EP1407256A2

EP1407256A2 - Gas sensor

Info

Publication number: EP1407256A2
Application number: EP02748608A
Authority: EP
Inventors: Helmut Weyl; Juergen Wilde; Dirk Bluemmel; Andreas Pesch
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2001-07-06
Filing date: 2002-07-04
Publication date: 2004-04-14
Also published as: KR100927809B1; WO2003005009A3; US7191640B2; KR20030023773A; JP2004521361A; JP4411065B2; WO2003005009A2; US20040025565A1; DE10132826C1

Abstract

Electrical connecting lines of a sensor element are held in a non-positive manner and, to be precise, are held by a annularly closed spring element, which tensions the connecting lines against contact surfaces on the sensor element by means of pressure bodies.

Description

gas sensor

State of the art

The invention relates to a gas sensor for detecting a parameter of a gas component, in particular a lambda probe, with a sensor element, a contact surface arranged on the outside thereof and a connecting line electrically connected therewith, which by means of a spring element encompassing the sensor element between the contact surface and one of the spring element against the pressure element clamped under tension is clamped.

The electrodes of a lambda probe or another gas sensor must be electrically connected to connecting lines via which the electrodes are electrically connected to the input side of an electronic evaluation circuit or an electronic motor control of an internal combustion engine to which the gas sensor or the lambda probe is assigned are. In this case, clamping connections are often preferred between the connecting lines and the contact surfaces arranged on the sensor element, as are known, for example, from EP 0 506 897 B1. When arranged in an exhaust pipe of an internal combustion engine, gas sensors or lambda probes are exposed to extremely high temperatures of up to 1,200 ° C. It is therefore essential to design the spring elements that maintain the frictional connection to be temperature-insensitive.

Advantages of the invention

According to the invention, it is provided that the spring element is closed in a ring and to be arranged with a preload which is retained even when the temperature rises sharply.

Due to the ring-shaped closed configuration, particularly high prestresses can be permitted, so that sufficient clamping forces remain even at high temperatures.

According to a first embodiment, the spring element can be designed as a sleeve-like ring which presses the pressure element against the sensor element in the manner of a tension ring, the spring element being shrunk onto the pressure element and / or being pushed onto a cone-shaped section formed by the pressure element with great force. In this way, a heavy-duty press fit is created.

According to a further preferred embodiment of the invention, the spring element has at least one spring section which, in the clamped state, is deformed in one direction with an essential component parallel to the longitudinal axis of the sensor element. In this embodiment, particularly simple contacting of the sensor element and simple assembly are possible. A special embodiment with two approximately diametrically opposite first spring sections and at least two diametrically opposite further spring sections is particularly advantageous, the first spring sections defining a virtual plane curved with respect to a radial axis of the annular spring element and the further spring sections between the first spring sections on or in front the convex side of the curved surface are arranged.

With this spring element, in which the transition areas between the first and the further spring sections are subjected to torsion, a large effective spring length is achieved, with the result that the spring characteristic is comparatively flat and a well reproducible clamping force is ensured. In addition, temperature fluctuations have only a slight influence on the clamping force, because an expansion of the first spring sections can be largely compensated for by an expansion of the further spring sections.

The annularly closed spring elements are preferably designed such that they act on the pressure bodies with radially inwardly directed regions (tongues). In such a configuration of the spring elements, counteracting size changes occur on the spring element when the temperature rises, in that on the one hand the outer diameter of the spring element and on the other hand the radial length of the radially inwardly directed regions increases.

Such spring elements can be designed in a particularly advantageous manner as stamped parts. The pressure elements are preferably designed such that the tension of the spring element is inevitably increased when the spring element is displaced from one axial end of the pressure elements on the pressure elements in the direction of the other axial ends.

In a particularly expedient embodiment of the invention it is provided that the pressure bodies are already held together under spring tension when the spring element is pushed onto one axial end.

