EP0877860A1

EP0877860A1 - Fuel injection valve

Info

Publication number: EP0877860A1
Application number: EP97944733A
Authority: EP
Inventors: Ferdinand Reiter
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1996-11-18
Filing date: 1997-09-23
Publication date: 1998-11-18
Anticipated expiration: 2017-09-23
Also published as: KR19990077251A; WO1998022707A1; EP0877860B1; DE19647587A1; DE59702381D1; US6019128A; JP2000504387A; CN1075166C; ES2151294T3; CN1207159A

Abstract

Fuel injection valves in which a fuel filter is inserted or pressed into the end of a fuel inlet manifold on the inlet side are already known per se. Interaction between the fuel filter and the through-passing fuel can however cause the filter to expand or contract. This can result in impaired sealing between the fuel filter and the inlet manifold. The novel fuel injection valve possesses a fuel inlet manifold (60) with a swelling inside (67) and slanting flank areas (80, 81). A holder section (50) of the fuel filter (61) is designed with a groove (69) which interacts with the swelling (67) to form a snap-in connection. According to the invention the groove (69) is so shaped that the holder section (50) of the fuel filter (61) is fitted closely to and seals the sloping flank areas (80,81) of the swelling (67).

Description

Fuel injector

State of the art

The invention relates to a fuel injector according to the preamble of the main claim. A fuel injector is already known from US Pat. No. 4,946,107, in which a fuel filter is inserted into the fuel inlet connection at the inlet end of the fuel injector. In this case, a projection provided on the inside on the inlet-side end of the fuel inlet connector snaps into a groove provided on the lateral surface of the fuel filter in order to lock the fuel filter on the fuel inlet connector. The fuel inlet connector has a stepped bore, the step of which offers a stop for the fuel filter to be used. In addition, a retaining collar is provided which projects radially beyond the inlet end of the fuel inlet connector and also abuts the inlet side end face of the fuel inlet connector. This prevents the fuel filter from penetrating too far into the fuel inlet connection. The known fuel injector has several disadvantages. The stepped bore provided in the fuel inlet connector and the design of the projection which engages in the groove of the fuel filter require a machining manufacturing process, so that there is no insignificant manufacturing outlay in order to prepare the fuel inlet connector for receiving the fuel filter. On the other hand, training the Retaining collar on the fuel filter is a relatively complex injection molded part for the production of the fuel filter in a plastic injection molding process.

However, it is particularly disadvantageous that there is no completely satisfactory sealing effect between the fuel inlet connection and the fuel filter. The seal between the fuel filter and the inlet end of the fuel inlet connector is particularly affected by the fact that the plastic material of the fuel filter can swell or shrink due to a chemical or physical interaction with the fuel to be filtered, which can significantly affect the fit between the fuel inlet connector and the fuel filter.

Other fuel injectors with fuel filters inserted into the inlet end of the fuel inlet port are known from DE-OS 43 25 842 and US Pat. No. 5,356,079. These known fuel injection valves differ from the fuel injector known from US Pat. No. 4,946,107 essentially in that the latching connection between the fuel inlet connector and the fuel filter is not provided on the inside but on the outside of the fuel inlet connector. The disadvantages described above, in particular that the locking elements to be provided on the fuel inlet connection must be produced by means of a machining manufacturing process, that the fuel filter is relatively complex in shape due to the retaining collar and that due to the swelling behavior or shrinking behavior of the plastic material of the fuel filter there is an unsatisfactory seal between the fuel filter and the fuel inlet nozzle results are also given for the fuel injectors resulting from the latter two publications.

From DE-OS 40 03 228 a fuel injector is known in which the fuel filter is pressed into the fuel inlet port. This fuel filter is provided on the circumference with a brass ring, for example, which forms a pairing with the wall of the fuel inlet connection when the fuel filter is pressed in. However, when the fuel filter provided with a brass ring is pressed in, there is a risk of the occurrence of abrasion and chips which, due to the compressive stress, between Fuel filter and fuel inlet connector can be detached and can cause contamination in the fuel injector. Again, this can be an unsatisfactory one

Seal between the brass ring of the fuel filter and the

Fuel inlet port result if the fuel inlet port is made of a different metal that has a different coefficient of thermal expansion than that

Brass of the mounting ring of the fuel filter, so that as a result of

If the fuel injector heats up due to engine heat, there is a risk of non-sealing gaps. Another disadvantage is that due to the relatively large pressing forces to be applied when pressing the brass ring of the fuel filter into the fuel inlet port, it is practically impossible to detach the fuel filter from the fuel inlet port.

