Patent ID: 7753292

Claim:
An electromagnetic fuel injection valve comprising: a valve housing which includes: a valve seat member having a valve seat at a front end thereof; a magnetic cylinder connected coaxially to a rear end of the valve seat member; a nonmagnetic collar connected coaxially to a rear end of the magnetic cylinder; and a stationary core fittingly fixed to a rear part of the nonmagnetic collar; a valve assembly, the valve assembly including: a valve element capable of being seated on the valve seat; and a movable core connected to a rear end of the valve element and facing an attraction surface of a front end of the stationary core; a valve spring for urging the valve assembly in a direction in which the valve element is seated on the valve seat; a coil assembly disposed so as to surround a substantial entirety of a lower portion of the nonmagnetic collar and the stationary core, said coil assembly including a bobbin; and a magnetic coil housing which houses the coil assembly, and magnetically connects the magnetic cylinder and the stationary core to each other; the magnetic coil housing including: a shell part surrounding the coil assembly; a front end wall part facing a front end of the coil assembly; and a boss part press-fitted to an outer peripheral surface of the magnetic cylinder, the shell part, the front end wall part and the boss part are integrally connected together, wherein the front end wall part is formed such that a thickness thereof in an axial direction is larger than a thickness of the shell part in a radial direction, wherein a magnetic path forming part is formed by the front end wall part and a rear-side cylinder part of the magnetic cylinder which is fitted to an inner peripheral surface of the front end wall part, the magnetic path forming part surrounding the movable core substantially by the entirety of an inner peripheral surface thereof to magnetically connect the movable core and the shell part to each other, and wherein a positioning step part is formed at a rear-side cylinder part of the magnetic cylinder so as to support a front end of the coil assembly to define an axial position of the coil assembly, and the magnetic cylinder further includes a front-side cylinder part which forms a further positioning step part against which a front end of the boss part abuts to define an axial position of the coil housing; wherein a front end surface of the nonmagnetic collar is welded to an inner periphery side of a rear end surface of the rear-side cylinder part of the magnetic cylinder, and the positioning step part is annular on an outer periphery side of the rear end surface of the rear-side cylinder part to support the front end of the coil assembly, thereby defining an axial position of the bobbin, and the front end wall part of the magnetic coil housing faces the front end of the bobbin with a gap therebetween so as not to hinder contact of the bobbin with the positioning step part.