EP2208268B1 - Spark plug comprising a ground electrode support - Google Patents

Abstract

The invention relates to a spark plug of an internal combustion engine, especially for use in Otto gas engines. Said spark plug comprises, supported by an insulating body (1), a preferably one-piece spark plug shell (2) and a center electrode (3), which is especially rod-shaped or has a plurality of electrode fingers, and at least one ground electrode (4), preferably a plurality of ground electrodes, the center electrode (3) and the at least one ground electrode (4) being surrounded by a chamber, especially a pre-chamber (5a) or a swirl chamber (5b) supported by the spark plug shell (2), or being located inside said chamber (5a, 5b). The invention is characterized in that the ground electrode(s) (4) has/have a support (6) secured to the spark plug shell (2) or arranged thereon as the base, or branch(es) off therefrom, and in that said ground electrode support (6) and every finger-type ground electrode (4) branching off therefrom is arranged at a distance (21) from the inner wall surface (7) of the chamber (5a, 5b).

Description

The invention relates to a spark plug according to the preamble of claim 1.

Such spark plugs are known from the prior art, for example JP-A-2007 035570 ,

The aim of the invention is to simplify the production of such spark plugs, especially in view of the fact that complicated to be made complex components are avoided and the spark plug is made of easily manufacturable parts. This is particularly important for mass production. Furthermore, the electrical properties of such spark plugs should at least match those of comparable spark plugs, if not exceed these properties. Accordingly, care must be taken to ensure optimum power supply to the individual ground electrodes. Furthermore, a spark plug according to the invention should allow it to be formed as a prechamber spark plug or as a swirl chamber spark plug. Finally, the ignition properties and the thermal conductivity of the ignition electrodes should be optimized to achieve better hot corrosion resistance.

These objects are achieved in a spark plug of the type mentioned above with the features mentioned in the characterizing part of claim 1.

The arrangement of the ground electrodes on a separate carrier ensures a uniform supply of current to the ground electrodes, without any current dissipation, e.g. via an antechamber or vortex chamber in direct contact with the ground electrodes. Since the ground electrode carrier is arranged at a distance from the inner wall surface of the chamber, that is, an antechamber or vortex chamber, the ground electrodes and their support constitute a system independent of the wall portion of the chamber. This allows easy readjustment of the electrodes and thus can Use-related electrode burn-off to be corrected. Due to the possibility of making the carrier and the ground electrodes in particular as a one-piece component, considerable advantages in terms of manufacture result. Furthermore, the fact that the ground electrodes can be manufactured as a one-piece component and that there is a gap between the ground electrode carrier and the inner wall of the pre-chamber or swirl chamber results in improved thermal conductivity from the ignition electrodes to the spark plug housing. The particular shape of the ground electrodes and the manner of application of noble metal alloy provides further advantages in terms of improved ignition performance.

A particularly simple production with stable construction of the spark plug is achieved by the special shape of the mass electrode carrier. The cylindrical ring Cross-section having mass electrode support is adjusted in a simple manner in a circumferentially constant distance from the inner wall surface of the wall part of the vortex or pre-chamber, so that defined conditions with respect to combustion and power line arise. Furthermore, the structure and assembly of the spark plug are simplified, since the cylindrical annular ground electrode carrier and also a cylindrical ring-shaped cross-section vortex chamber or an antechamber in a simple manner can be placed on the spark plug and fastened there. The ground electrode carrier can be formed on its inner wall surface with a thread or also have a smooth surface; the same applies to a vortex chamber or antechamber. Either the ground electrode carrier or the vortex chamber or the pre-chamber are screwed onto the respective protruding paragraphs of the spark plug housing and possibly set by welding in position or these components are pushed with the most accurate fit on the spark plug and secured in position, in particular by welding.

The features of claim 2 provide a simply constructed ground electrode.

Soferne between the wall part of a prechamber or a vortex chamber and the ground electrode carrier a metallic or ceramic cylinder ring is used, there is a good heat transfer from the ground electrode carrier to the vortex chamber or on the antechamber. Ceramic materials allow for electrical separation of the vortex chamber and ground electrode support while providing good heat dissipation from the ground electrode support over the cylinder ring and the vortex chamber to the spark plug housing. Furthermore, such a constructed spark plug can be easily manufactured. First, the ground electrode carrier is positioned or welded on its heel in position. Then the cylinder ring is pushed over the ground electrode carrier. Then, the chamber is placed with its cylindrical wall part on the intended paragraph of the spark plug housing, that is pushed or screwed and / or secured by welding. On the inner wall surface of the pre-chamber or the vortex chamber, at least one nose can be formed, which fixes the cylinder ring in its position. In operation, it is advantageous if the ground electrode carrier, the cylinder ring and the pre-chamber or the swirl chamber abut each other to ensure good heat transfer and / or good power line.