Advantages of the invention

The fuel injector according to the invention with the characterizing features of the main claim has the advantage that the fuel filter and the fuel inlet connector are made particularly cost and material saving.

A particular advantage is that the seal between the fuel filter and the fuel inlet port is guaranteed even when the

Fuel filter shrinks or swells due to a chemical or physical interaction with the fuel flowing through the fuel filter. This is achieved by the special shape of the groove provided on the holding section of the fuel filter and the bead of the fuel inlet connector which engages in the groove. The bead has at least one, usually two, beveled flank area (s), the opening cross section of the fuel inlet connector being in the area of the beveled area

Flank areas continuously narrowed or expanded. The sealing effect between the retaining section having the groove and the bead of the fuel inlet connector is maintained due to the beveling of the flank regions even when the retaining section, which is preferably made of a plastic material, swells or shrinks. As a result of the stretching or shrinking of the holding section, only the

Point of contact of the holding section on the bead within the flank area moved without interrupting the sealing effect. A fuel flow between the fuel filter and the fuel inlet connection bypassing the fuel filter is thereby reliably avoided, so that unfiltered fuel does not enter the fuel filter

Can get fuel injector.

The measures listed in the subclaims are advantageous

Developments and improvements to that specified in the main claim

Fuel injector possible.

Another advantage is that the bead can be molded onto the fuel inlet connector using a non-cutting manufacturing process. The bead can e.g. B. be pressed into the fuel inlet port by rolling. Machining of the fuel inlet connection e.g. turning to prepare it for the fuel filter is not necessary. The fuel filter can be made entirely of a plastic material and e.g. be produced by means of a plastic injection molding process. It is not necessary to insert or attach metal parts. The groove cooperating with the bead of the fuel inlet connector can be formed during the production of the fuel filter, without the need for an additional processing step. As a result, manufacturing costs can be saved to a considerable extent.

drawing

Embodiments of the invention are shown in simplified form in the drawing and explained in more detail in the following description. Show it:

1 shows a fuel injector with a fuel filter according to the invention, FIG. 2 shows an enlarged view of FIG. 1 in the area of the fuel filter, FIG. 3 shows an enlarged view of FIG. 2 in the area of the snap-in connection between the fuel filter and the fuel inlet connector, and FIG. 4, FIGS. 5 and 6 show alternative exemplary embodiments of the latching connection between the fuel filter and the fuel inlet connection. Description of the embodiments

The electromagnetically actuated valve, for example shown in FIG. 1, in the form of an injection valve for fuel injection systems of mixture-compressing, spark-ignited internal combustion engines has a tubular core 2 surrounded by a magnet coil 1. A coil body 3, which is stepped in the radial direction, takes up and enables the magnet coil 1 to be wound in connection with the core 2, a particularly compact design of the injection valve in the area of the magnetic coil 1.

With a lower core end 9 of the core 2, a tubular metal intermediate part 12 is tightly connected concentrically to a longitudinal valve axis 10, for example by welding, and thereby partially surrounds the core end 9 axially. The stepped coil body 3 partially overlaps the core 2 and, with a step 15 of larger diameter, the intermediate part 12 at least partially axially. A tubular valve seat carrier 16 extends downstream of the bobbin 3 and the intermediate part 12 and is, for example, firmly connected to the intermediate part 12. A longitudinal bore 17 runs in the valve seat carrier 16 and is formed concentrically with the longitudinal axis 10 of the valve. In the longitudinal bore 17, for example, a tubular valve needle 19 is arranged, which is connected at its downstream end 20 to a spherical valve closing body 21, on the periphery of which, for example, five flats 22 are provided for the fuel to flow past, for example by welding.

