DE8914109U1 - Pair of ignition electrodes for a burner - Google Patents

Description

for a burner

The invention relates to a pair of ignition electrodes for a burner according to the preamble of claim 1.

In oil atomizer or gas burners, the finely atomized or gaseous fuel is blown through a nozzle into a combustion chamber, usually designed as a flame tube. A certain amount of combustion air is also mixed with the fuel. In order to be able to maintain the optimal flow and mixing ratios, especially in so-called blue burners, it is known to close off the combustion chamber with a partition wall that only has defined openings for the passage of the fuel and combustion air. To ignite the burner flame, ignition electrodes are provided that are led through this partition wall in an isolated manner. An example of this state of the art is shown in DE-PS 34 20 077.

f'ostglroamt: Karleruhe 76979-754 Bank account^Deutsche Bank«A$ ^Hingen (bank code 69470039) 146332

The exact positioning of the ignition electrodes causes difficulties with this known design. The passage of the ignition electrodes through the partition wall leads to leaks in the partition wall, which can have a detrimental effect on the exact setting of the burner.

The invention is based on the object of creating a pair of ignition electrodes that can be positioned precisely, reliably and permanently and that enables a sealed passage through the partition wall of the burner.

''■: This object is achieved according to the invention in an ignition electrode pair of the type mentioned at the beginning by the features &Iacgr;< of the characterizing part of claim 1.

Advantageous embodiments of the invention are specified in the subclaims.

According to the invention, a sleeve is located on the insulating tube of each ignition electrode, and the two electrodes of the ignition electrode pair are clamped axially in the area of these sleeves by the fastening part. The sleeves ^enable stable clamping of the electrodes. Since the sleeves are axially immovable and non-rotatable on the insulating tube, this axial clamping in the fastening part that can be fastened to the partition wall results in an exact, permanent positioning of the electrodes both in the axial direction and in their mutual angle and distance. The spark gap between the tips of the two electrodes can therefore be precisely adjusted by the angular position of the electrodes.

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This spark gap can also be positioned axially precisely in the combustion chamber.

When screwing the fastening part onto the partition wall, the expanded end of the sleeve on the partition wall side is pressed against the partition wall and thereby seals the passage hole for the electrodes.

The sleeves are preferably thin-walled metal sleeves that are sufficiently stable to absorb the clamping pressure of the fastening part and the axial contact pressure on the partition wall. The end on the partition wall side can be widened to seal the through holes by flanging the edge of the sleeve or by upsetting a compression bead. The axially immovable, rotationally fixed connection between the insulating tube and the attached sleeve can be made purely force-fitting by gluing, pressing or shrinking. Form-fitting connections are also possible. For this purpose, the insulating tube can have a thickening, whereby the sleeve is first pushed over the thickening in an expanded manner and then pressed together again behind the thickening. Indentations in the area of the thickening, e.g. in the form of axial notches, bring about the rotationally fixed connection by pressing the sleeve into these indentations. It is also possible to provide one or more flat ribs running in the axial direction on the outer circumference of the insulating tube. The sleeve is forced to slide over these ribs, whereby the height of the ribs and the material of the sleeve are selected so that the sleeve only deforms within the elastic range. The sleeve is thus stretched elastically over these ribs and draws into the axially parallel grooves formed between the ribs.

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grooves so that the positive connection is achieved both in the axial direction and in the direction of rotation.

The fastening part is conveniently formed from two symmetrical sheet metal yokes that hold the electrodes between them and form a passage opening for the fastening screw in the area between the electrodes. The two sheet metal yokes are connected to one another by spot welding.

The invention is explained in more detail below using embodiments shown in the drawing. Show:

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

a side view of a pair of ignition electrodes, with the sleeve of the upper electrode cut open axially,

a section through the ignition electrode pairs of Figures 1, 4 and 5 along the line II-II,

a section through the ignition electrode pair of Figure 1 along the line III-III,

a pair of ignition electrodes in a second embodiment and

a pair of ignition electrodes in a third embodiment.