The features of claim 4 offer advantages in terms of the function of the spark plug. The features that in the wall portion of the chamber at least one, preferably circular cross-section, Spülausnehmung or opening for the passage of fuel-air mixture and / or at least one preferably slit-shaped recess for the release of at least the combustion chamber-side end portions of the finger-shaped ground electrodes are formed opposite to the respective end region, contribute to improved combustion and good heat dissipation. It is advantageous if one, three or five ground electrodes are carried by the ground electrode carrier and / or if the ground electrodes are distributed on the ground electrode carrier equidistant from each other about the center electrode and / or if each of the finger-like ground electrodes extending from the ground electrode carrier is transverse to its longitudinal extent has at least in some areas rechteckfömigen or cylindrical ring section-shaped cross-section. The ground electrode supports are easy to manufacture or give good burn-off properties. For good combustion performance of the spark plug contributes when the at least one or each of the ground electrode (s) in the form of a finger goes off the carrier and its brennraumseitiger end portion extending parallel to the longitudinal axis and / or the facing surface region of the center electrode and / or if the spark gap between is formed parallel to the longitudinal axis extending, opposite surface areas of the ground electrode and the center electrode.

A simple construction of the spark plug according to the invention and a rapid assembly, in which the corresponding tolerances can be well maintained, results if it is provided that on the concentric Endabsätzen each have an external thread and on the inner wall surface of the wall part of the chamber and on the inner wall surface of the Support each adapted to the respective external thread internal thread is formed and / or that the ground electron carrier and the cylindrical wall part of the chamber are concentrically arranged to form the predetermined distance to each other and / or that the cylindrical wall part and the carrier attached to the respective paragraph and there by Welding is attached. The spark plug housing can be manufactured with the required accuracy without too much effort. By correspondingly accurate production of the ground electrode carrier and the prechamber or the vortex chamber, the distances between ground electrode carrier and prechamber or vortex chamber can be maintained exactly over the entire circumference of the spark plug.

It is advantageous with regard to the ignition properties and the thermal behavior of the spark plug that the distance between the outer surface of the ground electrode carrier and the wall part of the chamber is smaller than the thickness of the wall part of the chamber and / or that the thickness of the ground electrode carrier is three to fifteen times, preferably is five to ten times, the thickness of the spark gap and / or that the distance between the outer wall surface of the ground electrode carrier and the inner wall surface of the chamber 50 to 200% of the thickness of the spark gap. Good burn-off properties arise when it is provided that in peripheral regions or on locally limited elevations or on radially outwardly facing surface areas of the center electrode and / or on the center electrode facing surface of the respective finger-shaped ground electrode or elevations formed on this surface, in adjacent and optionally superimposed webs, noble metal alloy or at least one platelet of noble metal alloy applied or melted or welded. For good heat conduction contributes, if it is provided that the center electrode is designed in the form of a compact component or in the form of a filled with a material of high thermal conductivity quiver-shaped component and optionally pushed onto the base center electrode and welded circumferentially with this once or more times.

The features that the combustion chamber end of the wall portion of a vortex chamber overhangs the combustion chamber end of the center electrode and / or the ground electrodes and / or that in the wall portion of the chamber opposite each ground electrode extending parallel to the ground electrode, optionally open to the combustion chamber end of the Wandungsteiles slot is formed, which frees the access to the end region of the ground electrode, improve the ignition characteristics of the spark plug or allow readjustment of the ground electrodes relative to the center electrode.

For the ignition properties and the current transport or heat dissipation and corrosion resistance of the spark plug, it is beneficial if the wall part of the chamber and the carrier are electrically conductive and are electrically connected to the spark plug housing and / or if each finger-shaped ground electrode from its wearer in the direction is bent toward the center electrode and after another turn in a direction substantially parallel to the center electrode and / or if the wall part of the chamber, the envelope and / or the at least one ground electrode with its support of nickel-based alloy and / or high temperature stainless steel and / or hot corrosion resistant , are made of heat conductive metal alloys, and / or that the antechamber is made of brass.

An embodiment of a spark plug which is optimized with regard to the burn-off properties and the accuracy of the ignition is achieved if it is provided that the wall part of the chamber and the carrier are electrically conductive and electrically conductively connected to the spark plug housing and / or that each finger-shaped ground electrode is separated from its Carrier is bent in the direction of the center electrode and after a further turn in a direction approximately parallel to the center electrode and / or that the wall portion of the chamber, the envelope and / or the at least one ground electrode are made with its support made of nickel-based alloy and / or high-temperature stainless steel and / or hot corrosion-resistant, good thermal conductivity metal alloys, and / or that the pre-chamber is made of brass.

Preferred embodiments of the invention will become apparent from the following description, the drawings and the claims.