In addition, in this position of the spring element, the mutually facing sides of the pressure elements can form a mouth open to the other axial ends of the pressure elements for inserting the sensor element, which then moves with great force between the pressure elements when the spring element is displaced towards the other axial ends of the pressure elements is held.

drawing

The invention is described in more detail below with reference to the drawing, in which particularly preferred embodiments are shown. Show

Fig. 1 shows a longitudinal section of an inventive

Gas sensor, Fig. 2 is a sectional view corresponding to the cutting line

II-II in Fig. 1, Fig. 3 shows a modified embodiment of the

Detail III in Fig. 1, Fig. 4 is a perspective view of an advantageous spring element with associated

pressure bodies, 5 shows an illustration corresponding to FIG. 3 of an arrangement with a spring element and pressure elements according to FIG. 4, FIG. 6 shows a further advantageous spring element, FIG. 7 shows a further modified spring element, FIG. 8 shows a particularly advantageous spring element and

9 to 14 different views of a pressure body for the spring element of FIG. 8th

In Fig. 1, a longitudinal section of a gas sensor 1 is shown schematically. This has a housing which essentially consists of a protective gas pipe 3 on the measuring gas side provided with openings 2, a central sleeve part 4 and a pipe part 5. These parts are firmly connected to one another, for example by welding.

Within the sleeve part 4, two ceramic molded parts 6 and 7 are arranged, between which a ceramic sealing element 8 is accommodated, which prevents gas passage from the interior of the protective tube 3 to the interior of the tube part 5. The ceramic molded parts 6 and 7 hold a ceramic sensor element 9 passing through the sealing element 8 and the ceramic molded parts 6 and 7, the lower end of which in FIG. 1 is designed in a generally known manner as a lambda probe, the electrodes of which are housed in the sensor element 9 via electrical electrodes, not shown Conductor tracks with contact surfaces 10 arranged on the body of the sensor element 9 at its other end are electrically connected.

These contact surfaces 10 are electrically connected

Connected to connecting lines 11, which pass through a sealing disc 12 which closes the upper end of the tubular part 5 and is held in the sealing disc 12 and is made of electrically insulating material. The electrical contact between the contact surfaces 10 and the connecting lines 11 is maintained in that the connecting lines 11 by means of ceramic pressure bodies

13 are pressed against the contact surfaces 10. For this purpose, the pressure bodies 13, which according to FIG. 2 together have an approximately circular cross section, are within a spring element designed as a clamping ring

14 arranged, which includes the pressure body 13 with great bias and tensions against the facing sides of the sensor element 9. Accordingly, the connecting lines 11 are non-positively held between a respective pressure body 13 and the associated contact surface 10 in electrical connection with the respective contact surface 10.

In addition, the connecting lines 11 can be glued to the sensor element 9 and / or welded to the respective contact surfaces 10.

According to a preferred embodiment of the invention, the tension ring-like spring element 14 can be shrunk onto the pressure body 13. For this purpose, the spring element 14 is manufactured with an undersize with respect to the cross section of the pressure body 13 and the sensor element 9 connected between them and sufficiently expanded by strong heating, utilizing the associated thermal expansion of the steel material forming the spring element 14, so that the spring element 14 after the sensor element 9 has been interposed and the connecting lines 11 between the pressure body 13 can be pushed axially onto the pressure body 13.

Instead, it is also possible and advantageous to conically design the outer circumference of the pressure bodies 13 according to FIG. 3 and the inner circumference of the tension ring-like one To form the spring element 14 accordingly as an inner cone, so that the spring element 14 can be pushed onto the pressure body 13 with increasing tension and can be held thereon by self-locking.

In the embodiment of FIGS. 4 and 5, the spring element 14 is an annular, closed, stamped disk part with an essentially H-shaped opening in cross section, in such a way that inwardly directed tabs 15 are formed on the disk-shaped spring element. These tabs 15 engage in axial channels 16 which are formed on the outer sides of the pressure bodies 13. The bottoms of the channels 16 can be designed as inclined ramps which rise from the left ends of the pressure elements 13 in FIG. 5 to their right ends.

