Injection valve

Abstract

An injection valve for injecting fuel into a combustion chamber includes: a housing having at least one spray discharge orifice on a discharge side; a solenoid coil; a magnet armature linearly movable by the solenoid coil; a valve needle for opening and closing the spray discharge orifice, which valve needle projects through the magnet armature and is linearly movable along a longitudinal axis, the magnet armature being linearly movable in relation to the valve needle between a first stop and a second stop, the second stop being formed by a stop element having a stop face and a counter element having a counter face situated opposite the stop face, the stop element having an elastic design so that an angle between the longitudinal axis and the stop face is changed when the counter face strikes the stop face.

Claims

1. An injection valve for injecting fuel into a combustion chamber, comprising a housing having at least one spray discharge orifice on a discharge side; a solenoid coil; a magnet armature linearly movable by the solenoid coil; a valve needle for opening and closing the spray discharge orifice, the valve needle being linearly movable along a longitudinal axis and projecting through the magnet armature, wherein: the magnet armature is linearly movable in relation to the valve needle between a first stop and a second stop, the second stop is formed by a stop element having a stop face and a counter element provided with a counter face situated across from the stop face, at least part of the stop face is not coplanar with the counter face when the stop face is not in contact with the counter face, the stop element has an elastic configuration so that an angle between the longitudinal axis and the stop face changes when the counter face strikes the stop face, and when the solenoid is energized or shortly after the armature is energized, the armature moves in a direction towards the first stop such that the armature is released entirely from contact with the stop face of the stop element.

2. The injection valve as recited in claim 1, wherein the stop element is permanently connected to the valve needle and the counter element is permanently connected to the magnet armature.

3. The injection valve as recited in claim 2, wherein the angle between the longitudinal axis and the stop face without contact between the stop face and the counter face is at least locally smaller than 90, the angle being defined on the side of the stop face facing the counter face.

4. The injection valve as recited in claim 3, wherein the angle without contact between the stop face and the counter face is maximally 89.85.

5. The injection valve as recited in claim 3, wherein the angle is elastically deformed by at least 0.15 as a result of the counter face striking the stop face.

6. The injection valve as recited in claim 3, wherein the stop face is subdivided into an inner section and an outer section, the inner section being situated closer to the longitudinal axis than the outer section, and the angle without contact between the stop face and the counter face is greater at the outer section than at the inner section.

7. The injection valve as recited in claim 6, wherein the inner section without contact between the stop face and the counter face is one of (i) parallel to the counter face, (ii) inclined toward the counter face, or (iii) concave.

8. The injection valve as recited in claim 3, wherein an outer surface of the stop element facing away from the counter face is at least one of (i) locally inclined in relation to the stop face, (ii) locally developed parallel to the stop face, and (iii) locally developed in concave form.

9. The injection valve as recited in claim 3, wherein the stop element has at least one circumferential groove.

10. The injection valve as recited in claim 3, wherein the first stop is formed by one of a ring or a step on the valve needle.

11. The injection valve as recited in claim 1, wherein the stop face and the counter face are not in contact only when the solenoid coil is excited or shortly after energization of the solenoid coil has ended.

12. The injection valve as recited in claim 1, wherein, the magnetic armature returns to the stop element until making contact with the stop element after the energization of the solenoid coil has ended.

13. The injection valve as recited in claim 1, wherein in a non-excited state of the solenoid coil, the magnetic armature rests permanently against the stop element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows an injection valve according to the present invention for all exemplary embodiments.

(2) FIG. 2 shows a detail of an injection valve of the present invention, according to a first exemplary embodiment.

(3) FIG. 3 shows a further detail of an injection valve of the present invention, according to the first exemplary embodiment.

(4) FIGS. 4 through 7 show a movement sequence at the injection valve of the present invention, according to the first exemplary embodiment.

(5) FIG. 8 shows the injection valve of the present invention, according to a second exemplary embodiment.

(6) FIG. 9 shows the injection valve of the present invention, according to a third exemplary embodiment.

(7) FIG. 10 shows the injection valve of the present invention, according to a fourth exemplary embodiment.

(8) FIG. 11 shows the injection valve of the present invention, according to a fifth exemplary embodiment.

(9) FIG. 12 shows the injection valve of the present invention, according to a sixth exemplary embodiment.

(10) FIG. 13 shows the injection valve of the present invention, according to a seventh exemplary embodiment.

DETAILED DESCRIPTION OF THE INVENTION

(11) In the following text, a first exemplary embodiment of injection valve 1 will be discussed with the aid of FIGS. 1 through 7. Identical components or functionally identical components are designated by identical reference symbols in all exemplary embodiments.