Fig. 1 shows a schematic longitudinal section through an embodiment of a spark plug according to the invention. Fig. 2 . 2a, 2b, 2c, 2d and 2e show embodiments of a center electrode. Fig. 3 shows an applied noble metal alloy. 4 and 5 show views of an embodiment of a spark plug according to the invention. Fig. 6 . 7 . 10 and 11 show embodiments of a spark plug according to the invention. Fig. 8, 9 . 12, 13 and 14a to f schematically show the application of noble metal alloy on corresponding surface areas of a ground electrode or a center electrode. Fig. 15 shows in detail a cylinder ring inserted between a ground electrode carrier and the inner wall surface of a vortex chamber.

Fig. 1 shows a spark plug for use in an internal combustion engine, in particular for their use in a gasoline engine. From a insulating body 1, a spark plug housing 2 is supported, wherein from the insulating body 1, a base center electrode 3a is enclosed or going off. On this base center electrode 3a of the spark plug, the center electrode 3 is mounted. This center electrode 3 may be formed of a single pin-like component. It can be provided that, as in the present case, the center electrode 3 is filled with a material 3b of high thermal conductivity in order to allow a better heat conduction from the electrode surfaces 12 to the base center electrode 3a. The combustion-chamber-side end of the center electrode 3 may be formed by a quiver 28, which is advantageously fastened to the base center electrode 3 a, in particular by repeated welding, in the region 3 '. This leads to a further improvement in heat dissipation.

To form at least one ignition gap 13, at least one ground electrode 4 is arranged over the circumference of the center electrode 3. Advantageously, one, three or five ground electrode (s) 4 are supported by a ground electrode support 6, and desirably the ground electrodes 4 are distributed on the ground electrode support 6 equidistantly around the center electrode 3. The ground electrode carrier 6 is carried by the spark plug housing 2, or is fixed thereto or departing therefrom.

How out Fig. 1 it can be seen, the at least one ground electrode 4 is in the form of a finger from the carrier 6 or finger-like ground electrodes 4 may be fixed or welded to the carrier 6. The fingers 4 and the carrier 6 can also be designed as a one-piece component. The combustion chamber side end portion 11 of the fingers extends parallel to the longitudinal axis A of the spark plug or to the facing surface region 12 of the center electrode 3. The ignition gap 13 is formed between the opposing surface areas 26, 12 of the ground electrode 4 and the center electrode 3.

For fastening the carrier 6 to the spark plug housing 2, it is provided that the spark plug housing 2 has two concentric, cylindrical end shoulders 17, 18, of which the inner end shoulder 17 projects beyond the outer end shoulder 18 in the direction of the combustion chamber. On the inner end paragraph 17 of the support 6 of the ground electrodes 4 and on the outer end shoulder 18 of the wall part 8 of the respectively provided chamber 5a or 5b placed, plugged or screwed and optionally secured by, in particular point or seam-shaped, welding. The inner dimensions of the wall part 8 and the ground electrode carrier 6 are adapted to the respective outer dimensions of the end paragraphs 17 to 18.

Thus, a simple and accurate attachment of the carrier 6 on the spark plug housing 2 can take place or an exchange of the ground electrodes 4 in the course of a service is possible.

A simple mounting of the carrier 6 or a chamber 5a or 5b results when on the concentric, circular periphery owning Endabsätzen 17, 18 each have an external thread and on the inner wall surface 19 of the Wandungsteils 8 of the respective chamber 5a, 5b and on the inner wall surface 20 of the carrier 6 is formed in each case one adapted to the respective external thread internal thread. The heat conduction from the electrodes 4 to the spark plug housing 2 is improved when the carrier 6 is screwed or welded onto the end paragraph 18 or screwed or placed and then welded or connected by multiple circumferential welds with the final paragraph 18.

The ground electrode carrier 6, and in particular also the portion 41 of each finger-like ground electrode 4 leaving the carrier 6, are arranged at a distance 21 from the inner wall surface 7 of the chamber 5a or 5b. This distance is provided in order to ensure a defined or independent current flow in the ground electrode carrier 6 and the chamber 5a and 5b and the wall part 8 regardless of the ground electrode support 6 screw on the spark plug housing 2 or to be able to remove it. Furthermore, as already mentioned above, the distance 21 enables an independent or defined heat dissipation from the electrodes 4 to the spark plug housing 2.

In Fig. 1 and 11 a spark plug is shown with a chamber which is formed as antechamber 5a and thus surrounds the mass electrodes 4 and the center electrode 3 on the peripheral side and the combustion chamber side, ie on all sides. In Fig. 4, 5 . 6 and 10 is a Spark plug with a vortex chamber 5b shown, which surrounds the ground electrodes 4 and the center electrode 3 only circumferentially. The spark plug according to the invention may have an antechamber 5a or a swirl chamber 5b. Also, mixed types or modifications of such chambers can be provided.

