EP1322945A1 - Gas sensor - Google Patents
Gas sensorInfo
- Publication number
- EP1322945A1 EP1322945A1 EP01978186A EP01978186A EP1322945A1 EP 1322945 A1 EP1322945 A1 EP 1322945A1 EP 01978186 A EP01978186 A EP 01978186A EP 01978186 A EP01978186 A EP 01978186A EP 1322945 A1 EP1322945 A1 EP 1322945A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- gas
- substrate
- sensor
- gas sensor
- exhaust
- 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- Withdrawn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
- 239000000758 substrate Substances 0.000 claims abstract description 31
- 239000007789 gas Substances 0.000 claims description 145
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims description 18
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 16
- 239000001301 oxygen Substances 0.000 claims description 16
- 229910052760 oxygen Inorganic materials 0.000 claims description 16
- 230000002452 interceptive effect Effects 0.000 claims description 14
- 238000001514 detection method Methods 0.000 claims description 10
- 229910044991 metal oxide Inorganic materials 0.000 claims description 7
- 150000004706 metal oxides Chemical class 0.000 claims description 7
- 238000000034 method Methods 0.000 claims description 7
- 229930195733 hydrocarbon Natural products 0.000 claims description 6
- 150000002430 hydrocarbons Chemical class 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 5
- 238000009792 diffusion process Methods 0.000 description 9
- 238000005259 measurement Methods 0.000 description 4
- 239000000523 sample Substances 0.000 description 4
- 230000003197 catalytic effect Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
- G01N33/0011—Sample conditioning
- G01N33/0016—Sample conditioning by regulating a physical variable, e.g. pressure or temperature
Definitions
- the invention relates to a gas sensor, a use thereof and a method for gas detection.
- a gas sensor for the detection of a gas often has a cross sensitivity to another gas (“interfering gas”).
- the gas sensor has at least one gas-sensitive area which is applied to a substrate.
- the substrate is open to diffusion in at least one partial area, so that at least one interfering gas can diffuse through the substrate to the gas-sensitive area through the porous partial area.
- the substrate it is not necessary for the substrate to be completely open to diffusion, but it can also only be open to diffusion in one or more partial areas, for example for producing increased strength.
- the material of the substrate comes, for. B. A1 2 0 3 , Al 2 Mg0 or Zr0 2 in question.
- the gas sensor also contains all the devices known to the person skilled in the art for operating the gas sensor, such as measuring electrodes or, in the case of heated gas sensors, heating elements and / or temperature sensors.
- the gas sensor can also be suitable for the diffusion of your own disturbing gases, the composition or presence of which depends on the individual application, for example, but not limited to, oxygen. It tu cn s ⁇ , H ⁇ ⁇ Q s: ⁇ ⁇ . rt cn tu ⁇ tr N ö tu cn M d cn s: HM cn P ) ⁇ cn 0 cn P- ⁇ > ⁇ P ) ⁇ P P- P ⁇ J ⁇ ⁇ -5 ⁇ ⁇ ⁇ ⁇ d ⁇ ⁇ P- P - Cn 0 rt P- ⁇ cn * ⁇ d ⁇ ⁇ ⁇ ⁇ cn
- a gas-permeable insulating layer is present between the gas-sensitive area and the cover layer.
- a gas sensor is preferred in which the gas-sensitive region is designed in the form of a layer of semiconducting metal oxide, for example as a high-temperature metal oxide sensor.
- a heatable metal oxide sensor typically contains comb-shaped measuring electrodes and a heater, each made of platinum.
- the gas sensor is typically exposed to a gas atmosphere to be measured, e.g. B. an exhaust gas, while at the same time the interfering gas can diffuse to the gas-sensitive area through the diffusion-open area of the substrate. It implicitly contains that the gas sensor is mounted in such a way that it is not completely in the gas atmosphere to be measured, but with the surface of the substrate opposite the gas-sensitive area borders on another gas atmosphere containing the interfering gas in higher concentrations, for example air.
- a gas atmosphere to be measured e.g. B. an exhaust gas
- gas sensor is particularly expedient for the detection of hydrocarbons and / or nitrogen oxides in an exhaust gas, with at least oxygen diffusing as an interfering gas through the substrate to the gas-sensitive area.
- exhaust gas control in particular, there is an advantage over the methods known hitherto for this purpose and which are complex or can only be used to a limited extent in their use.
- the gas sensor is installed in a wall of an exhaust pipe or another container that holds the exhaust gas. This is done in a simple manner such that the gas-sensitive area of the gas sensor is inserted through a recess in the exhaust pipe, so that a surface of the substrate is still exposed to the air.
