WO2008009533A2

WO2008009533A2 - Gas sensor with sensor element and sealing member

Info

Publication number: WO2008009533A2
Application number: PCT/EP2007/056121
Authority: WO
Inventors: Imke Heeren; Ulrich Eisele; Philipp Spies; Thomas Loibl; Ralf Niklaus
Original assignee: Robert Bosch Gmbh
Priority date: 2006-07-19
Filing date: 2007-06-20
Publication date: 2008-01-24
Also published as: DE102007025626A1; WO2008009533A3

Abstract

A gas sensor is disclosed for determining a physical property of a measurement gas, in particular the concentration of a gaseous component or the temperature of the measurement gas. The gas sensor comprises a sensor element (11) with an end section (111) on the measurement gas side and an end section (112) on the connection side, and a sealing member (17) that surrounds the sensor element (11) for separating in a measurement gas-tight manner the end section (111) on the measurement gas side from the end section (112) on the connection side. In order to save manufacturing costs and shorten the assembly time, the sealing member (17) is joined in a gas-tight manner to the sensor element (11), forming an assembly module (30). The sealing member (17) is preferably a ceramic body (20) produced by a die-casting method, and the assembly module (30) is formed by sintering the ceramic body (20) on the sensor element (11).

Description

description

Title gas sensor

State of the art

The invention is based on a gas sensor for determining a physical property of a measurement gas, in particular the concentration of a gas component or the temperature of the measurement gas, according to the preamble of claim 1.

A known gas sensor of this type (DE 195 32 090 Al) has a provided with a mounting thread and a mounting sleeve, metallic housing and a rod-shaped, planar sensor element which is fixed in the housing and protrudes axially with two end portions on mutually remote housing sides of the housing , Gas-sensitive electrodes are arranged in the so-called measuring-gas-side end section of the sensor element, and contact surfaces are arranged on the so-called connection-side end section of the sensor element and are connected to the electrodes via conductor tracks. The contact surfaces are connected via contact holders or contact plug made of ceramic with guided to the sensor element leads. The measuring gas side end portion is covered by a multi-walled protective tube having gas passage holes through which the sample gas reaches the gas-sensitive electrodes.

For gas-tight passage of the sensor element through the housing, a sealing element enclosing the sensor element is provided, which is arranged between two ceramic moldings and axially compressed by axially pressing the ceramic moldings so that it presses on the one hand to the sensor element and on the other hand to an inner wall portion of the housing radially. The axial pressing force is maintained by means of a metal cap which is caulked with its cap edge on the metal housing. The cap bottom presses the one ceramic part against the sealing member, while the other ceramic part rests against an annular shoulder formed in the housing, which constitutes an abutment. The sealing member is in three parts and consists of two steatite discs and a boron nitride disc arranged in between, which are individually inserted into the housing during assembly of the gas sensor. Contact plugs or contact holders which come into use on the end face on the measuring gas side and force-fit, for example, the connecting conductors onto the contact surfaces on the sensor element are known in different configurations, for example from DE 101 32 827 A1, DE 101 32 828 A1 or DE 101 32 823 C1. Structure and operation of a sensor element for measuring the oxygen concentration in the exhaust gas of an internal combustion engine is described for example in DE 199 41 051 Al.

Such a gas sensor used as an exhaust gas sensor or lambda probe is inserted into an exhaust pipe of an internal combustion engine and protrudes into the exhaust gas flow guided in the exhaust pipe with the measuring gas side end portion of the sensor element surrounded by a protective tube. To install the exhaust gas sensor on the exhaust pipe, the exhaust pipe is provided with an opening in which a male thread bearing, hollow cylindrical connector is welded. The gas sensor with its housing, which is provided with a sealing flange, inserted into the connector so that the bottom of the sealing flange rests on the annular end face of the connector. A guided over the housing union nut is screwed with an internal thread in the external thread of the connector and presses the annular flange on the end face of the connector, so that a sealing seat of the housing is made in the connector (DE 197 39 435 Al).

Disclosure of the invention

The gas sensor according to the invention with the features of claim 1 has the advantage that only a few parts must be assembled during assembly of the gas sensor, whereby the assembly time is significantly shortened and the assembly cost is significantly reduced. The assembly comprises the obstruction of the mounting element consisting of sensor element and sealing element in a sensor housing or directly in a connection piece on a sample gas tube carrying the measurement gas and establishing the axial seal between the sealing element and sensor housing or connection piece.

When obstructing the mounting module in a sensor housing according to an advantageous embodiment of the invention, the sealing element is provided with two spaced, circumferential flanks, of which a first flank is formed on the messgasseitigen front side of the sealing element. The first edge is close to a formed on the housing, circumferential first shoulder. The second flank of the sealing element is overlapped gas-tight by a likewise circumferential second shoulder of the housing and thus clamped the sealing member axially against the other housing shoulder. This second shoulder is made by locally heating the housing in the region of the second flank and swaging the heated area. The process of local heating and compression of the housing, which is also used in the manufacture of ignition candles is extremely inexpensive. The gas-tight assembly module of sealing member and sensor element is produced in a pre-assembly stage.

