UNIT FOR HIGH-TEMPERATURE USES

Abstract

A unit for high-temperature for uses above 700° C. is provided. The unit includes a housing and an electrical functional element. The functional element has a non-conducting substrate, an electrically conductive element, and at least one connection wire or pad. The functional element has a first section, a second section, and a third section. The first section is within the housing and shielded from a local environment. The second section includes the at least one connection wire or pad and is accessible externally to the housing. The third section is between the first and second sections and is embedded in an electrically insulating material. The insulating material seals off the housing from the functional element. A physical and/or chemical bond at an interface between the insulating material and the functional element.

Claims

1. A unit for uses above 700° C., comprising: a housing; and at least one electrical functional element having a non-conducting substrate, an electrically conductive element, and at least one connection wire or pad, wherein the at least one electrical functional element has a first section within the housing and shielded from a local environment by the housing, wherein the at least one electrical functional element has a second section that includes at least a portion of the at least one connection wire or pad that is accessible externally to the housing, wherein the at least one electrical functional element includes a third section that is between the first and second sections, the third section being embedded in an electrically insulating material of the housing, wherein the electrically insulating material seals off the housing from the at least one electrical functional element, and wherein the electrically insulating material is selected from a group consisting of a glass, a glass ceramic, and a combination or a composite of glass and glass ceramic; and a physical and/or chemical bond at an interface between the electrically insulating material and the at least one electrical functional element.

2. The unit of claim 1, wherein the housing includes a cap made of temperature-resistant material that at least partially surrounds the electrically insulating material.

3. The unit of claims 2, wherein the temperature-resistant material of is selected from a group consisting of temperature-resistant steel, temperature-resistant steel alloy, a temperature-resistant ceramic, alloy 600, steel 1.4762, Al.sub.2O.sub.3 ceramic.

4. The unit of claim 1, wherein the housing includes a protective tube made of a temperature-resistant material that surrounds at least a portion of the second section, wherein the protective tube is connected to a cap of the housing.

5. The unit of claim 4, wherein the temperature-resistant material of is selected from a group consisting of temperature-resistant steel, temperature-resistant steel alloy, a temperature-resistant ceramic, alloy 600, steel 1.4762, Al.sub.2O.sub.3 ceramic.

6. The unit of claim 1, wherein the housing includes a protective element made of a material selected from a group consisting of glass, glass ceramic, ceramic, and any combinations thereof.

7. The unit of claim 1, wherein the first section is in a cavity of the housing, wherein the cavity is evacuated or filled with an inert gas.

8. The unit of claim 7, wherein the cavity has walls comprising the electrically insulating material and/or a protective element.

9. The unit of claim 1, further comprising a covering material that is different from the electrically insulating material, the covering material being configured to cover the electrically conducting element and/or an electrical contact point between the at least one connection wire or pad and the electrically conductive element.

10. The unit of claim 1, wherein the first section is embedded in an entirety in the electrically insulating material.

11. The unit of claim 1, further comprising an electrical contact point between the at least one connection wire or pad and the electrically conductive element, the electrical contact point is within the third section and embedded in the electrically insulating material.

12. The unit of claim 1, further comprising at least one retaining element configured to support the at least one connection wire.

13. The unit of claim 12, wherein the at least one retaining element is made of the same material as the electrically insulating material and is configured as a single unit therewith.

14. The unit of claim 12, wherein the at least one retaining element is made a material selected from a group consisting of glass, glass ceramic, and ceramic, wherein the at least one retaining element is partially embedded in the electrically insulating material and held in place by the electrically insulating material.

15. The unit of claim 1, wherein the electrically insulating material has a coefficient of thermal expansion that is matched to a coefficient of thermal expansion of the at least one electrical functional element.

16. The unit of claim 1, wherein the electrically insulating material has a coefficient of thermal expansion that differs from a coefficient of thermal expansion of the at least one electrical functional element by less than 5.Math.10.sup.−6/K.

