves are hardly affected by changes in the process conditions of the air above the measuring medium; and the propagation loss of microwaves is extremely low. A disadvantage of microwave measuring devices is that the small differences in the characteristic impedance when reflecting on non-conductive materials lead to much smaller echo amplitudes compared to those in the case of conductive surfaces. Inappropriate design of the sensor can also be noticeable electrical interference in the environment do. High reliability of the sensor statement with low cross sensitivity and high immunity against environmental influences and noise are in the foreground of every sensor development. In order to check the plausibility of sensor statements and to reduce failure rates, redundant multi-sensor systems are often designed that combine several identical single sensors in a parallel structure. With the evaluation of the received signals of different types of individual sensors with output signals of complementary events, an extension of the response of the total sensor is sought. These so-called diversified multi-sensor systems have steadily become more attractive in recent years and are used for a variety of tasks in industrial process automation technology, such as the DE 100 37 715 A1 shown used. In the DE 100 37 715 A1 a combination of two measurement methods for plausibility of the measurements is shown, in which the level is determined alternately or simultaneously by a transit time measurement method of a high-frequency signal or by a capacitance measurement by means of a measuring probe touching the medium. The higher dimensionality of the observation space leads to sensor statements that can not be achieved with simple multi-element arrangements of identical sensor elements. Particular importance for the expansion of the possibilities of sensors have diverse multi-sensor systems, which are based on direct comparability of the useful signals, while noise signals are statistically uncorrelated. By evaluating this so-called diverse redundancy, the fusion result has a significantly increased robustness against interference influences of the individual sensors, whereby the credibility of the sensor statement is increased. Sensor systems that simultaneously use acoustic waves and microwaves for level measurement and evaluate the redundancy of the received signals from a covering spatial detection area suitably meet this requirement.

One Another advantage of combining both measuring methods is that the ultrasound measurement delivers stronger echo signals. In particular, with organic solvents is also a large part of the microwave radiation is not at the The product surface reflects, but penetrates in the contents and is instead at the bottom of the tank reflected. At low level, then the small Level echoes poorly distinguished from the large tank bottom echo become. In an ultrasound measurement, this problem does not occur on. The disadvantage, however, is that the ultrasonic measurement is inaccurate will, as soon as the speed of sound in the container due from the temperature and gas stratifications fluctuates and / or can not be determined is. In contrast, the propagation velocity of the microwaves almost independent of these environmental influences of the Process. In cases where the ultrasound and the microwave measurement at the same time provide clear results, For example, it is possible to use the ultrasound measurement to calibrate using the results of the microwave measurement. The described interference, such. B. temperature fluctuations or reflection differences, have different effects on microwaves or on ultrasonic waves, but the useful signals are despite the different operating principle redundant and thus comparable with each other.

Further Details, features and advantages of the subject matter of the invention result from the following description with the associated Drawings in which preferred embodiments of the Invention are shown. Embodiments illustrated in the figures the invention are for better clarity and simplification the Elements that correspond in their structure and / or function provided with the same reference numerals.

It shows:

1 a schematic representation of an embodiment of the inventive device for determining the level in a container,

2 1 is a schematic representation of a top view of a first exemplary embodiment of the device according to the invention with the multi-sensor unit,

3 a sectional view of a side view of the first embodiment of the device according to the invention according to the section AB 2 .

4 a schematic sectional view of the first embodiment of the device according to the invention with attached antenna horn 3 .

5 a schematic representation of a plan view of a second embodiment of the device according to the invention with the multi-sensor unit, and

6 a sectional view of a side view of the second embodiment of the device according to the invention according to the section CD 5 ,

In 1 becomes a device 1 for determining the filling level f of a product 5 in a container 7 according to a transit time measurement method of signals S shown. The device 1 is for example a flange on a nozzle or process connection to the container 7 attached, so that the sensor unit 3 , in the process room 6 is located while the transmitter 2 with the transmitting / receiving unit 24 . 25 with the control / evaluation unit 26 and with the interface unit 27 outside the process room 6 located.

