Electro-magneto fuel injector

Abstract

An injector used for an internal combustion engine includes a valve needle which closes a fuel passage by being contacted on a valve seat and opens the fuel passage by separating from the valve seat, a coil and a magnetic core which are provided as a drive means of the valve needle, an anchor held in a relatively displaceable state with respect to the valve needle, a first biasing means biasing the valve needle in a direction opposite to a direction of a drive force, a second biasing means biasing the anchor in the direction of the drive force with a set load smaller than that of the first biasing means, and a restricting means restricting relative displacement of the anchor with respect to the valve needle in the direction of the drive force.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a sectional view showing an embodiment of a fuel injector according to the present invention;

FIG. 2 is an enlarged sectional view of the vicinity of a collision part of an anchor and a valve needle of a fuel injector according to a first embodiment of the present invention;

FIG. 3 is a view showing an assembly process of the fuel injector according to the first embodiment of the present invention;

FIGS. 4A to 4D are schematic views showing states of motion of the anchor and the valve needle at the time of opening the valve of the fuel injector according to the first embodiment of the present invention;

FIGS. 5A to 5D are schematic views showing states of motion of the anchor and the valve needle at the time of closing the valve of the fuel injector according to the first embodiment of the present invention;

FIG. 6 is a time chart showing an opening and closing valve operation of the fuel injector according to the first embodiment of the present invention;

FIG. 7 is a sectional view of a fuel injector according to a second embodiment of the present invention;

FIG. 8 is a sectional view of a fuel injector according to a third embodiment of the present invention; and

FIG. 9 is a sectional view of a fuel injector according to a fourth embodiment of the present invention.

Claims

1. An electromagnetic fuel injector, comprising: a valve needle which closes a fuel passage by being contacted on a valve seat and opens the fuel passage by separating from the valve seat;an electromagnet provided as a drive means of the valve needle, and having a coil and a magnetic core;an anchor held by the valve needle in a state of being relatively displaceable with respect to the valve needle in a drive direction of the valve needle;a first biasing means which biases the valve needle in a direction opposite to a direction of a drive force by the drive means;a second biasing means which biases the anchor in the direction of the drive force with a set load smaller than a set load of the first biasing means; anda restricting means which restricts relative displacement of the anchor with respect to the valve needle in the direction of the drive force.

2. The electromagnetic fuel injector according to claim 1, wherein the first biasing means and the second biasing means are both constituted by springs, the spring which constitutes the first biasing means has one end supported on a side of a housing containing the valve needle and the other end contacted on the valve needle, and the spring which constitutes the second biasing means has one end supported on the side of the housing and the other end contacted on the anchor.

3. The electromagnetic fuel injector according to claim 2, wherein in the spring which constitutes the first biasing means has the one end supported on the side of the housing which end is contacted on a spring retainer provided inside the housing for adjusting a set load of the spring, and the spring which constitutes the second biasing means has the one end supported on the side of the housing which end is contacted on a spring seat fixed to the housing.

4. The electromagnetic fuel injector according to claim 3, wherein the spring seat is formed in a guide member which guides the valve needle in its drive direction.

5. The electromagnetic fuel injector according to claim 1, wherein the restricting means is configured as contact surfaces of the anchor and the valve needle which surfaces face each other, the contact surface constructed on the anchor is contacted on the contact surface constructed on the valve needle only by the set load of the second biasing means.

6. The electromagnetic fuel injector according to claim 5, wherein when the anchor receives the drive force in a state where it remains stationary while being contacted on the valve seat, the contact surface constructed on the anchor is contacted on the contact surface constructed on the valve needle before the anchor starts to move.

7. The electromagnetic fuel injector according to claim 1, wherein movement of the valve needle in a direction away from the valve seat is restricted only by the first biasing means.

8. The electromagnetic fuel injector according to claim 1, wherein the valve needle is pressed against the valve seat by a set load obtained by subtracting the set load of the second biasing means from the set load of the first biasing means, and when the valve needle is driven by the electromagnet, it is driven against the set load obtained by subtracting the set load of the second biasing means from the set load of the first biasing means.