(12) FIG. 1 illustrates the general structure of injection valve 1 for all the exemplary embodiments. Injection valve 1 includes a housing 2 having a spray discharge orifice 4 on a discharge side 3. Housing 2 supports a solenoid coil 5. A valve needle 6 including a ball 7 is disposed along a longitudinal axis 15 in the interior of housing 2. Ball 7 together with housing 2 forms a valve seat for opening and closing spray orifice 4.

(13) In addition, a magnet armature 8, which is connected to a spring cup 9, is situated inside housing 2. On a side of magnet armature 8 that faces away from the discharge is a ring 10, which is fixedly secured on valve needle 6. This ring 10 forms a first stop for magnet armature 8. On a side of magnet armature 8 facing the discharge is a stop element 12. This stop element 12 forms a second stop together with magnet armature 5.

(14) Both valve needle 6 and magnet armature 8 are linearly movable along longitudinal axis 15. The movement of magnet armature 8 is delimited by the first and second stop.

(15) A plurality of channels 16 for the medium to be injected are developed in magnet armature 8. In addition or as an alternative, valve needle 6 may also have a hollow design.

(16) Valve needle 6 is loaded in the direction of discharge side 3 by means of a first spring 11. A second spring 13 between spring cup 9 and stop element 12 loads magnet armature 8, likewise in the direction of discharge side 3.

(17) Magnet armature 8 is moved by energizing solenoid coil 5. By way of the first and second stop, magnet armature 8 carries valve needle 6 along. The distance between the two stops defines an armature free travel 14.

(18) FIG. 2 shows a detail of injection valve 1 according to a first exemplary embodiment. It is obvious that stop element 12 is integrally formed with a sleeve 20. Sleeve 20 is situated on valve needle 6 and permanently joined to valve needle 6. Magnet armature 8 is simultaneously developed as so-called counter element 18.

(19) A surface on stop element 12 facing counter element 18 is referred to as stop face 17. Situated across from stop face 17 is a counter face 19 on counter element 18. A side on stop element 12 facing away from counter element 18 is referred to as outer surface 21. The plotted angle is defined between stop face 17 and longitudinal axis 15. Angle is measured on the side of stop face 17 facing counter element 18.

(20) Stop element 12, and thus also stop face 17, are elastically deformable. When counter element 18, i.e., magnet armature 8, strikes stop element 12, stop element 12 is elastically deformed, so that angle becomes larger.

(21) FIG. 3 shows sleeve 20 and stop element 12 in detail. Sleeve 20 and stop element 12 have a through hole 28 that is coaxial with respect to longitudinal axis 15. Valve needle 6 is situated in this through hole 28.

(22) A first height 25 extends parallel to longitudinal axis 15, from the upper end of through hole 28 to the outer end of stop face 17. The outer end of stop face 17 is referred to as peak 27. A second height 26 designates the extension of stop element 12 parallel to longitudinal axis 15. The elasticity of stop face 17 in the illustrated exemplary embodiment is achieved in that the two heights 25, 26 are greater than 0.

(23) FIGS. 4 through 7 show a movement sequence during the opening and closing of the injection valve. FIG. 4 shows the idle state, in which solenoid coil 5 is not energized and magnet armature 8 merely rests lightly on stop element 12. Accordingly, stop face 17 is not deformed and stop face 17 is inclined toward counter face 19 at an angle of less than 90 degrees.

(24) In the following figures, reference numeral 29 denotes a throttle flow of the medium to be injected. The dashed illustration of stop element 12 shows the elastic deformation.

(25) Because of the applied magnetic field at solenoid coil 5, magnet armature 8 is pulled in the direction of the inner pole in FIG. 5, i.e., in the upward direction in the illustration. Valve needle 6 remains in the valve seat, until magnet armature 8 has overcome armature free travel 14 and carries valve needle 6 along via ring 10 (first stop). As long as a relative movement is present between magnet armature 8 and valve needle 6, throttle flow 29 comes about between magnet armature 8 and valve needle 6, i.e., between stop face 17 and counter face 18. Throttle flow 29 between stop face 17 and counter face 19 decreases with rising clearance, so that the injection valve is able to open rapidly. In FIG. 6, the current at solenoid coil 5 is switched off, and the magnetic field decays. Valve needle 6 is in the seat, and magnet armature 8, coming from the first stop on ring 10, is able to continue its movement in the direction of the second stop on stop element 12. Because of the relative movement between magnet armature 8 and valve needle 6, a throttle flow 29 is once again created between stop face 17 and counter face 19. Throttle flow 29 increases with decreasing clearance, so that the movement of magnet armature 8 is damped to a growing extent. When magnet armature 8 makes contact with stop element 12, i.e., counter element 19 exerts pressure on stop face 17, stop element 12 is elastically deformed by the push, and the damping volume situated between stop face 17 and counter face 19 turns into a squish gap. This state is illustrated in FIG. 7. The movement of magnet armature 8 is decelerated as a result. The elastic deformation of stop element 12 aligns stop face 17 in a coplanar manner in relation to counter face 19, so that the damping of the magnet armature movement by the squish gap is maximized.

