Measuring and testing – Simulating operating condition – Marine
Patent
1997-07-02
1999-07-27
Dombroske, George
Measuring and testing
Simulating operating condition
Marine
B01J 3502, B01J 3702, B01D 5386, B01D 5394
Patent
active
059293276
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a catalytic converter to be placed in the flowing exhaust of exhaust gas installations, preferably internal combustion engines, with a carrier material provided with a catalyst-containing ceramic coating and at least one temperature sensor applied in a thick film technique.
This catalytic converter in which a coating of catalyst-containing material (wash coat) with an overlying temperature sensor applied in thick film technique is applied to the carrier material is known (EP-0 589 169 A1).
These known catalytic converters have proven essentially effective. However their service life is limited at high operating temperatures.
SUMMARY OF THE INVENTION
Therefore the object of the invention is to devise a generic catalytic converter operable at higher operating temperatures with a longer service life, in which the service lives of especially sensitive temperature sensor or catalyst materials are improved.
This object is achieved in a catalytic converter by locating the temperature sensor on the surface of the carrier material and providing a catalyst-containing ceramic coating covering the temperature sensor.
In the catalytic converter according to the invention it has been surprisingly found that when the temperature sensor is placed under the overlying catalyst coating, on the one hand, higher operating temperatures can be tolerated, on the other hand, at these higher temperatures longer service lives, especially of the temperature sensor components, can be expected. When a metallic carrier material is used, the temperature sensor is located on an electrical insulator. When a nonconductive carrier material is used, for example a monolith, this is unnecessary.
According to one special feature of the invention, the insulator has a borosilicate enamel and is produced at temperatures from 960 to 1250.degree. C., the temperature sensor impressed on the insulator in thick film technique, being annealed at a temperature which is the same or lower than the annealing temperature of the insulator, and that a catalyst layer is applied to the temperature sensor in thick film technique and is annealed at an annealing temperature which is the same as or lower than the annealing temperature of the temperature sensor.
The catalytic converters according to the invention, besides improved service lives, have the advantage that the temperature signals delivered by the temperature sensor reproduce the temperature of the catalyst-containing ceramic; coating without being influenced by the gases flowing around the catalyst.
BRIEF DESCRIPTION OF THE DRAWINGS
One preferred embodiment which shows a catalytic converter according to the invention with a metallic carrier material in the form of a sheet of high quality steel foil in a schematic cross section is shown in the drawing.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Electrically insulating insulator layer 6 which has borosilicate enamel is applied, preferably by printing, to a metallic carrier material which is labelled 5 throughout. Known temperature sensor 7 is impressed on this insulator layer in thick film technique.
According to alternative embodiments, two temperature sensors can be provided in the flow direction of the exhaust gas, one at the input and one at the output of the catalytic converter, optionally on the insulator layer, or both at the output. In the latter case, one can be covered with a gas-impermeable layer and one with a gas permeable porous protective layer.
Carrier material 5 and insulator 6 as well as temperature sensor 7 are coated by catalyst-containing ceramic coating 8 which is applied for example by immersion.
Here, first of all, insulator layer 6 is annealed onto the surface of carrier material 5 by pressing and subsequent annealing at roughly 960 to 1250.degree. C. Afterwards, following completed cooling, actual platinum-containing temperature sensor 7 is impressed on insulator 6 in thick film technique and is likewise annealed at a temperature between 960 and 1250.degree. C. o
REFERENCES:
patent: 4328780 (1982-05-01), Andrew
patent: 4351182 (1982-09-01), Schmidberger
Dombroske George
Heraeus-Electro-Nite International NV
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