- a gas sensor installed in this way for exhaust gas control in a motor vehicle for example as part of a lambda probe, or as part of a heating system, for example in single or multi-family houses or also in commercial thermal power plants, is particularly favorable.
- the invention is not restricted to a specific sensor type, e.g. B. semiconducting and / or heatable, still on the application of exhaust gas diagnosis.
- the invention is also not limited to oxygen as an interfering gas. Rather, depending on the application, the gas sensor can be designed and / or attached in a flexible and versatile manner.
- the gas sensor is shown schematically in more detail using a high-temperature metal oxide gas sensor for the detection of hydrocarbons and / or nitrogen oxides in an exhaust gas.
- FIG. 1 shows a gas sensor installed in an exhaust pipe
- Figure 2 shows this gas sensor enlarged.
- FIG. 1 shows a sectional side view of an exhaust pipe 5, within which exhaust gas E flows (indicated by the arrow shown from the center, leading from left to right).
- the exhaust gas E contains hydrocarbons and / or nitrogen oxides as target gases Z.
- the exhaust pipe 5 is in turn in an ambient atmosphere of air L, which contains the interfering gas G oxygen in a higher concentration than the exhaust gas E.
- Such a configuration is typical, for example on the exhaust pipe of a motor vehicle.
- the gas sensor S is let into a recess in the exhaust pipe 5, so that the gas-sensitive area 2 of the gas sensor S is flowed around by the exhaust gas E.
- the porous substrate 1 holds the gas-sensitive area 2 and is exposed to the air L with its underside opposite the gas-sensitive area 2. At least the oxygen 0 2 present in the air L diffuses through the porous substrate 1 to the surface exposed in the exhaust gas E (small arrows pointing from top to bottom) and produces there a laminar boundary layer LZ with an increased 0 2 concentration.
- the porosity of the substrate 1 is 10 to 40%, preferably 20% to 30%. Due to the large area of the substrate 1 compared to the gas-sensitive area 2, the oxygen can diffuse from the air side to the exhaust gas side of the substrate 1 because of the 0 2 concentration difference, so that the exhaust gas E in the area of the gas-sensitive layer 2 with approx. 2-5% Oxygen is enriched.
- a typical diffusion rate for the 0 2 molecules is in the range of 1-10 cm / s, with which a particle current density of approx. 1 mol-s -1 cm -2 can be achieved.
- FIG. 2 shows a sectional side view of a gas sensor S with a cover layer 4.
- the gas-tight cover layer 4 is applied over a large area over the gas-sensitive area 2 and filled with a diffusion-open porous insulating layer 3. Opposite the gas-sensitive area 2, a defined gas inlet opening (aperture) 5 is introduced into the cover layer 4.
- the cover layer 4 prevents the diffusing oxygen from being carried away immediately by the exhaust gas stream which flows through the exhaust pipe 5 at a typical speed of 10-100 m / s.
- the presence of the cover layer 4 is advantageous for the oxygen supply to the gas-sensitive area 2, because the oxygen that has diffused through the substrate 1 necessarily flows past the gas-sensitive area 2 and is thus prevented from escaping prematurely into the exhaust gas E.
- 0 2 diffuses into the insulating layer 3, within which an increasing 0 2 concentration results toward the center of the substrate 1 (the direction of the oxygen flow in the insulating layer 3 is symbolized by the horizontal arrows).
- the ratio of the size of the aperture 5 compared to the area of the porous substrate 1 under the cover layer 4 sets a 0 2 concentration at the gas-sensitive region 2, and there can be a difference between the 0 2 diffusion speed and the speed of the exhaust gas E to be balanced.
- Such a gas sensor S is usually constructed using thick-film technology and, in addition to electrodes for determining the conductivity of the gas-sensitive region 2, contains a heating structure and a temperature sensor.
- the substrate 1 can be integrated into a lambda probe screw connection with little effort.
- a corresponding thread can be provided at any location of the exhaust system with little effort.
- a typical, but not necessary, flat design which results from the usual use of a flat substrate 1, together with the corresponding gas flow, means that such a gas sensor can generally be planned in an exhaust system without geometric restrictions.
- the gas sensor S can also be installed at a location that was previously inaccessible to other exhaust gas electrodes.
- the amount of oxygen that enters the exhaust gas E through the diffusion corresponds only to approximately 1/1000 of the amount of the exhaust gas E
- an installation of the gas sensor is also possible in front of a catalytic converter, because the exhaust gas E in its entirety is due to a small amount additional amount of oxygen is hardly affected. This opens up the possibility speed, with two gas sensors S before and after the catalytic converter to carry out a differential measurement.