To install the mounting module directly on the sample gas tube, a radial flange is integrally formed according to an advantageous embodiment of the invention on the sealing member on the one hand rests on an annular shoulder of a introduced into the sample gas tube, hollow cylindrical connector and on the other hand is covered with a metallic sealing ring on which a directed to the annular shoulder axial force acts, which is produced by means of a hollow screw.

The measures listed in the further claims advantageous refinements and improvements of the claim 1 gas sensor are possible.

According to an advantageous embodiment of the invention, the sealing member is a sintered ceramic body on the sensor element, which is preferably produced by injection molding. In this case, the ceramic body is prefabricated as a green compact with an axially continuous, preferably central longitudinal channel whose channel cross-section is dimensioned larger by a material shrinkage which occurs during sintering than the cross-section of the sensor element. The sintering process is then carried out with inserted into the longitudinal channel sensor element.

According to a preferred embodiment of the invention, the ceramic body has a

Inner ceramic component surrounding sensor element, which is easily flowing and soft, and an outer ceramic component enclosing the inner ceramic component, which has high strength and thermal shock resistance. This has the advantage that the inner ceramic component snugly and seamlessly adhere to the sensor element during sintering, so that a gas-tight connection between the ceramic body and the sensor element is formed. By the ceramic outer body sprayed on the inner ceramic component, the ceramic body has high strength and thermal shock resistance, so that it is sufficiently resistant to stone and water hammer. The manufacture of the seal body in a multi-component injection molding process is production-friendly and cost-effective.

According to an advantageous embodiment of the invention, the sealing member extends over the terminal-side end portion of the sensor element and has means for fixing electrical connection lines on the end portion of the sensor element. This design of the sealing body eliminates not only a separate contact holder for connecting the connecting lines to the sensor element, but is also a heat conduction or

Heat radiation from the hot housing to the terminals significantly reduced. Thereby the length of the gas sensor can be shortened and / or a use of the gas sensor in a higher temperature range possible.

The means for fixing the electrical connection lines can be designed in different ways. You can in the sealing member integrated spring elements that the

Press connection lines on the arranged in the terminal-side end portion of the sensor element electrical contact surfaces, or the contact surfaces releasing recesses, which are shaped so that the inserted into the recesses ends of the connecting lines are basically pressed on the recesses on the contact surfaces.

According to an advantageous embodiment of the invention, the ceramic body forming the sealing member has, in its region covering the connection-side end portion of the sensor element, a third ceramic component which has a high degree of toughness. The ceramic component with the high toughness ensures a sufficient elasticity of the ceramic body in the region of the contact surfaces of the sensor element.

According to an advantageous embodiment of the invention, the assembly module for installation in a connection piece on a sample gas tube leading the sample gas is set in a short, metallic mounting sleeve, which has a screw thread for screwing with the connection piece and a tool engagement surface for carrying out the screw assembly. The mounting sleeve can be designed as a hollow screw and the tool engagement surface may be formed as a key hexagon or elliptical or wavy key surface. Due to the short metallic mounting sleeve, which encloses preferably designed as a ceramic body with good thermal insulation properties sealing member in a small, practically limited to the installation area in the connector body region, the heat input of the reduced

Connecting piece on the hot sample gas tube to the end region of the ceramic body, in which the electrical contacting of the sensor element takes place. Thus, the advantages of the temperature reduction in the Kontaktierbereich of the sensor element achieved with the gas-tight obstruction of the sensor element in the thermally insulating ceramic body are not nullified by the subsequent obstruction of the gas sensor in the connection piece of the sample gas tube, but remain unrestricted. The temperature in the contact region of the sensor element can thus be kept relatively low overall and the cable outlet can be created in a less temperature-resistant, more cost-effective design. In an advantageous manner, the surface of the ceramic sealing member adjoining the mounting sleeve is kept as large as possible up to the contacting region, for which purpose the sealing member has a waisted shape in this region. By fixing the mounting sleeve on the mounting module, the volume of the preferably designed as a ceramic body sealing member can be reduced and the diameter the screw thread on the mounting sleeve thus the usual M 18 to M 14 can be reduced. The volume of construction is reduced, and material costs are saved. In addition, is completed by the permanently connected to the ceramic sealing member mounting sleeve of the gas sensor for installation on the sample gas tube, so that no additional mounting hardware is required, which are not captive in the uninstalled state and strike during transport and handling on the ceramic seal member and can damage this ,

According to an advantageous embodiment of the invention, the determination of the mounting module is made by pressing the sealing member in the mounting sleeve and then caulking the mounting sleeve, wherein preferably the caulking is carried out at a temperature between 400 ⁰ C to 800 ⁰ C. By these measures, the connection between the mounting sleeve and the sealing member is not solved when heating the gas sensor in the hot gas sample tube. A reduction in the caulking force occurring due to the different coefficients of thermal expansion of the mounting sleeve and the sealing member is not critical, since the actual holding position of the sealing member in the metal sleeve takes place via the compression.

According to an advantageous Ausführangsform of the invention, the compression takes place via a on the sealing member at the measuring gas side end portion of the sensor element end portion formed cone and a formed in the interior of the mounting sleeve counter cone, wherein the cone and counter cone are pressed together with their conical surfaces. Cone and counter-cone are designed so that due to self-locking a shaking of the compression is prevented by vibrations on the sample gas tube. For this purpose, cone and counter-cone are preferably designed such that the cone angles have an acute angle smaller than 15 °.

