KR20170077827A - Sensor for detecting at least one property of a measuring gas in a measuring gas chamber - Google Patents

Abstract

The invention relates to a sensor (10) for detecting at least one characteristic of a measuring gas in a measuring gas chamber, in particular a ratio of the gas component in the measuring gas or the temperature of the measuring gas. The sensor 10 includes a sensor housing 12 and a sensor element 32 for detecting at least one characteristic of a measurement gas in the measurement gas chamber. The sensor housing 12 includes a longitudinal bore 16 and the longitudinal bore 16 extends along a longitudinal axis 18. The sensor element 32 is connected to the seal 42 in a material coupling manner. The sensor element 32 is disposed in the longitudinal bore 16.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a sensor for detecting at least one characteristic of a measurement gas in a measurement gas chamber,

The present invention relates to a sensor for detecting at least one characteristic of a measuring gas in a measuring gas chamber.

The prior art discloses a number of sensors and methods for detecting at least one characteristic of a measurement gas in a measurement gas chamber. The characteristic may basically be any physical and / or chemical characteristic of the measuring gas, in which case one or more characteristics can be detected. The present invention will be described in the following with reference to the qualitative and / or quantitative detection of the gas component of the measurement gas, particularly with regard to the detection of the oxygen ratio in the measurement gas. The oxygen ratio can be detected in the form of partial pressure and / or in the form of a percentage. Alternatively or additionally, other properties of the measured gas, such as temperature, can also be detected.

These sensors are based on the use of properly designed sensor elements. An example of such a sensor is formed as a so-called lambda probe as is known, for example, in Konrad Reif (published): Sensoren im Kraftfahrzeug (Autosensor), Vol. 1, By means of a broadband lambda probe, in particular a flat broadband lambda probe, for example, the oxygen concentration in the exhaust gas is determined over a wide range, and thus the air / fuel ratio in the combustion chamber is estimated. Air ratio? Represents the air-fuel ratio. In particular, ceramic sensor elements based on the electrolytic properties of particular solids, i.e. the ionic conductivity of the solids, are known in the prior art. In particular, the solids can be ceramic solid electrolytes, such as zirconium dioxide, especially yttrium-stabilized zirconium dioxide and scandium-doped zirconium dioxide, which can contain small amounts of additives such as aluminum oxide and / or silicon oxide.

DE 197 14 203 A1 and DE 195 32 090 C2 disclose lambda probes with sealing packing systems, which consist of a combination of a plurality of sealing discs consisting of stearate and boron nitride. The statorite sealing disk is a non-sintered stearate raw material. Boron nitride is a hexagonally hot pressed boron nitride. During assembly, the sealing packing system is received in the sensor housing by two adjacent supporting ceramic bushes of rigid sintered stataite, powdered and compressed by axial force introduction. In this case, the gap is closed and the sealing property is increased. The sealing system must separate the exhaust gas and moisture from the reference air chamber of the sensor.

There are still room for improvement in the advantages of the sensors known in the prior art. Although the above-described sealing packing system has good sealing properties against gas and moisture, in low temperature applications, water vapor enters the crystal lattice of boron nitride and reacts with boron oxide contained in boron nitride to form boric acid. If the lambda probe is heated during engine startup, the combined water can be discharged from the boron nitride disk into the reference air chamber, which can cause distortion of the probe signal. In this case, a considerable reduction in the insulation resistance appears.

It is an object of the present invention to provide a method and apparatus for measuring a gas concentration in a measuring gas chamber in which the disadvantages of known sensors are at least widely prevented and in particular an improved sealing effect on moisture and exhaust gases is realized and the insulation resistance between the sensor element and the sensor housing is improved, To detect at least one characteristic of the sensor.

A sensor according to the invention for detecting at least one characteristic of a measuring gas in a measuring gas chamber, in particular for detecting the ratio of a gas component in the measuring gas or the temperature of the measuring gas, comprises a sensor housing, And a sensor element for detecting at least one characteristic. The sensor housing includes a longitudinal bore. The longitudinal bore extends along the longitudinal axis. The sensor element is connected to the seal in a material coupling manner. The sensor element is disposed in the longitudinal bore.

