Patent ID: 9651010
Date: 2017-05-16
CPC Classifications: F02M

Claim:
1. A fuel injector for directly injecting fuel into a combustion chamber of an engine, comprising: a valve needle that is disposed within a valve housing that constitutes an exterior of the fuel injector in a lengthwise direction and that opens and closes a spray hole opened to one side of the valve housing; an electromagnetic coil that is installed at a side opposite to the spray hole and causes a spray hole opening/closing operation of the valve needle to be performed; an armature that is coaxially mounted on an outer circumferential surface of the valve needle to be slidable along the outer circumferential surface of the valve needle in an axial direction so as to be positioned between the valve needle and the electromagnetic coil; a pressurizing spring that is installed to pressurize the valve needle toward the spray hole and causes the valve needle to close the spray hole in normal times; a stop ring that is fixed to an upper side of the valve needle and pressurized by the pressurizing spring; and a stop sleeve that is fixed to a lower side of the valve needle; wherein the armature is slidably movable along the valve needle between the stop ring and the stop sleeve; wherein the armature is pressurized toward the stop sleeve by a buffer spring so that when the spray hole is closed by the valve needle, a buffer gap is formed between the armature and the stop ring, and the armature is in direct contact with the stop sleeve; and wherein the buffer spring has a smaller elastic coefficient than the pressurizing spring and is configured to attenuate and suppress a bounce of the valve needle.