DE19636537B4 - Spark plug for internal combustion engines - Google Patents

Abstract

spark plug with a metallic, tubular Casing, that on its outside for installation the spark plug in an internal combustion engine a screw thread for screwing the spark plug in a cylinder head and a key polygon for tightening the spark plug having in the cylinder head, wherein in a through bore of the housing a essentially rotationally symmetrical insulating body sealing off the housing is included and at the combustion chamber side end portion of the housing at least a ground electrode is arranged, which at a distance from the Held insulating body Facing center electrode, the spark plug has a means for contacting with a high voltage terminal, where between the screw thread (12) and the key polygon (13) a cylindrical projection (18) is provided, wherein the key width of the key-edge (13) is less than or equal to 15 mm and wherein the means for contacting with the high-voltage connection inside the insulating body (15) is arranged.

Description

The Invention relates to a spark plug, as they already varied is known. Such spark plugs have a cylindrical, metallic housing, in which, in an insulator embedded, there is a center electrode, and wherein the housing at least a ground electrode is attached. On the lateral surface of the housing In this case, a thread is provided, with which the spark plug is screwed into the cylinder head becomes. To tighten the spark plug in Cylinder head is out of the housing worked out a polygon, then put on the appropriate key is, with whose help the spark plug can be tightened in the thread.

From the DE 2 022 685 A a spark plug is known which has a cylindrical approach between a screw thread and a key polygon. In the GB 2 179 397 A is described a spark plug, the mounting dimensions are reduced with otherwise unchanged dimensions in that the usually hexahedral tool approach has more than six surfaces. In the GB 2 016 596 A It is described that the reduction of the diameter of the tool attachment of a spark plug leads to a saving of the installation space.

Advantages of invention

The Spark plug according to the invention has the advantage that by reducing the wrench size also the outside diameter of the candle key can be reduced, bringing the plug shaft in the cylinder head can also be reduced. This results in a total more compact design of the space requirement of spark plug and spark plug key in the Cylinder head, with a key width of 15mm insulator geometry can be maintained. By contacting within the ceramic becomes the length reduced the spark plug.

drawing

One embodiment The invention is illustrated in the drawing and in the following description explained in more detail. The single figure shows a spark plug in partially cut representation.

description the embodiments

The illustrated spark plug has a substantially tubular metal housing 11 , which on its outside a screw thread 12 , a key-polygon 13 having. In the area of its combustion chamber end, the housing has 11 at least one ground electrode 14 , wherein here two ground electrodes are shown. The metal case 11 comprises in a stepped through hole in a known manner a rotationally symmetrical, Elektroisolierkörper 15 which consists essentially of alumina, for example. The insulator 15 is in the metal case 11 firmly and tightly held and has in a known manner a longitudinal bore which in its connection-side region the connecting bolt 16 wearing. On the combustion chamber side of the insulator 15 is the center electrode 17 introduced into a longitudinal bore of the insulating body and over the longitudinal bore of the insulating body 15 with the combustion chamber remote connection bolt 16 electrically connected. The spark plug comes with its screw thread 12 screwed in the cylinder head, not shown. In the present spark plug is the combustion chamber side portion of the metal housing 11 with the screw thread 12 designed so that the length of the screw thread 12 is extended compared to conventional spark plugs. Furthermore, the cylindrical metal tube has a cylindrical extension 18 on. The wrench size of the key-edge 13 , which in the present case is a twelve-edged, is reduced compared to conventional candles to 15 mm and smaller. The cylindrical approach 18 , which has no thread, increases the effective clamping length and reduces the risk of loosening the spark plug. Finally, the contact is made with the high voltage terminal within the ceramic, whereby the risk of flashovers on the insulator head is reduced. This also reduces the overall length of the spark plug.

All in all results from the shortened design the spark plug and the smaller wrench size a more compact unit of spark plug, Candle plug and connection with cylinder head.

Claims (1)

Spark plug with a metallic, tubular housing having on its outside for the installation of the spark plug in an internal combustion engine a screw thread for screwing the spark plug in a cylinder head and a key polygon for tightening the spark plug in the cylinder head, wherein in a through hole of the housing in the essentially rotationally symmetrical insulating body is sealed by the housing and at the combustion chamber-side end portion of the housing at least one ground electrode is arranged, which is spaced from a center electrode held by the insulating, wherein the spark plug has a means for contacting with a high voltage terminal, wherein between the screw thread ( 12 ) and the key polygon ( 13 ) a cylindrical approach ( 18 ), the key width of the key multi-edge ( 13 ) is less than or equal to 15 mm, and wherein the means for contacting the high voltage terminal within the insulating body ( 15 ) is arranged.