A simple construction and a simple production of the corresponding parts result if, as in Fig. 1 . 4 . 5 6, 10 and 11 shown, the wall part 8 of the combustion chamber side open vortex chamber 5b or the wall part 8 of the center electrode 3 and the ground electrodes 4 surrounding prechamber 5a and the ground electrode carrier 6 have annular cross-section or are each formed by a cylinder ring.

In a pre-chamber spark plug, as in Fig. 1 is shown, it is advantageous if the combustion chamber side of the cylindrical wall portion 8 of the antechamber 5a a delimiting or final, preferably flat or dome-shaped, end wall 9 is worn or integrally formed with the wall part 8, wherein advantageously in Wall part 8 and / or in the end wall 9 passage recesses 10 are formed for the passage of ignited gas jets.

For an improvement of the ignition properties, it may be provided that the total area of the passage recesses 10 in the end wall 9 of the antechamber 5a is 1 to 3%, preferably 1.5 to 2.5%, of the surface of the end wall 9.

A simple production and the ignition properties are supported when the carrier 6 and the cylindrical annular wall part 8 of the respective chamber 5a, 5b are arranged concentrically to form a predetermined distance 21 to each other.

The distance 21 between the support 6 and the wall part 8 of the respective chamber 5a, 5b is advantageously less than the thickness 22 of the wall part 8 of the chamber 5a, 5b. The thickness 23 of the carrier 6 may be three to fifteen times, preferably five to ten times, of the spark gap 13.

The distance 21 between the outer wall surface 29 of the carrier 6 and the inner wall surface 7 of the chamber 5a and 5b is advantageously 50 to 200% of the thickness of the spark gap 13. The above-mentioned features positively influence the ignition and heat conduction properties.

Each finger-shaped ground electrode 4 is advantageously bent from its support 6 directly or by forming a direction of the support wall continuing section 41 in the direction of the center electrode 3 and has after another turn 30 to the center electrode 3 approximately parallel direction. This ensures that the base formed by the ground electrode support 6 a correspondingly greater distance from the center electrode 3 than those surfaces of the ground electrode 4, which limit the spark gap 13 with the center electrode 3.

How out Fig. 2 . 2a, 2b, 2c, 2d and 2e As can also be seen in FIGS. 4 and 5, side-by-side tracks 40 made of a noble-metal alloy 24 are applied or melted in circumferential regions or on radially outwardly facing surface regions 12 of the center electrode 3 and / or on the surface 26 of the respective finger-shaped ground electrodes facing the center electrode 3. Instead of a directly applied or melted noble metal alloy sheet accordingly Fig. 2b can the noble metal alloy accordingly Fig. 2 and 2a be applied to areas 48 of the cylindrical portion of the center electrode 3, which are formed at most of welded or integrally molded plate-shaped areas or elevations. Also on the ground electrodes 4 such raised portions 48 can be formed, to which the noble metal alloy is melted.

For the operation of the spark plug, it has proven to be advantageous if the ground electrode (s) 4 is finger-shaped and are the combustion chamber end located end portions 11 of the individual ground electrodes 4 at a constant distance from the center electrode 3 in the longitudinal direction and / or parallel extend to the ignition gap 13 forming surface 12 of the center electrode 3. On the center electrode 3 facing end portions 11 of the ground electrode (s) 4 and / or on these end portions 11 opposite peripheral surface portions 12 of the center electrode 3, preferably only on the end portions 11 of the ground electrode 4 opposite portions of the center electrode, noble metal alloy 24 is applied or formed , in particular melted or welded. The noble metal alloy 24 is in particular formed from Ir / Rh, Pt / Rh, Ir / Pt / Rh and is alloyed or melted onto the respective surface by means of a laser operated continuously or advantageously discontinuously.

The wall part 8 of the chamber 5a, 5b, the sheath 28 of the center electrode 3 and / or the at least one ground electrode 4 with its carrier 6 are made of nickel-based alloy and / or high-temperature stainless steel and / or hot corrosion-resistant, good thermal conductivity metal alloys; the antechamber 5a can also be made of brass.

For the stable operation of such a spark plug, it has proven to be advantageous if the noble metal alloy 24 in adjacent, optionally overlapping or closely dense or merging with their lateral areas tracks 40 parallel or transverse to the longitudinal extent of the center electrode 3 on the the ignition gap 13 limiting surfaces of the center electrode 3 and / or on the end portions 11 of the individual ground electrodes 4 is applied. Advantageously, the deposition of the noble metal or the formation of the webs takes place in the axial direction of the spark plug or parallel to the longitudinal direction of the center electrode 3.

It may be advantageous if the noble metal alloy 24, in particular in adjacent webs 40, is applied in a plurality of superimposed layers 41 in order to form corresponding layer thicknesses. It is also possible to melt the precious metal alloy 24 scaly webs and / or applied in adjacent and / or superimposed webs, such as Fig. 3 shows in section.

