Fuel injector

Abstract

A fuel injector configured as a high-pressure injection valve for the direct injection of fuel into a combustion chamber includes: a housing having an housing end face on the combustion chamber side; an actuator; a valve-closure member operable by the actuator; at least one outlet orifice in the housing end face on the combustion chamber side for the fuel, the valve-closure member selectively closing or opening the outlet orifice; and a ring provided round about the outlet orifice in the housing end face on the combustion chamber side.

Claims

1. A fuel injector configured as a high-pressure injection valve for direct injection of fuel into a combustion chamber, comprising: a housing having a housing end face on the combustion chamber side, wherein at least one outlet orifice is provided in the housing end face for the fuel; an actuator; a valve-closure member operable by the actuator, wherein the valve-closure member is configured to selectively close and open the outlet orifice; and a ring provided round about the outlet orifice on the housing end face on the combustion chamber side; wherein, with respect to each of at least one of the at least one outlet orifice: the respective outlet orifice includes (a) a spray orifice and (b) a pre-stage chamber that extends from the spray orifice to a terminal edge of the respective outlet orifice on the combustion chamber side of the respective outlet orifice; the terminal edge is formed by the housing end face, which extends away from the terminal edge inside the ring; the spray orifice has a first diameter; the pre-stage chamber has a second diameter that is larger than the first diameter; an inside of the ring has a third diameter that is larger than the second diameter; a transition from the first diameter to the second diameter: (a) occurs below the housing end face within a thickness of the housing, the ring extending above the housing end face; and (b) defines a first stepped cross-sectional profile, defining a first surface that is approximately perpendicular to a longitudinal extension of the respective spray orifice, the surface being located at a transition from the respective spray orifice to the pre-stage chamber; a transition from the second diameter to the third diameter coincides with the extension of the housing end face away from the terminal edge inside the ring, which extension defines a second stepped cross-sectional profile, defining a second surface that is approximately perpendicular to the longitudinal extension of the respective spray orifice; and the second surface that is approximately perpendicular to the longitudinal extension of the respective spray orifice continues on an outside of the ring, the ring thereby interrupting between a first region of the second surface that is on the outside of the ring and that is approximately perpendicular to the longitudinal extension of the respective spray orifice and a second region of the second surface that is inside the ring and that is approximately perpendicular to the longitudinal extension.

2. The fuel injector as recited in claim 1, wherein the housing end face on the combustion chamber side is dome-shaped.

3. The fuel injector as recited in claim 1, wherein the at least one outlet orifice includes a plurality of outlet orifices on the housing end face on the combustion chamber side, each having a ring.

4. The fuel injector as recited in claim 1, wherein a ring end face of the ring on the combustion chamber side is situated one of (i) parallel to the housing end face or (ii) parallel to the tangential area of the housing end face.

5. The fuel injector as recited in claim 1, wherein a ring end face of the ring on the combustion chamber side is one of (i) inclined with respect to the housing end face or (ii) inclined with respect to the tangential area of the housing end face.

6. The fuel injector as recited in claim 5, wherein the ring end face of the ring on the combustion chamber side is gable roof-shaped in cross section.

7. The fuel injector as recited in claim 5, wherein the ring end face of the ring on the combustion chamber side is one of (i) inclined with respect to the housing end face or (ii) inclined with respect to the tangential area of the housing end face by at least 10.

8. The fuel injector as recited in claim 5, wherein the wall thickness of the ring is between 0.1 mm and 0.3 mm.

9. The fuel injector as recited in claim 5, wherein the ring extends by 0.1 mm to 0.5 mm beyond the housing end face.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 showsa sectional view of a fuel injector according to the present invention, according to all the exemplary embodiments.

(2) FIG. 2 shows a detail of a fuel injector according to the present invention according to a first exemplary embodiment.

(3) FIG. 3 shows a detail of a fuel injector according to the present invention according to a second exemplary embodiment.

(4) FIGS. 4 and 5 show details of a fuel injector of the present invention according to a third exemplary embodiment.

(5) FIGS. 6 and 7 show details of a fuel injector of the present invention according to a fourth exemplary embodiment.

DETAILED DESCRIPTION OF THE INVENTION

(6) FIG. 1 shows a sectional view of a fuel injector 1 according to the present invention. Fuel injector 1 is developed as a high-pressure injection valve for the direct injection of fuel into a combustion chamber. FIG. 1 illustrates the structure for all the exemplary embodiments.