Brief description of the drawings

The invention is explained in more detail in the following description with reference to a Ausführangsbeispiels shown in the drawings. Show it:

1 shows a longitudinal section of a gas sensor with sensor housing and a mounting module built therein sensor element and sealing member,

2 is a perspective view of the mounting module of the gas sensor in Fig. 1,

3 is a bottom view of the mounting module in the direction of arrow III in Fig. 2, 4 shows a similar view as in FIG. 3 in the green state of the sealing member, FIG.

5 shows a half section of a gas sensor with a mounting module of sensor element and sealing element installed directly in the connection piece of a sample gas tube,

6 shows a same illustration of the gas sensor as in FIG. 5 with modified protective tube attachment, FIG.

7 shows an enlarged view of the detail VII in FIG. 5 with connecting leads mounted by means of a holder,

8 shows a detail of an end portion of the mounting module according to another

Embodiment in half section with mounted by means of a holder

Connecting cables,

9 is a plan view of the holder in Fig. 8,

10 is a view similar to FIG. 8 of the mounting module according to two further and eleven embodiments,

12 is a longitudinal section of a gas sensor according to another embodiment,

13 shows a detail of a half section of the gas sensor in FIG. 12 with a modified connection between the mounting module and the mounting sleeve, FIG.

14 is a half section of the mounting sleeve in Fig. 13 with attached caulking,

Fig. 15 are each a same view as in Fig. 13 with further modifications of the connection and 16 düng between mounting module and mounting sleeve.

Embodiments of the invention

The gas sensor shown in section in FIG. 1 with a sensor element 11 for determining a physical property of a measuring gas serves, for example, for determining the oxygen concentration in the exhaust gas of an internal combustion engine. With another conceptual design of the sensor element, the gas sensor can also be used for determining the concentration of nitrogen oxides in the exhaust gas or for measuring the temperature of the exhaust gas. The gas sensor has a rotationally symmetrical metallic housing 10 in which the planar sensor element 11 which is rod-shaped in the exemplary embodiment is guided. In this case, the sensor element 11 emerges from the housing 10 with a measuring-gas-side end section 111 and a connection-side end section 112 on end faces of the housing 10 facing away from one another. The test gas exposable measuring gas end portion 111 carries gas-sensitive in a known manner

Electrodes and is covered with a protective tube 13. Of the gas-sensitive electrodes, a so-called outer electrode 12 arranged on the surface of the sensor element 11 is indicated schematically in FIGS. 1 and 2. The protective tube 13 is provided with Gasdurchtrittsöffhungen 14 through which the sample gas or exhaust gas can reach the sensor element 11. The protective tube 13 is fixedly connected to the housing 10, wherein in the illustrated embodiment, the protective tube 11 is integral with the housing 10. For installation of the gas sensor in a not shown here, the sample gas leading sample gas tube

- In an exhaust pipe leading the exhaust pipe of an internal combustion engine or an internal combustion engine - the housing 10 is provided with a mounting winch 15 and a mounting hexagon 16. A sealing member 17 located in the housing 10 encloses the sensor element 11 in sections and seals it against the housing 10, so that no measuring gas can reach the connection side of the gas sensor from the side of the measuring gas. The connection-side end portion 112 of the sensor element 11 carries in a known manner contact surfaces, which serve for connecting the gas sensor to an evaluation. Of the contact surfaces are in Fig. 1, two contact surfaces 18, 19 indicated schematically. The contact surfaces are connected via conductor tracks, not shown here with the electrodes in the measuring gas side end portion 111.

For a simplified assembly, the sealing member 17 is gas-tightly connected in a pre-assembly stage with the sensor element 11 to a mounting module 30 (FIG. 2), which is axially inserted into the housing 10 and fixed gas-tight therein. The sealing member 17 is a rotationally symmetrical

Ceramic body 20 which is produced as an injection molded part by injection molding and sintered onto the sensor element 11, so that a solid, gap and gap-free, gas-tight connection between the sensor element 11 and the ceramic body 20 is made. In this case, the ceramic body 20 encloses the portion of the sensor element 11 which is inserted in the housing 10 and extends with a body portion reduced in diameter over the measuring gas side end portion 111 of the sensor element 11 protruding from the housing 10. In the area of the contact surfaces 18, 19 of the sensor element 11, the ceramic body 20 integrated spring elements 21, 22 are formed, which serve for clamping connection leads to the contact surfaces 18, 19 of the sensor element 11. The number of formed, integrated spring elements 21, 22 corresponds to the number of existing contact surfaces 18, 19 on the sensor element 11. The ceramic body 20 is produced in a multi-component injection molding of two or optionally three ceramic components (FIGS. 2 and 3). An inner ceramic component 201 that immediately surrounds the sensor element 11 is soft and light fluently. An outer component 202 enclosing the inner ceramic component 201 has high strength and thermal shock resistance. An optional third ceramic component 203 (FIG. 2) provided in the region covering the terminal-side end portion 112 of the sensor element 11 has a high toughness. The ceramic body 20 produced from these two or three ceramic components in the multi-component injection molding process as green body 23 is provided with a central, axially continuous longitudinal channel 24 (FIG. 4). The rectangular in cross-section to the rod-shaped, planar sensor element 11 channel cross-section of the longitudinal channel 24 is dimensioned by a material shrinkage during sintering larger than the cross section of the sensor element 11, so that after insertion of the sensor element 11 in the longitudinal channel 24, a circumferential gap 25 between the sensor element 11th and green body 23 remains, as shown in Fig. 4. By sintering, to which the sensor element 11 and the green element 23 pushed onto the sensor element 11 are exposed together, the inner ceramic component 201 shrinks onto the sensor element 11 and snuggles against the sensor element 11 in a gap-free and gapless manner (FIG. 3) that the mounting module 30 is gas-tight. The outer ceramic component 202 gives the ceramic body 20 a sufficiently high resistance to stone and water hammer and the toughness of the third ceramic component 203 ensures a damage-free clamping of the connection conductors on the contact surfaces 18, 19 by the ceramic body 20 formed on the spring elements 21, 22 with sufficiently high pressure ,

