SENSOR FOR DETERMINING GAS PARAMETERS

Abstract

A high-temperature sensor, having at least one completely ceramic heater and at least one first sensor structure arranged on a first side of the completely ceramic heater, at least in areas. And a method for producing a sensor.

Claims

1-15. (canceled)

16. A high-temperature sensor, comprising: at least one completely ceramic heater; and at least one first sensor structure arranged on a first side of the completely ceramic heater, at least in areas.

17. The sensor according to claim 16, wherein the completely ceramic heater comprises: at least one electrically conductive ceramic; wherein the electrically conductive ceramic makes contact with electrodes in at least two positions separate from one another; and at least one electrically insulating ceramic, wherein the electrically insulating ceramic completely encloses the electrically conductive ceramic.

18. The sensor according to claim 17, wherein the electrically conductive ceramic comprises ceramic powders comprising silicide, carbonate, and/or nitride powder, and at least one element from the tungsten, tantalum, niobium, titanium, molybdenum, zirconium, hafnium, vanadium, and/or chromium group, and in that the electrically insulating ceramic is formed from heat-conducting ceramic powders comprising silicon nitride and/or aluminum nitride.

19. The sensor according to claim 16, wherein the completely ceramic heater has a thickness between 0.5 mm and 1.5 mm.

20. The sensor according to claim 16, wherein the sensor comprises: at least one first insulating layer arranged on the first side of the completely ceramic heater, at least in areas; and/or at least one second insulating layer arranged, at least in areas, on a second side of the completely ceramic heater, which is opposite the first side.

21. The sensor according to claim 20, wherein the first insulating layer and/or the second insulating layer comprises an electrically insulating ceramic.

22. The sensor according to claim 16, wherein the first sensor structure and/or a second sensor structure, which is arranged on the first side or on a second side of the completely ceramic heater, comprises at least one meandering measuring resistance structure for temperature measurement.

23. The sensor according to claim 16, wherein the first sensor structure and/or a second sensor structure, which is arranged on the first side or on a second side of the completely ceramic heater, comprises at least one comb structure, IDK structure, for measuring a concentration of a deposit of soot particles.

24. The sensor according to claim 16, wherein the first sensor structure and/or a second sensor structure, which is arranged on the first side or on a second side of the completely ceramic heater, comprises at least one electric heating element and at least one temperature sensor for an anemometric measurement.

25. The sensor according to claim 16, wherein the first sensor structure and/or a second sensor structure comprises at least one platinum material.

26. The sensor according to claim 16, wherein the sensor comprises: at least one first ceramic intermediate layer arranged on the first sensor structure, at least in areas; and/or at least one second ceramic intermediate layer, arranged on a second sensor structure, at least in areas, wherein the first and/or second ceramic intermediate layer comprises aluminum oxide and/or magnesium oxide.

27. The sensor according to claim 26, wherein the sensor comprises: at least one first covering layer arranged on the first ceramic intermediate layer, at least in areas; and/or at least one second covering layer arranged on the second ceramic intermediate layer, at least in areas.

28. A use of a sensor according to claim 16, in the exhaust system of a motor vehicle, as a temperature sensor, soot sensor, flow sensor, and/or as a multi-sensor, which comprises a combination of temperature sensor, soot sensor, and/or flow sensor.

29. A method for producing a high-temperature sensor, comprising: providing at least one completely ceramic heater; and placing at least one first sensor structure on a first side of the completely ceramic heater, at least in areas.

30. The method according to claim 29, wherein the providing further comprises: producing of the completely ceramic heater by means of co-sintering of an electrically conductive and an electrically insulating ceramic; and/or wherein the placement comprises: printing of the first insulating layer, especially in thin-film technology, with a platinum material.

Description

[0053] Further features and advantages of the invention result from the following description, in which preferred embodiments of the invention are explained by means of schematic drawings.

[0054] The following is shown:

[0055] FIG. 1 a schematic exploded view of a sensor according to an embodiment of the invention;

[0056] FIG. 2 a schematic layered view of a sensor according to an embodiment of the invention;

[0057] FIGS. 3a, 3b schematic views of a completely ceramic heater according to an embodiment of the invention as an exploded view and a view of the completely ceramic heater in the assembled state; and

[0058] FIG. 4 a method for producing a sensor according to an embodiment of the invention.