If the disk-shaped spring element 14 according to FIG. 5 is increasingly pushed axially in the direction of the slope of the aforementioned ramps onto the pressure bodies 13, the tabs 15 are bent away against the direction of the pushing open. At the same time, the disc-shaped spring element 14 bulges, the concave side of the curved disc pointing in the direction of being pushed open. As a result, the areas of the disk-shaped spring element 14 connecting the tabs 15 to one another form first spring sections 14 ^x , while the tabs 15 form further spring sections 14 ' ^% , the disk areas between the spring sections 14' and 14 ^{λ x being} subjected to torsion. The free ends of the tabs 15 seated on the bottoms of the channels 16 lie in front of the convex side of the curvature formed by the disk-shaped spring element 14.

With appropriate dimensioning of the tabs 15 and the thickness of the disk-shaped spring element 14, which in turn is made of a spring steel material, for example Inconell, the pressing bodies 13 are pressed against the sensor element 9 with high pressing forces, so that the connecting lines 11 are in turn securely held on the associated contact surfaces 10 by frictional engagement, cf. Fig. 5.

Optionally, to increase the pressing forces, there is the possibility of pushing a plurality of disc-shaped spring elements 14 onto the pressure body 13.

Radial extensions 17 can be provided on the outer circumference of the disk-shaped spring element 14, which are preferably arranged transversely to the tabs 15 and are able to support the spring element 14 with elastic bending on the inner circumferential wall of the tubular part 5 (cf. FIG. 1). This ensures on the one hand an additional mounting of the spring element 14 on the tubular part 5 of the housing of the gas sensor 1 and on the other hand also vibration damping for the parts clamped by the spring element 14 - pressure element 13, sensor element 9 and connecting lines 11.

The spring element 14 shown in FIG. 6 is designed as an annularly closed wire bracket part with the first spring sections 14 ′ and the second spring sections 14 ^{× λ} , the first spring sections 14 ′ again defining an arched plane and the areas of the second spring sections seated on the pressing bodies 13 14 '' in front of the convex side of the curved plane.

FIG. 7 shows a modified embodiment in which the first spring sections 14 ″ are again designed in the manner of wire clips and the second spring sections 14 ^{v are designed} in the form of bending tongues, the free ends of which sit on the respective pressure bodies 13 under tension.

The spring element 14 of FIG. 8 is designed as a circular disk-shaped stamped part made of spring steel sheet. It has a thickness of, for example, 4 to 7 mm and a circular outer circumference with an outer diameter D _a of, for example, 10.2 mm. Two trapezoidal tongues Z are formed on the inner circumference, with which the spring element 14 clamps the pressure body described below with reference to FIGS. 9 to 14. Otherwise, the inner circumference of the spring element 14 is of non-circular design, for example an inner diameter D _x of 6 mm, an inner diameter D ₂ of for example 6.4 mm and an inner diameter D ₃ of 6.6 mm. The different radial width of the spring element 14 takes into account the locally different bending or torsional forces that occur on the spring element when it is used as intended for bracing the pressure elements on the sensor element. In the form shown, the spring material is loaded approximately equally everywhere. In particular, an approximately linear increase in force is achieved when the mutually facing ends of the tongues Z are pushed apart.

The spring element 14 of FIG. 8 interacts with pressure bodies 13 of the type shown in FIGS. 9 to 14. This pressure body is used in pairs - analogous to the pressure bodies 13 in FIGS. 4 and 5. The tongues Z of the spring element 14 shown in FIG. 8 correspond to the spring sections 14 ′ ^{l of} the spring element 14 in FIGS. 4 to 7.

9 shows the side facing the sensor element to be held (not shown). The opposite side of the pressure body 13 is shown in Fig. 11. 13 and 14 show the two end faces of the pressure body, and FIGS. 10 and 12 show sectional images corresponding to the section lines XX in FIG. 9 and XII-XII in FIG. 11, respectively.

