CN114324570A - Method for operating a sensor device, sensor device - Google Patents
Method for operating a sensor device, sensor device Download PDFInfo
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- CN114324570A CN114324570A CN202111142943.4A CN202111142943A CN114324570A CN 114324570 A CN114324570 A CN 114324570A CN 202111142943 A CN202111142943 A CN 202111142943A CN 114324570 A CN114324570 A CN 114324570A
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- 238000000034 method Methods 0.000 title claims abstract description 31
- 238000001514 detection method Methods 0.000 claims abstract description 32
- 239000000463 material Substances 0.000 claims abstract description 12
- 230000010355 oscillation Effects 0.000 claims abstract description 12
- 239000007788 liquid Substances 0.000 claims abstract description 9
- 230000000717 retained effect Effects 0.000 claims abstract description 3
- 238000005259 measurement Methods 0.000 claims description 26
- 230000008859 change Effects 0.000 claims description 5
- 239000008186 active pharmaceutical agent Substances 0.000 claims description 3
- 238000002604 ultrasonography Methods 0.000 abstract description 13
- 230000004044 response Effects 0.000 description 13
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 5
- 239000004202 carbamide Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 230000005284 excitation Effects 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/02—Analysing fluids
- G01N29/024—Analysing fluids by measuring propagation velocity or propagation time of acoustic waves
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/022—Liquids
- G01N2291/0228—Aqueous liquids
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/028—Material parameters
- G01N2291/02809—Concentration of a compound, e.g. measured by a surface mass change
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/04—Wave modes and trajectories
- G01N2291/045—External reflections, e.g. on reflectors
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- Biochemistry (AREA)
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- General Physics & Mathematics (AREA)
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- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
Abstract
A method for operating a sensor device and a sensor device, which is designed to determine a material property of a gaseous and/or liquid medium and can be arranged in a medium, having at least one ultrasonic transmitter, a first reflector, at least one ultrasonic receiver and a second reflector, the path of an ultrasonic signal from the ultrasonic transmitter to the first reflector and from the first reflector to the ultrasonic receiver forming a first measuring section, the path from the ultrasonic transmitter to the second reflector and from the second reflector to the ultrasonic receiver forming a second measuring section which is longer or shorter than the first measuring section, a first propagation time of the ultrasonic signal along the first measuring section being detected in order to detect the material property of the medium. The detection threshold is changed if a first propagation time of a current detection deviating from a previous detection exceeds a tolerance range depending on the period of oscillation of the ultrasound signal and/or if a second propagation time of a current detection deviating from a previous detection exceeds the first tolerance range, the detection threshold being retained if the respective deviation lies within the first tolerance range.
Description
Technical Field
The invention relates to a method for operating a sensor device which is designed for determining material properties of a gaseous and/or liquid medium and can be arranged in the medium, having at least one ultrasonic transmitter for generating an ultrasonic signal, having a first reflector arranged opposite the ultrasonic transmitter at a distance, having at least one ultrasonic receiver for receiving the ultrasonic signal reflected at the reflector, wherein a path of the ultrasonic signal from the ultrasonic transmitter to the first reflector and from the first reflector to the ultrasonic receiver forms a first measuring section, and having a second reflector for reflecting the ultrasonic signal, wherein a path of the ultrasonic signal from the ultrasonic transmitter to the second reflector and from the second reflector to the ultrasonic receiver forms a second measuring section, the second measurement section is shorter or longer than the first measurement section, wherein a first propagation time of the ultrasonic signal along the first measurement section is detected in order to detect a material property of the medium.
The invention also relates to a sensor device which is designed to carry out the above-mentioned method.
Background
Methods of the type mentioned at the outset are already known from the prior art. Ultrasonic sensor devices are used to determine a specific property of a liquid or gaseous medium in the medium. In this way, for example, the urea concentration in the urea aqueous solution of the exhaust gas aftertreatment system can be determined from the sound velocity of the solution. For this purpose, an ultrasonic transmitter is electrically excited in order to emit an ultrasonic signal or an ultrasonic pulse. The ultrasonic signal is reflected back at the first reflector or back to a separate receiver, where the reflected ultrasonic waves are converted again into a voltage and the voltage is analyzed. The ultrasonic signal travels along a first path forming a first measuring section. Since the signal response or the reflected ultrasonic signal has a plurality of oscillations, it is required that the measurement is always performed at the same position of the signal response for detecting the correct propagation time of the signal. Thus, for example, in known solutions, the measurement always occurs at the nth positive zero crossing after the adjustable detection threshold is exceeded. Here, it is required that the detection threshold can be adjusted in response to possible instabilities. In order to make the information required for this purpose available, it is known to use a second reflector which provides a second path for the ultrasonic signal, wherein the second path forms a measuring section which is longer or shorter than the measuring section of the first path. With the aid of the then detected propagation times of the ultrasonic signals arriving at the signal receiver, the ratio of the propagation times to one another can be used as a characteristic variable for adjusting the detection threshold.
