EP1265328B1 - Spark plug of an internal combustion engine - Google Patents

Abstract

The device has an insulator body (1), at least one fixed earth electrode bearer arrangement and at least one fixed central electrode bearer. An ignition plug housing of at least two parts encloses the insulator body and has upper and lower parts (3,4). At least the insulator body part on the combustion chamber side is preferably completely enclosed by the lower housing part together with the upper housing part in a pressure tight manner. AN Independent claim is also included for a method of manufacturing an inventive device.

Description

The present invention relates to a spark plug of an internal combustion engine, in particular for use in gasoline engines, with an insulator body, with at least one fixed ground electrode support assembly and with at least a fixed center electrode carrier, wherein at least one housing upper part and a housing lower part having spark plug housing the insulator body at least partially surrounds, wherein at least the combustion chamber side of the Insulator body of the lower housing part together with the upper housing part pressure-resistant, preferably completely, is included.

Currently available spark plugs for industrial gas engines are in many cases products derived from the automotive industry and by corresponding improvements for preferential use in industrial gas engines were adjusted. These candles usually have a fixed cylindrical Center electrode, which is provided with a noble metal pin. At the fixed Ground electrodes become both the hook electrode and two to four laterally mounted electrode fingers used. Such ground electrodes can also be provided with a precious metal plate. Spark plugs of this type are made EP 0834973 A2, EP 0859436 A1, EP 1049222 A1, DE 19641856 A1 and from the WO 95/25372 known. Spark plugs with multi-part spark plug housings are e.g. out GB 156,087 A or US 6,152,095 A. A major disadvantage This known in the prior art spark plugs is that their compressive strength is not sufficiently well trained for a permanent operation. So It often happens with spark plugs according to the prior art for unintentional Squeezing the insulator body or the base center electrode. Happens this in operating conditions in which a high internal pressure in the cylinder of the internal combustion engine prevails, it may in the prior art to an explosive Imposition of insulator body and / or base center electrode come under what also pose a threat to the operating staff present.

In US 5,918,571 as well as in GB 22 49 345 A is in each case a spark plug according to the preamble of claim 1 shown in which an upper housing part and a lower housing part of the insulator body include. In said US Patent upper housing part and lower housing part an overlap area in which they are pressed together. Through this Measure is indeed achieved a certain compressive strength. At the especially at Industrial gas engines occurring peak pressures in the combustion chamber reaches this but not yet. In GB 22 49 345 A is alternatively proposed, the Screw housing parts together. When screwing it is difficult to always achieve the same bias. This carries the risk that the Gaskets between the housing parts and the insulator body not optimal seal and thereby it comes to the gas outlet from the spark plug. Furthermore requires a gland sufficient wall thickness of the upper housing part and Lower part into which the threads can be cut. This leads to that Disadvantage that these relatively wide spark plugs have an increased space requirement.

The object of the invention is therefore to avoid the disadvantages listed above and a particularly flameproof, but also easy to manufacture spark plug available to deliver.

This is inventively achieved in that the upper housing part and the Housing base are welded together.

Due to the inventive design of the spark plug with a Housing base and an upper housing part, the individual parts can be very pressure resistant manufactured, then pushed onto the insulator body and by welding be assembled in such a way that a very pressure-resistant spark plug arises. Following welding occurs when cooling the spark plug housing a shrinkage process, which leads to a further bias. As a result, the conveniently provided seals between Insulator body and spark plug housing additionally pressurized, thereby a particularly good seal is achieved.

In the case of the spark plug thus produced, the composite comprises housing lower part and Housing upper part of the insulator body of the spark plug in such a way that an unwanted Extruding the insulator body or the base center electrode from the spark plug housing effectively prevented. The terms housing lower and upper part refer to the normal installation position of a spark plug, in which the Lower part of the housing towards the combustion chamber and the upper part of the housing pointing upwards in the direction of the spark plug connector.

With regard to the connection of the individual parts of the spark plug housing it is particularly favorable that these in their contact area before welding pushed together and / or optionally additionally pressed. By this kind the connection in the contact area between the individual parts of the Spark plug housing is made a particularly flameproof spark plug.

