Patent ID: 6712297
Filing Date: 2004-03-30
Classification: F02M

Abstract:
A fuel injection device comprising:a cylindrical member, which includes a first magnetic portion, a magnetic shield portion and a second magnetic portion arranged in this order from a downstream end of the cylindrical member toward an upstream end of the cylindrical member; a valve body, which is held by the first magnetic portion of the cylindrical member and includes at least one fuel injection hole and a vale seat arranged on an upstream side of the injection hole; a valve member, which is reciprocably received in the cylindrical member and includes an abutting portion, wherein the abutting portion is seatable on the valve seat to close the injection hole and is also liftable from the valve seat to release the injection hole; a movable core, which is arranged on an upstream side of the valve member and is reciprocable together with the valve member; a stationary core, which is arranged on an upstream side of the movable core and is opposed to the movable core in the cylindrical member; an urging means for urging the valve member against the valve seat; and a coil, which is arranged radially outward of the cylindrical member to generate a magnetic force for attracting the movable core toward the stationary core upon energization of the coil, wherein the cylindrical member, the stationary core and the coil are sized to satisfy the following conditions: 5 mm&lE;La&lE;10 mm, 0 mm&lE;Lb&lE;1.0 mm, Lb&lE;Lc, and 0.5&lE;Ld/La&lE;1.5, wherein La is an axial length of the coil, Lb is an axial distance between a downstream end surface of the coil and a downstream end surface of the magnetic shield portion, Lc is an axial distance between the downstream end surface of the coil and a downstream end surface of the stationary core, and Ld is an axial length of the magnetic shield portion.