Corresponding processes are known, for example, from the publications DE 102018202587 a1 and DE 102014213233.
Disclosure of Invention
The invention relates to a method for operating a sensor device which is designed for determining material properties of a gaseous and/or liquid medium and which can be arranged in the medium, having at least one ultrasonic transmitter for generating an ultrasonic signal, having a first reflector arranged opposite the ultrasonic transmitter at a distance, having at least one ultrasonic receiver for receiving the ultrasonic signal reflected at the reflector, wherein a path of the ultrasonic signal from the ultrasonic transmitter to the first reflector and from the first reflector to the ultrasonic receiver forms a first measuring section, and having a second reflector for reflecting the ultrasonic signal, wherein a path of the ultrasonic signal from the ultrasonic transmitter to the second reflector and from the second reflector to the ultrasonic receiver forms a second measuring section, the second measurement segment is longer or shorter than the first measurement segment, wherein a first propagation time of the ultrasonic signal along the first measurement segment is detected in order to detect a material property of the medium. The method according to the invention has the following advantages: in an advantageous manner, incorrect setting of the detection threshold is prevented. According to the invention, this is achieved by: if the currently detected first propagation time deviates from the previously detected first propagation time by more than a tolerance range depending on the oscillation period of the ultrasound signal and/or if the currently detected second propagation time deviates from the previously detected second propagation time by more than the first tolerance range, the detection threshold for the detection of the first propagation time and/or the second propagation time is changed. However, if the respective detected deviation lies within the first mentioned tolerance range, the detection threshold value is retained (beibehalten) or is not changed until now. The detection threshold is therefore selected according to the operating frequency of the ultrasonic signal and the resulting oscillation period. This is achieved in that shifting the signal response of an oscillation does not lead to storing, processing and outputting of incorrect propagation times. By this advantageous configuration of the method, the storage of erroneous propagation time values, which may lead to an erroneous determination of the medium properties, is avoided. In particular, therefore, at least the first propagation time is checked with respect to the above-mentioned deviation. Optionally, the second propagation time is additionally monitored, so that, for example, an error measurement of the first propagation time can also be checked for plausibility.
According to a preferred embodiment of the invention, the tolerance value is predefined as half the oscillation period of the ultrasound signal. It is thereby advantageously possible to reliably detect sudden changes in the oscillation period and to avoid erroneous evaluation of the measured propagation times.
It is also preferably provided that the ratio of the propagation times to one another and the ratio of the lengths of the measurement sections to one another are compared, and that the method is only carried out if the ratios deviate from one another within a second predetermined tolerance range. The check of the propagation time plausibility is therefore carried out only for the case in which the otherwise detected propagation time values lie within the desired second tolerance range, as was described previously. If the travel time lies outside the second tolerance range, it must always be determined that either a faulty measurement is present or the travel time signal is undesirably far from the previously detected value, which leads to a readjustment of the detection threshold.
Particularly preferably, a range of-500 ns to +500ns is predefined for the first tolerance range.
It is also preferably provided that the second tolerance range is predefined as-0.020 to +0.020, in particular-0.015 to + 0.015.
According to a preferred embodiment of the invention, when the detection threshold changes, the change is based on the last detected first or second propagation time, i.e. finally on the currently detected first or second propagation time. The time of the measurement is thus determined by the last or current detected propagation time. If the detection threshold is not changed, because the detected deviation does not exceed the selected tolerance range, the travel time variation can be considered to vary within an allowed range that ensures that the travel time measurement is still taken at the correct instant (i.e., e.g., at the nth zero crossing of the signal-responsive or reflected ultrasonic signal).
It is also preferably provided that, for the case in which no previously detected first or second propagation time is available, the currently detected first and/or second propagation time is stored and the change in the detection threshold is based on the currently detected first and/or second propagation time. Thus, for example, if the method is performed for the first time, the currently detected travel time is assumed to be the valid travel time, and the determination of the detection threshold is based on this travel time. Deviations from this are then detected and compensated for in a further method by the steps mentioned above.