To attach the spark plug in the cylinder, it is particularly advantageous that at least a part of the spark plug housing a thread for screwing in a Cylinder head has.

Favorable embodiments provide that the individual parts of the Spark plug housing made of electrically conductive material and / or the Connections of the individual parts of the spark plug housing in their respective Contact area are formed conductive. This allows the spark plug as electrically conductive connector between at least one ground electrode and the cylinder or engine block are used.

The compressive strength of the spark plug is particularly preferred Embodiments further reinforced by the fact that the insulator body at least one preferably extending over its entire circumference bead which preferably has at least one contact area of at least two Housing parts, is arranged, with the welding offers on the bead.

Cheap embodiments of the multi-part constructed and electrically conductive Spark plug housing provide that the Masselektrodenträgeranordnung am Spark plug housing is arranged and has at least one ground electrode. The Designation Ground electrode carrier assembly refers to a Arrangement of at least one ground electrode carrier on which in turn at least one ground electrode is arranged.

To ensure a long life of the spark plug see individual preferred embodiments, that the ground electrode support assembly, preferably four perpendicular to each other, flat, preferably after having pointing inside, ground electrodes. Here again it is favorable that at least a ground electrode and / or at least one ground electrode support assembly welded to at least a portion of the spark plug housing and / or is integrated in at least part of the spark plug housing.

In the counterpart to the ground electrodes and the ground electrode support assembly specially designed center electrode carrier is special favorable, that at least one, preferably four, arranged perpendicular to each other - planar - preferably outwardly facing - center electrode (s) on the central electrode support is arranged (are). Here, the center electrode carrier as also the ground electrode carrier arrangement one or more individual electrode carrier and electrodes. It is particularly favorable that the electrodes of the Center electrode carrier and the ground electrode carrier assembly in pairs plane-parallel opposite an insulating air gap between each other are arranged. By such an arrangement is a very good and reliable ignition of the fuel-air mixture as well as a long time Life of the flameproof spark plug reached.

A particularly pressure-resistant variant is achieved in that the center electrode carrier is shouldered on the insulator body and / or the Base center electrode surrounds and / or with the base center electrode preferably completely welded. This is mainly an unwanted expressions of Base center electrode from the spark plug prevented.

In terms of a long life of the spark plug look particularly favorable Embodiments before that the edge length of the center electrodes and / or the Ground electrodes greater than 4 mm, preferably greater than 6 mm. Another Improving the life of the electrodes is achieved in that the Electrodes of the center electrode support assembly a coating of precious metal and / or precious metal platelets.

For producing such a spark plug provides a favorable method that the individually manufactured housing parts of the spark plug housing, via a standard standard insulator body pushed and / or pushed over each other and welded. As a result, a standard insulator body for the production a spark plug according to the invention can be used, which the production costs significantly reduced for such a spark plug. It is preferably provided that the housing parts be welded together by laser. It is particularly favorable about it In addition, the center electrode carrier made in advance, flush on a Base center electrode of the insulator body pushed to the insulator base and is welded.

Further favorable embodiments provide that the ground electrode carrier assembly with at least a portion of the spark plug housing welded or integrated in at least part of the spark plug housing is manufactured and that for welding a pulsed and / or continuously working laser welding process and / or electron beam welding process and / or plasma welding and / or high vacuum soldering and / or Electrode beam welding process and / or plasma welding process and / or high vacuum soldering and / or resistance welding technique becomes.

Fig. 1 eine Schnittdarstellung einer erfindungsgemäßen Zündkerze.

Further features and details of the present invention will become apparent from the following description of the figures. Showing:

Fig. 1 is a sectional view of a spark plug according to the invention.

In the spark plug according to the invention is on a standard insulator body like him used commercially by various spark plug manufacturers is resorted to.

This insulator body 1 (usually made of ceramic) is under double-sided supplement a seal 2 inserted into a spark plug housing upper part 3. The Spark plug housing lower part 4 is also pushed onto the insulator body 1. In a further production step, upper and lower part 4 are preferably in Area of Isolatorwulst 15 pressed together. Being in the pre-stressed state the housing parts welded together by means of laser 5.