In the transmitter 2 is from the send / receive unit 24 . 25 generates an excitation signal in the sensor unit 3 a transmission signal S _TX causes. The sensor unit 3 emits this transmission signal S _TX in the direction of the medium 5 in the process room 6 from. The on the surface 4 of the contents 5 Reflected reflection signal S _RX is from the sensor unit 3 received again and in the sender / receiver unit 24 . 25 in the transmitter 2 signal processing further processed. The control / evaluation unit 26 in the transmitter 2 evaluates the transmission signals S _TX and reflection signals S _RX , for example, by determining a time-dependent or distance-dependent echo signal curve and / or envelope, which is a further signal processing and / or evaluation in the transmitter 2 is available. The term signals S summarize the transmission signals S _TX and the reflection signals S _{RX together} under one term. The control / evaluation unit 26 has the task of evaluating a useful echo in the reflection signals S _RX by the reflection signals S _RX by signal processing and special signal processing algorithms are processed and evaluated, and hence the term of the individual echo signals is determined. From the duration of the signals S can be, for example, with knowledge of the propagation speed of the signals S in the process space 6 the distance d and thus with knowledge of the height h of a container 7 the level f of a product 5 determine. From the time difference between the transmission of the transmission signals S _TX and the reception of the reflection signals S _RX can be the distance of the device 1 to the surface 4 of the contents 5 determine.

In 2 is a plan view of the first embodiment of the device according to the invention 1 consisting of the transmitter 2 and from the sensor unit 3 with a concentric, annular and / or annular ultrasound membrane 20 of the ultrasonic sensor 10 in the sensor housing 12 and with the fitting element 30 on the waveguide 13 of the microwave sensor 11 shown. In this first embodiment, the sensor housing 12 the sensor unit 3 one-piece and hermetically sealed. This is the bottom of the sensor housing 12 in the range of the ultrasonic sensor 10 to an annular ultrasonic membrane 20 formed by, for example, in this area, a reduction in the material thickness of the bottom of the sensor housing 12 is provided. In the area of the microwave sensor ( 11 ) are the material of the bottom of the sensor housing ( 12 ) and its strength designed so that the microwave signal S _{μW is} not attenuated. The multisensor from ultrasonic sensor 10 and microwave sensor 11 is for these reasons in a sensor housing 12 from a process resistant, microwave transparent material, e.g. As a plastic of polytetrafluoroethylene PTFE or polyvinylidene fluoride PVDF embedded. Because the sensor housing 12 at least on the process side is made in one piece, is the sensor unit 3 hermetically sealed against the medium 5 and the process conditions in the process room 6 completed.

In 3 is a sectional view of a first embodiment of the device according to the invention 1 for determining the filling level f in a container 7 according to the section AB in 2 shown. The device 1 is essentially a sensor unit 3 and a transmitter 2 built up. The sensor unit 3 is designed according to the invention as a multi-sensor. The sensor element 3 has a microwave radiating and receiving, as a waveguide 13 trained microwave sensor 11 concentric, annular and / or annularly arranged by an ultrasonic sensor 10 is surrounded. This microwave sensor 11 is in a hole 33 in the ring-shaped ultrasonic sensor 10 which consists of at least one annular ultrasonic transducer 19 , an annular matching layer 21 and an annular ultrasonic membrane 20 exists, permanently or reversibly releasably inserted. The ultrasonic sensor 10 basically consists of at least one annular ultrasonic transducer 19 receiving the ultrasonic signals S _U via an annular matching layer 21 through an annular ultrasonic membrane 20 as transmission signals S _TX in the process space 6 emits and receives the reflection signals S _RX again. For this purpose, the ultrasonic transducer 19 briefly to vibrate in the resonance range of the ultrasonic sensor 10 stimulated. The vibrations of the ultrasonic transducer 19 are decayed after sending the ultra / sound signals S _U after some time. During this time is the ultrasonic sensor 10 blocked as a receiving element, because the decay covers weak reflection signals S _RX . Accordingly, reflectors that are too close to the ultrasonic sensor can not be detected 10 are mounted and their reflection signals S _RX therefore already within this blocked period of time to the ultrasonic sensor 10 Come back. One therefore speaks of the 'blocking distance' of the ultrasonic sensor 10 ,

The decay time and / or the blocking distance can be achieved by mechanical damping of the composite oscillating system made of ultrasonic transducers 19 , made of matching layer 21 and ultrasound membrane 20 shorten. This mechanical damping is achieved, for example, by a damping casting 22 that surrounds some parts of the compound vibration system, he said enough. The stronger the mechanical damping due to this damping compound 22 is, the faster the composite vibration system swings out.

