Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
  • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
  • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
  • G01F23/28—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
  • G01F23/296—Acoustic waves
  • G01F23/2962—Measuring transit time of reflected waves
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
  • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
  • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
  • G01F23/28—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
  • G01F23/296—Acoustic waves
  • G01F23/2968—Transducers specially adapted for acoustic level indicators
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
  • G01F25/00—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume
  • G01F25/20—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume of apparatus for measuring liquid level

Definitions

• the invention relates to an apparatus and a korrespondie ⁇ rendes method of determining a height of a Fluidoberfla ⁇ che in a fluid container.
• an acoustic measuring device can be used in particular.
• a sound transducer of the acoustic Messvor ⁇ direction can work both as a sound generator and as a sound ⁇ receiver.
• For determining the amount of Fluido- ber Structure in the fluid container can by means of the baffle ⁇ coupler sound pulses in the fluid to be measured given the ⁇ . The sound pulses are reflected from a boundary surface of the Flu ⁇ ids to another medium. From the duration of the sound pulses can be drawn conclusions about the height of the fluid surface in the fluid container.
• the object on which the invention is based is to provide a device for determining a height of a fluid surface in a fluid container, which enables a reliable determination of the height of the fluid surface, and a corresponding method for operating the device.
• the invention is characterized by a device for determining a height of a fluid surface in a fluid container.
• the device comprises a first sound transducer for transmitting and receiving first sound signals in the direction of the fluid surface and one second sound transducer for transmitting and receiving second sound signals.
• the device comprises a reference element which has a predetermined distance to the second sound transducer ⁇ .
• the reference element is arranged in a fluid space of the fluid container.
• the device further comprises a first deflection element which is arranged in the fluid space for deflecting the second
• the device to identify further comprises a control unit which is adapted, depending on the second sound signals, a sound speed within a fluid in the Flu ⁇ idraum.
• the control unit is further to be ⁇ forms, depending on the first acoustic signals to detect the second acoustic signals and the speed of sound within the fluid, the height of the fluid surface over a bottom portion of the fluid container.
• the first transducer radiates for this purpose directly in the direction of the fluid surface.
• a determination of the Schallge ⁇ speed within the fluid allows precise determining a signal propagation time.
• To even at low filling ⁇ stands the speed of sound within the fluid to ermit ⁇ stuffs, it has been found advantageous to send the second acoustic signals in a low height above the Bodenab ⁇ section of the fluid container and to receive.
• the second transducer thus serves primarily to determine the Sound velocity within the fluid, and secondary to Gustand measurement.
• the first deflecting element for example made of metal, glass or Kera ⁇ mik formed. Relatively container to the fluid in the fluid, the first deflection element in such a high akusti ⁇ specific impedance. Thus, a reliable deflection of the sound signals is possible. Furthermore, this allows for ⁇ play a robust arrangement of the deflecting element as a free standing component.
• the first deflecting element is designed, for example, as a hollow body.
• the first Umlenkele ⁇ element is filled with air, is comparable Ringert advantageously a thermally induced expansion of the first deflecting element. Furthermore thereby be reduced, for example, Mate ⁇ rial modifier and a weight of the device. Relative to the fluid in the fluid container, the first deflecting element thus also has a low acoustic impedance. Advantageously, this allows a reliable deflection of the sound signals.
• the bottom portion of the fluid container has, for example, a bulge, with which the first deflecting gekop ⁇ pelt.
• the bulge projects into the fluid space.
• a second deflection element is arranged at a predetermined distance from the first deflection element in the fluid space for deflecting the second sound signals by a second predetermined angle in the direction of the first deflection element.
• the two sound transducers are designed, for example, as piezo transducers.
• An assembly of the two transducers is in ⁇ example complicated by their small size.
• the arrangement of the two transducers to the bottom portion of the fluid container contributes advantageously to the fact that the assembly is accurate and efficient.
• the bottom portion of the fluid container is formed in this context, for example, separately from side walls of the Fluidbenzol ⁇ age , which additionally contributes to a simple installation of the two transducers.
• the second deflecting element is designed, for example, analogously to the first deflecting element.
• a sound guide tube is arranged in the fluid space.
• Sound guide tube is formed to guide the second deflected by the first deflecting second sound signals along sei ⁇ ner longitudinal axis in the direction of the fluid surface.
• the sound guide tube allows reliable Determined ⁇ averaging the height of the fluid surface, substantially independent of a dynamics of the fluid surface. For example, by movement of the fluid container or by an inclined position of the fluid container, the fluid surface has a particularly pronounced dynamics, which lead without a sound guide to a scattering of the sound signals or otherwiseMitbe ⁇ liable determination of the height of the fluid surface.
