PURPOSE: To prevent water and fuel supplied to the interior of a fuel sump of an injection valve from leaking from a clearance between the outer peripheral surface of a needle valve and the inner peripheral surface of a nozzle tip to the spring chamber side in a water injection type diesel engine adapted to inject fuel and water into a cylinder.
CONSTITUTION: A first annular groove 101 communicating with the atmosphere is provided a little to a fuel sump 12 along the longitudinal direction of a needle valve 11, and a second annular groove 203 to which pressurized oil is supplied is provided a little to the needle valve spring chamber 16 side on the sliding surface 34 of a nozzle tip 10 of an injection valve 200, whereby water and fule can be completely prevented from leaking to the needle valve spring chamber 16 by the atmosphere open operation of the first annular groove 101 and the sealing operation of pressurized oil in the second annular groove 203.
TOSA YOZO
YASUEDA SHINJI