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In the first embodiment shown in Figures 1 to 3, the ignition electrode pair consists of two electrodes 10, the free front ends of which protrude into the combustion chamber of the burner and form the ignition spark gap. A plug pin 12 of a connection plug connector is attached to the rear end of the electrodes 10. In the middle area, in which the electrodes 10 are led through the partition wall of the burner (not shown), the electrodes 10 are each enclosed by a ceramic insulating tube 14.

On the outside of each insulating tube 14 there is a steel sleeve 16 with a small wall thickness of about 0.5 mm. The inner diameter of the sleeve 16 corresponds to the outer diameter of the insulating tube 14, so that the sleeve 16 can be pushed onto the insulating tube 14 without play. In the middle area, the insulating tube 14 has a thickening 18 of small axial length, in the outer circumference of which four axially parallel notches 20 offset by 90° are cut. The sleeve 16 is widened at its rear end and pushed over the insulating tube 14 from the front so that its widening overlaps the thickening 18. The widened end of the sleeve 16 is then pressed together again behind the thickening 18, whereby the material of the sleeve 16 is also pressed into the notches 20 of the thickening 18. The sleeve 16 is thus fixed axially by the thickening 18 and by the notches 20 in a rotationally fixed manner on the insulating tube 14: The front end of the sleeve 16 is preferably flanged outwards by compression so that an edge 22 is formed which widens outwards in a funnel shape.

With the cylindrical area between the thickening 18 and

The sleeves 16 are clamped into a fastening part β at the edge 22. The fastening part consists of two symmetrical sheet metal yokes 24 bent from a mild steel strip. The width of the sheet metal strips corresponds to the axial length of the cylindrical middle section of the sleeve 16. As Figure 2 shows, the two sheet metal yokes are designed symmetrically to a parting plane that contains the axes of the two electrodes 10. The sheet metal yokes 24 form two cylindrical receptacles at a predetermined distance, in which the sleeves 16 of the insulating tubes 14 are received and clamped. Between these two receptacles, the sheet metal yokes 24 are bent again in a semicircular shape in order to form a passage opening 26 for a fastening screw that is parallel to the axis of the electrodes 10. Between the two receptacles for the sleeves 16 and the passage opening 26, the two sheet metal yokes 24 lie flat against one another and are connected to one another by spot welds 28.

The pair of ignition electrodes is guided with the insulating tubes 14 through through holes in the partition wall of the combustion chamber so that the free ends of the electrodes 10 protrude into the combustion chamber. The widened edges 22 of the sleeves 16 come into contact with the partition wall and cover the annular gap of the through holes remaining around the insulating tubes 14. The fastening part and thus the entire pair of ignition electrodes is screwed to the partition wall -i by means of a fastening screw inserted into the through opening 26 -i. When the fastening screw ^! | is tightened, the edges 22 are pressed against the partition wall, whereby they :| lie against the partition wall with elastic deformation and w seal the through holes.

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Figure 4 shows a second embodiment of the ignition electrode pair. To the extent that this corresponds to the first embodiment, the same reference numerals are used and reference is made to the preceding description.

In contrast to the first embodiment, in the embodiment of Figure 4 the sleeves 16 are glued, pressed or thermally shrunk onto the insulating tubes 14 for axially non-displaceable and rotationally fixed connection to the latter. The thickening 18 and the work step required to apply the sleeve to this thickening can therefore be omitted.

Instead of the edge 22, a compression bead 30 with an enlarged diameter is provided on the end of the sleeve 16 on the partition wall side by axial compression. When the fastening parts formed by the sheet metal yokes 24 are screwed onto the partition wall, the compression beads 30 of the sleeves 16 are compressed axially between the partition wall and the sheet metal yokes 24 and seal the through holes in the partition wall.

Figure 5 shows a third embodiment of the ignition electrode pair β. Here, too, reference is made to the description of the embodiment in Figures 1 to 3.