A high stability is achieved when the noble metal alloy 24 by melting or welding of platinum and / or iridium and / or Pt / Rh and / or Ir / Rh or fused with surface areas (n) of the center electrode 3 and / or end regions (n ) 11 of the respective ground electrode (s) 4 is formed or applied. Instead of the noble metal alloy sheets 40, 4 noble metal alloy electrode platelets may be applied, in particular welded, to the raised regions 48 of the center electrode 3 and / or the end surface regions 11 of the respective ground electrode (s). Fig. 2c, 2d, 2e ).

For the production and operation of the spark plugs, it has proven to be advantageous if the number of finger-shaped ground electrodes 4 is odd or that the ground electrodes 4 do not face each other with respect to the central axis A of the center electrode 3. Thus, the application of the noble metal alloys 24 to the outgoing from the carrier 6 ground electrodes 4 is easily possible.

In particular, in this case, the production of such ground electrodes is easily possible if they are already attached to the ground electrode support 6 or integral with it, as with the corresponding application tools, that is laser welders and a correspondingly supplied noble metal alloy wire, easy access to the noble metal alloy 24 to be coated surface areas Is found.

The surface of the ground electrode 4 facing the center electrode 3 and / or its noble metal alloy 24 may be adapted to the surface course of the center electrode 3 or the noble metal alloy 24 applied thereto or have a comparable curvature.

Furthermore, it can be provided that in the wall part 8 of a chamber 5a, 5b opposite each ground electrode 4 extending parallel to the ground electrode 4, optionally open to the combustion chamber end of the Wandungssteiles 8, slot 16 is formed, the access to the end portion 11 of the respective ground electrode 4 is released for maintenance.

Good burning properties arise when, as in Fig. 4 shown, the combustion chamber-side end of the Wandungsteiles 8 a vortex chamber 5b the combustion chamber-side end of the center electrode 3 and the provided ground electrodes 4 surmounted.

For the operation of such spark plugs, it has proven to be advantageous if the ignition gap 13 or the distance between the individual ground electrodes 4 and the center electrode 3 and the noble metal alloy 24 applied to the respective ground electrode 4 and / or on the center electrode 3 0.1 to 1.0 mm, preferably 0.15 to 0.5 mm.

Stable ignition surfaces are obtained when the noble metal alloy 24 is applied in particular adjacent tracks 40, wherein the width B of the applied webs 40 is 1.5 to 8 times, preferably 2 to 5 times, the height H of the applied web 40 , It is advantageous if the width B of an applied web 40 is one third to one tenth, preferably one quarter to one eighth, the width of the end region 11 of a finger-shaped ground electrode 4 in the region of the ignition gap 13. The cross-section of the tracks 40 may be rectangular or correspond to the elongated half of an ellipsoid.

Also in the embodiments of spark plugs according to 4 and 5 is provided that the surrounded by a vortex chamber 5b, finger-shaped ground electrodes 4 are bent from its support 6 to the center electrode 3 and that at this bent portion 51, an end portion 11 of the finger-like ground electrode 4 connects, which is substantially parallel to the surface of the center electrode. 3 runs and the center electrode 3 facing surface 26 and / or the surface 14 of the end portion 11 of the ground electrode 4, the noble metal 24 has.

For the operation and the ignition behavior of the spark plugs, it is, as in Fig. 1 illustrated, advantageous when in the wall part 8 and / or in the top wall 9 of the antechamber 5a through recesses 10 are formed, exits through the ignited in the antechamber 5a fuel in the form of burning gas jets, the arrangement and direction of the individual Durchtrittsausnehmungen 10 is made so that a number, preferably all, of the gas jets leaving the pre-chamber 5a propagate in diverging directions.

The end wall 9 and the cylindrical wall 8 of the antechamber 5a may be integrally formed or joined together by welding.

When applying the noble metal alloy 24 on the corresponding surfaces of the spark plug can, as in the Fig. 8, 9 and 12 to 14 shown schematically, proceed. In principle, it is provided that on the surfaces 26 of the On the combustion chamber side, the central electrode 3 facing end portions 11 of the ground electrodes 4 and / or on the center electrode 3, in particular on the radially oriented, combustion chamber side surface areas 12, optionally in several steps, precious metal alloy 24 on or melted and / or welded. For this purpose, a wire or rod 44 made of noble metal alloy 24 of the respective surface 12, 26 is approximated and moved either parallel or transversely relative to the respective longitudinal extension of the finger of the ground electrode 4 and the surface or axis of the center electrode 3 and with the material of the finger 4th or the center electrode 3 or with already applied noble metal alloy firmly connected or welded or fused.

The melting and / or welding is carried out according to the invention throughout with a pulsed laser beam 43.