• be ⁇ carries a length of the sound guide tube between 30 mm and 100 mm.
• the length of the sound guide ⁇ tube is between 50 mm and 70 mm.
• the County ⁇ ge of the sound guide tube is 60 mm.
• Such dimensioning of the sound tube made light ⁇ a reliable and precise determination of the height of the fluid surface.
• the length of the Schalltre approximately ⁇ pipe is less than the height H of the fluid surface.
• the length of the sound guide tube of at least 30 mm made ⁇ light the sound guide for low heights of Fluidoberflä ⁇ che, in which a precise determination of the height is particularly important ⁇ tig.
• a mechanical load capacity of the sound guide tube made light ⁇ a reliable and precise determination of the height of the fluid surface.
• Sound guiding tube ensured. Since the fluid example ⁇ as freezes at low temperatures the mechanical ⁇ withstand capability of the sound tube of special importance.
• be ⁇ carries a diameter of the sound tube is between 5 mm and 15 mm.
• the diameter of the sound ⁇ guide tube is 10 mm.
• Such dimensioning of the sound tube made light ⁇ a reliable and precise determination of the height of the fluid surface.
• the diameter of the sound guide tube of At least 5 mm allows reliable Signaleinkopp ⁇ ment, especially with regard to mounting tolerances, so that a signal attenuation is kept low.
• a mechanical load capacity of the sound guide tube si ⁇ cher adopted by the diameter of the sound guide tube of at most 15 mm. In addition, such an effective sound guidance is ensured by the sound guide tube.
• a ratio of the length of the sound guide tube to the diameter of the sound guide tube is between 20: 1 and 2: 1. In particular, the ratio is between 12: 1 and 4: 1. In particular, the ratio is 6: 1.
• Such a dimensioning of the sound guide tube contributes in particular to the mechanical strength of the Schalltre ⁇ tion tube.
• a reflector is arranged on an inner wall of the sound guide tube.
• the reflector has a predetermined reference distance to the bottom portion.
• the reflector allows a determination of a minimum height of the fluid surface.
• the invention is characterized by a method for operating the device.
• the height of the fluid surface above the bottom portion of the fluid container becomes dependent on a signal quality of the first
• the signal quality of the first sound signals and the second sound signals is determined as a function of a respective signal dispersion of a plurality of temporally successive recorded sound signals.
• the signal quality of the first sound signals and the second sound signals is determined as a function of a respective signal power of the recorded sound signals.
• FIG. 1 shows a first embodiment of a device for determining a height of a fluid surface in a fluid container
• FIG. 2 is a flowchart for operating the device.
• Figure 3 shows a second embodiment of the device for
• Figure 4 shows a third embodiment of the device for
• Figure 5 shows a fourth embodiment of the device for
• Figure 6 shows a fifth embodiment of the device for
• Figure 1 shows a fluid container 1 with a bottom portion 3 and a fluid space 5, which is filled with a fluid F.
• the fluid F is, for example, be a flüssi ⁇ ges medium for reducing pollutants in exhaust gases, the preferential ⁇ as a reducing agent and / or a reducing agent precursor ⁇ , for example, a urea aqueous solution up.
• a first sound transducer 10 and a second sound transducer 20 are arranged on the bottom portion 3 of the fluid container 1.
• the height H is defined as a distance between the fluid surface 0 of the bottom portion 3, ge ⁇ measure in a neutral position of the fluid container 1, ie when there is no inclination of the fluid container 1 is present and the fluid surface 0 is parallel to the bottom portion. 3
• the height H can also be characterized as a level of the fluid container 1 be ⁇ .
• the two sound transducers 10, 20 are designed, for example, as piezo converters and coupled through a housing wall of the fluid container 1.
• the Gezzau ⁇ sewandung is formed of a plastic such as beispielswei ⁇ ses from so-called high-density polyethylene (high density polyethylene, HDPE), so that the bottom portion 3 in the Ge ⁇ reheatwandung can be welded.
• the two sound transducers 10, 20 glued, for example, with the housing ⁇ wall or pressed mechanically to this, possibly even with a further intermediate layer to compensate for unevenness or roughness.
• the first sound transducer 10 comprises a transmitter, the first
• Sound signals 12 in the direction of the fluid surface 0 emits.
• the first transducer 10 is aligned so that a main radiation direction of the sound signals ⁇ 12 is directed perpendicular to the bottom portion 3 to the Fluido ⁇ berflache 0 transmitted first.
• the fluid chamber 5 above the fluid F is filled with a further medium, such as air, so that the gesende ⁇ th first acoustic signals 12 ber Structure at a junction of the Fluido- 0 reflect on the air and reflected first acoustic signals 14 at first transducer 10 meet.
• the reflected first sound signals 14 are recorded.
