I missed that. Water injection has been around since the 1940s. I've used it myself, although not cylinder direct injection. Water both slows the flame front (more complete combustion, less preignition without TEL) and air carrying water is much more effective than dry air at turning a temp increase into expansion - and that expansion is is what an ICE is 'harvesting' via force against the top of the piston.
I'd guess the patent is around *direct* injection.
Bright side, that direct water injection might eventually be used to increase fuel economy.