To provide a cylinder direct injection CNG engine enabling the co-existence of a homogeneous combustion and a stratified combustion and a fuel injection control method for the device.

This cylinder direct injection CNG engine 10 capable of switching between the stratified combustion and the homogeneous combustion according to operating conditions comprises an ignition plug 14 disposed at the inside center of a combustion chamber 10a, an injector for stratified combustion disposed on the intake side, an injector 25 for homogeneous combustion disposed on the exhaust side, and a piston 12 having a cavity 12a for stratified combustion. In the injector 23 for stratified combustion which solely allows stratified combustion, the orientation/spraying angle of an injection hole is set so that fuel can be injected into the cavity 12a. In the injector 25 for homogeneous combustion, the orientation (θ)/spraying angle of the injection hole is set so that fuel spray 25a does not directly enter into the cavity 12a. In both injectors 23 and 25, an injection rate is set so that injection is allowed in a compression stroke even in the maximum injection/maximum rotation, and also the minimum injection amount is maintained.

COPYRIGHT: (C)2005,JPO&NCIPI