To seal the ceramic body 20 relative to the housing 10, two flanks 26, 27 are formed on the ceramic body 20 at an axial distance from each other, which rotate on the ceramic body 20 and may have a flat, a concave or a convex contour (FIGS. 1 and 2). The one flank 26 is formed on the end face of the ceramic body 20 which is close to the measuring gas side end portion 111, and the other flank 27 on the transition to the reduced diameter body portion, which surrounds the connection-side end portion 112 of the sensor element 11. The flank 26 is in a form-fitting manner on an annular shoulder 28 formed in the housing 10. The other flank 27 is overlapped by a circumferential second shoulder 29 of the housing 10 such that on the one hand the flank 26 and the shoulder 28 and on the other hand the flank 27 and the shoulder 29 are pressed gas-tight. This axial strain of the ceramic body 20 between the shoulders 28, 29 in the housing 10 is achieved in that after insertion of the mounting module 30 of ceramic body 20 and sensor element 11 in the housing 10 such that the flank 26 is positively supported on the shoulder 28, the Housing 10 in the region of the second edge 27 of the ceramic body 20, ie at the housing end, is locally heated, for example by inductive heating, and the housing 10 is compressed in the heated area. Thus, the self-gas-tight mounting module 30 is also gas-tight in the housing 10 in a simple assembly process. In the case of the gas sensor shown in half section in FIG. 5, a housing is dispensed with and the assembly module 30 consisting of the sensor element 11 and the sealing member 17 'sintered as ceramic body 20 is installed directly in a measuring gas tube 31 carrying the measuring gas. The elimination of the metallic housing not only means a manufacturing advantage, but also reduces the heat absorption of the sample gas tube 31. To install the gas sensor, the sample gas pipe 31 has a measuring opening 32 which is enclosed by a hollow cylindrical connecting piece 33. In the illustrated embodiment of FIG. 5, the connecting piece 33 is designed in one piece with the sample gas pipe 31. However, the connecting piece 33 can also be used as a separate component in the measuring opening 32 and welded to the pipe wall of the sample gas pipe 31. The mounting module 30 is inserted into the connecting piece 33 such that the measuring gas side end portion 111 of the sensor element 11 projects into the interior of the sample gas pipe 31. The partially received in the connector 33 sealing member 17 'is sealed against the inner wall of the connecting piece 33. For this purpose, a radial flange 34 is integrally formed on the sealing member 17 'and ceramic body 20 having a the connection-side end portion 112 of the sensor element 11 facing radial edge 341, which is perpendicular to the sealing member axis, and facing away from it, the measuring gas side end portion 111 facing oblique edge 342 , which is cone-shaped. The connecting piece 33 has a peripheral annular shoulder 35 upstream of the measuring opening 32, which is adapted to the inclined flank 342 of the radial flange 34 and thus has a funnel-shaped form. When inserted into the connector 33 mounting module 30, the seal member 17 'is located on the inclined shoulder 342 of the radial flange 34 on the annular shoulder 35 and protrudes with a protruding into the interior of the sample gas pipe 31 inside. On the radial edge 341, a metallic sealing ring 36 is placed. A sealing member 17 'surrounding hollow screw 37 which is bolted to an external thread 38 in a formed on the connector 33 female thread 39, presses with its annular end face the sealing ring 36 on the radial edge 341 on the radial flange 34 and presses the radial flange 34 with the

Oblique flank 342 against the annular shoulder 35 on the connecting piece 33. In its protruding into the sample gas tube 31 above the sealing member 17 'carries a circumferential groove 40. A projecting into the sample gas tube 31 measuring gas side end portion 111 of the sensor element 11 enclosing protective tube 41 is with its protective tube end in the Grooved 40 into it.

In order to clamp the electrical connection conductors to the electrical contact surfaces 18, 19 arranged at the connection-side end section 112 of the sensor element 11, a central recess 42 is introduced into the sealing element 17 'from its end remote from the measurement gas, releasing the contact surfaces 18, 19 and thus forming them is that after insertion of the connecting conductor into the recess 42, the connecting conductors are pressed in the base of the recess 42 on the contact surfaces 18, 19. Of the contact surfaces 18, 19, only the one contact surface 18 on the one large surface of the sensor element 11 can be seen in FIG. 5. The contact surface 19 is located on the thereof In addition, a locking receptacle for a connecting leads holding holder is provided, which is designed in the embodiment of FIGS. 5 and 6 as a circumferential locking groove 43. Holder and connecting lines are illustrated in the detail VII in FIG. 5 enlarged in FIG. 7 and are described in detail below.