Fig. 8 schematically shows the application of noble metal alloy 24 in tracks 40 which are parallel to the longitudinal axis A of the center electrode 3. Similarly, the noble metal alloy can be applied in tracks on the surface 26 of the end portion 11 of the ground electrodes 4. When applying the noble metal alloy 24, a relative movement takes place between the rod or wire 44 and the surface 12 or 26.

Fig. 9 shows the application of noble metal alloy 24 on the end portion 11 of a finger-like ground electrode 4 transverse to the longitudinal extent of the ground electrode 4. This ground electrode 4 is advantageously already connected during the application of the noble metal alloy 24 with the ground electrode support 6 or formed integrally therewith.

As in Fig. 3 As shown, the noble metal alloy 24 may be deposited in adjacent webs 40 and / or limited local elongate regions, or deposited in superimposed layers 41. Depending on the desired composition of the noble metal alloy 24, mixing or alloying of, if appropriate, applied in successive application steps, possibly different noble metal alloys 24 with one another or with the surface material can take place during application.

FIGS. 12 and 13 show the application of noble metal alloy 24 on elevations 48, which are formed on a center electrode 3 in particular integrally therewith. Such surveys are from the Fig. 2 and 2a to 2e seen. Again, the noble metal alloy 24 is melted in the course of a relative movement between the center electrode 3 and the rod or wire 44 by means of a laser beam 43.

In another embodiment of the invention, the wire or bar 44 is made of noble metal alloy 24 accordingly Fig. 14a positioned on the region of the electrode 3 to be alloyed and then at the front and rear ends by means of a Melting point 56 fixed. In the same way can be applied to the surfaces 26 of the ground electrodes 4 noble metal alloy. In a further manufacturing step according to Fig. 14f the fixed piece of wire 57 is then melted or bonded to the surface 12. It can also gem. Fig. 14a to 14e a plurality of wire portions 57 are attached side by side and only as a final step, the entire noble metal wire pieces with the surface of the center electrode 3 and the surface of the end portion 11 of the ground electrode carrier fingers 4 fused or applied to these surfaces.

FIGS. 6, 10 and 11 show an embodiment of a spark plug according to the invention, in which the center electrode 3 has a plurality of substantially mutually parallel, identically formed, fingers 31, which in each case a finger-shaped ground electrode 4 is opposite. The mutually facing, the ignition gap 13 bounding surfaces 26 of the fingers 31 of the center electrode 3 and the finger-shaped ground electrodes 4 carry adjacent molten sheets 40 of precious metal alloy 24. The facing surfaces 12, 26 of the individual finger-like center electrodes 3 and the finger-like ground electrodes 4 with the corresponding In this embodiment, the individual finger-shaped ground electrodes 4 are arranged on a ground electrode carrier 6, which is arranged at a distance 18 from the inner wall surface of the wall electrode 8 surrounding this grounding member 8 an antechamber 5a and a swirl chamber 5b.

The tracks 40 of the noble metal alloy 24 on the center electrode 3 and on the ground electrode 4 are parallel to each other. The tracks 40 on the center electrode 3 are parallel with respect to the tracks 40 on the ground electrode 4.

The ground electrode carrier 6 and the wall part 8 of the chamber 5 a, 5 b are electrically conductively connected to the spark plug housing 2. The center electrode 3 is connected to the base center electrode 3a of the spark plug by welding, and this base center electrode 3a is guided in the insulator body 1 and electrically insulated from the housing by the insulator body.

The shape, number and size of the passage openings 10 and the flushing openings 15 in the wall part 8 is adapted to the intended use.

As Fig. 11 can be seen, the top wall 9 of the antechamber 5a is advantageously formed integrally with the wall part 8. Fig. 4 shows a spark plug with a swirl chamber 5b.

In Fig. 1 it is shown that the finger-shaped ground electrodes are integrally formed with the carrier 6; However, it is readily possible to weld the ground electrodes 4 to the carrier 6.

Fig. 3 shows the application of a noble metal alloy 24 in the form of juxtaposed, possibly laterally overlapping webs 40, wherein the individual webs 40 can also be applied in the form of superposed layers 41. The ratio of the width B and the height H of the individual webs depends on the selected alloy material and the base material.

Fig. 2 shows an enlarged view of a center electrode 3, which is composed of an electrode inner part 27 and a cylindrical inner shell 28 surrounding this cylindrical shell 28, are formed on the elevations 48. The electrode inner part can be advantageously carried out of good heat conducting material 3b.

The opposite, the ignition gap delimiting surfaces 11, 26 of the finger-shaped ground electrodes 4 and the center electrode 3 may be formed such that over the width and height of the Zündspaltes 13, the opposing surfaces, apart from the curves of the individual webs 40, parallel.

The noble metal alloy layers applied to the ground electrodes 4 and the electrode 3 may advantageously have the same structure or surface structure.

Under a noble metal alloy 24 not only the alloys of precious metals used but also the pure metals are understood. It is possible to apply pure metals or different noble metal alloys and to melt an alloy during application. The pure metals can also be deposited or applied unalloyed and form the ignition surfaces.

