DE102006023841A1 - electrode assembly - Google Patents

Abstract

The The invention relates to an electrode assembly comprising at least a with a holding element (8) attached to a burner electrode (3), wherein the burner is a burner environment (1) of a combustion chamber (2) separating wall (4) with an insertion opening (5) for the electrode (3) and wherein the electrode (3) consists of an electrode wire (6) and one at least in the region of the through-opening (5) enclosing ceramic sleeve (7) is formed. According to the invention it is provided that the through opening (5) a first, larger, burner environment side (D1) and a second, smaller, combustion chamber side (D2) diameter in that the wall (4) has a continuous transition from the first to the second Diameter (D1, D2), that the ceramic sleeve (7) at least in the area between the two diameters (D1, D2) a continuous, to the insertion opening (5) contoured outer contour having.

Description

The The invention relates to an electrode arrangement according to the preamble of patent claim 1.

An electrode arrangement of the aforementioned type is realized in a boiler (product name: VITODENS ^® ) of the applicant (see 3 ). This comprises at least one electrode fixed to a holding element on a burner (gas burner), wherein the burner has a wall separating a burner environment from a combustion chamber with an insertion opening for the electrode and wherein the electrode consists of an electrode wire and at least in the region of the insertion opening Ceramic sleeve is formed. Said electrode is used in a conventional manner either as a starting electrode or for ignition monitoring.

at this known solution has the insertion opening a cylindrical shape. The ceramic sleeve, which passes through the insertion opening with clearance is also cylindrical. On the ceramic sleeve is the already mentioned, fastened as holding plate designed holding element (clamp connection), which in turn with the interposition of a sealing element on the ambient side wall of the burner is screwed.

• – Der Kraftschluß zwischen Halteblech und Keramik kann zur Schädigung der Keramik führen (Haarrisse mit der Folge von Spannungsüberschlägen oder Kriechströmen);
• – Durch die Schraubverbindung erfolgt indirekt auch eine Krafteinwirkung auf die Elektrode, welche insbesondere über die lange Hebelwirkung an der Spitze des Elektrodendrahtes zu unzulässigen Positionsabweichungen führen kann;
• – Bei Brennwertgeräten mit Überdruck in der Brennkammer läßt sich die Verbindung Halteblech zur Keramik kaum zufriedenstellend abdichten;
• – Bei Brennwertgeräten tritt permanent Kondensatanfall in der Brennkammer auf; dieser wirkt an den oftmals nur mit einem Oberflächenschutz versehenen (und durch die Elektrodenmontage teilweise zerstörten) Halteblechen stark korrosiv.

This solution has the following problems:

• - The frictional connection between the holding plate and ceramic can lead to damage to the ceramic (hairline cracks with the result of voltage flashovers or leakage currents);
• - Due to the screw indirectly takes place a force on the electrode, which can lead to inadmissible position deviations in particular on the long leverage at the top of the electrode wire;
• - For condensing boilers with overpressure in the combustion chamber, the connection holding plate to the ceramic can hardly satisfactorily seal;
• - For condensing boilers occurs permanently condensate accumulation in the combustion chamber; this has a very corrosive effect on the holding plates, which are often only provided with a surface protection (and partly destroyed by the electrode assembly).

Of the Invention is the object of an electrode arrangement of the type mentioned above to improve the mentioned disadvantages. In particular, the production cost be reduced at the same time improved tightness.

These Task is with an electrode assembly of the aforementioned Type by the features listed in the characterizing part of patent claim 1 solved.

To The invention is therefore intended that the insertion opening a first, larger, burner environment side and a second, smaller, combustion chamber-side diameter, that the wall a (in the mathematical sense) continuous transition from the first to the second diameter, that the ceramic sleeve at least in Range between the two diameters one (in mathematical Sense) steady, to the insertion opening conformal outer contour having.

With in other words, has the ceramic sleeve in the area of the insertion opening for example, a cone-shaped outer contour on, which fits exactly to the correspondingly formed contour of the insertion opening. In this way a snug fit (guide) seat of the sleeve is ensured in the opening, the above In addition, a waiver of other sealing elements (as previously required) allows. According to the invention must this only one towards the burner environment steadily widening Through opening be provided, which together with the appropriately trained ceramic sleeve ensures a good fit of the electrode on the wall.

