JP2002535648A - Sensor for analyzing gas - Google Patents

Abstract

(57) Abstract: A to have sensors suitable for analyzing sensor for determining gas components and or gas concentration in the gas mixture, in particular HC in the engine exhaust gas, the NO _x and CO, the substrate (10) on top of that, the thermal range (40) exposed to the gas, and the external electrode (16) and the MO _x electrode (20) is disposed on, in the cold range (30), the external electrode feeder conductor (21) and those in which the MO _x electrode power supply lead (17) is arranged are proposed. In this case, at least in the cold range (30), at least one of the electrode feed wires (17, 21) is separated from the substrate (10) by at least one electrically insulating layer (15). This electrically insulating layer is preferably connected at least in part to the substrate (10) via a deposition nap (22).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The invention relates to a sensor for analyzing gases of the type described in the preamble of the independent claim.

Such sensors are described, for example, in German patent application D, which has not yet been published.
From E 198 37 515.8, an electrical insulation layer is provided between the electrode supply conductor and the solid electrolyte body, the electrical insulation layer surrounding the electrode supply conductor at least partially over all sides. I have. German Patent DE 38 1
From 1 713 C2 a flat sonde is known, which serves to determine the lambda value of the gas mixture. In this sonde, one electrically insulating intermediate layer is arranged on each of the conductor paths of the electrode power supply wires on a solid electrolyte body having two electrode power supply wires.

The gas sensor according to the invention with the features of the independent claims has the following advantages over the prior art: That is, especially when used in an exhaust gas catalytic converter of a motor vehicle, the resistance of the existing sensor to continuous operation and the resistance to temperature changes are improved, and interruption of the electrical contact connection or the electrode power supply line is avoided. Furthermore, the adhesion between the substrate and the electrode supply line extending over the substrate is improved, the electrode supply line being separated from the substrate by an electrically insulating layer.

[0004] Since the electrode power supply conductor is separated from the substrate via the insulating layer, no potential is generated between the substrate and the electrode power supply conductor, which causes an error in the measurement result, and the potential adjustment related to the measurement is performed. It is ensured that it only takes place between the electrodes within the thermal range of the gas sensor.

[0005] In this case, the thermal range is the range of the gas sensor that is exposed to the measurement gas or in which the measurement signal is formed, whereas the cold range is the region that is clearly exposed to lower temperatures and forms the measurement signal. Means the range of the electrode feeder conductor which hardly contributes to the above.

[0006] Advantageous embodiments of the invention result from the measures recited in the dependent claims.

[0007] For example, the mounting of the adhesive naps is very advantageous because of the increased surface and the additional mechanical engagement that takes place between the insulating layer and the substrate, and thus between the substrate and the electrode. This produces a tight connection with the conductor. In this case, in particular, ZrO ₂ is used for the substrate material, and Al ₂ O ₃ is preferably used for the insulating layer.

[0008] It is further advantageous if the deposition nap extends into the insulating layer after the deposition nap has been mounted and especially printed on the substrate and then the insulating layer has been applied.

Due to the different sintering properties of the substrate and the insulating layer during the fabrication process, and due to the mechanical stress between the insulating layer and the substrate during operation (particularly during temperature fluctuations), This is very advantageously reduced if the applied nap is made of the same material as the substrate or the insulating layer.

[0010] It is furthermore advantageous if the MO _x electrode supply lead, which is one of the electrode supply leads, is also separated from the substrate by an electrically insulating layer in the thermal range of the sensor. This is also in the thermal range by, between the MO _x electrode bus conductor and Pt reference electrode, adverse chemical changes in potential or the substrate give rise to errors in the gas sensor of the measuring results are guaranteed not occur.

In order to further improve the adhesion of the insulating layer on the substrate, an adhesion nap is provided between the insulating layer and the substrate in the heat range, similarly to the electrode power supply conductor in the cold range. It is advantageous. In this case, it is particularly advantageous if, in the thermal range, the MO _x electrode supply conductor is surrounded by the MO _x electrode above it and the insulating layer which is mounted below it.

Embodiment Hereinafter, an embodiment shown in the drawings will be described in detail.

FIG. 1 shows a plan view of the gas sensor 5 having a hot range 40 and a cold range 30. In this case, two strip-shaped electrical insulating layers 15 made of Al ₂ O ₃ extend on a substrate made of ZrO ₂ , and these insulating layers should be formed in the form of only one continuous insulating layer. The external electrode power supply conductor 21 and M
An O _x electrode power supply lead 17 extends. In this case, the MO _x, refers to for example, Ti _0.95 Nb _{0. 05} O 2 ₊ precisely defined non-stoichiometric per se known mixing oxides, such as _x.
Heat range 40 is first covered with MO _x electrode 20.

FIG. 2 shows a cross-sectional view of the cold range 30 along the line II in FIG. Inside the substrate 10, there are a heater 13 surrounded by a heater insulator 14, a reference air passage 11, and a Pt reference electrode 12. The insulating layer 15 extends between the electrode feed wires 17 and 21 and the substrate 10. The connection between the insulating layer 15 and the substrate 10 is made by adhesive naps 22, which are made of the same material as the substrate and are mounted on the substrate 10 by, for example, silk-screen printing. These deposited naps protrude into the insulating layer 15 and tightly couple the insulating layer to the substrate 10.