The surface 26 of the ground electrodes 4, which faces the center electrode 3, extends over a length range of the ground electrode 4 as it leaves the electrode carrier 6 to an extent of about 30 to 70%, in particular 40 to 60%. The ground electrodes have over their longitudinal extension a substantially constant cross-sectional shape, in particular in its portion along which the surface 26 is formed. This particular from the Fig. 1 . 4 and 5 apparent form of the ground electrodes 4 allows easy production of existing sheets or blanks and results in a defined power and heat dissipation. This constant cross-section is present in particular in the section of the ground electrodes 4, which is located on the combustion chamber side of the turn 51.

In the specific embodiment of a spark plug according to the invention FIGS. 6, 10 and 11 the ground electrodes 4 are designed such that they extend from their support 6 substantially straight and without bending in the direction of the combustion chamber and have a constant cross-sectional shape over their longitudinal extension. After a turn in the end in the direction of the intended center electrode ends the bent portion of the ground electrode 4 and forms an ignition surface 26 from. The finger-like center electrodes opposite the ground electrodes 4 have a surface 12 facing the surface 26 and are derived from a center electrode 3 placed on a base electrode 3a.

FIG. 15 shows a detailed view of a spark plug according to the invention. In a gap 21 between the ground electrode support 6 and the wall part 8 of an antechamber or a vortex chamber, a cylinder ring 50 is inserted. This cylinder ring 50 can be held in position with at least one nose 53 formed on the inner wall surface 19 of the wall part 8 and / or welded to the support 6 and / or the shoulder 17. The wall portion 50 is in operation after appropriate thermal expansion with its outer surface on the inner wall surface 19 of the chamber and with its inner wall surface on the outer wall surface 52 of the ground electrode carrier 6 at. The cylinder ring 50 is just like the ground electrode support 6 on the end paragraph 17, of which the ground electrode support 6 is supported or supported. The cylinder ring 50 may be made of brass. The height H of the cylinder ring 50 is 50 to 100% of the distance between the end paragraph 17 and the bend 51 of the finger-like electrodes. The cylinder ring 50 may advantageously be made of metal or ceramic and thus have a good thermal conductivity, such as brass.

Claims (13)

1. Spark plug of a combustion engine, particularly for the use in Otto gas engines, comprising a spark plug barrel (2) supported by an insulating body (1), and being preferably in one piece, as well as a rod-shaped or multiple fingered central electrode (3) and at least one ground electrode (4),
   wherein said central electrode (3) and said at least one ground electrode (4) are surrounded by a chamber borne by said spark plug barrel (2), particularly an antechamber (5a) or a turbulence chamber (5b), or are situated within this chamber (5a, 5b)
   wherein a wall portion (8), near said barrel, of said turbulence chamber (5b), open to the combustion chamber, or a wall portion (8), near said barrel, of said antechamber (5a), surrounding said central electrode (3) and said at least one ground electrode (4), have a circular ring-shaped cross-section or are formed each by a cylindrical ring,
   wherein the at least one ground electrode (4), as a basis, comprises a carrier (6), mounted on said spark plug barrel (2) or being arranged on it, and departing from this carrier (6) and
   wherein this ground electrode carrier (6) and every finger-shaped ground electrode (4), which departs from it, are arranged at a distance (21) from the inner wall surface (7, 19) of the chamber (5a, 5b), characterised in

   - that said ground electrode carrier (6), seen in perpendicular direction to the longitudinal axis of the spark plug, has a circular ring-shaped cross-section or is formed by a cylindrical ring,
   that two concentric cylindrical final shoulders (17, 18) are formed on said spark plug barrel (2), the inner final shoulder of which optionally surmounting the outer final shoulder (18) in the direction of the combustion chamber, and