The Axial fixation is done with the above-mentioned holding element, preferably in the form of a tension spring, which will be discussed in more detail below becomes.

Other advantageous developments emerge from the dependent claims.

For the sake of completeness is still on the farther prior art according to the DE 195 05 218 C1 and EP 1 605 206 A1 directed.

The Inventive electrode arrangement including their advantageous developments according to the dependent claims will be below with reference to the drawing of a preferred embodiment explained in more detail.

It shows

1 on average, the inventive arrangement of two electrodes on a burner wall;

2 in perspective, a preferred embodiment of the holding element according to 1 for fixing the electrodes according to the invention; and

3 in section, an electrode arrangement known from the prior art.

First, it will open 3 directed. There is the aforementioned, known in the prior art electrode arrangement of the applicant shown. This includes exactly like the electrode arrangement according to the invention at least one (shown in both cases two) with a holding element 8th attached to a burner electrode 3 wherein the burner is a wall separating a burner environment BU from a combustion chamber BK 4 with an insertion opening 5 for the electrode 3 and wherein the electrode 3 from an electrode wire 6 and one of these at least in the region of the insertion opening 5 enclosing ceramic sleeve 7 is formed.

How out 3 it can be seen in the known prior art between the holder 8th and the wall 4 inserted or required a seal. The holder 8th has in the illustrated embodiment, two through holes 10 on, with the ceramic sleeves 7 each in a press fit in the through holes 10 are arranged. As mentioned above, this can damage the ceramic sleeves 7 and accordingly lead to voltage flashovers or leakage currents.

To avoid these disadvantages, is now according to the invention with reference to 1 and 2 provided that the insertion opening 5 a first, larger, brennerumgebungsseitige and a second, smaller, combustion chamber-side diameter D1, D2, that the wall 4 has a continuous transition from the first to the second diameter D1, D2 and that the ceramic sleeve 7 at least in the area between the two diameters D1, D2 a steady, to the insertion opening 5 having conformed outer contour.

In other words, on the one hand, the outer contour of the ceramic sleeve 7 and on the other hand, the inner contour of the insertion opening 5 so conformed to each other that automatically results in a fit, which makes a seal dispensable (so-called "sealant-free" arrangement).

How out 1 can be seen, it is provided that the outer contour of the ceramic sleeve 7 between the two diameters D1, D2 is cone-shaped. Of course, other outer contours come into consideration; only the continuous slope from smaller to larger diameter, on the one hand ensures the tightness and on the other hand enables the mountability of the electrode: between the two diameters D1 and D2 no diameter may be smaller than the combustion chamber side diameter D2, otherwise there is an undercut would occur and the electrode then no longer through the insertion opening 5 would be pluggable.

Furthermore, it is advantageously provided that the outer contour between the two diameters D1, D2 of the ceramic sleeve 7 is formed rotationally symmetrical. This proviso ensures, for example, in comparison to a truncated pyramidal design a particularly good tightness, with such, rather off-truncated pyramidal training said diameter D1, D2 are of course not literally, but in a figurative sense to understand (similar to the so-called hydraulic diameter in a channel flow [Example from the fluid mechanics]).

Again with reference to 1 is provided that the ceramic sleeve 7 a support collar 9 for the holding element 8th having. This consists in principle of an enlargement of the diameter of substantially (this will be discussed below) cylindrical ceramic sleeve, and precisely at the point where the holding element 8th from the back (ie burner environment side) on the electrode 3 acting, in which case the retaining element 8th one pointing in the combustion chamber direction, on the electrode 3 having acting spring force. This spring effect can be achieved that the holding element 8th as 2 shows is formed as an elastic bleaching strip. The embodiment according to 1 and 2 shows a holding element 8th for fixing two electrodes. Alternatively, of course, a single fixation or a multiple fixation of electrodes is possible in this way.

To join the abovementioned support collar 9 to be able to support is on the holding element 8th a passage opening 10 per electrode 3 provided, wherein the retaining element 8th in the region of this passage opening 10 is formed flat surface to the spring force evenly in the Abstützbund 9 to contribute.

So that the electrode 3 not only good axial on the wall 4 is fixed, it is further provided that optionally at the insertion opening 5 or in the area of the passage opening 10 of the holding element 8th an anti-rotation is arranged. How out 2 it can be seen that this is preferably one at both the passage opening 10 as well as on the ceramic sleeve 7 provided, rectilinearly extended contact surface 11 or contact edge is formed (insofar as the ceramic sleeve, as mentioned above, is not cylindrical over its entire length, but at this point has a correspondingly formed singularity).