The gas sensor shown in half section in Fig. 6 is substantially the same structure as the gas sensor described in Fig. 5, so that the same components are provided with the same reference numerals. The gas sensor in FIG. 6 differs only in the connection of the protective tube 41 to the sealing member 17 '. The protective tube 41 is not crimped as in Fig. 5 to the sealing member 17 ', but tightened by the axial contact pressure of the union nut 37 between the oblique shoulder 342 on the radial flange 34 of the sealing member 17' and formed on the connector 33 annular shoulder 35.

In FIG. 7, the detail VII in FIG. 5 is enlarged and supplemented by the connection lines 44 fixed to the contact surfaces 18, 19 at the connection-side end section 112. The leads 44 are spaced from a holder 46 made of a temperature resistant thermoplastic or thermoset, spaced from its line end, e.g. by injecting the holder 46 to the connecting line 44, taken. The cable ends are formed to contact eyelets 45. The holder 46 is formed so that it engages over the front side of the sealing member 17 'on its outer circumference and in the latching groove 43 there existing can be clipped. If the holder 46 is mounted on the front side of the sealing member 17 'and pressed on the sealing member 17' so far that it snaps with its outer edge in the locking groove 43, the contact lugs 45 are inserted so far on the connecting lines 44 in the recess 43 that they are between the contact surfaces 18, 19 and the sealing member 17 'are clamped.

8, the sealing member 17 'projects beyond the connection-side end portion 112 of the sensor element 11 and has a locking receptacle 47 for a holder 47 in the Überstehbereich the still existing recess 42 arranged upstream locking groove 48 for clipping of the holder 47. The holder 47, which can be seen in plan view in FIG. 9, in turn grips the connection conductors 44 at a distance from their line end, and the line ends are in turn formed into contact loops 45. The holder 47 has two diametrically arranged spring elements 49 which engage in the latching groove 48 on the sealing member 17 '. If the holder 47 is locked in the latching groove 48, the contact lugs 45 are clamped in the recess 42 between the contact surfaces 18, 19 and the sealing member 17 ', so that a good electrical connection between connecting conductors 44 and contact surfaces 18, 19 is ensured. This embodiment of the electrical connection between connecting conductors 44 and contact surfaces 18, 19 has over the structural design shown in Fig. 7, the advantage that the contact surfaces 18, 19 better shielded against water and stone chips and the holder 47 in the case of the arrangement of the gas sensor in the exhaust pipe of an internal combustion engine better against the influence of temperature the exhaust pipe is protected.

In the modified mounting module 30 illustrated in detail in FIG. 10 in its connection-side end region, the sealing member 17 ', which in turn is provided with a recess 42, protrudes beyond the connection-side end portion 112 of the sensor element 11 and has a recess 42 for locking a conical holder 50 adjoining, to the end of the sealing member 17 'toward widening funnel 51, which has an adapted to the cone of the holder 50 funnel opening. The holder 50 is in turn molded onto the connection lines 44 at a distance from the conductor ends, and the conductor ends of the connection lines 44 are in turn formed as contact eyelets 45. If the holder 50 is inserted with its cone in the hopper 51, the contact lugs 45 are clamped in the recess 42, while the holder 50 is fixed on the Konuspassung. In this embodiment of locking receptacles on the sealing member 17 'and holder 50 accounts for both spring elements and undercuts in the ceramic body 20 for obtaining the locking groove 43, as in the embodiment of FIGS. 8 and 9 is present.

In the case of the modified assembly module 30 illustrated in half section in FIG. 11, the sealing member 17 'designed as a ceramic body 20 is configured identically as in FIG. 8, with the difference that the contact surfaces 18, 19 release on the connection-side end portion 112 of the sensor element 11 Recess 42 'has a larger clear diameter. The locking receptacle for a holder 52 is arranged on the inner wall of the protruding region of the sealing member 17 'in turn as a recess 42' upstream locking groove 48. The molded onto the connecting lines 44 holder 52 has axial projecting webs 521, from each of which a spring element 53 protrudes from electrically conductive material and is directed radially inwardly towards the end portion 112 of the sensor element 11. The spring elements 53 are injected into the holder 52 and each contacted with one of the overmolded connecting lines 44. The holder 52, like the holder 47 in FIGS. 8 and 9, has two spring webs 54 which lock the holder 52 snapped into the annular groove 48 and inserted into the recess 42 'with the webs 521 against axial withdrawal from the sealing member 17'. Alternatively, the spring elements 53 connected to the line ends of the connection lines 44 are not injected into the holder 52 but are inserted into the holder composed of two half-shells and clamped between the half-shells.

