The hole-type nozzle ought to transport the fuel with very high pressure in a pointed injection spray into the wall of the piston of the direct injection diesel-engine. The fuel subsequently combusts layer by layer. Variations in pressure should be avoided.
How it works
One or two preloaded springs in the case, above the nozzle, keep the needle closed.The fuel is pressed with high-pressure (see the arrow) into the nozzle case, lifting the needle in the center. This releases 1 - 8 bores, dependent on the design. For passenger cars, the diameter of the bores is less than 0,2 mm. The smaller the volume of the bores, the better the combustion, and, of course, the fewer the exhaust emissions.
Only few companies own a patent for the fittings of less then 1/1000 mm between nozzle and nozzle case. The needle should not be touched from aside. The assembly of the needle is difficult.
Due to the sensitivity of the nozzle, the diesel fuel has to be filtered very well, and there are special regulations for the disassembly of the nozzle. Furthermore, one should always use appropriate tools. (see picture 4)
Throttle pintle nozzle