The longitudinal bore may be formed as a cylinder, for example, a cylinder. The sensor element may be formed in a flat surface. The sensor element may extend in the longitudinal direction. The seal can completely surround the sensor element in the circumferential direction about the longitudinal direction. The sensor element may be fixed axially and / or radially with respect to the longitudinal axis within the longitudinal bore. The seal may be made of at least one ceramic material. The sensor elements can be connected to the seals in a material bonded manner by common sintering. The sensor element may include a connection side end and a measurement gas side end. The seal may be disposed between the connection-side end and the measurement gas-side end. The sensor may also include a sealing member. The sealing member may be disposed between the seal and the gas side end of the sensor element in the longitudinal bore. The sensor may also include a steel sleeve. The steel sleeve may be disposed in the longitudinal bore between the seal and the end of the connection side of the sensor element. The sensor may also include an example stress member. The example stress member may be disposed in the longitudinal bore between the seal and the contact side end of the sensor element. The example stress member is formed so as to exert a pre-stress on the seal in the direction toward the sealing member. The seal may be made of at least one ceramic material. The sensor element can be connected to the seal in a material bonded manner by means of an adhesive, in particular a ceramic adhesive and / or a glass solder. The sensor element may include a connection side end and a measurement gas side end. The seal is disposed between the end of the connection portion and the end of the measurement gas. The sensor also includes a sealing member. The sealing member is disposed between the seal and the gas side end of the sensor element in the longitudinal bore. The sensor also includes an example stress member. The example stress member may be disposed in the longitudinal bore between the seal and the contact side end of the sensor element. The example stress member may be formed to exert pre-stress on the seal in the direction toward the sealing member. The sealing member may be a sealing lip.

The seal may be a sleeve, and the sleeve may be made of at least one metallic material. The sensor element can be connected to the sleeve in a material coupling manner by solder joints. The sleeve may include an outer section and an inner section. The outer section and the inner section may be connected to each other. The outer section may be configured to contact the longitudinal bore. The sensor element can be connected to the inner section in a material coupling manner by solder joints.

The extension along the longitudinal axis means an extension about a centerline or centerline axis defined by an extension parallel to the longest dimension of the part or about the centerline or centerline axis.

Material coupling The coupling means in the scope of the present invention that the coupling partner is bound by the force of an atom or a molecule. This connection is an inseparable connection that can be separated only by the destruction of the connection means at the same time.

The planar formation of the sensor element means in the scope of the present invention the formation of a sensor element in which the sensor element has a substantially cubic design, in which case the cubic shape has a height much smaller than other dimensions such as width and length.

The end portion on the connection side of the sensor element means the end of the sensor element formed to be connected to the electrical connection means of the sensor, for example, the lines of the plug portion in the scope of the present invention.

In the scope of the present invention, the measuring gas side end portion of the sensor element means an end portion that can be exposed to the measuring gas in the inserted state of the sensor.

The example stress member refers to a member formed to provide pre-stress to other components in the sense of the present invention to press the component in a specific direction. Yes Stress can occur elastically. In other words, the example stress members can be resiliently deformed and nevertheless provide example stress.

Other optional details and features of the present invention are set forth in the following description of a preferred embodiment schematically illustrated in the drawings.

1 is a cross-sectional view of a first embodiment of a sensor element according to the present invention;
2 is a cross-sectional view of a second embodiment of a sensor element according to the present invention;
3 is a cross-sectional view of a third embodiment of the sensor element according to the present invention.
4 is a cross-sectional view of a fourth embodiment of the sensor element according to the present invention.
5 is a cross-sectional view of a fifth embodiment of a sensor element according to the present invention.

1 shows a sensor 10 according to a first embodiment of the present invention for detecting at least one characteristic of a measuring gas in a measuring gas chamber, in particular for detecting the ratio of the gas component in the measuring gas or the temperature of the measuring gas. Is shown in a cross-sectional view. The sensor can be used in particular for the detection of the physical and / or chemical properties of the measuring gas, in which case one or more properties can be detected. The present invention will be described in the following with reference to the qualitative and / or quantitative detection of the gaseous component of the measuring gas, in particular with regard to the detection of the oxygen ratio in the measuring gas. The oxygen ratio can be detected, for example, in the form of partial pressure and / or in the form of a percentage. However, basically different kinds of gas components such as nitrogen oxides, hydrocarbons and / or hydrogen can be detected. Alternatively or additionally other properties of the measured gas may be detected. Since the present invention can be used in particular in the field of automotive engineering, the measuring gas chamber can be in particular an exhaust gas system of an internal combustion engine, and the measuring gas can in particular be an exhaust gas.