The gas sensor shown as a further exemplary embodiment in FIG. 12 in turn has the mounting module 30, which in a pre-assembly stage consists of the connection of sensor element 11 and The sealing member 17 "is in turn a rotationally symmetrical ceramic body 20, which is produced as an injection molded part by injection molding and sintered onto the sensor element 11, so that a solid, gap and gap-free, gas-tight connection between the sensor element 11 and the ceramic body 20 exists. The ceramic body 20 in turn extends over the entire sensor element 11 with the exception of the measuring gas auszusetzenden, measuring gas side end portion 111. The ceramic body 20 is in turn made in a multi-component injection molding of the two ceramic components 201 and 202, wherein the inner, immediately the sensor element 11th surrounding ceramic component 201 ensures sufficient electrical insulation and the outer ceramic component 202 enclosing the inner ceramic component 201 offers high mechanical strength for protection against assembly forces, stone chipping and thermal shock.

The measuring gas side end portion 111 of the sensor element 11 facing the end portion of the ceramic body 20 is designed as a cone 55 which tapers towards the end of the ceramic body 20 and at the tapered cone end via radially extending shoulders 56, for example, a circumferential radial shoulder 56, to the outer diameter of the Ceramic body 20 drops. The cone 55 is designed so that its cone angle is an acute angle less than 15 °.

In order to contact the sensor element 11 with the contact surfaces 18, 19 carried by the connection-side end section 112, recesses 42 are again provided in the end section of the ceramic body 20 facing away from the cone 55, which recesses are introduced from the free front end of the ceramic body 20. In each recess 42 locking grooves 48 are provided in the contact surface 18 and 19 opposite wall of the ceramic body 20. In each recess 42, a contact spring 57 is inserted. Each contact spring 57 is designed to be U-shaped at the end and engages with its free spring leg in the latching groove 48, so that the contact spring 57 is secured against removal. Due to the spring tension between the two U-legs, the other spring leg presses against the contact surface 18 or 19. At its end remote from the U-shaped end, each contact spring 57 is electrically and mechanically firmly connected to a connecting line 44. The junction of the contact spring 57 and connecting cable 44 are located in a contact spring holder 58 made of temperature-resistant plastic, which is placed on the front side of the ceramic body 20 and held by means of a crimped on the ceramic body 20 cuff 59. The intermediate region between the cone 55 and the end portion of the ceramic body 20 covering the contacting region of the sensor element 11 is designed to be waisted in order to enlarge the body surface. Alternatively, instead of a sidecut, a rib structure or a simple rectangular geometry can be provided. For the obstruction of the gas sensor in a connecting piece of a sample gas tube, as the latter is shown for example in FIGS. 5 and 6, the mounting module 30 is fixed in a short, metallic mounting sleeve 60. The mounting sleeve 60 has a screw thread 61 and a Werkzeugangrifffläche 62. The latter can be designed, for example, as a key hexagon, as shown in FIGS. 12 to 16, or as an elliptical or wavy key surface. The fixing of the mounting module 30 is effected by pressing the sealing member 17 "forming ceramic body 20 in the mounting sleeve 60 and then caulking the mounting sleeve 60. For this purpose, the mounting sleeve 60 adapted to the cone 55 of the ceramic body 20 counter-cone 63, which has a same cone angle Like the cone 55 on the ceramic body 20, so that when inserting the mounting module 30 in the mounting sleeve 60 cone 55 and counter cone 63 are flush with each other.For fixing the mounting module 30 in the mounting sleeve 60 of the ceramic body 20 is first pressed in the mounting sleeve 60, wherein the Cone 55 is inserted deeper into the counter-cone 63. Subsequently, the mounting sleeve 30 is caulked on the ceramic body 20, whereby caulked lugs 64 are formed, which press on the shoulder 56 formed on the ceramic body 20 at the end of the cone 55. The caulking preferably takes place at elevated temperatures between 400 ⁰ C and 800 ⁰ C, d amit when heating the gas sensor in the hot sample gas tube, the caulking is not solved. A resulting from the different coefficients of thermal expansion of ceramic body 20 and metallic mounting sleeve 60 reduction of Verstemmkraft is not critical, since the actual fixing of the mounting module 30 in the mounting sleeve 60 via cone 55 and counter-cone 63 takes place. At the

Mounting sleeve 60, the protective tube 41 is fixed, which is formed in the embodiment of FIG. 12 by a double protective tube, consisting of an inner protective tube 411 and an outer protective tube 412, which are arranged concentrically to the sensor element 11 and the measuring gas side end portion 111 of the sensor element 11 overlap. The double protection tube has in a known manner Gasdurchtrittsöffhungen 14, through which the sample gas reaches the measuring gas side end portion 111 of the sensor element 11.

In the detail shown in Fig. 13, compared to Fig. 12 modified gas sensor cone 55 on the ceramic body 20 and counter-cone 63 in the mounting sleeve 60 with respect to FIG. 12 carried out in opposite directions, ie the cone 55 on the ceramic body 20 takes the messgasseitigen end of the ceramic body 20 steadily to. Correspondingly, the counter-cone 63 in the interior of the mounting sleeve 60 widens, the cone angle being kept smaller than 15 °. The caulking of the mounting sleeve 60 after pressing of ceramic body 20 and mounting sleeve 60 via cone 55 and counter-cone 63 is then carried out on the free end face of the ceramic body 20 with splitting off of lugs 64 of an integrally formed on the mounting sleeve 60 annular web 66, which then at the front of the Ceramic body 20 abut. In Fig. 14, the mounting sleeve 60 is shown in front of its assembly in the mounting module 30 in half section. In addition, a caulking tool 65 is sketched in half section, which attaches to the integrally formed on the mounting sleeve 60 annular web 66 and from this the caulked nose 64 is separated and folded over to the end face of the ceramic body 20, as shown in Fig. 13.