The microwave sensor 11 is as a waveguide 13 formed the axisymmetric in the continuous, central bore 33 of the annular ultrasonic sensor 10 is introduced. The waveguide 13 consists of either a metallic hollow cylinder 16 or one as a cylindrical element 17 formed dielectric filling body 15 made of plastic, z. As perfluoroalkoxy copolymer PFA or polytetrafluoroethylene PTFE, at least partially on the outer surface with an electrically conductive coating 18 is provided and thus filled with a dielectric material waveguide 13 generated. In these waveguides 13 is the microwave signal S _μW by means of at least one coupling element 14 , which is designed for example as a pin, stage, or group radiator coupling, coupled. In a circular-polarized or an elliptically-polarized P _C radiation characteristic of the transmission signals S _TX are in the waveguide 13 at least two coupling elements 14 configured, which are arranged for example at an angle of 90 ° to each other. On the other hand, in a linear-polarized P _L electromagnetic wave as a radiation characteristic of the transmission signal S _TX in the waveguide 13 only one coupling element 14 educated. In the emission direction Z is at the waveguide 13 a conical fitting element 30 formed, the wave impedance at the transition of the microwave signal S _μW from the waveguide 13 on the process room 6 adapts accordingly.

Method for determining the level over the duration of ultrasonic signals as well as other measurement signals, such. B. Radar exploit the physical law, according to which the running distance is equal to the product of the time t and the propagation speed. In order to determine the propagation speed of the signals S accurately is in the sensor unit 3 a temperature sensor 34 integrated, which determines the process temperature. This temperature sensor 34 is for example via an additional third connection line 29 and a connecting cable 29 of the ultrasonic transducer 19 with the ultrasonic transmitting / receiving unit 24 electrically connected. By means of this current process temperature is in the ultrasonic transmitting / receiving unit 24 determines the adapted propagation speed of the signals S and calculates with this the running distance of the signals. Taking into account the geometry of the container interior and the container 7 Then, as already described, the filling level f of the medium 5 is determined as a relative and / or an absolute variable.

Specifically, in the following embodiments, primarily only the measurement setup of the concentric, annular and / or annularly arranged ultrasonic transducer will be described 19 as a combined transmitting / receiving element or the ultrasonic transceiver for transmitting and receiving signals S closer considered, but is also a separate embodiment of the transmitting element and the receiving element of the ultrasonic sensor 10 in the sensor unit 3 conceivable. The term "transceiver" was created by combining the terms "transmitter" transmitter and "receiver" receivers and is a commonly used term in these technical fields of process measurement technology 10 is usually considered an electromechanical ultrasonic transducer 19 formed, which is operated for example by an electrostatic, electromagnetic or in particular according to a piezoelectric principle. As the piezoelectric ultrasonic transducer 19 For generating and measuring ultrasonic signals S _U over the other principles offers some advantages, this piezoelectric transducer principle has prevailed as a general standard. However, all electromechanical transducer principles are applicable as drive mechanisms in the following embodiments of the invention.

The geometric design of a piezoelectric ultrasonic transducer 19 are hardly subject to restrictions. The piezoelectric ultrasonic transducer 19 may be disc or ring, round or angular. For example, according to the invention round discs, the at least two end faces with one or more holes 33 used in the disc. This continuous, central bore 33 in the piezoelectric ultrasonic transducer 19 can according to the invention for receiving a further sensor element, for. B. a microwave sensor 11 , for connecting cables 29 or for fixing the piezoelectric ultrasonic transducer 19 for example, on the sensor housing 12 be used. It is also possible that the piezoelectric ultrasonic transducer 19 in its entire geometry has different polarization directions, whereby opposing force components in a piezoelectric ultrasonic transducer 19 can be generated. This makes it possible the radiation characteristic of the ultrasonic signals S _U and / or the radiation pattern of the ultrasonic sensor 10 adapted to the optimal measurement conditions and can be changed.