• Example ⁇ example can be a single piezoelectric element used as a transmitter and receptions and seminars ⁇ ger.
• the orientation of the first baffle ⁇ lers 10 also leads to a substantially vertical spread th the first reflected sound signals 14 to the bottom portion 3 of the fluid container 1.
• the propagation of the first sound signals 12, 14 takes place directly, so that a power loss prevents obstacles and thus a determination of high levels of the fluid container 1 is made possible.
• the second sound transducer 20 comprises a transmitter which emits second sound signals 22 and a receiver, the reflected second sound signals 24 receives.
• a first reference element 30 and a second reference element 40 are arranged in the fluid space 5.
• the two Refe rence ⁇ elements 30, 40 are preferably ge ⁇ forms of a material comprising a metal.
• the two reference elements 30, 40 are formed from a piece of metal and coupled by H formulateverstemmte plastic tabs with the Bodenab ⁇ section 3 of the fluid container 1.
• the two reference elements 30, 40 reflect at least part of the egg ⁇ NEN transmitted second sound signal 22.
• the ers ⁇ th reference member 30 has the second transducer 20 ei ⁇ NEN predetermined first distance.
• the second reference element 40 has the second transducer 20 a predetermined second distance and in particular a precisely known from ⁇ stand to the first reference element 30.
• a first value Hl for the height H of the fluid surface O is determined via the bottom portion 3 of the fluid container 1.
• Sound signals 22 is the main radiation direction in wesent ⁇ union perpendicular to the bottom portion 3 of the fluid container. 1 To determine the speed of sound, the latestsen ⁇ Deten second sound signals 22 are deflected such that they are substantially parallel to the bottom portion 3 on the two reference elements 30, 40 overall is directed in a second portion 22b. Further, parallel reflected second sound signals 24 are deflected in such a way in a second portion 24b to the bottom portion 3 is substantially that they are directed in a non-illustrated third section 24c in Wesentli ⁇ surfaces perpendicular to the second sound transducer 20th
• the second sound ⁇ signals 22, 24 in addition to determining the speed of sound also used to determine the height H of the fluid surface 0, so that depending on one of the second sound signals 22, 24 second value H2 is determined for the height H of the fluid surface.
• a first deflecting element 50 is arranged in the fluid space 5.
• a second deflection element 60 is disposed in the fluid space 5.
• the two deflecting elements 50, 60 close to the Bodenab ⁇ section 3 of the fluid container 1 each have a 45 ° angle, so that the sound signals 22, 24 respectively by the predetermined angle Wl, W2, by + 90 ° or -90 ° are deflected ,
• the two deflection elements 50, 60 are formed, for example, depending ⁇ wells a piece of metal and have a high acoustic impedance relative to the acoustic impedance of the fluid F, so that a large part of the sound signals 22, 24 is reflected.
• the deflecting elements 50, 60 are formed, for example, as a cavity, which is filled with air, for example. The latter has a low acoustic impedance relative to the fluid F in the fluid space 5, so that a large part of the sound signals 22, 24 is reflected.
• the bottom portion of the fluid container 1 bulges, on which the deflecting elements 50, 60 lie on ⁇ or into which the deflecting elements 50, are integrated 60th
• a program and data memory of the control ⁇ device a program is stored, which is explained in more detail below with reference to the flowchart of Figure 2.
• the program is started in a step S1 in which, for example, variables are initialized.
• a step S3 the first value Hl for the height H of the fluid surface 0 is determined and the second value H2 for the height H of the fluid surface 0 is determined.
• a first signal power SL1 of the first reflected sound signals 14 and a second signal power ⁇ SL2 of the second reflected sound signals 24 are ⁇ it averages.
• a signal quality SQ1 of the first reflected sound signals 14 determined and dependent on the second Sig ⁇ nalstreuung SSI of the second reflected sound signals 24 and the second signal power SL1 of the second reflected sound signals 24 determines a signal quality SQ1 of the second reflected ⁇ sound signals 24.
• a step S the height H of the fluid surface 0 determined depending on the first signal quality SQ1 of the first reflected sound signals 14 and from ⁇ pending from the second signal quality SQ2 of the second reflectors ⁇ formatted sound signals 24 in the fluid container. 1 For example, this is done by weighting with the respective signal quality SQ1, SQ2 of the reflected signals 14, 24.
• the height H of the fluid surface O of the fluid F in the fluid container 1 is determined analogously to the first exemplary embodiment from FIG. 1.
• the second sound transducer 20 is attached to one side of the housing wall of the fluid container 1 ⁇ orders.
• the orientation of the second transducer 20 includes with the first transducer 10 a 90 ° angle, so that transmitted second sound signals 22 of the second transducer 20 are directed onto the first deflection element 50 parallel to the bottom portion 3, while the ers ⁇ th sound signals 12 , 14 as in the first embodiment in Spread substantially perpendicular to the bottom portion 3.