   - that said ground electrode carrier (6) is on said inner final shoulder (17) and the wall portion (8) of the chamber (5a, 5b) is on the outer final shoulder (18) either superimposed or plugged or screwed and/or fastened by, optionally spot-shaped or seam-shaped, welding.
2. Spark plug according to claim 1, characterised in that said at least one ground electrode (4) and its carrier (6) are integrally formed or are interconnected by welding.
3. Spark plug according to claim 1 or 2, characterised in that a metallic and/or well heat conductive cylindrical ring (50) is inserted between said wall portion (8) and said ground electrode carrier (6), which, particularly during operation of the spark plug, engages the inner wall surface (19) of said wall portion (8) and the outer surface (52) of said ground electrode carrier (6).
4. Spark plug according to any of claims 1 to 3, characterised in that a, preferably plane or dome-shaped, terminal wall (9) is born by said cylindrical wall portion (8) of the antechamber (5a) at the side of the combustion chamber, which bounds or confines the inner space of the antechamber (5a), or is integrally formed with said wall portion (8), passing through recesses (10) being formed in said wall portion (8) and/or in said terminal wall (9) for allowing passage of ignited gas jets.
5. Spark plug according to any of claims 1 to 4, characterised in that one, three or five ground electrodes (4) are born by said ground electrode carrier (6) and/or that the ground-electrodes (4) on said ground electrode carrier (6) are arranged distributed at equal distances relative to each other around said central electrode (3) and/or that each one of the finger-shaped ground electrodes (4) departing from said ground electrode carrier (6), transversely to its longitudinal extension, has a rectangular or cylindrical ring portion shaped cross-section at least in partial regions.
6. Spark plug according to any of claims 1 to 5, characterised in that the at least one or each ground electrode (4) departs in the form of a finger from said carrier (6), and its terminal region (11) at the side of the combustion chamber extends parallel to the longitudinal axis (A) and/or to the facing surface region (12) of the central electrode (3) and/or that the ignition gap (13) is formed between opposing areas (12, 14) of said ground electrode (4) and said central electrode (3), which extend parallel to said longitudinal axis (A).
7. Spark plug according to any of claims 1 to 6, characterised in that at least one scavenging recess or opening (15), which preferably has a circular cross-section, is formed in said wall portion (8) of said chamber (5a, 5b) for the passage of a fuel/air mixture and/or at least one, preferably slot-shaped, recess (16) is formed for setting free at least the terminal regions (11) of the finger-shaped ground electrodes (4) at the side of the combustion chamber opposite the respective terminal region (11).
8. Spark plug according to any of claims 1 to 7, characterised in that a respective external thread is formed on the concentric terminal shoulders (17, 18), and an internal thread is formed each on the inner wall surface (19) of said wall portion (8) of the chamber (5a, 5b) and on the inner wall surface (20) of said carrier (6), which is adapted to the respective external thread, and/or that said ground electrode carrier (6) and the cylindical wall portion (8) of the chamber (5a, 5b) are concentrically arranged forming a predetermined distance (21) to each other and/or that said cylindrical wall portion (8) and said carrier (6) are plugged onto the respective shoulder (17, 18) and are fastened there by welding.
9. Spark plug according to any of claims 1 to 8, characterised in that the distance (21) between the outer surface of said ground electrode carrier (6) and the wall portion (8) of the chamber (5a, 5b) is smaller than the thickness (22) of the wall portion (8) of the chamber (5a, 5b) and/or that the thickness (23) of said ground electrode carrier (6) is the threefold up to the fifteen-fold, preferably the five-fold up to the ten-fold, of the thickness of the ignition gap (13) and/or that the distance (21) between the outer wall surface (29) of said ground electrode carrier (6) and the inner wall surface (7) of the chamber (5a, 5b) amounts to 50 to 200% of the thickness of said ignition gap (13).
10. Spark plug according to any of claims 1 to 9, characterised in that a precious metal alloy (24) or at least one lamina of a precious metal alloy is applied or fused or welded in in tracks next to each other and, optionally, on top of each other in circumferential regions or on locally limited elevations or on areas (12) outwardly oriented in radial direction of said central electrode (3) and/or on that surface (26) of the respective finger-shaped ground electrode (4), which faces said central electrode (3), or on elevations (48) formed on this surface.
11. Spark plug according to any of claims 1 to 10, characterised in that said central electrode (3) is executed in the form of a compact component or in the form of a stiffupright-leather-case-shaped component (28) filled with a material of high heat conductivity, and is optionally slipped onto the basis central electrode (3a) and is welded aroound it either once or repeatedly.
12. Spark plug according to any of claims 1 to 11, characterised in that the end of the wall portion (8) at the side of the combustion chamber of a turbulence chamber (5b) surmounts the end at the side of the combustion chamber of said central electrode (3) and/or of said ground electrodes (4) and/or that a slot (16) is formed in the wall portion (8) the chamber (5a, 5b), opposite each ground electrode (4), which extends parallel to said ground electrode (4) and, optionally is open towards the end of the wall portion (8) at the side of the combustion chamber, which makes the access free to the end region (11) of said ground electrode (4).
13. Spark plug according to any of claims 1 to 12, characterised in that the wall portion (8) of the chamber (5a, 5b) and said carrier (6) are electrically conductive and are connected to said spark plug barrel (2) in an electrically conductive manner and/or that each finger-shaped ground electrode (4) is bent (51) from its carrier (6) in the direction towards said central electrode (3) and, after a further bent (30), extends in a direction approximately parallel to said central electrode (3) and/or that the wall portion (8) of the chamber (5a, 5b), the casing (28) and/or said at least one ground electrode (4) with its carrier (6) are made of a nickel base alloy and/or high-temperature, high-grade steel and/or of hot corrosion resistant, well heat conductive metal alloys, and/or that said antechamber (5a, 5b) is made of brass.

Images