In the two in Fig. 15 and 16 in half section partially shown gas sensors is dispensed with the formation of a counter-cone 63 in the mounting sleeve 60 and the counter-cone 63 formed on a clamping ring 67 which is inserted between the cone 55 on the ceramic body 20 and the mounting sleeve 60 , In the embodiment of FIG. 15, the cone 55 is formed so that it tapers towards the measuring gas side end of the ceramic body 20, while in

Embodiment of FIG. 16, the cone 55 is designed so that it widens steadily in diameter to the measuring gas side end of the ceramic body 20 out. The caulked lugs 64 are in the embodiment of FIG. 15 on the clamping ring 67 and in the embodiment of FIG. 16 aufgestemmt on the free end face of the ceramic body 20. The caulked lugs 64 are, as described above, in turn bent from the integrally formed on the mounting sleeve 60 annular web 66.

Claims

claims

1. A gas sensor for determining a physical property of a measurement gas, in particular the concentration of a gas component or the temperature of the measurement gas, comprising a sensor element (11) which exposes the measurement gas exposing the measurement gas side end portion (111) and a connection-side end portion (112) for covering with electrical Connecting lines (44), and with a sensor element (11) enclosing seal member (17; 17 ') for measuring gas-tight separation of the measuring gas and the connection-side end portion (111, 112) of the sensor element (11), characterized in that the sealing member ( 17, 17 ') is connected in a gas-tight manner to the sensor element (11) to form an assembly module (30).

2. Gas sensor according to claim 1, characterized in that the mounting module (30) in one

Housing (10) with axially from the housing (10) protruding end portions (111, 112) installed and the sealing member (17) is sealed axially against the housing (10).

3. Gas sensor according to claim 2, characterized in that for the axial sealing on the sealing member (17) has two mutually axially spaced flanks (26, 27) are formed on the housing (10) formed, mutually facing shoulders (28, 29) rest gas-tight.

4. Gas sensor according to claim 3, characterized in that the flanks (26, 27) of the sealing member (17) and the shoulders (28, 29) of the housing (10) are flat or curved and lie without a gap on each other.

5. Gas sensor according to claim 4, characterized in that the said measuring gas side end portion (111) of the sensor element (11) facing flank (26) of the sealing member (17) on a in the housing (10) elaborated shoulder (28) is applied and that by upsetting in the region of the flank (27) of the sealing member (17), which is the connection-side end portion (112) of the sensor element (11) facing locally heated housing (10) the other shoulder (29) on the housing (10) formed and the gas-tight Seal between the flanks (26, 27) and the shoulders (28, 29) is made.

6. Gas sensor according to claim 5, characterized in that the connection-side end portion (112) of the sensor element (11) facing flank (27) of the sealing member (17) with little

Axial distance within the housing (11) near the housing end lies.

7. Gas sensor according to claim 1, characterized in that the mounting module (30) in a connecting piece (33) is installed, which encloses a Meßöffhung (32) in a measuring gas measuring gas tube (31) and that the sealing member (17 ') against the Inner wall of the connecting piece (33) is sealed.

8. Gas sensor according to claim 7, characterized in that on the sealing member (17 '), a radial flange (34) is formed, on the one hand on a measuring opening (32) enclosing, on the connecting piece (32) formed annular shoulder (35) and on the other on its facing away from the flange side with a preferably metallic sealing ring (36) is occupied, acts on the one to the annular shoulder (35) on the connecting piece (33) directed biasing force.

9. Gas sensor according to claim 8, characterized in that the biasing force of a sealing member (17 ') comprising hollow screw (37) is applied, which is screwed with an external thread (38) in a connection piece (33) formed internal thread (39) and with its annular end face aufbresst on the sealing ring (36).

10. Gas sensor according to claim 8 or 9, characterized in that the connecting piece (33) formed annular shoulder (35) on and on the annular shoulder (35) flat flange side of the radial flange (34) are each cone-shaped.

11. Gas sensor according to one of claims 8 to 10, characterized in that between the formed on the connecting piece (33) annular shoulder (35) and the radial flange (34) has an end portion of the measuring gas side end portion (111) of the sensor element (11) covering the protective tube ( 41) is clamped.

12. Gas sensor according to one of claims 8 to 10, characterized in that the sealing member (17 ') in its the measuring gas side end portion (111) of the sensor element (11) lying near a circumferential groove (40) for flaring the edge of the measured gas side End section (111) of the sensor element (11) overlapping protective tube (41).

13. Gas sensor according to claim 1, characterized in that the mounting module (30) is fixed for installation in a connection piece on a sample gas tube leading the sample gas in a short, metallic mounting sleeve (60) having a screw thread (61) for screwing with the connection piece and a tool engagement surface (62), preferably a key hex.

