Direct injection implies the fuel is injected at the top of compression stroke, but the animation shows the fuel being added during the intake stroke. This is just an inaccurate drawing showing the injector attached to the cylinder rather than the intake manifold.
Interestingly, this could be a drawing of a ultra modern gas direct injection system running in classic mode. Ford's EcoTech will, under certain conditions, operate like this picture, though I am sure that is not what the author had in mind.
This totally amazed me when I started working on cars. Both carburetors and direct injection creates a mixture of gasoline and air BEFORE this mixture enters the cylinder. Direct injection now seems like a misnomer ;) It makes a lot of sense if you think about the incredibly violent conditions inside the cylinder head though. I'm always surprised that spark plugs survive as easily as they do, I imagine a high accuracy injector nozzle in that situation would not last as long as current injectors. Has anyone done a true direct-injection design?
Jacob, can you update the drawing slightly? "The fuel injectors spray gas into the cylinder..." is incorrect, it should be closer to "The fuel injectors spray gas into the intake manifold where it mixes with air before being sucked into the cylinder"
There are true common-rail direct cylinder injection gasoline engines out there. They're not so common though, since there aren't as many advantages to it compared to a diesel engine.
Cars marketed as GDI, such as the Ford EcoBoost, inject directly in the cylinder.
Interestingly, this could be a drawing of a ultra modern gas direct injection system running in classic mode. Ford's EcoTech will, under certain conditions, operate like this picture, though I am sure that is not what the author had in mind.