[0059] FIG. 1 shows a schematic exploded view of a sensor 1 according to an embodiment of the invention. The sensor 1, which is shown as an example, has a completely ceramic heater 3 comprising a heating conductor made of an electrically conductive ceramic and a shell made of an electrically insulating ceramic. In the embodiment shown, the electrically conductive ceramic and the electrically insulating ceramic are sintered into a homogenous body.

[0060] Furthermore, FIG. 1 shows two electrodes 5a, 5b, which are arranged on the completely ceramic heater 3. In the embodiment shown, the electrodes 5a, 5b are designed as electrical feed lines. The electrodes 5a, 5b make contact with the electrically conductive ceramic in two different positions such that the area of the electrically conductive ceramic is formed between the electrodes 5a, 5b as a heating conductor or heating resistor. An energy source, such as a current source (not shown in FIG. 1) for example, can be connected to the electrodes 5a, 5b so that the ceramic heats up when current flows through it. The resistance of the heating conductor can be determined by means of the arrangement of the electrodes 5a, 5b on the ceramic and is formed by means of the resistance section between the electrodes 5a, 5b. In the embodiment shown in FIG. 1, the electrodes 5a, 5b are arranged next to one another on one side of the completely ceramic heater 3. One skilled in the art knows, however, that the electrodes 5a, 5b can also be arranged, in embodiments not shown, at another position of the completely ceramic heater 3, for example on opposing sides of the completely ceramic heater 3. Furthermore, in an embodiment not shown, more than two electrodes can also be arranged on the completely ceramic heater 3. For example, four electrodes can be arranged on the completely ceramic heater 3 and can make contact with the electrically conductive ceramic in order to connect two electrical circuits, which are independent of one another. In the embodiment not shown, two independently switchable heating resistors with different heat outputs can hereby be formed in one completely ceramic heater.

[0061] Optionally, in the embodiment shown in FIG. 1, a first insulating layer 7 is shown, which is arranged on the first side of the completely ceramic heater 3. For example, the first insulating layer 7 can be produced by means of screen printing an electrically insulating ceramic paste. As an alternative to this, the first insulating layer 7 can also be produced by means of coating with metal oxides using methods such as sputtering, thermal vapor deposition, or aerosol deposition. The first insulating layer 7 can completely cover a surface of the completely ceramic heater 3 or be arranged only on a partial area of the surface of the completely ceramic heater 3. In addition, in an embodiment not shown, recesses can be placed in the material of the first insulating layer in order to enable contacting of the electrodes by the first insulating layer.

[0062] A first sensor structure 9, which may be designed, for example, as a platinum resistance structure, is arranged on the completely ceramic heater 3 or on the optionally applied first insulating layer 7. The indicated first sensor structure 9 shows a meandering resistance structure as can be used, for example, for temperature measurements. The meandering resistance structure can have two terminals, as shown in FIG. 1, in order to connect the resistance structure to evaluation electronics (not shown in FIG. 1). Alternatively or in addition to the resistance structure shown, further sensor structures and/or heating elements can be arranged on the first surface of the completely ceramic heater 3, in embodiments not shown.

[0063] For example, an IDK structure can be arranged instead of or next to the meandering resistance structure to determine soot particles.

[0064] Furthermore, FIG. 1 shows, as an option merely, that the first sensor structure 9 and areas of the completely ceramic heating element 3, which are not covered by the first sensor structure 9, can be at least partially covered by a ceramic intermediate layer 11. Merely as an option, the ceramic intermediate layer 11 can, in turn, be at least partially covered by a covering layer 13. However, one skilled in the art knows that an intermediate layer 11 and/or a covering layer 13 are not necessary for use of the sensor 1 shown in FIG. 1 as a temperature sensor, soot sensor, flow sensor, and/or as a multi-sensor in the exhaust system of a motor vehicle.

[0065] In the embodiment shown in FIG. 1, a second insulating layer 7, which may comprise a similar material as the first insulating layer 7, is arranged on the second sides of the completely ceramic heating element 3.