The invention further relates to a sensor device which is designed for determining a material property of a gaseous and/or liquid medium and which can be arranged in the medium, having at least one ultrasonic transmitter for generating an ultrasonic signal, having a first reflector arranged opposite the ultrasonic transmitter at a distance, having at least one ultrasonic receiver for receiving the ultrasonic signal reflected at the reflector, wherein a path of the ultrasonic signal from the ultrasonic transmitter to the first reflector and from the first reflector to the ultrasonic receiver forms a first measuring section, and having a second reflector for reflecting the ultrasonic signal, wherein a path of the ultrasonic signal from the ultrasonic transmitter to the second reflector and from the second reflector to the ultrasonic receiver forms a second measuring section, the above-mentionedThe second measurement segment is longer or shorter than the first measurement segment. The sensor device according to the invention is characterized by a control device which is specially designed (hererichtet) for the conventional sensor device
In use, the method according to the invention is carried out. This yields the advantages already mentioned.
Particularly preferably, the second reflector is arranged opposite the first reflector in such a way that the ultrasound signals are conducted from the first reflector also to the second reflector and from the second reflector back to the first reflector and from there to the ultrasound receiver. This ensures a particularly large or long path of the second measuring section. Alternatively, the first and second reflectors are arranged at different distances from the ultrasound transmitter and the ultrasound receiver and reflect the ultrasound signals directly back to the ultrasound receiver, respectively. Particularly preferably, the ultrasonic transmitter and the ultrasonic receiver are formed by an ultrasonic transducer.
Drawings
Further advantages and preferred features emerge from the foregoing description and from the claims. The invention is intended to be explained in more detail below on the basis of the figures. For this purpose, it is shown that:
fig. 1 shows an advantageous sensor device in a simplified diagram;
FIGS. 2A and 2B show schematic diagrams for explaining the operation of the sensor device;
fig. 3 shows a flow chart for illustrating an advantageous method for operating the sensor device.
Detailed Description
Fig. 1 shows an advantageous sensor device 1 in a simplified plan view, which has a carrier 2 on which an ultrasonic transducer 3 is arranged. The ultrasonic transducers represent an ultrasonic transmitter 4 and an ultrasonic receiver 5. That is to say, the ultrasonic transducer is designed to generate an ultrasonic signal by electrical excitation and to convert the detected ultrasonic signal into an electrical signal. According to an alternative embodiment, the ultrasonic transmitter 4 and the ultrasonic receiver 5 are present as components or structural units which are constructed independently of one another. The arrangement of an ultrasound transducer which integrates both functions has, in particular, advantages with regard to the construction space.
The first reflector 6 is arranged opposite the ultrasonic transmitter 4 at a distance D0. The reflector 6 is oriented to reflect the ultrasonic signals generated by the ultrasonic transmitter 4 back to the ultrasonic receiver or transducer 3. This results in a first measuring section M0, which is calculated from the doubled distance D0. The transmitted ultrasonic signal requires a travel time T0 for passing through the first measurement segment M0.
The reflector 6 is also designed to reflect the ultrasonic signals emitted by the ultrasonic transmitter 4 to a second reflector 7, which is located at a distance D1 from the first reflector 6. This results in a further measuring section M1 between the first reflector 6 and the second reflector 7, which corresponds to twice the distance D1. The ultrasonic signal conducted from the first reflector 6 to the second reflector 7 and from the second reflector 7 back to the first reflector 6 requires a propagation time T1 for this purpose. The ultrasonic signals from the ultrasonic transmitter 4 to the first reflector 6, from the first reflector 6 to the second reflector 7, from the second reflector 7 back to the first reflector 6 and from there back to the ultrasonic receiver 5 pass through the total measurement section Mg M0+ M1 Mg and require a total propagation time Tg for this purpose.
The sensor device 1 is in particular placed in a liquid medium and is used to determine the material properties of the medium. The following facts are fully utilized for this: the speed of sound of the medium varies according to the determined characteristic. In this way, the sensor device 1 is designed in particular as a urea concentration sensor, which is arranged in a tank for an exhaust gas aftertreatment agent (which is an aqueous urea solution) in order to detect the urea concentration of the liquid present in the tank.
The operation of the sensor device 1 will be explained below on the basis of fig. 2A and 2B. Fig. 2A shows the electrical behavior of the ultrasonic transducer 3 in a first schematic diagram, wherein the voltage U is plotted over time t. Fig. 2B shows an enlarged section from fig. 2A, which is outlined there with a dashed box.
If the ultrasonic transducer 3 is electrically excited (as can be seen, for example, by the first signal S1 in fig. 2A), it emits an ultrasonic pulse in the direction of the reflector 6. The ultrasonic waves or reflected ultrasonic signals reflected directly back by the reflector 6 to the receiver 5 are converted into another voltage, which is labeled signal 2 in fig. 2A. The ultrasound pulse which is also conducted to the second reflector 7 and from there back to the first reflector and to the ultrasound receiver 5, i.e. the ultrasound pulse which passes through the larger path segment Dg, is detected by the receiver 5 at a later instant as signal S3.
