Technical Paper
A Procedure for the Assessment of Pintle Injector Nozzle Blockage (Nozzle Coking) In Indirect Injection Diesel Engines
1986-10-01
861409
The use of small indirect injection (IDI) diesel engines in passenger cars has gained popularity, as fuel economy becomes a salient feature of vehicle running costs. The broadening in the application of this engine from light commercial vehicles has placed a greater emphasis on customer acceptability. Particular concern is being given to noise levels at low loads and speeds and at idle. Coupled with this is the need to meet the more stringent exhaust emission regulations being imposed both in the United States and Europe. The IDI engine is fitted with variable geometry pintle type nozzles, which allow small quantities of fuel to be sprayed into the combustion chamber before the main injection period. Combustion is initiated by the fuel/air mixture produced during the nozzle prelift, and the remainder of the fuel burns steadily as it is injected. Deposit formation in injector nozzles (Nozzle Coking) causes partial or total blockage in the prelift range.