PURPOSE: To secure high injection accuracy in a wide operating range by setting pressure difference between fuel pressure and air pressure larger as engine speed becomes higher in a device for injecting air and fuel directly into a cylinder by switching a nozzle through a valve.
CONSTITUTION: A cylinder head 4 is provided with an air-fuel injection device 19 with a fuel injection valve 22, at a part corresponding to the upper part of a combustion chamber 17 for each cylinder. Each air-fuel injection device 19 is connected to an air supply device 55 for feeding compressed air into an air chamber in the injection body of the air-fuel injection device 19 with the specified pressure, and a fuel supply device 61 for feeding fuel to the fuel injection valve 22 with the specified pressure. The fuel supply device 61 is provided with a fuel regulator 66, and the switching valve 66a thereof is moved by an electromagnetic coil, thus setting the fuel pressure to the specified value. The switching valve 66a is controlled by a control unit 67, but in this case, controlled in such a way that pressure difference between fuel pressure and air pressure is enlarged as the engine speed becomes higher.
MOTOYAMA TAKESHI
KAKO JUNICHI