The transmitter according to the invention 2 comprises at least one ultrasonic transmitting / receiving unit 24 , a microwave transmitting / receiving unit 25 , a control / evaluation unit 26 and an interface unit 27 , The ultrasonic transducer 19 is via connection lines 29 with the ultrasonic transmitting / receiving unit 24 connected. The ultrasound transceiver 24 generates an incentive transmission signal, which briefly excites the ultrasonic transducer to vibrate. After a construction-related, predetermined settling time, the reflection signals S _{RX are} again from the electromechanical ultrasonic transducer 19 received and over the connecting lines 29 as an electrical echo signal to the ultrasonic transmitting / receiving unit 24 transmitted. These electrical echo signals are in the ultrasonic transmitting / receiving unit 24 signal-technically preprocessed and for signaling evaluation to the control / evaluation unit 26 transmitted. For generating the microwave signals S _μW by the microwave sensor 11 is that in the waveguide 13 introduced coupling element 14 via an RF cable to the microwave transmitter / receiver unit 25 connected. The microwave transmitter / receiver unit 25 comprises at least one RF module, for example by generating high-frequency, pulse-shaped transmission signals S _TX in the gigahertz range, and a homodyne and heterodyne receiver, which preprocesses the reflection signals S _{RX by} signal technology. Via a communication line 31 communicates the microwave transmitting / receiving unit 25 the signal-technically processed echo signals to the control / evaluation unit 26 , About supply lines 32 become the individual components of the transmitter 2 , such as B. Transceiver units 24 . 25 and the rule evaluation unit 26 supplied with the necessary energy.

About the power supply line 8th and the interface unit 27 becomes the device 1 supplied with the required energy. The control / evaluation unit 26 communicates via an interface unit 27 and the fieldbus 9 with a remote control point and / or with other devices, eg. B. field devices that are not explicitly shown. An additional power supply line 8th to power the device 1 does not apply if it is in the device 1 or the measuring device is a so-called two-wire measuring device, its communication and power supply through the fieldbus 9 takes place exclusively and simultaneously via a two-wire line. The data transmission or communication via the fieldbus 9 takes place, for example, according to the CAN, HART, PROFIBUS DP, PROFIBUS FMS, PROFIBUS PA, or FOUNDATION FIELDBUS standard. Will the device of the invention 1 operated as an autonomous field device of process automation technology, the device communicates 1 For example, via a wireless communication unit and is supplied for example by an energy storage unit or an autonomous power supply unit with the necessary energy. This independent embodiment of the power supply and the wireless communication unit is not explicitly shown in the figures. The device 1 communicates via the wireless communication unit with the feeder or other field devices by radio according to at least one of the known standards, such as by infrared, radio, GSM, ZigBee, Bluetooth, UMTS, WLAN. As an autonomous power supply unit for powering the device, for example, at least one accumulator, a fuel cell, a solar cell or their hybrid systems are provided.

The measurements of the transit time by means of the device according to the invention 1 done by the microwave sensor 11 with the microwave transmitting / receiving unit 25 and the ultrasonic sensor 10 with the ultrasonic transmitting / receiving unit 24 in an alternating alternating or simultaneous measuring cycle. Since the measuring principles of the transit time measurement of the microwave signals S _{μW of} the microwave sensor 11 and the ultrasonic signal S _{U of} the ultrasonic sensor 10 hardly affect themselves, a simultaneous measurement by both measuring principles is possible. Another possible implementation of the different measuring cycles of the multi-sensor is that after a predetermined number of measurements, the running time with the ultrasonic sensor 10 a comparison measurement of the transit time through the microwave sensor 11 done, and vice versa. By means of this measure, it is possible to check and / or calibrate the measurement of the fill level according to the transit time measurement method.

By utilizing the competing and complementary sensor integration, it is possible to increase the measurement uncertainty by utilizing the diversity of the ultrasonic sensor 10 and the microwave sensor 11 to reduce and increase the reliability of the sensor statement or measurement results by utilizing the similarity (redundancy) of the received signals of the microwave signals S _μW and the ultrasonic signals S _U.

Due to the inventive design of the multi-sensor from a microwave sensor 11 in the through, central hole 33 of the annular ultrasonic sensor 10 an acceptable amplitude distribution of the transmission signal S _{TX of} the ultrasonic signal S _{U is} achieved. The resulting directional diagram or the radiation characteristic of the ultrasonic signals S _U is still worse than in a conventional ultrasonic sensor 10 , However, this emission characteristic can be improved even further by the fact that the antenna _horn required for the microwave signals S _μW anyway 23 used simultaneously to bundle the ultrasonic signal S _U. This is done on the sensor housing 12 mounted in the direction of radiation Z diverging funnel. The divergence of the funnel is designed so that the microwave signals S _μW and the ultrasonic signal S _{U are} focused and focused. This embodiment of the multi-sensor microwave sensor 11 and ultrasonic sensor 10 with an antenna horn 23 is in 4 shown.

