CORONA IGNITION DEVICE WITH WIRE IGNITION TIPS

Abstract

A corona ignition device is described comprising a central electrode, to which at least one ignition tip leads, and an insulator, which surrounds the central electrode. According to this disclosure, provision is made for the at least one ignition tip to comprise a plurality of wires touching each other.

Claims

1. A corona ignition device, comprising: a central electrode leading to at least one ignition tip; and an insulator surrounding the central electrode; wherein the at least one ignition tip comprises a plurality of wires touching each other.

2. The corona ignition device according to claim 1, wherein the wires are surrounded by a coating made of a different material than the wires.

3. The corona ignition device according to claim 2, wherein the different material is formed predominantly of one or more transition metals.

4. The corona ignition device according to claim 1, wherein the wires are twisted or stranded together.

5. The corona ignition device according to claim 4, wherein the plurality of wires comprises a central wire and remaining wires, the remaining wires being twisted or stranded around the central wire.

6. The corona ignition device according to claim 5, wherein the central wire is thicker than the remaining wires.

7. The corona ignition device according to claim 5, wherein the central wire is formed of a material having less burn-up-resistance than the remaining wires.

8. The corona ignition device according to claim 1, wherein the plurality of wires comprises a central wire and remaining wires, the central wire being formed of a different material than the remaining wires.

9. The corona ignition device according to claim 1, wherein at least some of the wires are formed of an alloy based on one or more metals of the platinum group.

10. The corona ignition device according to claim 1, wherein the central electrode supports a head to which the ignition tips are attached.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The above-mentioned aspects of exemplary embodiments will become more apparent and will be better understood by reference to the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0012] FIG. 1 shows an embodiment of a corona ignition device;

[0013] FIG. 2 shows a sectional view of FIG. 1;

[0014] FIG. 3 shows a partially sectional view of an embodiment of an ignition tip; and

[0015] FIG. 4 shows a top view of the ignition tip.

DESCRIPTION

[0016] The embodiments described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of this disclosure.

[0017] The corona ignition device shown in FIGS. 1 and 2 generates a corona discharge for the purpose of igniting fuel in a combustion chamber of an engine. The corona ignition device has a holder 1, which surrounds an insulator 2. Inside the insulator 2 there is a central electrode 3, which supports a head 4 with several ignition tips 6, for example in that the ignition tips are plugged into the head 4. A section 3a of the central electrode 3 may be formed of electrically conductive glass, which acts as a seal.

[0018] The central electrode 3 together with the insulator 2 and the holder 1 forms a capacitance, which is connected in series with a coil 5 connected to the central electrode 3. This capacitance and the coil 5 are part of an oscillating circuit through which, if excited, corona discharges can be generated at the ignition tips 6 of the ignition head 4. In the embodiment shown the holder 1 forms a housing in which the coil 5 is arranged. There is no need for a closed housing in which to arrange the coil. In the embodiment shown the coil 5 is arranged in a metal housing formed by the holder 1, and this houses the insulator body 2. Alternatively, the coil 5 may be arranged in some other place and may for example be connected to the central electrode 3 via a cable.

[0019] One of the ignition tips 6 of this corona ignition device is shown enlarged in FIGS. 3 and 4. The ignition tip comprises a plurality of wires 7, 8 which are touching each other and which all extend along the longitudinal direction of the ignition tip. The wires 7, 8 are surrounded by a coating 9. The ignition tip 6 may be mechanically tapered to a point, before it is placed into operation for the first time.

[0020] The wires 7, 8 are twisted or stranded. One of the wires 8 may be arranged in the center and surrounded by the other wires 7, thereby forming a core. If a central wire exists, this may be thicker than the other wires. A thicker wire 8 in the center of the ignition tip can mechanically stabilize the same.

[0021] If a thicker wire 8 is arranged in the center of the ignition tip, this may contain less burn-up-resistant material than the wires 7 surrounding it. The wires 7 may, for example, be manufactured from an alloy based on platinum metals, for example from an iridium-based alloy. If a thicker wire 8 is arranged in the center of the ignition tip, this may be formed of, for example, an alloy based on transition metals, such as an alloy based on iron, nickel or chrome.

[0022] The wires 7, 8 may be coated, twisted or stranded or generally arranged in many different configurations.

[0023] Following twisting or stranding of the wires 7, 8 they can be encased in a coating, such as with an alloy based on one or more transition metals. Iron-based, nickel-based or chrome-based alloys are particularly suitable.

[0024] While exemplary embodiments have been disclosed hereinabove, the present invention is not limited to the disclosed embodiments. Instead, this application is intended to cover any variations, uses, or adaptations of this disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

LIST OF REFERENCE SYMBOLS

[0025] 1 holder [0026] 2 insulator [0027] 3 central electrode [0028] 4 ignition head [0029] 5 coil [0030] 6 ignition tips [0031] 7 wire [0032] 8 wire [0033] 9 coating