(7) Fuel injector 1 includes a housing 2, an actuator 3, a valve-closure member 4 and a plurality of outlet orifices 5. Housing 2 is made up of a base element 6 and an insert 7 on the combustion chamber side. The side of insert 7 facing the combustion chamber is designated as housing end face 12. In this housing end face 12 are situated the plurality of outlet orifices 5.

(8) Actuator 3 includes a coil 8, that is able to be supplied with current, and a core 9. By supplying current to coil 8, valve-closure member 4 is moved via armature 9. Valve-closure member 4 includes a needle 10 and a ball 11. At the appropriate position of needle 10, ball 11 simultaneously closes all the outlet orifices 5.

(9) In FIGS. 2 through 7 an outlet orifice is in each case bordered by a broken line. This bordered outlet orifice shows a comparative example 14 as in the related art. Actually, all outlet orifices 5 are developed on housing end face 12, according to the present invention.

(10) Identical components or functionally identical components are designated by identical reference symbols in the exemplary embodiments.

(11) FIG. 2 shows a detail of fuel injector 1 according to a first exemplary embodiment. A cutout of housing end face 12 is shown facing the combustion chamber. This housing end face 12 is designed to be dome-shaped. One of the plurality of outlet orifices 5 is shown. The combustion chamber is located in the upper region, and accordingly, an injection direction 13 for the fuel is drawn in.

(12) Outlet orifice 5 is composed of a spray orifice 17 and a pre-stage chamber 18. Pre-stage chamber 18 is situated on the combustion chamber side of spray orifice 17. On the combustion chamber side of pre-stage chamber 18, a ring 15 is located on housing end face 12. Ring 15 is an integral component of housing 2, particularly of insert 7. Ring 15 has a ring end face 16 on the combustion chamber side. The edge at the transition to ring end face 16 is designated as edge 28. This edge 28 is developed as sharp-edged as possible, in order to achieve a tearing off of the flow at this point.

(13) Spray orifice 17 has a first diameter 19. Pre-stage chamber 18 has a second diameter 20. Spray orifice 17 extends over a first length 21. Pre-stage chamber 18 extends over a first length 22. The inner space of ring 15 extends over a third length 23. Ring 15 has a wall thickness 24.

(14) In the first exemplary embodiment, second diameter 20 corresponds to the inside diameter of ring 15. Moreover, second diameter 20 is developed substantially larger than first diameter 19.

(15) Wall thickness 24 is developed as small as possible, preferably between 0.1 mm and 0.3 mm, in order to avoid deposit of the fuel on ring end face 16 to the greatest extent.

(16) Third length 23 is between 0.1 mm and 0.5 mm.

(17) FIG. 3 shows in detail a second exemplary embodiment of fuel injector 1. By contrast to the first exemplary embodiment, in the second exemplary embodiment, ring end face 16 is inclined with respect to the tangential area towards housing end face 12 by an angle . Angle is about 10 in this case. Ring end face 16 is inclined outwards. This improves the blowing away of deposits on ring end face 16. Furthermore, FIG. 3 shows a radius 15 at the transition from ring 15 to housing end face 12.

(18) FIGS. 4 and 5 show a detail of fuel injector 1 according to a third specific embodiment. By contrast to the first exemplary embodiment, in the third exemplary embodiment, ring end face 16 is not developed in parallel to the tangential area of housing end face 12. In the third exemplary embodiment, ring end face 16 is gable roof-shaped, as seen in cross section. The two subareas of ring end face 16 are inclined by an angle , so that the peak, or rather the gable roof shape is created. This development of ring end face 16 promotes the blowing away of deposits.

(19) FIGS. 6 and 7 show fuel injector 1 according to a fourth specific embodiment. In the fourth exemplary embodiment, ring end face 16 is gable roof-shaped, as in the third exemplary embodiment. Furthermore, in the fourth exemplary embodiment, an inside diameter 27 of ring 15 is enlarged. Inside diameter 27 is thus larger than second diameter 20. This creates a step or a shoulder at the transition from pre-stage chamber 18 to the inner space of ring 15.

(20) This different development of the inside diameter at ring 15 and pre-stage chamber 18, and the edge thereby created at the transition may advantageously be used on all the exemplary embodiments, and is not dependent upon the gable roof-shaped embodiment of ring end face 16.