• Figure 4 shows a third embodiment, with two order ⁇ steering elements 50, 60 according to the first embodiment, but which are arranged so that acoustic paths of the two transducers 10, 20, as shown in the second embodiment intersect.
• Such an arrangement results in a particularly compact design of the device, in which a mutual influence of the sound signals 12, 14, 22, 24 can be kept low.
• the arrangement of the sound measurement ⁇ converter 10, 20 in the following embodiments of the fi gures 5 and 6 corresponds to that discussed in FIG. 4
• the height H of the fluid surface O of the fluid F in the fluid container 1 is determined analogously to the first exemplary embodiment from FIG. 1.
• a sound guide tube 70 is arranged in the fluid space 5, in order to be able to perform as precise a determination of the height H as possible.
• the sound guide tube 70 is formed for example of the same plastic as the fluid container 1 and for mecha ⁇ African coupling to the fluid container 1, for example, plugged and / or locked with snap hooks.
• the sound guide tube 70 is adapted to be the bottom portion 3 perpendicularly oriented third portion 22c of the transmitted second sound signals 22 toward the fluid surface 0, and the vertically aligned ers ⁇ th portion 24a of the light reflected at the fluid surface 0 second sound signals 24 toward the first Umlenkele- ment 50 along a longitudinal axis of the sound guide tube 70 to lead.
• the height H of the fluid surface 0 is less than a length of the sound guide tube 70, that is, a level of the fluid surface 0 does not exceed the bottom portion 3 from ⁇ facing end of the sound guide tube 70, carries the sound guide tube 70 to a strong decoupling dynamics the fluid surface 0 within the sound transmission tube 70 to the dynamics of the fluid surface 0 outside the sound guide tube 70 at. Determining the height H is extremely reliable in this case, even with a highly dynamic fluid surface 0.
• the reflected reference sound signals receives 24d, 24e may be assumed with a high probability, that the level of the fluid surface 0 at least the cut the Bodenab ⁇ 3 facing away from the end of the sound tube 70 exceeds ⁇ because the determination of the height H at lower heights H is extremely reliable.
• the Flu- id F is a reducing agent
• this is of particular Inte ⁇ ress, since an operation of a vehicle without a sufficient level of the reducing agent, so for example, in Un ⁇ drops below an predetermined height H, is not allowed.
• an absolute gauge length of the height H of the fluid surface 0 is for example 500 mm or more, and there the fluid F at winter temperatures, for example, at below
• -10 ° C can freeze and the fluid container 1 is exposed to, for example, strong vibrations, are requirements for ei ⁇ ne mechanical strength of the sound guide tube 70 be ⁇ particularly high.
• a ratio of the length of the sound guide tube 70 to a diameter of the sound guide tube between 20: 1 and 2: 1 has been found to be advantageous he ⁇ .
• the length of the Schallpar ⁇ approximately tube 70 is for example 60 mm.
• Sound tube 70 is for example 10 mm, to determine the mechanical strength of the sound guide tube 70 securely ⁇ .
• the height H of the fluid surface O of the fluid F in the fluid container 1 is determined analogously to the third exemplary embodiment from FIG. 4.
• the sound guide tube 70 has a reflector 90 on its inner wall 80.
• the reflector ⁇ tor 90 is, for example, from the same material as the deflecting element 50, 60 or the reference element 30, 40 out ⁇ forms and preferably disposed on the bottom portion 3 remote from the end of the sound guide tube 70, so that it to the bottom portion 3 a predetermined reference distance having.
• the reflector 90 is, for example, fixedly coupled to the inner wall 80.
• the predetermined reference distance can be variably adjusted, for example.
• the second transducer 20 receives regardless of the dynamics of the fluid surface doo 0 a reflected on the reflector 90 sound ⁇ signal.

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• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• General Physics & Mathematics (AREA)
• Acoustics & Sound (AREA)
• Electromagnetism (AREA)
• Thermal Sciences (AREA)
• Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
• Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)

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• 2014
  • 2014-05-27 DE DE102014210077.1A patent/DE102014210077A1/de not_active Ceased
• 2015
  • 2015-05-26 KR KR1020167020508A patent/KR101938042B1/ko active IP Right Grant
  • 2015-05-26 EP EP15724646.3A patent/EP3063513A2/de not_active Withdrawn
  • 2015-05-26 CN CN201580006632.1A patent/CN106415217B/zh active Active
  • 2015-05-26 US US15/113,977 patent/US10101193B2/en active Active
  • 2015-05-26 WO PCT/EP2015/061495 patent/WO2015181107A2/de active Application Filing

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