FIELD: engineering of engines, possible use in spark plugs of internal combustion engines, operating with increased degree of compression.
SUBSTANCE: spark plug for internal combustion engine contains body with side electrode and belt for folding, isolator positioned in the body, and central electrode with end piece for wire, located in the isolator. Isolator consists of external part, located outside the body, and internal part, located in the body. External section of isolator includes mutually engaged ribbed and external cylindrical sections. Internal section of isolator has planting surface and includes middle cylindrical section with fillet and end cylindrical section, in base of which a circular recess is made coaxially to central electrode. Fillet is made in front of folding belt. Cross-section of fillet by plane passing through longitudinal symmetry axis of isolator is represented by a trapezium, greater base of which is less than height of folding belt. Diameter of isolator from planting surface to fillet is equal to diameter of isolator from fillet to position of engagement with ribbed section. End section of body, exiting into cylinder, may have cylindrical section, interacting with planting surface of isolator, made on basis of end cylindrical section up to circular recess, while diameter of isolator from base to fillet and after fillet to position of engagement of external cylinder section with ribbed section is made constant. A bench may be made on internal surface of body, on the surface of isolator between base and fillet a shelf may be made, interacting with the bench of body by means of planting surface, while diameter of isolator after base and up to planting surface is less than diameter of isolator after planting surface up to fillet and less than diameter of isolator after fillet and up to position of engagement of external cylindrical section with ribbed section. Diameter D of isolator from planting surface to fillet and diameter D of isolator from fillet up to position of engagement of external cylindrical section with ribbed section may be located in range from 14 mm to 22 mm, length K of external section of isolator may be in range from 40mm to 150mm, and length L of external cylindrical section may be in range from 25mm to 55mm.
EFFECT: prevented rupturing of isolator, and also increased efficiency and reliability of spark plug operation.
5 cl, 2 dwg