Furthermore, it is possible to use the microwave sensor 11 as a rod antenna perform by the fitting element 30 is extended as a dielectric rod radiator. This extension of the fitting element 30 by a rod radiator, for example, by the fact that in the range of the microwave sensor 11 at the bottom of the sensor housing 12 a corresponding rod radiator is glued or screwed. It must be ensured that the joints between the filler 15 , the bottom of the sensor housing 12 and the rod radiator done gap-free and they have similar material constants, otherwise disturbing reflections caused by impedance changes of the microwave signal S _μW . Another disadvantage is that due to the rod radiator noise signals of the ultrasonic signals S _{U are} generated and thus the measurement performance of the ultrasonic sensor 10 is worsened.

In addition, a TDR sensor in which a microwave signal S _μW to an electrical conductor, for. As rod or rope is guided in the inventive multi-sensor as a microwave sensor 11 with an annular ultrasonic sensor 10 integrated. However, here too by the cable or the rod corresponding spurious reflections of the ultrasonic signals S _U and thus a deterioration of the measurement performance of the ultrasonic sensor 10 expected. In such an embodiment of the multi-sensor, the electrical conductor of the TDR sensor must pass through the bottom of the sensor housing 12 passed through, whereby a seal of the electrical conductor to the sensor housing 12 , z. B. by an O-ring, is necessary.

In 5 and 6 is a second embodiment of the multi-sensor according to the invention, consisting of microwave sensor 11 and ultrasonic sensor 10 represented.

In this second embodiment, the outer antenna horn 23a mainly only to improve the radiation characteristics of the ultrasonic sensor 10 used and a smaller, inner antenna horn 23b serves to improve the radiation characteristic of the microwave sensor 11 , For high-frequency microwave sensors, z. B. at frequencies of 26 GHz, this inner antenna horn falls 23b quite small, z. B. diameter of the horn opening of about 40 millimeters, so that interference signals of the ultrasonic signals S _U through this inner antenna horn 23b hardly occur.

In 6 is a sectional view of a second embodiment of the device according to the invention 1 for determining the filling level f in a container 7 according to the section CD in 5 shown. For better presentation and clarity of the three-dimensional drawing, the sectional view has a slight inclination to the rear. The sectional view of the second embodiment of the device according to the invention 1 shows the multisensor with the outer antenna horn 23a and inner antenna horn 23b , The outer antenna horn 23a or ultrasonic focusing horn 23a is configured from a material reflecting the ultrasonic signals S _U.

The microwave sensor 11 is as a filled waveguide 13 with two mutually arranged by 90 ° coupling elements 14 executed. Due to the version with two 90 ° offset coupling elements 14 it is possible to produce a circle-polarized or elliptically-polarized P _C microwave signal S-. The two coupling elements 14 are via two RF cables with the microwave transmitting / receiving unit 25 connected, which by an in-phase control of the coupling elements 14 with a high-frequency signal a circular-polarized P _C microwave signal S _μW or by phase-offset control of the coupling elements 14 generates an elliptically-polarized P _C microwave signal S _μW with a high-frequency signal.

The annularly arranged ultrasonic transducer 19 For example, it can be made up of a plurality of piezoelectric elements that are connected via a plurality of connection lines 29 In phase or out of phase of the ultrasonic transmitting / receiving unit 24 be controlled. Due to the annular arrangement of the individual ultrasonic transducers 19 In the form of piezoelectric elements, a similar measurement performance is achieved, as with a ring-shaped piezoelectric element. About an adaptation to the shape or thickness of the ultrasonic membrane 20 These differences in the measurement performance between a plurality of annularly arranged ultrasonic elements 19 and a single annular ultrasonic element 19 be further adapted.

For improved decoupling of the two sensor units 3 one another is in the annular core gap between the annular or annularly arranged ultrasonic sensor 10 and the microwave sensor 11 at least one decoupling element 35 inserted, especially the waveguide 13 of the microwave sensor from the mechanical vibrations of the ultrasonic transducer 19 shields.