Since the respective signal response contains a plurality of oscillations, it is required that the measurement is always performed at the same position of the signal response S2, S3 for detecting the propagation time of the respective signal.
For example, as shown in fig. 2B, for the respective response signals S2, S3, the nth positive zero crossing is always detected at the time tx after the adjustable detection threshold DS is exceeded. In order not to get erroneous measurements, it is required to adjust the detection threshold DS for the respective signal in response to possible instabilities in the response signal. In order to make available the information required for this purpose, a second response signal S3 is considered, by means of which the total propagation time Tg is detected. In particular, the ratio T1/T0 of the propagation times forms a parameter which characterizes the system and is used to set the detection thresholds DS2, DS3 for the respective signals S2, S3. Since the two responses differ significantly in magnitude, the two responses are analyzed in separate excitation and reception processes.
Fig. 3 shows a flow chart, on the basis of which an advantageous method for operating the sensor device 1 is described, by means of which reliable and correct detection of the signal responses S2, S3 is ensured for correct detection of material properties.
In step S1, the ratio of the propagation times T1 and T0 to each other is calculated. To calculate the transit time T1, the transit time T0 of the first measurement segment M0 is subtracted in particular from the total transit time Tg: T1-Tg-T0.
In the following step S2, it is checked whether the calculated ratio and the ratio M1/M0 of the actually measured piece are within the tolerance range Δ2A tolerance range Δ of within, in particular-0.015 to +0.0152And (4) the following steps.
If the query is answered "yes" (j), then another query is made in step S3. Here, it is queried whether the system has been initialized and whether the old values are available. If no old values are available, the current detection value of the propagation time T1 and the current detection value of the propagation time T0 are stored as T1_ alt or T0_ alt in step S4. In the following step S5, the further method is guided back to step S1 and the method is executed anew.
If there is already an old value pair in the query in step S3, then initialization (n) need not be performed and the method proceeds to step S6. In step S6, a further query is made in which it is checked whether the currently detected propagation time T1 deviates from the previously detected propagation time value T1_ alt by more than the selected tolerance range Δ1. The tolerance range Δ is predefined in accordance with the frequency of the ultrasonic transducer 31. According to this embodiment, the Transducer (Transducer)3 operates at a frequency of 1 MHz. The half oscillation period of the frequency is predetermined as a tolerance range delta1So that in the present case the tolerance range Δ is1+/-500 ns. If the deviation of the propagation time T1 is within the tolerance range delta1Outside (n), the probing threshold DS3 for the second signal S3 is matched corresponding to the currently detected travel time in step S7. If the propagation time T1 deviates not beyond the tolerance range delta1(j) Then, in a further query S8, it is checked that the propagation time value T0 deviates from the previously detected propagation time value T0_ alt by more than a predefined tolerance range Δ1(n) still not exceeding the predetermined tolerance range Delta1(j) In that respect If the tolerance range delta is exceeded1Then in a subsequent step S9 the detection threshold DS2 for the first signal S2 is matched corresponding to the current travel time measurement T0. However, if the measurement lies within the tolerance range (j), the previously measured values T1_ alt and T0_ alt are stored and the detection threshold is not changed.
If in step S2 it is detected that the deviation of the ratio of the travel times from the ratio of the measured segments lies outside the tolerance range determined in step S2 (n), the process continues with step S7, in which the detection threshold DS3 for the second signal S3 is matched in correspondence with the currently detected travel time.
Claims (10)
1. Method for operating a sensor device (1) which is designed for determining material properties of a gaseous and/or liquid medium and can be arranged in the medium, having at least one ultrasonic transmitter (4) for generating an ultrasonic signal, having a first reflector (6) arranged opposite in a spaced-apart manner to the ultrasonic transmitter (4), having at least one ultrasonic receiver (5) for receiving the ultrasonic signal reflected at the reflector (6), wherein the path of the ultrasonic signal from the ultrasonic transmitter (4) to the first reflector (6) and from the first reflector to the ultrasonic receiver (5) forms a first measuring section (M0), and having a second reflector (7) for reflecting the ultrasonic signal, wherein the path of the ultrasonic signal from the ultrasonic transmitter (4) to the second reflector (7) and from the second reflector (7) to the ultrasonic receiver (5) forms a second measurement segment (M1) which is longer or shorter than the first measurement segment (M0), wherein a first propagation time (T0) of the ultrasonic signal along the first measurement segment (M0) is detected in order to detect a material property of the medium, characterized in that if the currently detected first propagation time (T0) deviates from a previously detected first propagation time (T0_ alt) by more than a tolerance range (Δ) depending on the oscillation period of the ultrasonic signal1) And/or if the currently detected second propagation time (T1) deviates from the previously detected second propagation time (T1_ alt) outside the first tolerance range (Δ)1) -changing a detection threshold (DS2, DS3) for the detection of the first propagation time (T0) and/or the second propagation time (T1) and if the respective deviation lies within the first tolerance range (Δ 3)1) Within, the detection threshold is retained (DS2, DS 3).