By this construction, the upper housing 3 can be designed very stable pressure. A motor pressure conditional expressions of the insulator body 1 is thus prevented. By the welding process in the contact region 5 on the biased housing 3 are the housing components permanently biased and thus it comes to a seal between housing 3.4 - seal 2 and insulator body. 1

As materials for housing top and bottom 3,4 can weldable structural steels, Stainless steels and their alloys but also nickel-based alloys or Brass alloys are used. The advantage of the brass housing is in the better heat dissipation.

Due to the selected bivalve shape of the housing can be a very compact High pressure candle with eg M18 x 1.5 thread 13 are made.

At the lower housing part 4, a ground electrode carrier arrangement 6 can be provided on the motor side be applied. In the specific case, for reasons of temperature and Hot corrosion resistance of a ground electrode support assembly 6 from Inco Alloy 600 (WNr 2.4816) welded by laser to the housing in area 7. As alternatives also other nickel base alloys or High-temperature stainless steels are used. Of the If appropriate, ground electrode carrier arrangement 6 could also be made in one piece be made as an integral part of the housing base 4.

By the execution of the ground electrode support assembly 6 with 4 electrode fingers ensures good mixture accessibility.

The ground electrode carrier arrangement 6 are provided with noble metal plates (= Ground electrodes 9) provided, these are by laser on one side or both sides with welded to the carrier 6. The weld is attached to the Electrode sides of the gap is closed. That means between precious metal tiles and electrode carrier fingers, there is no open gap (or opening) through which Gas can enter.

This construction makes it possible in relation to the compact Total component size to produce very long electrode erosion edges. It will be on the ground electrode support assembly noble metal plate 9 with an edge length greater than 4.0 mm used.

In the specific case, the edge length of the ground electrode 9 is 6.25 mm.

In the ground electrodes 9 come platelets with dimensions of 6.25 x 1.6 x 0.5 mm (other dimensions may be used). As Noble metal may e.g. Pt Rh alloys (90/10, 95/5, 80/20, 75/25) used become.

The welding process can be pulsed lasers, continuous lasers (CW lasers) , Electron beam welding or vacuum and Hochvakuumlötverfahren and plasma welding or Resistance welding technology can be used.

The base center electrode 12 of the insulator body 1 is provided with a Center electrode carrier 10 welded in the area 11. Through the center electrode carrier 10, in coordination with the ground electrode support assembly 6, the spark location be determined. The center electrode carrier 10 is placed on the base center electrode 12 pushed until it rests flush on the insulator base 14. In this position he will be with the base center electrode in the region 11 welded. By this arrangement, the Center electrode support 10 and the base center electrode 12 high pressure safe. On Squeezing out of the insulator base of the base center electrode due to the Motor pressure is not possible since the welded to the base center electrode 12 Center electrode support 10 is shouldered 14 on 14 insulator base. The Welded joint 11 between electrode carrier and electrode is through the Welding made with a pulsed laser. However, it can also be one continuous laser (CW laser), the electron beam welding process, a Soldering or resistance welding technology can be used.

The weld 11 may be along the entire length of the base center electrode 12 take place from the outside so by the center electrode carrier 10 on the Base center electrode 12 is welded through. It can be one or more Spot welds and one or more weld seams which in the Longitudinal axis if necessary several times on the circumference or radially if necessary several times on Scope can be arranged.

The center electrode carrier 10 is designed so that it has a good mixture accessibility allows. The inventive design is an easy readjustment possible. The center electrode carrier is designed so that center electrodes 8 with a Length greater than 4 mm can be welded. In the concrete invention the edge length of the center electrode 8 is 6, 25 mm. The center electrode carrier 10 is designed with 4 separate electrode fingers on which precious metal electrodes are welded as center electrodes 8.

The center electrode arrangement 10 are provided with noble metal platelets as center electrodes 8 These are laser-sided or on both sides with the carrier welded. The weld is mounted so that at the electrode sides of the Gap is closed. That means between precious metal plates and Electrode carrier fingers, there is no open gap (or opening) through which Gas can enter.