The injection valve is actuated electromagnetically in a known manner. For the axial movement of the valve needle 19 and thus for opening against the spring force of a return spring 25 or closing the injection valve, the electromagnetic circuit with the magnet coil 1, the core 2 and an armature 27 is used. The armature 27 is with the end facing away from the valve closing body 21 Valve needle 19 connected by a first weld 28 and aligned with the core 2. In the downstream end of the valve seat carrier 16 facing away from the core 2, a cylindrical valve seat body 29, which has a fixed valve seat, is tightly mounted in the longitudinal bore 17 by welding. A guide opening 32 of the valve seat body 29 serves to guide the valve closing body 21 during the axial movement of the valve needle 19 with the armature 27 along the valve longitudinal axis 10. The spherical valve closing body 21 interacts with the valve seat of the valve seat body 29 which tapers in the direction of a truncated cone in the direction of flow. The circumference of the valve seat body 29 has a slightly smaller diameter than the longitudinal bore 17 of the valve seat carrier 16. On its end facing away from the valve closing body 21, the valve seat body 29 is concentric and firm with an, for example, cup-shaped injection orifice plate 34, for example by a circumferential density, for example by means of a second weld 37 formed by a laser.

In addition to a base part 38 to which the valve seat body 29 is fastened and in which one or more, for example four, spray openings 39 formed by erosion or stamping, the pot-shaped spray perforated disk 34 has a circumferential, downstream holding edge 40. The holding edge 40 is conically outward downstream bent so that it bears against the inner wall of the valve seat carrier 16 determined by the longitudinal bore 17, with a radial pressure being present. A direct flow of fuel through an intake line of the internal combustion engine outside the spray openings 39 is also avoided by a third weld 41 between the spray plate 34 and the valve seat carrier 16. A protective cap 43 is arranged on the periphery of the valve seat carrier 16 at its downstream end facing away from the core 2 and is connected to the valve seat carrier 16, for example, by means of a catch.

The insertion depth of the valve seat body 29 with the cup-shaped spray orifice plate 34 determines the presetting of the stroke of the valve needle 19. The one end position of the valve needle 19 when the solenoid coil 1 is not energized is determined by the valve closing body 21 resting on the valve seat of the valve seat body 29, while the other end position is fixed the valve needle 19 results when the solenoid coil 1 is excited by the contact of the armature 27 at the core end 9. The magnet coil 1 is surrounded by at least one guide element 45, for example designed as a bracket and serving as a ferromagnetic element, which at least partially surrounds the magnet coil 1 in the circumferential direction and rests with its one end on the core 2 and its other end on the valve seat support 16 this can be connected, for example, by welding, soldering or gluing.

An adjusting sleeve 48, which is pushed into a flow bore 46 of the core 2 concentrically to the longitudinal axis 10 of the valve and is formed, for example, from rolled spring steel sheet, serves to adjust the spring preload of the return spring 25 abutting the adjusting sleeve 48, which in turn is located on the valve needle 19 with its opposite side supports.

The injection valve is largely enclosed by a plastic encapsulation 50 which, starting from the core 2, extends in the axial direction from the magnet coil 1 and the at least one guide element 45 to the valve seat support 16, the at least one guide element 45 being completely covered axially and in the circumferential direction. This plastic encapsulation 50 includes, for example, an injection-molded electrical connector 52. An upper side surface 54 of the plastic encapsulation 50 offers a bearing surface for an upper sealing ring 58.

The core 2 forms a fuel inlet connection 60 at its inlet end. The fuel filter 61 according to the invention is inserted into the fuel inlet connection 60, which can be seen more clearly from the enlarged illustration shown in FIG. 2, and ensures that such fuel components are filtered out due to their size can cause blockages and damage in the fuel injector. The fuel filter 61, which is produced from a plastic material, for example by means of a plastic injection molding process, has a circumferential holding section 62. The holding section 62 ends downstream at a shoulder 63. In the exemplary embodiment, three webs 64 are formed on the holding section 62 which run in the axial direction and are offset by 120 ° on the circumference of the fuel filter 61 and which are connected to one another at the downstream end of the fuel filter 61 via the filter base 65 . That the Filtering of the filter element serving the fuel flowing through the fuel filter 61

66 is thus surrounded by the holding section 62, the webs 64 and the filter bottom 65 and can e.g. consist of a polyamide fabric which is injected in the fuel filter 61 during manufacture.

