INJECTOR UNIT FOR THE INJECTION OF FUEL, AND METHOD FOR THE OPERATION OF AN INJECTOR UNIT OF THIS TYPE

Abstract

The injector unit according to the disclosure comprises a seat plate with a through opening extending through the seat plate, an armature element which can be placed onto the seat plate, in order to close the through opening, a spring element pushing the armature element in the direction of the seat plate, in order to close the through opening, an electromagnet designed to load the armature element with a force, in order to lift the armature element from the seat plate, and a stop for limiting a stroke of the armature element in a state in which it is lifted from the seat plate. The injector unit is characterized by a control unit designed to reduce an actuating signal of the electromagnet for lifting the armature element from the seat plate before the armature element contacts the stop for the first time after being lifted from the seat plate.

Claims

1. An injector unit for injecting fuel comprising: a seat plate having a passage opening that extends through the seat plate; an armature element that is placeable onto the seat plate to close the passage opening; a spring element that urges the armature element in the direction of the seat plate to close the passage opening; an electromagnet that is configured to apply a force onto the armature element to raise the armature element from the seat plate; and an abutment for bounding a stroke of the armature element in a state raised from the seat plate, wherein a control unit that is configured to reduce a control signal of the electromagnet to raise the armature element from the seat plate before the armature element contacts the abutment for the first time after a raising from the seat plate.

2. The injector unit in accordance with claim 1, wherein the control unit is configured to reduce the control signal of the electromagnet by more than 50% from a starting value at the start of the raising procedure.

3. The injector unit in accordance with claim 2, wherein the control unit is configured to raise the control signal again after a reduction of the control signal of the electromagnet of a starting value at the start of the raising procedure.

4. The injector unit in accordance with claim 3, wherein the control unit is configured to raise the control signal of the electromagnet again once the armature element has contacted the abutment for the first time after a raising from the seat plate; and/or when the stroke of the armature element reaches a reversal point or is close thereto in time.

5. The injector unit in accordance with claim 3, wherein the control unit is configured to transmit the control signal in a binary manner, that is only to transmit the control signal states On and Off.

6. The injector unit in accordance with claim 3, wherein the seat plate is configured in a closed state of the passage throttle to separate a low pressure region and a high pressure region of the fuel.

7. The injector unit in accordance with claim 3, wherein the space that is provided for the carrying out of the stroke of the armature element is filled with a fluid.

8. The injector unit in accordance with claim 3, wherein an armature guide is furthermore provided to guide the armature element on a stroke procedure, said armature guide.

9. The injector unit in accordance with claim 3, wherein the electromagnet has a magnetic core and a coil that partially or completely receives the magnetic core.

10. The injector unit in accordance with claim 3, wherein the abutment is a front surface of the electromagnet.

11. A method of operating an injector unit for injecting fuel wherein, in the method, an armature element is raised from a seat plate against a spring force exerted by a spring element in the direction of the seat plate by means of an electromagnet to release a passage opening of the seat plate, wherein the control signal of the electromagnet, that effects a raising of the armature element from the seat plate, is reduced before the armature element contacts an abutment that bounds the stroke of the armature element for the first time after a raising from the seat plate.

12. The method in accordance with claim 11, wherein the control signal of the electromagnet is reduced by more than 50%, from a starting value at the start of the raising procedure.

13. The method in accordance with claim 3, wherein the control signal is raised again after a reduction of the control signal of the electromagnet to a range of at least 50% of a starting value at the start of the raising procedure.

14. The method in accordance with claim 13, wherein the control signal of the electromagnet is raised again once the armature element has contacted the abutment for the first time after a raising from the seat plate; and/or when the stroke of the armature element reaches a reversal point or is close thereto.

15. The method in accordance with claim 3, wherein the control signal is of a binary nature, that is only the control signal states On and Off are transmitted to the electromagnet.

16. The injector unit in accordance with claim 2, wherein the control unit is configured to reduce the control signal of the electromagnet by more than 90%, from a starting value at the start of the raising procedure.

17. The injector unit in accordance with claim 3, wherein the control unit is configured to raise the control signal again after a reduction of the control signal of the electromagnet to a range of at least 90%, of a starting value at the start of the raising procedure.

18. The injector unit in accordance with claim 7, wherein the space that is provided for the carrying out of the stroke of the armature element is filled with the fuel.

19. The injector unit in accordance with claim 8, wherein the armature guide extends from the seat plate in the direction of the abutment.

20. The injector unit in accordance with claim 10, wherein the abutment is a front surface of a magnetic core of the electromagnet.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0038] Further details and features of the disclosure will become apparent with reference to the following description of the Figures. There are shown:

[0039] FIG. 1: a diagram for the illustration of the control signal in accordance with the disclosure with respect to the prior art; and

[0040] FIG. 2: an enlarged detail of a partial sectional view around the seat plate of a fuel injector.

