Patent attributes
A fuel injection valve includes a body having a high pressure fuel passage and a nozzle hole, which is connected to the passage, a nozzle needle opening/closing the hole and having a needle piston part, a piezo stack extended when the stack is charged and contracted when the stack discharges electric charge, a cylinder, in which the needle piston part is slidably inserted and which is driven by the stack, a fixed piston having a fixed piston part that is slidably inserted in the cylinder and that has a larger diameter than the needle piston part, an oil-tight chamber between the needle piston part and the fixed piston part in the cylinder, and a nozzle spring urging the needle in a valve closing direction. The cylinder is displaced due to extension/contraction of the stack, so that volume of the chamber increases/decreases and the needle opens/closes the hole.