The sensor 10 includes a sensor housing 12. The sensor housing 12 may be, for example, a metal housing. The sensor housing 12 includes threads 14 as securing means for mounting on the wall of a measurement gas chamber (not shown). The sensor housing (12) includes a longitudinal bore (16). The longitudinal bore 16 extends along the longitudinal axis 18. The longitudinal bore 16 includes a shoulder-shaped ring surface 20. The ring surface 20 is disposed adjacent the end surface side end 22 of the sensor housing 12 toward the measurement gas chamber. At the end surface side end 22, the protective tube assembly 24 is fixed, e.g., welded. The protective tube assembly 24 includes at least one protective tube. For example, the protective tube assembly includes an outer protective tube 26 and an inner protective tube 28 disposed therein. The outer protective tube 26 and the inner protective tube 28 include inlet and outlet openings 30 through which the measurement gas can flow into the interior space of the inner protective tube 28, As shown in FIG.

The sensor 10 also includes a sensor element 32 for detecting at least one characteristic of the measurement gas. The sensor element 32 is formed in a plane. The sensor element 32 extends in the longitudinal direction 34. The sensor element 32 includes a connection side end 36 and a measurement gas side end 38. The contact portion side end portion 36 is formed to be in electrical contact with the electrical contact portion 40 of the sensor 10. The measurement gas side end portion 38 is formed so as to be exposed to the measurement gas inside the inner protective tube 28.

The sensor 10 also includes a seal 42. The sensor element 32 is connected to the seal 42 in a material coupling manner. The seal 42 is disposed between the connecting portion side end 36 of the sensor element 32 and the measuring gas side end portion 38. In this case, the seal 42 is completely enclosed in the circumferential direction about the longitudinal direction 34 of the sensor element 32. The sensor element 32 is disposed in the longitudinal bore 16 with the seal 42. In this case, the connection side end 36 is connected to the electrical contact 40, and the measurement gas side end 38 is disposed in the inner space of the inner protection tube 28. In the case of the sensor 10 of the first embodiment, the seal 42 is made of at least one ceramic material. For example, the seal 42 is made of forsterite. The sensor element 32 may be connected to the seal 42 in a material bonded manner by common sintering. For example, the sensor element 32 is surrounded by a ceramic powder, such as forsterite, having a coefficient of thermal expansion similar to that of zirconium dioxide in the sensor element 32 and the sensor housing 12 in a press mold of a direct dry press method Landfill. The assemblies thus produced are then hard sintered together in a gas-tight manner. The sensor element 32 is then placed in the longitudinal bore 16 along with the seal 42 so that the seal 42 contacts the ring surface 20. The gas can not penetrate between the seal 42 and the sensor element 32 in the direction toward the electrical contact 40 because the airtight sealed assembly is manufactured by common sintering of the sensor element 32 and the seal 42. [ The seal 42 is designed to contact the sensor housing 12 in a radial direction with respect to the longitudinal direction 34 to form an airtight seal therein. Optionally, a sealing member 44 may be provided. The sealing member 44 is disposed between the seal 42 and the measurement gas side end 38 of the sensor element 32. [ The sealing member 44 contacts the ring surface 20 and contacts the seal 42 so that a sealing connection is formed between the seal 42 and the sealing member 44. In the case of the sensor 10 of the first embodiment, the sealing member 44 is formed as a sealing disk 46. Sealing disk 46 is made of soft heat resistant steel, copper or heat resistant mica, such as vermiculite or gold mica. Because the seal 42 may be pre-stressed axially with respect to the longitudinal direction 34 in the direction toward the ring face 20 with the sensor element 32, The gap between the housings 12 is radially sealed.

2 shows a sensor 10 according to a second embodiment of the present invention. Hereinafter, only the differences from the above embodiment will be described and the same parts are denoted by the same reference numerals. In the case of the sensor 10 of the second embodiment, the seal 42 has a smaller dimension in the longitudinal direction 34 than the sensor 10 of the first embodiment. In other words, the seal 42 is formed shorter in the axial direction. The sensor 10 also includes a steel sleeve 48. The steel sleeve 48 is disposed between the seal 42 and the connection side end 36. The steel sleeve 48 is formed of steel having a greater coefficient of thermal expansion than the material of the sensor housing 12. Thereby, the difference in thermal expansion coefficient between the sealing sheet and the sensor housing 12 can be compensated. The difference may cause a pre-stress loss at the operating temperature of the sensor 10. The seal 42 is formed to be shorter in the axial direction, so that better heat separation can be realized.

