Keihin Corporation

Manabu Shoji

Toshihiro Tahara

Tadao Tsuchiya

Koji Sonoda

Kiyomi Honda

A fuel injection valve is provided that includes an electromagnetic actuator (A) that moves a valve body () in an inwardly-opening direction, and a magnetostrictive actuator (A) that, by passing current therethrough, elongates a movable part assembly () extending from the valve body () to a movable core () of the electromagnetic actuator (A), wherein the magnetostrictive actuator (A) is formed from a solid magnetostrictive element () provided between the valve body () and the movable core () of the electromagnetic actuator (A) so as to couple the valve body () and the movable core (), a preload spring () provided between the valve body () and the movable core () so as to apply a compressive preload in the axial direction of the valve body () to the magnetostrictive element (), and a second coil () mounted on a valve housing (H) housing the valve body (), the movable core (), the magnetostrictive element (), and the preload spring (), the second coil () elongating the magnetostrictive element () against the preload by the passage of current. By combining in this way the electromagnetic actuator and the magnetostrictive actuator equipped with the solid magnetostrictive element, a fuel injection valve of an inwardly-opening type that has good responsiveness and is capable of operating at low power consumption can be provided.

Fuel injection valve

In an electromagnetic fuel injection valve, a valve housing is formed by sequentially connecting a valve seat member, a magnetic cylinder, a nonmagnetic collar, and a stationary core. A coil housing is fittingly fixed to an outer periphery of the magnetic cylinder, and houses a coil assembly provided in an outer periphery of the stationary core. The coil housing includes a shell part surrounding the coil housing, an annular bent part bent radially inward from a front end of the shell part, and a cylindrical boss part projecting forward from a front end of the annular bent part. An inner peripheral surface of the annular bent part and an inner peripheral surface of at least a rear half part of the boss part are shrinkage-fitted to an outer peripheral surface of the magnetic cylinder. Thus, it is possible to eliminate distortion propagating to the magnetic cylinder, and eliminate a gap from fitted portions between the magnetic cylinder and the coil housing to improve magnetic efficiency, thereby exerting stabile fuel injection characteristics.

Electromagnetic fuel injection valve

In an electromagnetic fuel injection valve, a fitting surface of a valve housing, over which a seal positioning ring is fitted, is formed of a diameter smaller than that of an annular sealing surface over which a seal member is fitted. A tapered surface is provided between the fitting surface and the sealing surface, and a resilient projection is formed on the seal positioning ring, so that the projection is in pressure contact with the tapered surface in a state in which the seal positioning ring has been fitted over the fitting surface. Thus, the seal positioning ring can be retained easily and precisely in a regular position on the outer peripheral surface of the valve housing by a reaction force provided by the resilient projection and hence, no post-treatment is required.

Growing community of inventors

Miyagi, Japan

Manabu Shoji