17. The unit of claim 1, wherein the electrical functional element is configured as a temperature-sensor element, wherein the temperature-sensor element comprises a ceramic substrate and a structured resistance layer arranged thereon.

18. The unit of claim 1, wherein the electrical functional element is configured as a heating element.

19. The unit of claim 1, wherein the at least one electrical functional element comprises a temperature-sensor element and a heating element, and wherein the unit is configured as a thermal flow meter.

20. The unit of claim 1, wherein the electrically insulating material is a glass ceramic, comprising: La.sub.2O.sub.3 greater than 0.3 mol % to less than 5 mol %, Nb.sub.2O.sub.5 0 mol % to 9 mol %, Ta.sub.2O.sub.5 0 mol % to 7 mol %, where Σ(A.sub.2O.sub.5) is greater than 0.2 mol % to 9 mol %, where A is an element is an oxidation state V+ and comprises an element selected from a group consisting of Nb, Ta, P, and combinations thereof.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0132] Illustrated in schematic form below:

[0133] FIG. 1 shows a schematic section view of an electrical functional element designed as a temperature-sensor element,

[0134] FIG. 2 shows a first embodiment of a unit having an electrical functional element for high- temperature uses,

[0135] FIG. 3 shows a second embodiment of a unit which additionally includes a retaining element,

[0136] FIG. 4 shows a third embodiment of a unit,

[0137] FIG. 5 shows a fourth embodiment of a unit,

[0138] FIG. 6 shows a fifth embodiment of a unit,

[0139] FIG. 7 shows a sixth embodiment of a unit,

[0140] FIG. 8 shows a seventh embodiment of a unit,

[0141] FIG. 9 shows an eighth embodiment of a unit,

[0142] FIG. 10 shows a ninth embodiment of a unit,

[0143] FIG. 11 shows a tenth embodiment of a unit, and

[0144] FIG. 12 shows an eleventh embodiment of a unit which includes two electrical functional elements.

DETAILED DESCRIPTION

[0145] FIG. 1 shows in schematic form an electrical functional element 10 designed as a temperature-sensor element in a section view from the side. The electrical functional element 10 includes a non-conducting substrate 16. Arranged on one surface of the non-conducting substrate 16 is an electrically conductive element 18 in the form of a thin layer. This is in the example of the temperature-sensor element structured such that a conductor track following a meandering path on the surface of the non-conducting substrate 16 is formed. This conductor track is here a temperature-measuring resistor, the electrical resistance of which changes in a characteristic manner with the temperature.

[0146] The electrically conductive element 18 and the conductor track formed by structuring is in electrical contact with contact points 20 via connection wires 14. In the case of a temperature-sensor element, two or four connection wires 14 are for example used to permit a two-point or four-point measurement of the electrical resistance, only one being visible in the section view in FIG. 1.

[0147] The electrically conductive layer 18 and the contact point 20 are in the example shown in FIG. 1 provided with a covering material 22, to provide protection from environmental influences. Instead of a single layer, as outlined in FIG. 1, the covering material 22 may also be formed as a layer system having a plurality of different layers.

[0148] FIG. 2 shows a first embodiment of a unit 1 for high-temperature uses, which includes an electrical functional element 10 and a housing 100. The unit 1 is here shown in a section view from the front. The housing 100 includes in this exemplary embodiment a cap 104 that is for example produced from a temperature-resistant metal alloy. The housing 100 includes in addition to the cap 104 an electrically insulating material 102 that closes the open side of the cap 104. The electrically insulating material 102 is for example a partially crystallized glass or a glass ceramic.

[0149] A first section 11 of the electrical functional element 10 is embedded in its entirety in the electrically insulating material 102. In the case of a temperature-sensor element as shown in FIG. 1, this first section includes the meandering conductor track and thus the active portion of the temperature-sensor element.

[0150] A second section 12 of the electrical functional element 10 that includes portions of the connection wires 14 is here not enclosed by the electrically insulating material 102 and is externally accessible for electrical contacting. In an alternative embodiment variant, the electrical functional element 10 also includes connection pads instead of connection wires 14. These would then be arranged on the non-conducting substrate 16 similarly to the contact point 20 shown in FIG. 1, such that the second section then accordingly includes a portion of the substrate 16. An exemplary embodiment in which the second section 11 includes a portion of the non-conducting substrate 16 is also described below with reference to FIG. 5.

