DE4210737A1 - Fuel tank contents measurement - exposing liq. to stray field of capacitor plates mounted on flexible insulating material, and stuck directly on tank. - Google Patents
Fuel tank contents measurement - exposing liq. to stray field of capacitor plates mounted on flexible insulating material, and stuck directly on tank.Info
- Publication number
- DE4210737A1 DE4210737A1 DE19924210737 DE4210737A DE4210737A1 DE 4210737 A1 DE4210737 A1 DE 4210737A1 DE 19924210737 DE19924210737 DE 19924210737 DE 4210737 A DE4210737 A DE 4210737A DE 4210737 A1 DE4210737 A1 DE 4210737A1
- Authority
- DE
- Germany
- Prior art keywords
- tank
- capacitor
- measurement
- stray field
- liq
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- B60K15/00—Arrangement in connection with fuel supply of combustion engines or other fuel consuming energy converters, e.g. fuel cells; Mounting or construction of fuel tanks
- B60K15/03—Fuel tanks
- B60K15/06—Fuel tanks characterised by fuel reserve systems
- B60K15/061—Fuel tanks characterised by fuel reserve systems with level control
-
- 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
- G01F23/26—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 variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
- G01F23/263—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 variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields by measuring variations in capacitance of capacitors
-
- 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
- G01F23/26—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 variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
- G01F23/263—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 variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields by measuring variations in capacitance of capacitors
- G01F23/266—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 variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields by measuring variations in capacitance of capacitors measuring circuits therefor
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Thermal Sciences (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Sustainable Energy (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Level Indicators Using A Float (AREA)
Abstract
Description
Die Tankinhaltsmessung von Kraftstofftanks in Fahrzeugen geschieht u. a. nach dem Schwimmerprinzip, wobei ins Innere des Tanks eingegriffen werden muß und damit ein erheblicher konstruktiver Aufwand zu leisten ist.The tank content measurement of fuel tanks in vehicles happens u. a. according to the float principle, being inside the tank must be intervened and thus a considerable constructive effort is to be made.
Eine wesentliche Vereinfachung für die Serienfertigung bietet das kapazitive Meßprinzip der Streufeldmessung, da hierbei lediglich zwei kupferbeschichtete Folien (Meßkondensator, Referenzkondensator) auf dem Kunststofftank beliebiger Form aufgeklebt werden müssen.A significant simplification for series production offers the capacitive measuring principle of stray field measurement, because only two copper-coated foils (Measuring capacitor, reference capacitor) on the plastic tank any shape must be glued.
Die Meßsignalerzeugung und -auswertung geschieht direkt am Tank (aktiver Fühler). D.h. die Schaltung erzeugt eine periodisch sich ändernde Spannung (Sinus oder Dreieckspannung) hoher Frequenz (ca. 100 KHz) die eine Brückenschaltung speist. Die Wechselspannung wird in eine Gleichspannung gewandelt und verstärkt. Die Gleichspannung kann dann über längere Leitungen einfach übertragen werden.The measurement signal generation and evaluation takes place directly on Tank (active sensor). I.e. the circuit generates one periodically changing voltage (sine or Triangular voltage) high frequency (approx. 100 KHz) the one Bridge circuit feeds. The AC voltage is converted into a DC voltage converted and amplified. The DC voltage can then be easily transmitted over longer lines.
Durch Integration der elektronischen Bauteile zu einem IC, wird die Meßanordnung bei großer Stückzahl sehr billig.By integrating the electronic components into an IC, the measuring arrangement becomes very cheap for large quantities.
