DE566633C - Spark plug with electrodes that consist of a mixture of high and low evaporation temperature components - Google Patents

Description

Spark plug with electrodes made from a mixture of components high and low evaporation temperatures exist. Spark gaps are already present long made the observation that the flashover voltage is very different from the nature depends on the electrode surface. This is because it cracks if the surface of the electrodes is rough a spark under a much lower voltage than with a smoothly polished surface. This is because of the peak discharges of the unevenness of the electrodes the spark gap is ionized. To use this phenomenon for spark plugs, the electrode made of any metal could be roughened, but by doing this the breakdown voltage would only be reduced for a short time because the peaks and edges of the rough surface from the heat of the jumping sparks rapidly would be burned away.

In the case of electrodes, which are made in a known manner from a mixture of components high and low evaporation temperature exist, according to the invention a permanent unevenness of the electrode created that the hard to evaporate Components in the form of very fine, elongated structures in the components lower Evaporation temperature are embedded.

At a certain temperature, which corresponds to the lower evaporation temperature of the more easily meltable constituent of the mixture, this part evaporates on the surface of the electrode, while the constituents with a high evaporation temperature remain unaffected. At the points where the less heat-resistant components of the mixture have evaporated, crater-like depressions are therefore formed in the electrode surface. In order to obtain the most effective possible roughening of the electrode, it is expedient to use the more difficult-to-evaporate constituents according to FIG. 3 in the form of very fine, preferably elongated grains b, e.g. B. of tungsten or tungsten carbide, in the more easily evaporating components c, z. B. made of chrome or * cobalt, to be embedded. You can also get electrodes with a good roughness by adding a number of tungsten wires d with a more easily evaporating material c, z. B. silver, platinum, soldered together to form a wire:

Claims (1)

PA'rENrANSYRÜCHE: i. Spark plugs with electrodes that come from a mixture consist of components of high and low evaporation temperature, characterized in that that the difficult to evaporate constituents in the form of very fine, elongated structures are embedded in the components with a lower evaporation temperature. a. Spark plugs with electrodes according to claim i, characterized in that the heavily evaporating Ingredients in the form of very fine, preferably elongated grains, e.g. B. made of tungsten or tungsten carbide, into easily evaporating constituents, e.g. B. chromium or cobalt, are embedded. 3. Spark plugs with electrodes according to claim i, characterized in that that a number of tungsten wires with a more easily evaporating material, e.g. B. silver, Platinum, to be soldered together to form an electrode pin.