As a center electrode carrier material Inco Alloy 600 (WNr. 2.4816). As alternatives, other nickel-based alloys may also be used or high-temperature stainless steels are used.

In the center electrodes 8 come platelets with dimensions of 6.25 x 2.0 x 0.5 mm (other dimensions may be used). As Noble metal may e.g. Pt Rh alloys (90/10, 95/5, 80/20, 75/25) used become.

Claims (16)

1. A spark plug of an internal combustion engine, in particular for use in Otto-cycle gas engines, with an insulator body (1), with at least one fixed ground electrode carrier arrangement and with at least one fixed central electrode carrier, wherein one spark plug housing having at least an upper housing portion (3) and a lower housing portion (4) encloses at least partly the insulator body, wherein at least the combustion chamber-side part of the insulator body (1) is, in particular completely, pressure-resistantly enclosed by the lower housing portion (4) jointly with the upper housing portion (3), characterised in that the upper housing portion (3) and the lower housing portion (4) are welded to each other.
2. A spark plug as set forth in claim 1 characterized in that the individual portions (3, 4) of the spark plug housing in their contact region (5) are pushed over one another.
3. A spark plug as set forth in claim 1 or 2 characterized in that the upper housing portion (3) and the lower housing portion (4) are welded to each other by means of a laser.
4. A spark plug as set forth in one of the claims 1 to 3 characterized in that the insulator body (1) has at least one bulge (15) which preferably extends over its entire periphery and which is preferably arranged in at least one contact region (5) of at least two housing portions (3, 4).
5. A spark plug as set forth in claim 4 characterized in that the upper housing portion (3) and the lower housing portion (4) are welded to each other on the bulge (15).
6. A spark plug as set forth in one of the claims 1 to 5 characterized in that at least one portion of the spark plug housing has a screwthread (13) for screwing into a cylinder head.
7. A spark plug as set forth in one of the claims 1 to 6 characterized in that the individual portions (3, 4) of the spark plug housing are made from electrically conductive material and/or the connections between the individual portions (3, 4) of the spark plug housing are adapted to be conductive in their respective contact region (5).
8. A spark plug as set forth in one of the claims 1 to 7 characterized in that the individual portions (3, 4) of the spark plug housing preferably each comprise at least one seal (2) in relation to the insulator body (1).
9. A spark plug as set forth in one of the claims 1 to 8 characterized in that the ground electrode carrier arrangement (6) is arranged on the spark plug housing and comprises at least one ground electrode (9).
10. A spark plug as set forth in one of the claims 1 to 9 characterized in that the ground electrode carrier arrangement (6) comprises, preferably four mutually perpendicularly arranged, flat, preferably inwardly facing, ground electrodes (9).
11. A spark plug as set forth in one of the claims 1 to 10 characterized in that at least one ground electrode (9) and/or at least one ground electrode carrier arrangement (6) is welded to at least one portion (4) of the spark plug housing and/or is integrated into at least one portion (4) of the spark plug housing.
12. A spark plug as set forth in one of the claims 1 to 11 characterized in that at least one, preferably four, mutually arranged perpendicularly - flat - preferably, outwardly facing - central electrode(s) (8) is (are) arranged on the central electrode carrier (10).
13. A process for producing a spark plug as set forth in one of the claims 1 to 12 characterized in that the individual portions (3, 4) of the spark plug housing are produced individually, pushed over a commercial standard insulator body (1) and/or pushed one over the other and welded to each other.
14. A process as set forth in claim 13 characterized in that the portions (3, 4) of the spark plug housing are welded to each other by means of a laser.
15. A process as set forth in claim 13 or 14 characterized in that the central electrode carrier (10) is produced first, pushed flush onto a base central electrode (12) of the insulator body (1) as far as the insulator base (14) and welded.
16. A process as set forth in one of the claims 13 to 15 characterized in that the ground electrode carrier arrangement (6) is welded to at least a portion (4) of the spark plug housing or produced integrated into at least a portion (4) of the spark plug housing.

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