- a gas sensor S which is preferably used and which preferably uses a semiconducting metal oxide as the material of the gas-sensitive region 2 is heated to typical temperatures of approximately 700.degree.
- the sensor heating can be initiated, for example, by opening the driver's door, by opening the central locking or by loading the driver's seat.
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Food Science & Technology (AREA)
- Combustion & Propulsion (AREA)
- Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE10048195A DE10048195C2 (en) | 2000-09-28 | 2000-09-28 | gas sensor |
DE10048195 | 2000-09-28 | ||
PCT/DE2001/003733 WO2002027311A1 (en) | 2000-09-28 | 2001-09-28 | Gas sensor |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1322945A1 true EP1322945A1 (en) | 2003-07-02 |
Family
ID=7658033
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP01978186A Withdrawn EP1322945A1 (en) | 2000-09-28 | 2001-09-28 | Gas sensor |
Country Status (5)
Country | Link |
---|---|
US (1) | US20040094415A1 (en) |
EP (1) | EP1322945A1 (en) |
JP (1) | JP2004510159A (en) |
DE (1) | DE10048195C2 (en) |
WO (1) | WO2002027311A1 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE202004015180U1 (en) * | 2004-09-30 | 2006-02-09 | T.E.M.! Technologische Entwicklungen Und Management Gmbh | Metal oxide gas sensor, which can be heated, is within a housing with a small inflow opening with the gas/vapor passing through by diffusion |
DE102008001394A1 (en) * | 2008-04-25 | 2009-10-29 | Robert Bosch Gmbh | Exhaust gas-suitable protective layers for high-temperature sensors |
Family Cites Families (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5644837A (en) * | 1979-09-21 | 1981-04-24 | Hitachi Ltd | Preparing method for oxygen concentration measuring element |
US4477403A (en) * | 1983-05-26 | 1984-10-16 | Teledyne Industries, Inc. | Method of making an electrochemical sensor |
US4571285A (en) * | 1984-05-29 | 1986-02-18 | Fujikura Ltd. | Oxygen sensor for and method of determining concentration of oxygen |
JP2509905B2 (en) * | 1985-02-06 | 1996-06-26 | 株式会社日立製作所 | Air-fuel ratio sensor |
JPH0827247B2 (en) * | 1987-11-04 | 1996-03-21 | 株式会社豊田中央研究所 | Broadband air-fuel ratio sensor and detector |
US5302274A (en) * | 1990-04-16 | 1994-04-12 | Minitech Co. | Electrochemical gas sensor cells using three dimensional sensing electrodes |
DE4344828A1 (en) * | 1993-12-28 | 1995-06-29 | Oehmi Forsch & Ingtech Gmbh | Removing particles from liquids |
GB9422334D0 (en) * | 1994-11-04 | 1994-12-21 | Central Research Lab Ltd | Gas sensor |
DE19549147C2 (en) * | 1995-12-29 | 1998-06-04 | Siemens Ag | Gas sensor |
JP3499421B2 (en) * | 1996-12-02 | 2004-02-23 | 日本特殊陶業株式会社 | NOx gas concentration measuring method and NOx gas concentration detector |
JP3546919B2 (en) * | 1998-01-30 | 2004-07-28 | 株式会社豊田中央研究所 | Nitrogen oxide and oxygen detection sensor |
-
2000
- 2000-09-28 DE DE10048195A patent/DE10048195C2/en not_active Expired - Fee Related
-
2001
- 2001-09-28 JP JP2002530639A patent/JP2004510159A/en not_active Withdrawn
- 2001-09-28 EP EP01978186A patent/EP1322945A1/en not_active Withdrawn
- 2001-09-28 WO PCT/DE2001/003733 patent/WO2002027311A1/en not_active Application Discontinuation
- 2001-09-28 US US10/381,799 patent/US20040094415A1/en not_active Abandoned
Non-Patent Citations (1)
Title |
---|
See references of WO0227311A1 * |
Also Published As
Publication number | Publication date |
---|---|
DE10048195A1 (en) | 2002-05-02 |
WO2002027311A1 (en) | 2002-04-04 |
JP2004510159A (en) | 2004-04-02 |
US20040094415A1 (en) | 2004-05-20 |
DE10048195C2 (en) | 2002-11-14 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
17P | Request for examination filed |
Effective date: 20030314 |
|
AK | Designated contracting states |
Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR |
|
RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: MEIXNER, HANS Inventor name: BAUSEWEIN, ANDREAS Inventor name: BRUECK, ROLF Inventor name: REIZIG, MEIKE |
|
RBV | Designated contracting states (corrected) |
Designated state(s): AT BE CH CY DE DK ES FR GB IT LI SE |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 20050401 |