With an efficiency of up to 45 per cent, diesel engines with pump-jet injection technology are among the most efficient internal combustion engines. In addition to the TDI engines with common rail injection, all TDI engines by SEAT have this modern, powerful technology.
In the pump-jet injection system, the high-pressure pump, injector valve and injector make up one structural unit. So at each cylinder the maximum injection pressure of up to 2,400 bar is produced separately. The pressure build-up is carried out mechanically. By an additional cam on the camshaft, a small piston, the so-called "plunger", is operated by a roller rocker and a plunger.
The cam is shaped so that this is done at high speed to quickly build up the required pressure. The advantages of pump-jet injection technology are lower emissions and lower fuel consumption with higher power output. The basic idea of the pump-jet system goes back as far as Rudolf Diesel himself, but who in 1905 still lacked the technical means to implement it. But he too already had the idea of introducing the fuel directly, without detours or prechambers, into the combustion chamber.
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