3 shows a cross-sectional view of a sensor 10 according to a third embodiment of the present invention. Hereinafter, only the differences from the above embodiment will be described and the same parts are denoted by the same reference numerals. The sensor 10 of the third embodiment is based on the sensor 10 of the first embodiment. The sensor 10 of the third embodiment includes an example stress member 50. Example The stress member 50 is designed as a leaf spring 52, for example. The example stress member 50 is disposed in the longitudinal bore 16 between the seal 42 and the connection side end 36. The stress member 50 is formed to exert a stress exerted on the seal 42 or the seal 42 and the sensor element 32 in the direction toward the seal member 44 or the ring face 20. In other words, there is no axial gap between the seal 42 and the sensor housing 12 because the seal 44 is pressed against the seal member 44 or ring face 20. [

4 shows a cross-sectional view of the sensor 10 according to a fourth embodiment of the present invention. Hereinafter, only the differences from the above embodiment will be described and the same parts are denoted by the same reference numerals. Compared to the sensor 10 of the first embodiment, the seal 42 is formed as a cylinder or as a ceramic cylinder 54. The sensor element 32 is connected to the seal 42 or the ceramic cylinder 54 by means of an adhesive 56 in a material coupling manner. The adhesive 56 may be a ceramic adhesive. Alternatively or additionally, the sensor element 32 may be connected to the ceramic cylinder 54 by glass solder in a material coupling manner. This can be realized, for example, by the fact that the ceramic cylinder 54 is a hollow cylinder and the sensor element 32 is inserted into the hollow cylinder. By the preformed channel extending radially with respect to the cylinder axis of the ceramic cylinder 54, the adhesive 56 is injected in the form of a ceramic adhesive or glass solder paste. Thereafter, the assembly consisting of the sensor element 32 and the ceramic cylinder 54 is heated by heat. An assembly consisting of the sensor element 32 and the ceramic cylinder 54 is then inserted into the longitudinal bore 16. Like the sensor 10 of the third embodiment, the seal 42 may be pre-stressed in the axial direction. For example, the exemplary stress member 50 is disposed in the longitudinal bore 16 in the form of a leaf spring between the seal 42 and the connection side end 36. The leaf spring 52 can be supported on the compensation disk 60 disposed near the connection side end 36. [ The sealing member 44 may be disposed within the longitudinal bore 16 between the seal 42 and the measurement gas lateral edge 38. [ The sealing member 44 comes into contact with the ring surface 20. The stress member 50 exerts a stress exerted on the seal 42 in the direction toward the sealing member 44. In the case of the sensor of the fourth embodiment, the sealing member 44 is formed as a sealing lip or includes a sealing lip 62. The sealing lip 62 protrudes in the axial direction opposite to the longitudinal direction 34 in the direction toward the connection portion side end portion 36 of the sensor element 32. The stress member 50 presses the seal 42 against the seal lip 62 so that no gap is formed between the seal member 44 and the seal 42. [ The compensation disc 60 may be supported by a caulking 64 of the sensor housing 12 in an inward radial direction.

Figure 5 shows a cross-sectional view of a sensor 10 according to a fifth embodiment of the present invention. Hereinafter, only the differences from the above embodiment will be described and the same parts are denoted by the same reference numerals. In the case of the sensor 10 of the fifth embodiment, the seal 42 is a sleeve 66. Sleeve 66 is made of at least one metallic material. For example, the sleeve 66 is made of Crofer 22 APU. Sleeve 66 includes an outer section 68 and an inner section 70. The outer section 68 and the inner section 70 are connected to each other. The outer section 68 and the inner section 70 are connected such that the connecting region is in contact with the ring surface 20. [ For example, since the sleeve 66 is formed of a deep drawn sleeve, the inner section 70 extends axially in the form of a folding into the outer section 68. The outer section 68 is formed to contact the longitudinal bore 16. For example, the outer section 68 is press fit and / or welded into the sensor housing 12 in the region of the longitudinal bore 16. The sensor element 32 is connected in a material coupling manner to the inner section 70 by solder joint 72. For example, the solder joint 72 is implemented by a nickel reactive solder such as NiSiBFeCr. The solder can be inserted as a solder paste or a solder film. For electrical insulation, the surface of the inner section 70 facing the sensor element 32 is coated with a ceramic insulating layer 74. The insulating layer 74 is made of, for example, inexpensive magnesium oxide and has a high thermal expansion coefficient. In this way, thermal separation of the sensor element 32 from the sensor housing 12 can be realized. By reducing the heat transfer, the heating output of the sensor element 32 or the heating element is reduced, so that the heating element of the sensor element 32 can be designed to be smaller. Correspondingly, since fewer boards are required for the heating element, a faster operating preparation can be realized. In the case of the sensor 10 of the fifth embodiment, since 90% or more of the sealing surface is metal, high airtightness is achieved. The magnesium oxide of the insulating layer 74 achieves an insulation strength greater than 200 MOhm. However, if the sensor element 32 is made of aluminum oxide, the insulating layer 74 can be omitted.