Die Ausführung des Sensors (Meßkondensators) ist eine der Höhe des Tanks entsprechende Folie auf der zwei parallele Kupferbahnen beschichtet sind. Der Referenzkondensator ist ähnlich aufgebaut und kann der Tankform entsprechend anders flächig sein (quadratisch oder rund). Er befindet sich bei spielsweise auf der Oberseite des Tanks an dessen Innenseite über längere Zeit kein Tankinhalt hinkommt. (Fig. 1 u. 2) Das zu messende Streufeld geht aus Fig. 2 hervor. Da die Kondensatorplatten eng aneinander liegen und der Tank üblicherweise ca. 5mm dick ist, ist die Änderung der relevanten elektrischen Dielektrizitätskonstanten (e4) des Meßkondensators sehr schwach. Dadurch ist eine sensitive Elektronik zur exakten Auswertung notwendig.The design of the sensor (measuring capacitor) is a film corresponding to the height of the tank, on which two parallel copper tracks are coated. The reference capacitor has a similar structure and can have a different area (square or round) depending on the shape of the tank. It is located, for example, on the top of the tank on the inside of which no tank contents can reach for a long time. ( Fig. 1 and 2) The stray field to be measured is shown in Fig. 2. Since the capacitor plates are close together and the tank is usually approx. 5mm thick, the change in the relevant electrical dielectric constant (e 4 ) of the measuring capacitor is very weak. This means that sensitive electronics are required for exact evaluation.
Es gibt bereits kapazitive Brückenschaltungen. Im vorliegenden Fall ist jedoch eine spezielle Ausführung erforderlich (Fig. 3).There are already capacitive bridge circuits. In the present case, however, a special version is required ( Fig. 3).
Es wird eine Sinuswechselspannung UAC mit einer Frequenz f von 100 kHz erzeugt, welche den Meßkondensator und den Referenz kondensator speist.An AC sine voltage U AC is generated with a frequency f of 100 kHz, which feeds the measuring capacitor and the reference capacitor.
Der Spannungsabfall am Meßkondensator ändert sich mit der Änderung des kapazitiven Widerstandes Xc gemäß der Beziehung:The voltage drop across the measuring capacitor changes with the change in the capacitive resistance X c according to the relationship:
UAC/Uc = (R+Xc)/Xc,
Uc = UAC * Xc/(R+Xc),
Xc = 1/(2 * Pi * f * C),
C = er * e₀ * d/A.U AC / U c = (R + X c ) / X c ,
U c = U AC * X c / (R + X c ),
X c = 1 / (2 * Pi * f * C),
C = e r * e₀ * d / A.
R: ohmscher Serienwiderstand der Meßbrücke,
Uc: Spannungsabfall am Meßkondensator,
C: Kapazität des Meßkondensators,
er: relative Dielektrizitätskonstante des Meßkondensators,
e₀: absolute Dielektrizitätskonstante,
d: elektrisch wirksamer Abstand der Kondensatorplatten des
Meßkondensators,
A: elektrisch wirksame Fläche des Meßkondensators.
R: ohmic series resistance of the measuring bridge,
U c : voltage drop across the measuring capacitor,
C: capacitance of the measuring capacitor,
e r : relative dielectric constant of the measuring capacitor,
e₀: absolute dielectric constant,
d: electrically effective distance between the capacitor plates of the measuring capacitor,
A: Electrically effective area of the measuring capacitor.
Die Kapazität C ändert sich in Abhängigkeit von er. Dieses wiederum ändert sich in Abhängigkeit von dem Tankinhalt hinter der Tankwand.The capacitance C changes depending on e r . This in turn changes depending on the tank content behind the tank wall.
Beide Spannungen, sowohl Uc als auch die Referenzwechselspannung UCR werden gleichgerichtet, voneinander subtrahiert und verstärkt. Die Gleichrichtung geschieht im Beispiel durch synchrone Abtastung mittels eines Abtast-Haltegliedes.Both voltages, both U c and the reference alternating voltage U CR, are rectified, subtracted from one another and amplified. In the example, the rectification is carried out by synchronous sampling using a sample and hold element.
Die Sinuswechselspannung UAC schaltet einen Komparator zu einer definierten Phase von UAC. Das Schaltsignal Us steuert das Abtast-Halteglied und setzt den Speicherschalter immer zur gleichen Phase auf Messung. Damit wird der Wechselspannung stets der gleiche Spannungswert entnommen, der proportional zur Amplitude von UAC ist.The sine AC voltage U AC switches a comparator to a defined phase of U AC . The switching signal U s controls the sample and hold element and always sets the memory switch to measurement at the same phase. The AC voltage is therefore always taken from the same voltage value, which is proportional to the amplitude of U AC .
