| 摘要 |
PURPOSE:To ensure stable engine performance by enabling an engine to ensure fuel of required minimum limit for continuing combustion even during water injection, in the case of the engine in which NOx is reduced by injecting water into a high pressure fuel passage to an injection nozzle in a period without actuating a fuel pump. CONSTITUTION:Fuel from a high pressure pump 10 is allowed to pass through a delivery valve 14 and a high pressure passage 12 and injected into a combustion chamber from an injection nozzle 20 to perform combustion. At this time, water 30, with the pressure increased by a pressure water pump, is injected into a high pressure fuel passage 12 from its water injection point 40 via an electromagnetic valve 31 and a check valve 32 in a period without actuating the high pressure pump 10. Here, a bypass fuel passage 50, bypassing a water injection point 12' of connecting a high pressure fuel passage 41 to the high pressure fuel passage 12, is provided, and a throttle 52 is provided between a branch point 53 and the water injection point 40 while providing a check valve 51 on the halfway of the passage 50. Flow path resistance of this throttle 52 is set to avalue equal to or larger than flow path resistance of the check valve 51, and fuel or water can be allowed to flow out from both the flow paths 12', 50 without closing the check valve 51 during injection of fuel. |
