The Liebherr LI3 common-rail injector has passed subsequent validation tests following a high runtime of 20,000 hours in field testing.
The injectors completed 20,000 hours in a field endurance test without any difficulties. This equals an increase of 25 per cent as compared to the expected service life of 15,000 hours.
Even after immense testing, the injectors enable reliable engine operation without performance loss. This is also confirmed by extensive validation tests in Liebherr’s own test centres.
The use of the LI3 injector offers notable benefits including longer maintenance intervals thanks to the robust components and materials, which lead to lower maintenance costs. Less wear with an above-average service life also ensures stable engine operation and reduces the likelihood of damage or warranty claims.
The tests show that even after running for more than 20,000 hours, the injectors deliver remarkable volume stability. Despite minor changes in the rate plateau, as well as the opening and closing delay, the injection rates remain in 96 per cent of the test points within the standard limits. This guarantees consistent engine performance combined with impressive reliability and durability of Liebherr technology under tough conditions.
A detailed analysis of the injector components revealed wear meets expectations and does not affect injector functionality.
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“In our tests, we paid particular attention to the wear of the nozzle needle,” said Georg Huber, a Validation Engineer at Liebherr-Components in Germany. “During opening and closing, the needle repeatedly contacts the seat area with high force, like a hammer striking the same spot over and over again. Eventually, both the hammer and the counterpart wear out. However, our needle is coated with a highly robust DLC layer, which reduces wear not only on the needle, but also on the nozzle.”
Another test focus was the examination of cavitation inside the nozzle, around the blind hole and the spray holes. Compared to reference injectors, the Liebherr injectors exhibit minimal cavitation effects in these areas. This test is of particular importance, as cavitation can cause considerable problems during engine operation.
With relatively low cavitation effects, the injection rate and engine performance remain stable. This means the risk of nozzle rupture and the associated engine damage is considered low.
Lastly, such effects also influence the shape of the fuel spray in the combustion chamber. If the latter is impaired by wear of the spray holes, it directly affects the emission output of the engine. Hence, the minimal cavitation of Liebherr injectors ensure stable emission values.
The LI3 thereby enhances the efficiency and reliability of large engines in the power range of up to 500 kW/cyl