[0151] A third section 13 of the electrical functional element 10 that is situated between the first section 11 and the second section 12, and that includes the contact points 20 shown in FIG. 1, is in the embodiment shown in FIG. 2 likewise embedded in the electrically insulating material 102, such that only a portion of the connection wires 14 protrudes from the electrically insulating material 102.

[0152] The electrically insulating material 102 is fused onto the connection wires 14 such that a hermetically sealed connection is present. The electrically insulating material 102 is likewise fused onto the cap 104 such that a hermetically sealed connection is present here too. As a result of this intimate connection between the electrically insulating material 102 and the at least one functional element 10 and between the electrically insulating material 102 and the cap 104, additional sealing elements are superfluous, which means that the proposed unit 1 is free of additional sealing elements.

[0153] The first section 11 containing the active portion of the electrical functional element 10 is advantageously encased in its entirety in the insulating material 102, which means it is unable to interact either with the local environment or with other constituents of unit 1 such as the cap 104. Therefore, contamination of the electrical functional element 10 with constituents of the cap 104 is for example excluded.

[0154] FIG. 3 shows a second embodiment of a unit 1. This corresponds essentially to the first embodiment described with reference to FIG. 2, except that it additionally includes a retaining element 106.

[0155] The retaining element 106 is here tubular in form and is held in place by the electrically insulating material 102. To this end, a portion of the retaining element 106 is embedded in the electrically insulating material 102. The retaining element 106 is arranged such that it surrounds the connection wires 14 and thereby mechanically supports them. The retaining element 106 may for example consist of a ceramic.

[0156] FIG. 4 shows a third embodiment of a unit 1. This corresponds essentially to the second embodiment described with reference to FIG. 3, except that it does not include a cap 104. The housing 100 here consists exclusively of a shaped body made of the electrically insulating material 102.

[0157] FIG. 5 shows a fourth embodiment of a unit 1. The housing 100 includes in this exemplary embodiment a cap 104, at the open end of which a protective tube 108 is connected. The cap 104 and the protective tube 108 consist for example in both cases of temperature-resistant metal alloys and are connected together for example by welding.

[0158] The electrical functional element 10 is inserted in the protective tube 108 as far as the region of the protective cap 104 and is held in place and sealed off from the protective tube 108 by means of a plug of the electrically insulating material 102, with the result that a closed cavity 112 is present in the region of the cap 104 and at the end of the protective tube 108. A first section 11 of the electrical functional element 10 is located in the cavity 112 and a second section 12 of the electrical functional element 10, which here includes the connection wires 14 in their entirety, is located outside the cavity and is not covered by the electrically insulating material 102, which means that the connection wires 14 are accessible from outside the housing 100. Instead of connection wires 14, the electrical functional element 10 could also have connection pads arranged in the second section 12.

[0159] A third section 13 situated between the first section 11 and the second section 12 is held in place by the electrically insulating material 102, wherein the electrically insulating material is in this third section connected to the electrical functional element 10 with the formation of a hermetic seal. More particularly, the electrically insulating material 102 is here fused onto the non- conducting substrate 16 and the covering material 22, cf. FIG. 1. The electrically insulating material 102 is likewise connected to the protective tube 108 with the formation of a hermetic seal, with the result that the cavity 112 is closed with a hermetic seal.

[0160] FIG. 6 shows a fifth embodiment of the unit 1, which corresponds essentially to the fourth embodiment described with reference to FIG. 5. However, in this case the third region 13 of the electrical functional element 10 that is connected to the electrically insulating material 102 additionally encases a portion of the connection wires 14, which means more particularly that contact points 20 between the electrically conductive element 18, cf. FIG. 1, and the connection wires are situated within the region surrounded by the electrically insulating material 102. This provides the contact points 20 with particularly good protection.

