DE10118061A1 - Capacitative sensor element comprises numerous electrodes which interlock, made of metal plates that are held by a plastic holding element - Google Patents
Capacitative sensor element comprises numerous electrodes which interlock, made of metal plates that are held by a plastic holding elementInfo
- Publication number
- DE10118061A1 DE10118061A1 DE2001118061 DE10118061A DE10118061A1 DE 10118061 A1 DE10118061 A1 DE 10118061A1 DE 2001118061 DE2001118061 DE 2001118061 DE 10118061 A DE10118061 A DE 10118061A DE 10118061 A1 DE10118061 A1 DE 10118061A1
- Authority
- DE
- Germany
- Prior art keywords
- electrodes
- sensor
- plastic
- liquid
- frame
- 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.)
- Ceased
Links
- 229910052751 metals Inorganic materials 0.000 title claims abstract description 27
- 239000002184 metals Substances 0.000 title claims abstract description 25
- 239000007788 liquids Substances 0.000 claims abstract description 25
- 238000005530 etching Methods 0.000 claims abstract description 4
- 238000001746 injection moulding Methods 0.000 claims abstract description 4
- 238000004519 manufacturing process Methods 0.000 claims description 9
- 238000006243 chemical reactions Methods 0.000 claims description 3
- 238000000465 moulding Methods 0.000 claims description 2
- 280000672474 Metal Structure companies 0.000 abstract 2
- 239000000969 carriers Substances 0.000 description 6
- 239000000463 materials Substances 0.000 description 4
- 230000000875 corresponding Effects 0.000 description 3
- 238000005516 engineering processes Methods 0.000 description 3
- 239000000758 substrates Substances 0.000 description 3
- 239000003570 air Substances 0.000 description 2
- 239000004020 conductors Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- 230000032683 aging Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000004364 calculation methods Methods 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000001427 coherent Effects 0.000 description 1
- 230000001419 dependent Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000005755 formation reactions Methods 0.000 description 1
- 239000000446 fuels Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000000203 mixtures Substances 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 239000002344 surface layers Substances 0.000 description 1
- 230000002123 temporal effects Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/08—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices
- G01V3/088—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices operating with electric fields
-
- 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, 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, indicating by means of an alarm by measurement of 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, indicating by means of an alarm by measurement of 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, indicating by means of an alarm by measurement of 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 using capacitors
- G01F23/265—Indicating or measuring liquid level, or level of fluent solid material, e.g. indicating in terms of volume, indicating by means of an alarm by measurement of 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 using capacitors for discrete levels
-
- 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, 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, indicating by means of an alarm by measurement of 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, indicating by means of an alarm by measurement of 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, indicating by means of an alarm by measurement of 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 using capacitors
- G01F23/268—Indicating or measuring liquid level, or level of fluent solid material, e.g. indicating in terms of volume, indicating by means of an alarm by measurement of 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 using capacitors mounting arrangements of probes
Abstract
Description
The invention is based on a capacitive sensor element or of a method for producing a capacitive Sensor element according to the genre of the independent Claims.
Capacitive sensor elements are already known, which serve as level sensors. Such sensor elements are shown in FIG. 1. The sensor elements have a printed circuit board 100 , on the upper side of which electrode structures 101 , 102 are formed as thin surface layers. The electrodes 101 are all electrically connected to one another. Likewise, the electrodes 102 are all connected to one another. A measurement capacitance consisting of the electrode group 101 and the electrode group 102 is thus formed. The capacitance between these electrodes depends on the electrode geometry and the dielectric constant of the surrounding medium. A corresponding partial capacitance is formed both on the upper side of the electrodes 101 , 102 and on the lower side of the electrodes. The partial capacitance which forms between the electrodes 101 , 102 downward is essentially determined by the dielectric constant of the carrier substrate 100 . The upper partial capacitance between the electrodes 101 , 102 is determined by the dielectric constant of the medium above the electrodes. When used as a level sensor, the sensor element according to FIG. 1 is arranged such that part of the electrodes 101 , 102 is immersed in the liquid and, depending on the level of the liquid, part of the electrodes 101 , 102 are not immersed in the liquid. Thus, if the dielectric constant of the liquid differs from the dielectric constant of air, the total capacitance measured between the electrodes 101 , 102 depends on how many of the electrodes 101 , 102 are immersed in the liquid and how many are not. Since the carrier 100 is arranged at the bottom, the capacity cannot be changed in this direction, so that the change in capacity due to the immersion or non-immersion in the liquid is relatively small. Furthermore, a printed circuit board 100 is usually used as a carrier, which has a relatively large dielectric constant. This also contributes to the fact that the measurement effect is relatively small. Furthermore, such circuit boards 100 can change over time, either due to aging or due to the diffusion of part of the measurement medium. There is then a slow shift in the measured capacitance, which is very difficult to compensate for in terms of measurement technology.