[0066] In the embodiment shown, an exemplary IDK structure for determining soot particles is applied as a second sensor structure 9 on the completely ceramic heater 3. In alternative embodiments, which are not shown here, the second sensor structure 9 may also comprise further/alternative structures, which are adapted to record one or more gas parameters of a gas flowing passed.

[0067] In addition, as has been already described herein with respect to the first side of the completely ceramic heater 3, a ceramic intermediate layer 11 can be arranged on the second sensor structure 9 at least in areas, wherein a covering layer 13 can be arranged, in turn, on said intermediate layer at least an areas.

[0068] However, an arrangement of structures on the second side of the substrate 3 is not essential for the invention. A sensor 1 according to the invention may also only comprise a completely ceramic heater 3, a first insulating layer 7, and a first sensor structure 9.

[0069] FIG. 2 shows a schematic layered view of a completely ceramic heater 3 according to an embodiment of the invention. The layered view shown in FIG. 2 may be a representation of the structure of the completely ceramic heater 3 already shown in FIG. 1.

[0070] In the left column of FIG. 2, multiple substantially similar layers 15-23 of a pressed, electrically insulating ceramic powder are shown as a so-called green body. As shown in FIG. 2, the layers 15-23 may have a substantially rectangular design. In embodiments not shown, the layers may also have a different geometry; for example, the layers can be round or oval.

[0071] In the middle column of FIG. 2, three layers 17-21 are shown, which may be the layers 17-21 shown in the left column, with recesses, which are placed, for example, by means of punching. In layers 17 and 21, geometries for contacting of the heating conductor with the electrodes are formed. A geometry for the heating conductor is shown in layer 19. The geometries shown are only by example; depending on the desired purpose of use, the geometries may also be formed differently than shown; for example, the heating conductor may also be designed in the shape of a rod or meandering.

[0072] In the right column of FIG. 3, three layers 17-21 are shown, which may be the layers 17-21 shown in the middle column, with an electrically conductive ceramic powder placed in the recesses.

[0073] FIGS. 3a and 3b show schematic views of a completely ceramic heater 3 according to an embodiment of the invention as an exploded view and a view in the assembled state.

[0074] The layers 15, 17, 19, 21, and 23 shown in FIG. 2 are shown arranged on a stack in FIG. 3a. In the embodiment shown in FIG. 3a, electrodes 5a, 5b are arranged in the form of contact pins or connection wires at the contacts shown in FIG. 2 for making contact with the heating conductor.

[0075] The stack shown in FIG. 3a is shown in the assembled state in FIG. 3b. For example, the layers can be connected to one another by means of sintering. For example, sintering can take place at a temperature of 1600-2000 C. in a nitrogen atmosphere.

[0076] FIG. 4 shows a method 1000 for producing a sensor 1 according to an embodiment of the invention. The method 1000 comprises the following steps:

provision 1010 of at least one completely ceramic heater 3; and
placement 1015 of at least one first sensor structure 9 on a first side of the completely ceramic heater 3, at least in areas.

[0077] Furthermore, the provision 1010 may also comprise production 1005 of the completely ceramic heater 3, 3 by means of co-sintering an electrically conductive and an electrically insulating ceramic. FIG. 4 shows the outline of the step in a dashed line, because the production 1005 of the completely ceramic heater is merely an option.

[0078] The features shown in the previous description, in the claims, and in the figures may be essential for the invention in its various embodiments both individually and in any combination.

LIST OF REFERENCE NUMERALS

[0079] 1 Sensor [0080] 3, 3 Completely ceramic heater [0081] 5a, 5a, 5b, 5b Electrode [0082] 7, 7 Insulating layer [0083] 9, 9 Sensor structure [0084] 11, 11 Ceramic intermediate layer [0085] 13, 13 Covering layer [0086] 15 First layer [0087] 17, 17, 17 Second layer [0088] 19, 19, 19 Third layer [0089] 21, 21, 21 Fourth layer [0090] 23 Fifth layer [0091] 1000 Method for producing a sensor [0092] 1005 Production [0093] 1010 Provision [0094] 1015 Placement