FIG. 3 shows a cross-sectional view of the thermal range 40 along the line III in FIG. In this case, the substrate 10
First, a Pt external electrode 16 extends, and this external electrode is contact-connected via an external electrode power supply lead wire 21. Further, a highly porous gas-permeable tunnel layer 23 is mounted on the external electrode 16. The tunnel layer 23 and the Pt external electrode 16 are laterally and upwardly surrounded by an electrolyte layer 19 made of tight or slightly porous ZrO ₂ . On the side of the Pt external electrodes 16, already insulating layer 15 which is present in the cold range 30 is guided also consistently wherein in the insulating layer, MO _x electrode sheet being Again guided Here An electric wire 17 extends. Thus, even in the heat range 40, the MO _x electrode power supply line 17 is electrically consistently separated from the substrate 10 and the electrolyte layer 19. Adhesive naps 22 are also mounted between the insulating layer 15 and the substrate 10 and are made of the same material as the substrate 10 and protrude into the insulating layer 15 for a tight connection. I have. In this case, the deposition nap 22 is applied in a manner known per se by silk-screen printing before sintering and dissociation of the various layers of the gas sensor 5.

Further, the tunnel layer 23 is configured to be flat, and is not covered by the MO _x electrode 20 and the electrolyte layer 19 at least in the direction of the cold region 30 of the gas sensor 5. through the gas to be analyzed can be directly reached Pt external electrode 16, there is no need to diffuse through the electrolyte layer 19 in this case pre-MO _x electrode and tight or slightly porous.

Further details of the structure of the gas sensor 5 which does not form the original object of the present invention and the functional form thereof are well known to those skilled in the art, and will not be described.

[Brief description of the drawings]

FIG. 1 is a plan view of a sensor for analyzing a gas.

FIG. 2 is a cross-sectional view taken along line II of FIG.

FIG. 3 is a sectional view taken along a line III in FIG. 1;

[Explanation of symbols]

5 gas sensor, 10 substrate, 11 reference air passage, 12 Pt reference electrode, 13 heater, 14 heater insulator, 15 electric insulating layer, 16 external electrode, 17 MO _x electrode power supply lead, 19 electrolyte layer, 20 MO _x electrode,
DESCRIPTION OF SYMBOLS 21 External electrode feeding wire, 22 Adhesive nap, 23 Tunnel layer, 24
Gas inlet opening, 30 cold range, 40 heat range

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Detraef Hyman Germany Gerlingen Unter les Bergstrasse 2 (72) Inventor Thomas Var Germany Pforzheim Maksimilianstrasse 40/42 (72) Inventor Margreet Schule Germany Federal Republic Weil der Stadt Besengasse 1 (72) Inventor Bernd Schumann Germany Ruthesheim dai Mullastraße 23 (72) Inventor Bernhard Bremer Germany Federal Republic Schuttgart Marg Greininger Strasse 69 F-term (reference) 2G004 BB04 BD04 BD17 BE03 BE04 BE13 BE17 BE22 BE27 BG11 BH08 BH15 BJ02 BM01 BM07 ZA04

Claims (9)

[Claims] A sensor for determining the gas composition and / or gas concentration of a gas mixture, in particular HC, NO _x and CO in the exhaust gas of an internal combustion engine, comprising a substrate (10).
Above, in the heat range (40) exposed to the gas, is disposed external electrode (16) and the MO _x electrode (20), and the cold range (30), the external electrode feeder conductor (21
In) and of the type MO _x electrode feeder conductor (17) is arranged, at least cold range (30) in at least the electrode feed wire (17, 21) while at least one electrically insulating layer of the (15) A sensor for analyzing a gas, the sensor being separated from a substrate (10). 2. The sensor according to claim 1, wherein the insulating layer is connected at least locally to the substrate via an adhesive nap. 3. The sensor according to claim 2, wherein the adhesion nap (22) is mounted on the substrate (10) and protrudes into the insulating layer (15). 4. The sensor according to claim 2, wherein the adhesion nap (22) is made of the same material as the substrate (10). 5. An external electrode power supply lead (21) and a MO _x electrode power supply lead (17).
Sensor according to claim 1, characterized in that the is separated from the substrate (10) by an electrically insulating layer (15). 6. The device according to claim 1, wherein the MO _x electrode power supply line is separated from the substrate by the electrically insulating layer even in the thermal range. Sensors. 7. The device according to claim 6, wherein in the thermal range (40) the MO _x electrode power supply line (17) is surrounded by the MO _x electrode (20) and the insulating layer (15). Sensor. 8. The sensor according to claim 1, wherein the insulating layer comprises at least for the most part Al ₂ O ₃ . 9. The sensor according to claim 1, wherein the substrate comprises at least for the most part ZrO ₂ .