For fastening the retaining element 8th on the wall 4 Finally, it is provided that this at least one (shown two) clip-like extension 12 having. This extension engages in one on the wall 4 provided recess 13 one, with barbs 14 on the extension 12 an un wanted release of the fort 12 from the recess 13 exclude. As shown, the clip-like extension 12 made by repeatedly bending the metal strip in different directions; the barbs 14 arise by suitable punching or breaking certain areas on the extensions 12 ,

BU

Brenner environment

BK

combustion chamber

3

electrode

4

wall

5

Through opening

6

electrode wire

7

ceramic sleeve

8th

retaining element

9

support collar

10

Through opening

11

contact surface

12

extension

13

recess

14

barb

D1

First, larger diameter

D2

second, smaller diameter

Claims (17)

Electrode arrangement comprising at least one with a holding element ( 8th ) electrode attached to a burner ( 3 ), wherein the burner has a wall which separates a burner environment (BU) from a combustion chamber (BK) ( 4 ) with an insertion opening ( 5 ) for the electrode ( 3 ) and wherein the electrode ( 3 ) from an electrode wire ( 6 ) and one at least in the region of the insertion opening ( 5 ) enclosing ceramic sleeve ( 7 ) is formed, characterized in that the insertion opening ( 5 ) has a first, larger, burner environment side (D1) and a second, smaller, combustion chamber side (D2) diameter that the wall ( 4 ) has a continuous transition from the first to the second diameter (D1, D2) that the ceramic sleeve ( 7 ) at least in the region between the two diameters (D1, D2) a continuous, to the insertion opening ( 5 ) has conformed outer contour. Electrode arrangement according to claim 1, characterized in that the outer contour of the ceramic sleeve ( 7 ) is cone-shaped between the two diameters (D1, D2). Electrode arrangement according to claim 1 or 2, characterized in that the outer contour between the two diameters (D1, D2) of the ceramic sleeve ( 7 ) is rotationally symmetrical. Electrode arrangement according to one of claims 1 to 3, characterized in that the ceramic sleeve ( 7 ) sealant-free in the insertion opening ( 5 ) is arranged. Electrode arrangement according to one of claims 1 to 4, characterized in that the ceramic sleeve ( 7 ) a support collar ( 9 ) for the retaining element ( 8th ) having. Electrode arrangement according to claim 1 to 5, characterized in that the holding element ( 8th ) is formed from a metal strip. Electrode arrangement according to one of claims 1 to 6, characterized in that the holding element ( 8th ) for fixing more than one electrode ( 3 ) is trained. Electrode arrangement according to one of claims 1 to 7, characterized in that the holding element ( 8th ) pointing in the direction of the combustion chamber, onto the electrode ( 3 ) has acting spring force. Electrode arrangement according to one of claims 1 to 8, characterized in that the holding element ( 8th ) for the electrode ( 3 ) a passage opening ( 10 ) having. Electrode arrangement according to claim 9, characterized in that the holding element ( 8th ) in the region of the passage opening ( 10 ) is planar. Electrode arrangement according to one of claims 1 to 10, characterized in that at the insertion opening ( 5 ) An anti-rotation is arranged. Electrode arrangement according to Claim 9, characterized in that in the region of the passage opening ( 10 ) of the retaining element ( 8th ) An anti-rotation is arranged. Electrode arrangement according to claim 12, characterized in that the anti-rotation lock from one both at the passage opening ( 10 ) as well as on the ceramic sleeve ( 7 ), rectilinearly extended contact surface ( 11 ) is formed. Electrode arrangement according to one of claims 1 to 13, characterized in that the holding element ( 8th ) for connection to the wall ( 4 ) at least one clip-like extension ( 12 ) having. Electrode arrangement according to claim 14, characterized in that on the wall ( 4 ) a recess ( 13 ) for the bracket-like fort sentence ( 12 ) is provided. Electrode arrangement according to claim 15, characterized in that the clamp-like extension ( 12 ) at least one barb ( 14 ) for anchoring in the recess ( 13 ) having. Electrode arrangement according to claim 15, characterized in that the clamp-like extension ( 12 ) is formed by multiple buckling of the metal strip in different directions.