1

Contraption; level meter

2

transmitters

3

sensor unit

4

surface

5

filling, medium

6

process space

7

container

8th

Power line

9

fieldbus

10

ultrasonic sensor

11

microwave sensor

12

sensor housing

13

waveguide

14

coupling element

15

packing

16

hollow cylinder

17

cylindrical element

18

coating

19

ultrasound transducer

20

ultrasonic membrane

21

matching layer

22

Dämpfungsverguss

23

antenna horn

23a

outer Antenna horn, ultrasonic focusing horn

23b

inner Antenna horn, microwave antenna horn

24

Ultrasonic transmitter / receiver unit

25

Microwave transmitter / receiver unit

26

Control / evaluation unit

27

Interface unit

28

RF cable

29

connecting cables of the ultrasonic transducer

30

matching element

31

communication line

32

supply line

33

drilling

34

temperature sensor

35

decoupling element

Z

radiation direction

S

signal

S _TX

send signal

S _RX

reflection signal

S _U

ultrasonic signal

S _μW

microwave signal

d

distance

f

level

H

height

P _L

linear-polarized

P _C

circular-polarized, eleptisch-polarized

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 10037715 A1 [0021, 0021]

Claims (12)

Contraption ( 1 ) for determining and monitoring the filling level (f) of a product ( 5 ) in a container ( 7 ) according to a transit time measuring method of emitted signals (S), consisting of a transmitter unit ( 2 ) and a sensor unit ( 3 ), characterized in that the sensor unit ( 3 ) at least one ultrasonic sensor ( 10 ) for emitting ultrasound signals (S _U ) and at least one microwave sensor ( 11 ) for emitting microwave signals (S _μW ), which in a common sensor housing ( 12 ) are installed. Device according to claim 1, characterized in that the microwave sensor ( 11 ) and the ultrasonic sensor ( 10 ) in the sensor housing ( 12 ) are arranged concentrically with one another and / or rotationally symmetrical with respect to a radiation direction (Z) of the signals (S). Device according to at least one of claims 1 or 2, characterized in that the ultrasonic sensor ( 10 ) a continuous, central bore ( 33 ) into which the microwave sensor ( 11 ) concentrically into the ultrasonic sensor ( 10 ) is inserted firmly or releasably. Device according to at least one of claims 1, 2 or 3, characterized in that the ultrasonic sensor ( 10 ) at least one annular or annularly arranged ultrasonic transducer ( 19 ). Device according to at least one of claims 1, 2 or 3, characterized in that the microwave sensor ( 11 ) at least one waveguide ( 13 ) with at least one coupling element ( 14 ) which generates and / or receives the microwave signals (S _μW ). Device according to claim 5, characterized in that the waveguide ( 13 ) as a metallic hollow cylinder ( 16 ) with a filling body ( 15 ) is made of a dielectric material. Device according to at least one of claims 5 or 6, characterized in that the waveguide ( 13 ) as a cylindrical element ( 17 ) formed filler ( 15 ), which consists of a microwave permeable, dielectric material and on the outer surface at least partially an electrically conductive coating ( 18 ) having. Device according to at least one of claims 6 or 7, characterized in that a conical, frusto-conical or pyramidal configuration of the filling body ( 15 ) in the emission direction (Z) as a matching element ( 30 ) is provided. Device according to claim 3, characterized in that at least one decoupling element ( 35 ) in an annular gap of the bore ( 33 ) between the ultrasonic sensor ( 10 ) and the inserted microwave sensor ( 11 ) is inserted. Device according to at least one of claims 5, characterized in that between the annular or annularly arranged ultrasonic transducer ( 19 ) and one on the sensor housing ( 12 ) in the emission direction (Z) formed, annular or annularly arranged ultrasonic membrane ( 20 ) at least one annular or ring-shaped matching layer ( 21 ) is arranged. Device according to at least one of claims 1 to 5, 9 or 10, characterized in that the ultrasonic sensor ( 10 ) and / or the microwave sensor ( 11 ) by a damping shock absorbing the ultrasonic waves ( 22 ) in the sensor housing ( 12 ) are shed. Device according to at least one of the preceding claims, characterized in that adjacent to the sensor housing ( 12 ) of the ultrasonic sensor ( 10 ) and / or the microwave sensor ( 11 ) at least one antenna horn ( 23 . 23a . 23b ) is provided in the emission direction (Z).