E there are reasons why direct injection has long since replaced manifold injection in gasoline engines. The efficiency is better, the throttle losses are lower, a higher compression is possible - which in combination leads to lower fuel consumption with better performance and higher torque. However, the technology also has a decisive disadvantage: the proportion of nitrogen oxide and, above all, soot particles in the exhaust gas is significantly higher. Sometimes as high as a 10 to 15 year old diesel that has not been cleaned of particles.
Lower emissions without extensive redesign
To solve the problem, the automotive supplier Delphi is presenting a new one at the Vienna Motor Symposium Injection system for GDI engines (with injection valve directly above the combustion chamber and with swirl duct). This works with injection pressures of more than 500 bar, which should reduce particle emissions by up to 50 percent. Compared to the previous system, which already worked with up to 350 bar. A smaller number of the particularly small and therefore dangerous particles should also be produced.
Delphi promises that its new system will work without major redesigns on the gasoline engine. The challenge was to achieve such pressures without increasing the drive loads on the GDI pump. In most engines, this is driven by the camshaft, which Delphi says does not need to be redeveloped in order to use the new 500 bar system. This should also reduce emissions before they reach the catalytic converter and make additional exhaust gas aftertreatment technology superfluous, although a direct injection gasoline engine should meet the requirements for RDE tests (Real Driving Emissions).
In series production from 2022
Delphi has redeveloped all associated components for the new injection system, which is also intended to reduce fuel consumption and thus CO2 emissions: injectors and pumps as well as the corresponding engine control and software. These too should only require minor changes to existing engine designs. The 500 bar system could be used in series production from 2022 onwards.