Fuel injection device

A fuel injection device for an internal combustion engine, comprising:

• a valve body having a passage for high-pressure fuel provided therein, and having a nozzle hole configured to inject the high-pressure fuel into a combustion chamber of the internal combustion engine at a tip of the valve body;
• a valve member movable in the valve body in an axial direction of the valve body to interrupt and allow supply of the high-pressure fuel to the nozzle hole;
• a housing member provided to face an end portion of the valve member, to define a pressure chamber for regulating a pressure of fuel acting on the valve member to control the movement of the valve member, the housing member having therein an inflow path for causing the high-pressure fuel to flow into the pressure chamber and an outflow path for causing the fuel to flow out of the pressure chamber;
• a control member arranged in the pressure chamber and brought into or out of contact with the housing member, to interrupt and allow communication at least between the inflow path and the pressure chamber;
• and
• a cylinder housing the control member such that the control member is movable in the axial direction, the cylinder comprising:
• a large-diameter inner circumferential surface opposed to an outer circumferential surface of the control member;
• a small-diameter inner circumferential surface having an inside diameter smaller than an outside diameter of the outer circumferential surface of the control member;
• and a stepped surface provided between the large-diameter inner circumferential surface and the small-diameter inner circumferential surface and opposed to an end face of the control member on a side of the pressure chamber, wherein
• a plurality of grooves are provided in at least one of the end face of the control member and the stepped surface of the cylinder, to divide a contact surface portion between the end face and the stepped surface into a plurality of island portions.