As can be seen in particular from FIGS. 11 and 12, the pressure body 13 has on its outside an axial channel 16 into which the spring element of FIG. 8 engages with one of its tongues Z. The bottom of the channel 16 has a first raster elevation 161 at the left end of the pressing body 13 in FIGS. 11 and 12, to which a first latching surface 162 is connected to the right. This merges to the right into a ramp 163, to which a further raster elevation 164 and a further latching surface 165 lie behind.

If the spring element 14 of FIG. 8 with its tongues Z is pushed over the first raster elevation 161 onto the first latching surface 162, the spring element 14 assumes a first latching position. With further displacement of the spring element 14 in FIGS. 11 and 12 to the right, the tongues Z

- With increasing bending of the tongues and the entire spring element 14 - brought over the ramp 163 and the further grid elevation 164 into a strongly tensioned latching position, in which the tongues are tensioned against the further latching surface 165 and the annular disk-shaped spring element on a stop surface 166 of the pressure element 13 lies close to it.

A special feature of the pressure body 13 shown in FIGS. 9 to 14 is that, together with a pressure body of the same type, it forms a mouth suitable for receiving the sensor element 9 (cf. FIG. 1), with which the sensor element 9 can be gripped like pliers. For this purpose, the pressure body 13 according to FIGS. 9, 10 and 12 has at its left end in the drawing a projection 171 with a recess 172 which is approximately semicircular in cross section and a further projection 173 with an elevation 174 opposite the recess 172.

When the pressure bodies 13 shown in FIGS. 9 to 14 are arranged in pairs, the depression 172 of the one pressure body receives the elevation 174 of the other pressure body and vice versa. The projections 171 and 173 with their depressions 172 or elevations 174 thus form a “jaw joint” which is held together by the spring element 14 of FIG. 8 when its tongues Z are seated on the first latching surfaces 162.

At the right end of the pressure body in FIGS. 9 and 12, a lateral projection 181 is arranged, which is also visible in the views of FIGS. 13 and 14. Thus, if two pressure bodies 13 of the type shown in FIGS. 9 to 14 are arranged in pairs to form the aforementioned jaw joint, the lateral projection 181 of each pressure body is directed against an opposite flat area without a projection on the other pressure body 13.

A sensor element can then be inserted between the mutually facing sides (cf. FIG. 9) of the two pressure bodies 13 in the area between the lateral projections 181 of the two pressure bodies 13 after the connecting wires to be contacted have previously been inserted into axial grooves 183, cf. Fig. 9, have been inserted or inserted.

If now the spring element 14 of FIG. 8 is pushed against the stop surface 166, that between the Pressure bodies 13 formed and the sensor element receiving mouth closed with great force, so that the connecting wires are pressed against the corresponding contact surfaces.

Claims

Expectations

1.Gas sensor (1) for detecting a parameter of a gas component, in particular a lambda probe or temperature sensor, with a sensor element (9), at least one contact surface (10) arranged on the sensor element and with a connecting line electrically connected to the contact surface (10) 11) which is non-positively clamped between the contact surface (10) and at least one pressure element (13) tensioned by a spring element (14) against the sensor element (9), characterized in that the spring element (14) is closed in a ring and as on the Pressure body (13) shrunk-on clamping ring or clamping sleeve is formed.

2. Gas sensor, (1) for detecting a parameter of a gas component, in particular a lambda probe or temperature sensor, with a sensor element (9), at least one contact surface (10) arranged on the sensor element and with a connecting line electrically connected to the contact surface (10) (11) which are tensioned between the contact surface (10) and at least one by a spring element (14) against the sensor element (9) The pressure element (13) is clamped non-positively, characterized in that the spring element (14) is closed in a ring shape, that the pressure element (s) (13) is / are at least partially conical and that the ring-shaped closed spring element (14) is clamped onto the cone is axially pushed or slidable.