14. Gas sensor according to claim 13, characterized in that the fixing of the mounting module (30) by pressing the sealing member (17 ") in the mounting sleeve (60) and then caulking the mounting sleeve (60), preferably at a temperature between 400 ⁰ C to 800 ⁰ C, is made.

15. Gas sensor according to claim 14, characterized in that the measuring gas side end portion (111) of the sensor element (11) facing the end portion of the sealing member (17 ") is formed as a cone (55) which is pressed in a counter-cone (63), and the countercone (63) is arranged on the front end of the mounting sleeve (60) facing the measuring gas side end section (111) of the sensor element (11).

16. Gas sensor according to claim 15, characterized in that the cone angle of cone (55) and counter-cone (63) is less than 15 °.

17. Gas sensor according to claim 15 or 16, characterized in that the counter-cone (63) is formed directly on the inner wall of the mounting sleeve (60).

18. Gas sensor according to claim 15 or 16, characterized in that the counter-cone (63) on the inner surface of a clamping ring (67) is formed, which is arranged between the cylindrical inner wall of the mounting sleeve (60) and the sealing member (17).

19. Gas sensor according to one of claims 15 to 18, characterized in that the sealing member (17) in front of or behind the cone (55) has a circumferential radial shoulder (56) is provided, on which the mounting sleeve (60) is clamped.

20. Gas sensor according to claim 18, characterized in that the cone (55) on the sealing member (17 ") to the measuring gas side end portion (111) of the sensor element (11) facing the end of the sealing member (17") tapers and that the mounting sleeve (60) is clamped on the end face of the clamping ring (67).

21. Gas sensor according to one of claims 13 to 20, characterized in that attached to the mounting sleeve (60) at least one the measuring gas side end portion (111) of the sensor element (11) covering the protective tube (411, 412), preferably welded, is.

22. Gas sensor according to one of claims 1 to 21, characterized in that the sealing member (17, 17 ') extends over the connection-side end portion (112) of the sensor element (11) and Has fixing means for fixing the electrical connection lines (44) on the end portion (112).

23. Gas sensor according to claim 22, characterized in that the fixing means in the sealing member (17) integrated spring elements (21, 21) for clamping the connecting lines (44) on the connection-side end portion (112) of the sensor element (11) arranged contact surfaces (18 , 19).

24. Gas sensor according to claim 22, characterized in that the fixing means in the end region of the sealing member (17 ') formed recess (42) which is open towards the free end of the sealing member (17') and at the connection-side end portion (112) and the contact elements (18, 19) arranged on the sensor element (11) have a locking receptacle for a holder (46; 47; 50; 52) holding the connection lines (44) at a distance from their line ends, and in that the recess (42; In the case of holders (46; 47; 50; 52) inserted in the arresting receptacle, the line ends of the connecting conductors (44) are pressed onto the contact surfaces (18, 19) at the bottom of the recess (42; 42 ').

25. Gas sensor according to claim 24, characterized in that the arresting receptacle is arranged in the outer jacket of the sealing member (17 ') near its free end, circumferential latching groove (43) into which the holder (46) is snapped with its outer edge.

26. Gas sensor according to claim 24, characterized in that the sealing member (17 ') projects beyond the connection-side end section (112) of the sensor element (11) and the locking receptacle is formed by at least one latching groove (48) arranged in the upstream region of the recess (42) is, in which the holder (47) is snapped with at least one spring element (49).

27. Gas sensor according to claim 24, characterized in that the sealing member (17 ') projects beyond the connection-side end portion (112) of the sensor element (11) and the locking receptacle of a at the recess (42) adjoining, to the end of the sealing member (17 ') opening funnel (51) is formed, in which the holder (50) can be pressed with a cone adapted to the cone shape.

28. Gas sensor according to one of claims 24 to 27, characterized in that in the recess (42) dipping line ends of the connecting lines (44) are formed to contact eyelets (45).

29. A gas sensor according to claim 26, characterized in that in the recess (42 ') dipping line ends of the connecting lines (44) are provided with spring contacts (53) in a with in the recess (42') dipping retaining projection (521) are arranged.

30. Gas sensor according to one of claims 1 to 29, characterized in that the sealing member (17; 17 '; 17 ") is a sintered on the sensor element (11) ceramic body (20), which is preferably an injection molded part.

31. Gas sensor according to claim 30, characterized in that the ceramic body (20) enclosing the sensor element (11), inner ceramic component (201), which is soft and easy flowing, and an inner ceramic component (201) enclosing outer ceramic component (202 ) having high strength and thermal shock resistance.

32. A gas sensor according to claim 31, characterized in that the ceramic body (20) in its over the terminal-side end portion (111) of the sensor element (11) extending portion has a third ceramic component (203) which has a high toughness.

33. Gas sensor according to claim 31 or 32, characterized in that the ceramic body (20) is a multi-component injection molded part.

34. Gas sensor according to one of claims 30 to 33, characterized in that the ceramic body (20) is prefabricated as a green compact (23) with an axially continuous, preferably central longitudinal channel (24) whose channel cross-section is dimensioned larger by a material shrinkage which occurs during sintering as the cross-section of the sensor element (11), and that the sintering is carried out with in the longitudinal channel (24) inserted sensor element (11).