The capacitive sensor element according to the invention and the method for producing a capacitive sensor element have the advantage over the fact that the electrodes no longer have to be attached to a surface of a carrier 100 due to the formation of the electrodes from a metal sheet. It is therefore possible to apply liquid to both the top, the bottom and the space between the electrodes and to measure a capacitance which changes in this way. Furthermore, sensor elements can be formed particularly easily from such metal sheets by forming a holding element by filling a mold with plastic, in which the metal sheets are also inserted.
The advantages of the dependent claims. It will be particularly easy Holding element formed as a frame, because the Electrode structures are held on both sides can. Electrodes can be especially simple as one piece Comb structures formed in the associated supply lines become. By adding electrodes you can easily Reference capacities are formed. Filling the form is particularly easy to do by injection molding or reaction molding. The metal sheets from which the electrodes are formed can be particularly easy by punching or etching to be edited. During production, the individual structures especially the sensitive ones Electrode structures through metallic bridges with each other can be connected, which makes handling particularly easy becomes.
Embodiments of the invention are shown in the drawings shown and in the following description explained. Show it
Fig. 1, a capacitive sensor element according to the prior art,
Fig. 2 is an external view of a sensor element according to the invention,
FIGS. 3 and 4 cross sections through the Fig. 2 and
Fig. 5 is a metal sheet as used for the manufacture.
In Figs. 2 to 4 show different views are shown of a sensor element according to the invention. In FIG. 2 an external view is shown in a top view, in the figure a cross section along the line III-III of FIG. 2 is shown and in FIG. 4 a cross section through the element of FIG. 2 parallel to the paper plane of FIG Fig. 2 shown.
FIG. 2 shows a sensor element which has a multiplicity of measuring electrodes 1 , 2 which are held in a frame 3 . The measuring electrodes 1 and 2 are designed as thin metal sheets, while the frame 3 is made of an insulating plastic. As can be seen in the top view according to FIG. 2 or in the section according to FIG. 3, the electrodes 1 and 2 are arranged in such a way that the electrodes interlock, ie an electrode 1 is always followed by an electrode 2 and an electrode 2 is always followed by an electrode 1 . Electrically, it is the case that the electrodes 1 are short-circuited to one another and that the electrodes 2 are short-circuited to one another. The electrodes 1 and 2 thus form two electrodes of a measuring capacity. The sensor is designed so that it can be immersed in a liquid medium. The level of the liquid can then be determined by measuring the capacitance between the interdigitated electrodes 1 , 2 . Depending on the dielectric constant of the liquid, the capacitance that is measured between the electrodes 1 , 2 will change. It is essential that this dielectric constant differs from the dielectric constant of air. The measured capacitance is influenced depending on how many of the electrodes 1 , 2 are immersed in the liquid and how many of the electrodes 1 , 2 are not immersed in the liquid. In contrast to the previously known sensors, in the sensor according to the invention the electrodes 1 , 2 which are immersed in the liquid are acted upon from all sides by the liquid, so that the measuring effect is greater than in conventional sensors in which the measuring electrodes are formed on the upper side of a substrate are. Furthermore, conventional sensors have the problem that the dielectric constant of the carrier substrate can change, in particular if the medium to be measured is diffused into the carrier plate. Then there is a slow temporal offset, which is difficult to compensate for in terms of measurement technology.