10 sensors
12 sensor housings
16 longitudinal bore
32 sensor element
36 Connection side end
38 Measurement gas side end
42 hours
44 sealing member
48 steel sleeves
50 Examples Stress member
66 Sleeve
68 outer section
70 internal section
72 soldering joint

Claims (15)

A sensor (10) for detecting at least one characteristic of a measuring gas in a measuring gas chamber, in particular for detecting the ratio of a gas component in the measuring gas or the temperature of the measuring gas, characterized in that the sensor housing (12) And a sensor element (32) for detecting at least one characteristic of the measurement gas in the sensor (10)
The sensor housing 12 includes a longitudinal bore 16 that extends along a longitudinal axis 18 and the sensor element 32 is coupled to the seal 42 in a material- And the sensor element (32) is disposed within the longitudinal bore (16). The sensor (10) according to claim 1, wherein the longitudinal bore (16) is formed in a cylindrical shape, in particular a cylinder. The sensor (10) according to claim 1 or 2, wherein the sensor element (32) is formed in a plane. 4. A device according to any one of the preceding claims, characterized in that the sensor element (32) extends in the longitudinal direction (34) and the seal comprises the sensor element (32) (10). ≪ / RTI > A sensor according to any one of claims 1 to 4, wherein the sensor element (32) is fixed axially and / or radially with respect to the longitudinal axis (18) within the longitudinal bore (16) (10). 6. Device according to any one of the preceding claims, characterized in that the seal (42) is made of at least one ceramic material and the sensor element (32) is connected to the seal (42) (10). The gas sensor module according to any one of claims 1 to 6, wherein the sensor element (32) comprises a connection side end (36) and a measurement gas side end (38), the seal (42) 36) and the measurement gas lateral edge (38), the sensor (10) also including a sealing member (44), the sealing member (44) being located within the longitudinal bore (16) (42) and the measuring gas side end (44) of the sensor element (32). 8. A device according to any one of claims 1 to 7, wherein the sensor (10) further comprises a steel sleeve (48), the steel sleeve (48) being located within the longitudinal bore (16) (36) of the sensor element (32). 8. The apparatus of claim 7, wherein the sensor (10) further comprises an example stress member (50), the pre-stress member (50) being positioned within the longitudinal bore (16) Wherein the first stress member is disposed between the contact side end portion of the seal member and the contact member side end portion of the seal member and wherein the exemplary stress member is configured to exert a stress on the seal in a direction toward the seal member. ). 6. Device according to any one of claims 1 to 5, characterized in that the seal (42) is made of at least one ceramic material and the sensor element (32) is bonded to an adhesive (56), in particular a ceramic adhesive and / Is connected to the seal (42) in a material coupling manner. The gas sensor according to claim 10, wherein the sensor element (32) comprises a connection side end (36) and a measurement gas side end (38), the seal (42) (38) and the sensor (10) further comprises a sealing member (44), the sealing member (44) being located within the longitudinal bore (16) (32) of the sensor (10). 13. The sensor element (10) of claim 11, wherein the sensor (10) further comprises an example stress member (50) Wherein the first stress member is disposed between the contact side end portion of the seal member and the contact member side end portion of the seal member and wherein the exemplary stress member is configured to exert a stress on the seal in a direction toward the seal member. ). 13. The sensor (10) according to any one of claims 1 to 12, wherein the sealing member (44) is a sealing lip (62). 6. A method according to any one of claims 1 to 5, wherein the seal (42) is a sleeve (66), the sleeve (66) is made of at least one metallic material and the sensor element (32) (72) to the sleeve (66) in a material coupling manner. 15. The method of claim 14, wherein the sleeve (66) comprises an outer section (68) and an inner section (70), wherein the outer section (68) and the inner section Is formed to contact the longitudinal bore (16) and the sensor element (32) is connected in a material coupling manner to the inner section (70) by the solder joint (72).

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