Da die Spannungsänderungen im Mikrovoltbereich liegen, ist ein Offsetabgleich erforderlich, der auch die Unterschiede von Meß- und Referenzkondensator ausgleicht. Bei einer Inte gration zu einem IC kann dieser Abgleich durch entsprechende Elektronik ersetzt werden.Since the voltage changes are in the microvolt range, an offset adjustment is required, which also shows the differences of measuring and reference capacitors. Inte This comparison can be achieved by an appropriate IC Electronics to be replaced.
Die Verwendung eines Sinussignals zur Messung hat den Vorteil geringerer Oberwellen und ist damit EMV sicherer.The use of a sine signal for measurement has the Advantage of lower harmonics and is therefore EMC safer.
Claims (5)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19924210737 DE4210737A1 (en) | 1992-04-01 | 1992-04-01 | Fuel tank contents measurement - exposing liq. to stray field of capacitor plates mounted on flexible insulating material, and stuck directly on tank. |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19924210737 DE4210737A1 (en) | 1992-04-01 | 1992-04-01 | Fuel tank contents measurement - exposing liq. to stray field of capacitor plates mounted on flexible insulating material, and stuck directly on tank. |
Publications (1)
Publication Number | Publication Date |
---|---|
DE4210737A1 true DE4210737A1 (en) | 1993-10-07 |
Family
ID=6455657
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
DE19924210737 Withdrawn DE4210737A1 (en) | 1992-04-01 | 1992-04-01 | Fuel tank contents measurement - exposing liq. to stray field of capacitor plates mounted on flexible insulating material, and stuck directly on tank. |
Country Status (1)
Country | Link |
---|---|
DE (1) | DE4210737A1 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19713267A1 (en) * | 1997-01-28 | 1998-07-30 | Abb Research Ltd | Method for determining the dielectric constant and / or the conductivity of at least one medium and device for carrying out the method |
EP1722203A2 (en) * | 2005-05-13 | 2006-11-15 | Joma-Polytec Kunststofftechnik GmbH | Measuring system for measuring the fill level of a liquid in a container |
DE10309769B4 (en) * | 2002-03-08 | 2017-10-05 | Ust Umweltsensortechnik Gmbh | Arrangement for determining state variables for liquids in a closed non-metallic container |
US10203238B2 (en) | 2014-03-07 | 2019-02-12 | Barrelogix, Llc | Liquid detection apparatus |
WO2020020534A1 (en) * | 2018-07-26 | 2020-01-30 | Kautex Textron Gmbh & Co. Kg | Checking the quality of a fluid concentration |
-
1992
- 1992-04-01 DE DE19924210737 patent/DE4210737A1/en not_active Withdrawn
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19713267A1 (en) * | 1997-01-28 | 1998-07-30 | Abb Research Ltd | Method for determining the dielectric constant and / or the conductivity of at least one medium and device for carrying out the method |
DE10309769B4 (en) * | 2002-03-08 | 2017-10-05 | Ust Umweltsensortechnik Gmbh | Arrangement for determining state variables for liquids in a closed non-metallic container |
EP1722203A2 (en) * | 2005-05-13 | 2006-11-15 | Joma-Polytec Kunststofftechnik GmbH | Measuring system for measuring the fill level of a liquid in a container |
EP1722203A3 (en) * | 2005-05-13 | 2007-10-03 | Joma-Polytec Kunststofftechnik GmbH | Measuring system for measuring the fill level of a liquid in a container |
US10203238B2 (en) | 2014-03-07 | 2019-02-12 | Barrelogix, Llc | Liquid detection apparatus |
WO2020020534A1 (en) * | 2018-07-26 | 2020-01-30 | Kautex Textron Gmbh & Co. Kg | Checking the quality of a fluid concentration |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
8139 | Disposal/non-payment of the annual fee |