[0161] FIG. 7 shows an sixth embodiment of a unit 1. This corresponds essentially to the fifth embodiment described with reference to FIG. 6, except that it additionally includes a retaining element 106.

[0162] The retaining element 106 is here tubular in form and is held in place by the electrically insulating material 102. To this end, a portion of the retaining element 106 is embedded in the electrically insulating material 102. The retaining element 106 is arranged such that it surrounds the connection wires 14 and thereby mechanically supports them. The retaining element 106 may for example consist of a ceramic.

[0163] FIG. 8 shows a seventh embodiment of a unit 1. This corresponds essentially to the fifth embodiment described with reference to FIG. 6, except that the walls of the cap 104 facing the interior of the cavity 112 are lined with a non-metallic material.

[0164] The wall at the closed end of the cap 104 is in this example lined with a protective element 110. The material of the protective element 110 is for example a glass, a ceramic or a glass ceramic. The lateral walls of the cavity 112 are lined with the electrically insulating material 102, these side walls in the exemplary embodiment shown in FIG. 8 being designed as a single unit with the plug-shaped piece of the electrically insulating material 112 which holds in place the third section 13 of the electrical functional element 10.

[0165] In addition, the first section 11 of the electrical functional element 10 is in the seventh embodiment chosen such that, when the electrical functional element 10 is designed as a temperature-measuring resistor, this contains the conductor track constituting the measuring resistor in its entirety. Thus, the active portion of the electrical functional element 10 is in this embodiment located entirely within the cavity 112.

[0166] FIG. 9 shows an eighth embodiment of a unit 1. This corresponds essentially to the seventh embodiment described with reference to FIG. 8, except that the eighth embodiment does not include a cap 104. The housing 100 thus consists of the electrically insulating material 102 and the protective element 110.

[0167] FIG. 10 shows a ninth embodiment of a unit 1. This corresponds essentially to the eight embodiment described with reference to FIG. 9, except that it additionally includes a retaining element 106.

[0168] The retaining element 106 is here tubular in form and is held in place by the electrically insulating material 102. To this end, a portion of the retaining element 106 is embedded in the electrically insulating material 102. The retaining element 106 is arranged such that it surrounds the connection wires 14 and thereby mechanically supports them. The retaining element 106 may for example consist of a ceramic.

[0169] FIG. 11 shows a tenth embodiment of a unit 1. This corresponds essentially to the ninth embodiment described with reference to FIG. 10, except that the tenth embodiment does not include a cap 104. The housing 100 thus consists of the electrically insulating material 102, which forms a cup-shaped shaped body, and the protective element 110.

[0170] FIG. 12 shows an eleventh embodiment of a unit 1 in a section view from the side. This is similar in design to the first embodiment described with reference to FIG. 1, but additionally has a further electrical functional element 10′. This is in this example designed as a heating element and arranged next to the electrical functional element 10, which is designed as a temperature-sensor element.

[0171] The unit 1 shown in FIG. 12 may be employed as a thermal flow sensor. In this case, the temperature determined by means of the electrical functional element 10 designed as a temperature-sensor element can be used to regulate a heating current in the further electrical functional element 10′ designed as a heating element such that the temperature is kept constant. The more fluid flowing past unit 1, the more heat is transferred to the fluid and the higher the heating current needs to be set for a constant temperature. The volume of fluid flowing past can then accordingly be concluded from the heating current.

LIST OF REFERENCE SIGNS

[0172] 1 Unit

[0173] 10 Electrical functional element

[0174] 10′ Further electrical functional element

[0175] 11 First section

[0176] 12 Second section

[0177] 13 Third section

[0178] 14 Connection wire

[0179] 16 Non-conducting substrate

[0180] 18 Electrically conductive element

[0181] 20 Contact point

[0182] 22 Covering material

[0183] 100 Housing

[0184] 102 Electrically insulating material

[0185] 104 Cap

[0186] 106 Retaining element

[0187] 108 Protective tube

[0188] 110 Protective element

[0189] 112 Cavity