For the torsion-free and axially immovable fastening of the sleeves 16 on the leolier tubes 14, in this version

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In the example, the insulating tubes 14 have flat, axially parallel ribs 32 distributed around the circumference behind the sheet metal yokes 24 on the side facing away from the partition wall. The ribs 32 are drawn greatly exaggerated in the drawing for the sake of clarity. The ribs 32 have a small radius so that the sleeve 16 can be pushed over the ribs 32 under reversible elastic deformation. The sleeve 16 therefore only has to be lifted over the ribs 32 under axial pressure and then lies elastically on these ribs 32 and in the grooves formed between the ribs 32, so that the sleeve 16 is fixed axially and non-rotatably on the insulating tube without any additional work steps.

Claims (1)

Dlpl.-lng. KUAUS WESTPHAL·".·,··, .; .tValdsfrafeeifcf. Telefon(07721)56007 &bull; · · · I..",'.,! Telex 7921573wemud Dr.rer.naiBERND MUSSSNUS. '.'.. ! ij-7730 V&VILUNGEN Fax (07721)55164 Dr.rer.nnt.OTTO BÜCHNER Flossmannstrasse30a Telephone(089)832446 Telex 5213177 webu d PATENTA NWA UTE D-8000 MUNICH 60 Fax (089) 8340966 European Patent Attorneys * raekO13 PROTECTION PROMISES Pair of ignition electrodes for a burner, in which the two electrodes are each enclosed by an insulating tube for passing through a partition wall closing off the combustion chamber of the burner, and the insulating tubes can be fastened to the partition wall by means of a common fastening part, characterized in that a sleeve (16) is seated on the insulating tubes (14) in a rotationally fixed and axially immovable manner, that the fastening part (sheet metal yokes 24) encloses the sleeves (16) in an axially guided clamping manner, and that the sleeves (16) are enlarged in diameter at their end protruding from the fastening part (sheet metal yokes 24) on the partition wall side. 2. Ignition electrode pair according to claim 1, characterized in that the sleeves (16) are thin-walled metal sleeves. 3. Ignition electrode pair according to claim 1 or 2, characterized in that the sleeves (16) have an outwardly flanged edge (22) at their end on the partition wall side. Postgiroamt: Karlsruhe 76979-764 ,B«fity«>qto:,f>eijtscheAan/«Aß,Vltl|ngen (BLZ 69470039) 146332 * 4. Ignition electrode pair · · · *
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1 # . * partition wall- side end a nacL claim &bull; the pods (16) 1 or 2 Upset bead (30) on their exhibit ■iii ff 5. Ignition electrode pair according to at least one of claims 1 to 4, characterized in that the sleeves (16) are fixed to the insulating tubes (14) in a force-fitting manner. 6. Ignition electrode pair according to claim 5, characterized in that the sleeves (16) are glued, pressed or shrunk onto the insulating tubes (14). 7. Ignition electrode pair according to at least one of claims 1 to 4, characterized in that the sleeves (16) are fixed in a form-fitting manner on the insulating tubes (14). 8. Ignition electrode pair according to claim 7, characterized in that the insulating tubes (14) on the side of the fastening part (sheet metal yokes 24) facing away from the separating zone have a thickening (18) with at least one depression (notches 20) in the outer circumference and that the sleeves (16) are pressed over the thickening (18) and into the depressions (notches 20). 9. Ignition electrode pair according to claim 7, characterized in that the insulating tubes (14) on the side of the fastening part (sheet metal yokes 24) facing away from the partition wall ·« It have at least one slightly raised rib (32) running parallel to the axis and that the sleeves (16) are pushed over these ribs (32) under reversible elastic deformation. 10. Ignition electrode pair according to at least one of claims 1 to 9; characterized in that the fastening part is a block provided with through-holes. 11. Ignition electrode pair according to at least one of claims 1 to 9, characterized in that the fastening part is divided in or parallel to the plane containing the axes of the electrodes (10). 12. Ignition electrode pair according to claim 11/ characterized in that a through-opening (26) of the fastening part intended to receive a fastening screw is formed by recesses in the parting plane. 13. Ignition electrode pair according to claim 11 or 12, characterized in that the fastening part consists of two bent sheet metal yokes (24). 14. Ignition electrode pair according to claim 13, characterized in that the sheet metal yokes (24) are connected to one another by spot welds (28).