In FIGS. 2 and 3 2 also other electrodes 4, 5 in addition to the level electrodes 1 shown forming a reference capacitance. The sensor is introduced into a measuring liquid so that the further electrodes 4 , 5 , which form the reference capacitance, are always surrounded by the liquid. By measuring the capacitance between the electrodes 4 , 5 of the reference capacitance, the dielectric constant of the liquid can thus be calculated. On the basis of this calculation, it can then be concluded for the measuring capacity how large the number of measuring electrodes 1 , 2 contained in the liquid or not immersed in the liquid is.
However, the invention is not based on level sensors limited. In particular, such Electrode structures are always used wherever Capacity is measured in a liquid. This is for example when determining the composition the liquid based on a capacity measurement, e.g. Example at Fuel type sensors, the case.
In FIG. 4 is a further view of the sensor is shown which represents a cross-section through the sensor element of FIG. 2 parallel to the plane of the paper. The cut is made in such a way that the electrodes 1 , 2 , 4 , 5 are exposed so that the embedding in the material of the frame 3 can be seen. As can be seen in the figure, the electrodes 1 are attached in one piece to a corresponding feed line 11 . Furthermore, the electrodes 2 are all attached in one piece to a corresponding feed line 12 . The feed lines 11 and 12 are completely embedded in the plastic material of the frame 3 and only protrude at the lower end in order to form connecting elements 21 and 22 . The electrode fingers 5 of the reference capacitance are also connected in one piece to the feed line 12 . The electrode fingers 4 of the reference capacitance have their own supply line 14 and their own connection 24 . The supply line 24 is also embedded in the material of the plastic frame 3 . The electrodes 1 , 2 , 4 , 5, the feed lines 11 , 12 , 14 and the connection elements 21 , 22 , 24 are formed in one piece by stamping or etching out of a metal sheet. The individual coherent metal pieces can be manufactured individually or it is possible to structure all of them from one piece at the same time. The structuring out of a single piece is explained in more detail in FIG. 5.
In FIG. 5 is a plan view is shown on a machined metal strip 51, as they are shown in FIGS. 2 to 4 from the basic structures for the electrodes are structured out. All metallic elements as explained in FIG. 4 are structured out of the metal strips 51 . In particular, the supply lines 11 , 12 , 14 and the electrodes 1 , 2 , 4 and 5 connected to them . However, a large number of connecting elements 31 , 32 are provided. The electrodes 1 , 2 and 4 , 5 are connected to one another by short connecting elements 31 so that they are joined to form a mechanically fixed grid. The conductor tracks 11 , 12 are connected by long connecting rods 32 to an outer edge 33 of the metal strip 51 . Starting from the strip 51 as it is shown in Fig. 5 is carried out the production of the plastic frame 3 by the strip is placed in a mold 51 and the plastic by injection molding or reaction casting is filled into the mold as the frame 3 that forms. The connecting elements 31 and 32 are then cut through a further processing step, in particular a stamping or sawing step, so that the electrodes 1 , 2 and 4 , 5 are then separated from one another and are no longer connected by metallic connecting elements 31 . Furthermore, the longer connecting elements 32 are severed, so that there is no longer any connection to an outer edge 33 of the metal strip 51 .
The connecting elements 31 and 32 ensure that the individual electrodes 1 , 2 , 4 , 5 and conductor tracks 11 , 12 , 14 cannot move relative to one another in the manufacturing phase. Handling is therefore particularly simple, in particular machining can be carried out without any problems. After parts of these sheet metal elements are then embedded in the plastic of the frame 3 , the individual elements are held by the frame 3 . The individual connecting elements 31 , 32 can then be severed without the relative position of the individual elements being able to be influenced thereby. A particularly simple manufacturing process can be realized in this way.
This is particularly possible to design the sheet metal strip 51 as a very long sheet metal strip, so that a large number of metal structures for a large number of sensor elements are arranged in succession on a sheet metal strip 51 . It is even possible to use a material for the sheet metal strip 51 which is of such thickness that a large number of elements 51 are located in a rolled sheet metal strip. In terms of production technology, a large number of elements can be automatically fed to a processing machine.