2. The method of claim 1, wherein the tolerance is adjustedValue (Delta)1) Is predefined as half the period of oscillation of the ultrasonic signal.
3. Method according to any of the preceding claims, characterized in that the ratio of the propagation times (T0, T1) to one another is compared with the ratio of the lengths of the measurement segments (D0, D1) to one another, and only if the deviations of the ratios from one another lie within a predefined second tolerance range (Δ [)2) The method is executed only when needed.
4. Method according to any of the preceding claims, characterized in that the second tolerance range (Δ) is predefined in dependence of an oscillation period of the ultrasonic signal2)。
5. Method according to any of the preceding claims, characterized in that the first tolerance range (Δ) is defined1) Is previously specified to be-500 ns to +500 ns.
6. Method according to any of the preceding claims, characterized in that the second tolerance range (Δ) is adjusted2) Is previously specified to be-0.020 to +0.020, and is particularly previously specified to be-0.015 to + 0.015.
7. The method according to any of the preceding claims, characterized in that when a change of the probing threshold (DS2, DS3) occurs, the change is based on the currently detected first or second propagation time (T0, T1).
8. The method according to any of the preceding claims, characterized in that for the case that no previously detected first or second propagation time (T0_ alt, T1_ alt) is available, the currently detected first and/or second propagation time (T0, T1) is stored, and the change of the probing threshold (DS2, DS3) is based on the currently detected first and/or second propagation time.
9. A sensor device (1) which is designed for determining a material property of a gaseous and/or liquid medium and can be arranged in the medium, having at least one ultrasonic transmitter (4) for generating an ultrasonic signal, having a first reflector (6) arranged opposite the ultrasonic transmitter (4) at a distance, having at least one ultrasonic receiver (5) for receiving the ultrasonic signal reflected at the reflector (6), wherein a path of the ultrasonic signal from the ultrasonic transmitter (4) to the first reflector (6) and from the first reflector to the ultrasonic receiver (5) forms a first measuring section (M0), and having a second reflector (7) for reflecting the ultrasonic signal, wherein, the path of the ultrasonic signal from the ultrasonic transmitter (4) to the second reflector (7) and from the second reflector (7) to the ultrasonic receiver (5) forming a second measuring section (M1) which is longer or shorter than the first measuring section (M0), characterized by a specially provided control device which is configured for carrying out the method according to any one of claims 1 to 8 in normal use.
10. Sensor device according to claim 9, characterized in that the second reflector (7) is arranged opposite the first reflector (6) in such a way that the ultrasonic signal is conducted from the first reflector (6) also to the second reflector (7) and from the second reflector (7) back to the first reflector (6) and from there to the ultrasonic receiver (5), wherein the path of the ultrasonic signal from the first reflector (6) to the second reflector (7) and back forms the second measuring section (M1).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102020212219.9A DE102020212219A1 (en) | 2020-09-28 | 2020-09-28 | Method for operating a sensor device, sensor device |
| DE102020212219.9 | 2020-09-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114324570A true CN114324570A (en) | 2022-04-12 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111142943.4A Pending CN114324570A (en) | 2020-09-28 | 2021-09-28 | Method for operating a sensor device, sensor device |
Country Status (2)
| Country | Link |
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| CN (1) | CN114324570A (en) |
| DE (1) | DE102020212219A1 (en) |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102014213233A1 (en) | 2014-07-08 | 2016-01-14 | Continental Automotive Gmbh | Device for determining a speed of sound of a sound signal in a fluid |
| DE102018202587A1 (en) | 2018-02-21 | 2019-08-22 | Robert Bosch Gmbh | Device for determining quality, tank device |
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2020
- 2020-09-28 DE DE102020212219.9A patent/DE102020212219A1/en active Pending
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- 2021-09-28 CN CN202111142943.4A patent/CN114324570A/en active Pending
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| DE102020212219A1 (en) | 2022-03-31 |
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