DETAILED DESCRIPTION

[0041] FIG. 1 shows two diagrams arranged above one another over the time t, with the upper one of the two diagrams showing the curve of a control signal I, or of the current supplied to the electromagnet in accordance with the disclosure (solid line A), and in accordance with the prior art (dashed line B). The diagram arranged therebelow shows the movement (x) of the armature element in dependence on the different control signals, with the dashed line representing the control behavior in accordance with the prior art and the continuous line showing the control in accordance with the disclosure.

[0042] It can be seen from the diagrams that the armature element lies on the seat plate at the time to so that the passage opening is sealed.

[0043] If now at the time to the current signal I for controlling the electromagnet is set to a value I.sub.1 that is different from zero and that has the result that the armature element is moved from the seat plate in the direction of a stroke-bounding abutment, the armature element first moves slowly and then at an ever faster speed in the direction of the abutment (cf. dashed line B). The attractive magnetic force increases constantly here as the distance between the armature and the electromagnet decreases and the armature element is increasingly accelerated until the armature element is abruptly braked by an abutment (X.sub.stop). There is subsequently a pronounced bounce behavior of the armature at the abutment. The bounce has a negative effect on the settability of the magnetic valve and on the feedback on the hydraulic switching behavior and increases the wear at the magnet and at the armature element.

[0044] On the termination of the bounce, the armature element remains at its abutment in the position remote from the passage opening until the control signal I.sub.1 is switched off at the time t.sub.0. The current flow through the coil is then completely depleted and the magnetic field degenerates, with some of the magnetic field being maintained for a brief time due to remanence effects and eddy current influences. As soon as the abating magnetic force no longer overcomes the spring force, the armature is urged back onto the seat plate by the spring.

[0045] The bounce at the maximum deflection of the armature element at the distance X.sub.stop is problematic here.

[0046] The bounce of the armature at the abutment X.sub.stop spaced apart from the seat plate should be prevented or at least greatly reduced with an improved control signal in accordance with the disclosure. Provision is made in accordance with the disclosure to interrupt or reduce the control signal at least once during the attraction of the armature in the direction of the abutment or of the magnet.

[0047] After the current signal I for controlling the electromagnet has been set to the value I.sub.1 at the time to—exactly as in accordance with the prior art—the armature element starts to move from the seat plate in the direction of the abutment.

[0048] Provision is, however, now made in accordance with the disclosure to already reduce the control signal, or to reset it to zero as shown in FIG. 1, before a contact of the armature element with the abutment. The attractive magnetic force is hereby reduced so much at times that the armature subsequently continues to move due to the forces acting on it such that it impinges on the upper abutment at a speed of zero or at least at a very low speed. The bounce is thereby completely prevented or at least very much reduced.

[0049] In the ideal case, the control signal is activated again (last control signal activation at the time t.sub.2) as soon as the armature impinges on the second abutment at a speed of zero or close to zero so that the armature is held in abutment until the control signal is finally ended (time t.sub.3). The case is, however, also covered by the disclosure according to which the armature either does not reach the abutment or reaches it at a speed greater than zero. The control signal is then activated again in a time range in which the armature speed is closed to zero (time t.sub.3). The bounce can, however, not be completely suppressed, but is significantly reduced in comparison with the conventional control.

[0050] If it is no longer desired that the armature element releases the passage opening of the seat plate, the control signal is deactivated at the time t.sub.3, whereby the armature element is urged by the spring element in the direction of the seat plate and impinges there—in a similar manner as at the abutment spaced apart from the seat plate on an energizing of the electromagnet in accordance with the prior art.

[0051] FIG. 2 shows an enlarged detail of a partial sectional view around the seat plate 2 of a fuel injector 1.

[0052] The representation is only shown on one side of the symmetrical axis 12. It can be recognized at the lower end of the representation that the seat plate 2 has a (centrally arranged) passage opening 3 that can be closed by the placing on of an armature element 4. The armature element 4 is here guided in an armature guide 9 that permits a targeted movement of the armature element 4. A spring element 5, typically in the form of a spiral spring, that urges the armature element 4 in the direction of the seat plate 2 is provided above the armature element 4, that is at the side of the armature element 4 remote from the seat plate 2. The spring element 5 is here automatically supported at an electromagnet 6, 7 and receives an abutment 8 that bounds the stroke movement (indicated by x) of the armature element 4 in the interior of its windings. The front side 10 of the electromagnet 6, 7 facing the armature element 4 can, however, also serve as an abutment in accordance with a variant of the disclosure. There can also be recognized by the reference numeral 11 a coil jacketing of the coil 7 that is arranged in a cutout of the magnet core 6. Reference numeral 13 furthermore shows the axial direction of the injector.

[0053] The symmetrical axis 12 here shows the substantially pivotably symmetrical or rotationally symmetrical basic design of the injector.