(26) FIG. 8 shows a detail of injection valve 1 according to a second exemplary embodiment. In the second exemplary embodiment, stop face 17 is subdivided into an inner section 23 and an outer section 24. Even without contact with counter face 19, inner section 23 is disposed perpendicularly to longitudinal axis 15, and thus also in parallel with counter face 19. In outer section 24, stop face 17 is inclined at angle in the direction of counter face 19.

(27) Outer surface 21 is situated partially in parallel with counter face 19 and partially inclines toward counter face 19. More specifically, outer surface 21 is inclined in the direction of the counter face roughly in the region of outer section 24, so that sufficient elasticity of stop element 12 is provided there.

(28) FIG. 9 shows a detail of injection valve 1 according to a third exemplary embodiment. In the third exemplary embodiment, stop face 17 is inclined in the direction of counter face 19 both in inner section 23 and in outer section 24. However, the inclination toward outer section 24 is more pronounced, so that the greatest deformation of stop element 12 occurs there.

(29) FIG. 10 shows a detail of injection valve 1 according to a fourth exemplary embodiment. In the fourth exemplary embodiment, stop face 17 is inclined in the direction of counter face 19 in inner section 23 and in outer section 24, in the same way as in the third exemplary embodiment. From sleeve 20, outer surface 21 is heavily inclined throughout in the direction of counter face 19. This creates a very narrow stop element 12, especially in the outer region, which is elastically deformable accordingly.

(30) FIG. 11 shows a detail of injection valve 1 according to a fifth exemplary embodiment. In the fifth exemplary embodiment, stop face 17 is disposed parallel to counter face 19 across inner section 23. Stop face 17 is concave along outer section 24. Outer surface 21 of stop element 12 likewise has a concave design. This creates a relatively narrow stop element 12 having rounded transitions between the various inclinations, so that a dependable elasticity is ensured. Angle is hereby defined by the tangent, is to the concave development of stop face 17 in outer section 24 and longitudinal axis 15.

(31) FIG. 12 shows a detail of injection valve 1 according to a sixth exemplary embodiment. In the sixth exemplary embodiment, a groove has been provided in outer surface 21 of stop element 12. This groove 22 is developed peripherally about longitudinal axis 15, in particular. Groove 22 weakens stop element 12 accordingly, so that the desired elasticity is provided.

(32) FIG. 13 shows a portion of injection valve 1 according to a seventh exemplary embodiment. Seventh exemplary embodiment once again shows a groove 22 for adjusting the elasticity of stop element 12. In the seventh exemplary embodiment, groove 22 is situated in an area of stop element 12 that extends in parallel with longitudinal axis 15. This has the result that groove 22 comes very close to peak 27 and stop face 17, so that not entire stop element 12 but only an upper portion is deformed in this exemplary embodiment.

(33) The various exemplary embodiments show possible geometries of stop element 12. In the exemplary embodiments, stop faces 17 are usually in the form of a wedge, since the wedge form is easy to measure and produce. The exemplary embodiments may naturally also be combined. For example, grooves 22 shown in FIGS. 12 and 13 with the appropriate form depth and number in the other exemplary embodiments as well. Furthermore, an adaptation of outer surface 21 according to FIGS. 9, 10 and 11 is possible in all exemplary embodiments. The different angles and concave developments of stop face 17 of the various exemplary embodiments can be combined with one another. In addition, all other concave and convex forms of stop element 12 are possible, as long as sufficient elasticity is ensured. Additional cross-sectional forms for groove 22 are triangles and ellipses, for example. Even more than one groove 22 per stop element 12 is possible in order to adapt the stiffness appropriately. The exemplary embodiments show rotationally symmetrical valve needles 6 that are not hollow. In the same way, it is possible to use the present invention with hollow and/or not rotationally symmetrical valve needles 6. Even stop face 17 or counter face 19 need not have a rotationally symmetrical design.

(34) All exemplary embodiments shown illustrate stop face 17 and counter element 19 in a form in which it is fixedly joined to valve needle 6. Accordingly, magnet armature 6 in the exemplary embodiments is defined as counter element 18 having counter face 19. In the same way, it is possible to develop an elastic stop element 12 which is permanently connected to magnet armature 6. Correspondingly, counter element 18 would then be fixedly joined to valve needle 6. In the simplest development, counter face 19 is a planar rigid surface. It is also possible for counter face 19 to have a certain inclination and elasticity.