Claims (7)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2001118061 DE10118061A1 (en) | 2001-04-11 | 2001-04-11 | Capacitative sensor element comprises numerous electrodes which interlock, made of metal plates that are held by a plastic holding element |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2001118061 DE10118061A1 (en) | 2001-04-11 | 2001-04-11 | Capacitative sensor element comprises numerous electrodes which interlock, made of metal plates that are held by a plastic holding element |
| PCT/DE2002/001332 WO2002084228A1 (en) | 2001-04-11 | 2002-04-10 | Capacitive sensor element and method for producing a capacitive sensor element |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| DE10118061A1 true DE10118061A1 (en) | 2002-10-24 |
Family
ID=7681219
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| DE2001118061 Ceased DE10118061A1 (en) | 2001-04-11 | 2001-04-11 | Capacitative sensor element comprises numerous electrodes which interlock, made of metal plates that are held by a plastic holding element |
Country Status (2)
| Country | Link |
|---|---|
| DE (1) | DE10118061A1 (en) |
| WO (1) | WO2002084228A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2003060438A1 (en) * | 2002-01-18 | 2003-07-24 | Robert Bosch Gmbh | Device for measuring levels |
| DE102008013530A1 (en) | 2007-10-02 | 2009-04-09 | Robert Bosch Gmbh | Fluid level sensor for fluid, particularly for fuel tank of motor vehicle, has printed circuit board and has outbound resistance structure at top of printed circuit board |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ITTO20030219A1 (en) * | 2003-03-25 | 2004-09-26 | Eltek Spa | Device for detecting physical variables of a fluid, |
| JP2014021073A (en) * | 2012-07-23 | 2014-02-03 | Aisan Ind Co Ltd | Liquid sensor |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07218318A (en) * | 1994-01-31 | 1995-08-18 | Kajima Corp | Liquid level and precipitate height measuring device |
| DE19644777C1 (en) * | 1996-10-28 | 1998-06-04 | Sican Gmbh | Filling level indicator sensors for automobile fuel tank |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1498404B2 (en) * | 1965-05-17 | 1973-05-30 | Capacitive measuring transducer for level measurement hoehe | |
| US5005409A (en) * | 1989-01-13 | 1991-04-09 | Teleflex Incorporated | Capacitive liquid sensor |
| JPH04110618A (en) * | 1990-08-30 | 1992-04-13 | Murata Mfg Co Ltd | Liquid level sensor |
| DE4313418A1 (en) * | 1993-04-24 | 1994-10-27 | Spohr Mestechnik Gmbh | Method and device for the digital determination and remote interrogation of filling levels and levels in liquids or media of limited high viscosity, using discrete sensor positions |
| GB9422911D0 (en) * | 1994-11-14 | 1995-01-04 | Moonstone Technology Ltd | Capacitive touch detectors |
-
2001
- 2001-04-11 DE DE2001118061 patent/DE10118061A1/en not_active Ceased
-
2002
- 2002-04-10 WO PCT/DE2002/001332 patent/WO2002084228A1/en not_active Application Discontinuation
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07218318A (en) * | 1994-01-31 | 1995-08-18 | Kajima Corp | Liquid level and precipitate height measuring device |
| DE19644777C1 (en) * | 1996-10-28 | 1998-06-04 | Sican Gmbh | Filling level indicator sensors for automobile fuel tank |
Non-Patent Citations (1)
| Title |
|---|
| Measur-Sci. Technol.7(1996), S. 79-86 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2003060438A1 (en) * | 2002-01-18 | 2003-07-24 | Robert Bosch Gmbh | Device for measuring levels |
| US6988405B2 (en) | 2002-01-18 | 2006-01-24 | Robert Bosch Gmbh | Device for measuring levels |
| DE102008013530A1 (en) | 2007-10-02 | 2009-04-09 | Robert Bosch Gmbh | Fluid level sensor for fluid, particularly for fuel tank of motor vehicle, has printed circuit board and has outbound resistance structure at top of printed circuit board |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2002084228A1 (en) | 2002-10-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| OP8 | Request for examination as to paragraph 44 patent law | ||
| 8131 | Rejection |