3.Gas sensor (1) for detecting a parameter of a gas component, in particular a lambda probe or temperature sensor, with a sensor element (9), at least one contact surface (10) arranged on the sensor element and with a connecting line (10) electrically connected to the contact surface (10) 11), which is clamped non-positively between the contact surface (10) and at least one pressure element (13) tensioned by a spring element (14) against the sensor element (9), characterized in that the spring element (14) has at least one spring section (14 ", Z), which is deformed in the clamped state in a direction that has an essential component parallel to the longitudinal axis of the sensor element (9).

4. Gas sensor according to claim 3, characterized in that the spring section (14 ", Z) of the spring element (14) is a radially inwardly directed, tongue-like area which engages in an axial channel (16) of the pressure body (13), and that the spring section (14 ", Z) of the spring element (14) is elastically deformed in the clamped state.

5. Gas sensor according to claim 3 or 4, characterized in that the spring element (14) is closed in a ring and in the clamped state two approximately diametrically opposed first spring sections (14 ') and at least two further spring sections (14 "), the first Spring sections one with respect to one Define the radial axis of the annular spring element (14) curved virtual plane and the further spring sections (14 ") are arranged between the first spring sections (14 ') on or in front of the convex side of the curved plane.

6. Gas sensor according to at least one of the preceding claims, characterized in that all spring sections are designed as spring clips.

7. Gas sensor according to claim 5 or 6, characterized in that the further spring sections (14 ") are designed as tongue-like parts.

8. Gas sensor according to one of claims 1 to 14, characterized in that the spring element (14) is designed as a spring ring in the form of an annular disc with regions of different radial widths.

9. Gas sensor according to at least one of claims 3 to 8, characterized in that the spring element (14) is designed as a stamped part.

10. Gas sensor according to at least one of the preceding claims, characterized in that the spring element (14) at least two mutually relative to the sensor element (9) approximately diametrically opposed pressure body (13) against the sensor element (9).

11. Gas sensor according to at least one of the preceding claims, characterized in that each pressure body

(13) holds at least one connecting line (11) on an associated contact surface (10) of the sensor element (9) with a non-positive connection caused by the spring element (14).

12. Gas sensor according to one of claims 10 or 11, characterized in that the at least two pressure bodies (13) are pressed against one another on their one axial ends of the spring element (14) and a mouth open to their other axial ends to accommodate the sensor element (9) form, and that this mouth can be closed by moving the spring element in the direction of the other axial ends of the pressure body or can be non-positively clamped on the sensor element.

13. Gas sensor according to at least one of claims 10 to 12, characterized in that the spring element (14) at one axial ends of the pressure body (13) in a first locking surface (162) at one end and / or upon displacement in the direction of engages other axial ends in a further locking surface (165) at the latter ends.

14. Gas sensor according to claim 13, characterized in that the spring element (14) in the further locking surface (165) at the other axial ends of the pressure body (13) sits with increased spring tension.

15. Gas sensor according to claim 13 or 14, characterized in that between two in the axial direction of the pressure body (13) spaced locking surfaces (162, 165) for the spring element (14) on the pressure bodies (13) ramps (163) are arranged, such that that the spring element with axial displacement in the direction of the further locking surface

(165) is increasingly tense.

16. Gas sensor according to one of claims 13 to 15, characterized in that the latching surfaces (162, 165) and / or ramps (163) are formed as partial areas of axial channels (16) on the pressure bodies (13).

17. Gas sensor according to at least one of the preceding claims, characterized in that the annularly closed spring element (14) has radially outwardly directed extensions (17) which the spring element (14) and the parts braced by it (9, 11, 13) Hold on the inner wall of a housing part (5) of the gas sensor (1) by clamping and / or support it with vibration damping.

18. Gas sensor according to at least one of the preceding claims, characterized in that two or more spring elements (14) are arranged in parallel in the manner of a spring assembly.