According to the invention, the fuel inlet connection 60 has a preferably circumferential, inwardly curved bead 67. The bead 67 is preferably produced by means of a non-cutting manufacturing process, since this is particularly inexpensive. The bead

67 can e.g. are formed in that the fuel inlet nozzle 60 rolls on a rail-like stamp, so that the bead 67 is pressed inwards and at the same time a groove 68 forms on the outside. During the subsequent extrusion coating with the plastic encapsulation 50, this also has the advantage that the plastic encapsulation 50 adheres better due to the groove 68 in the area of the fuel inlet connector 60.

The holding section 62 has a groove 69 which interacts with the bead 67 and is preferably formed all the way round in the holding section 62 of the fuel filter 61. The groove 69 can already be formed during the manufacture of the fuel filter 61 by means of a plastic injection molding process, without the need for a separate manufacturing step. When the fuel filter 61 is inserted or pressed into the fuel inlet connector 60, the tapered region downstream of the shoulder 63 can be easily pushed through the bead 67 until the shoulder 63 abuts the bead 67. By elastic deformation of a locking lug 70 located between the groove 69 and the shoulder 63 and possibly additional elastic deformation of the bead 67, the bead 67 engages in the groove 69. Since an area 71 of the holding section 62 upstream of the groove 69 is substantially longer and more solid than the locking lug 70, it can be prevented that the fuel filter 61 slips over the bead 67 by limiting the pressing force acting on the inlet-side end face of the fuel filter 61 by means of a press ram and thus penetrates into the flow bore 46 further than intended.

3, the configuration according to the invention of the bead 67 and the groove 69 and also their interaction will be described in more detail below. In the exemplary embodiment shown in FIG. 3, the bead 67 is wave-shaped and has an upstream, beveled flank area 80 and a downstream, beveled flank area 81. In the upstream, beveled flank area 80, the opening cross section of the fuel inlet connector 60 continuously narrows in the direction of flow of the fuel, while the opening cross section of the fuel inlet connector 60 in the downstream, beveled flank area 81 widens continuously. The groove 69 is formed in the holding section 62 in such a way that the holding section 62 rests on the beveled flank areas 80 and 81 of the bead 67 at two ideally linear, annular contact points 82 and 83. Due to the special design of the groove 69 and the bead 67, a gap is created between the contact points 82 and 83 and upstream of the contact point 82 and downstream of the contact point 83, which prevents the holding section 62 of the fuel filter 61 from directly contacting the fuel inlet connection 60 in these areas . The gap is divided into a first gap region 84a between the contact points 82 and 83, a second gap region 84b upstream of the contact point 82 and a third gap region 84c downstream of the contact point 83. Due to the slight elastic deformation of the holding section 62 and / or the fuel inlet connector 60 caused contact pressure is created at the contact points 82 and 83, which prevents fuel from flowing through the gap areas 84a, 84b and 84c bypassing the filter element 66 on the outside of the holding portion 62 of the fuel filter 61 unfiltered or by.

The above-described formation of the bead 67 and the groove 69 according to the invention has the advantage that the sealing closure between the holding section 62 of the fuel filter 61 and the fuel inlet connection 60 is maintained even when the plastic material of the fuel filter 61, in particular the holding section 62, is the result a chemical or physical interaction with the fuel to be filtered causes it to shrink or expand (e.g. due to swelling). If the holding section 62 expands during the operation of the fuel injector, the points of contact 82 and 83 are shifted outwards, as indicated by the radially acting pair of forces AA in FIG. 3. The lengthens

Gap area 84a and gap areas 84b and 84c are shortened accordingly. Since the

Contact points 82 and 83 bear against the beveled flank areas 80 and 81, but even if the holding section 62 is stretched and the associated contact points 82 and 83 are displaced, the sealing seal between the holding section 62 and the fuel inlet connection 60 is maintained.

Similarly, the sealing seal between the holding portion 62 and the fuel inlet port 60 is maintained even when the holding portion 62 shrinks due to the interaction with the fuel during operation of the fuel injector. In this case, an axial force component, which is illustrated by the axial pair of forces BB in FIG. 3, acts on the bead 67 and the contact points 82 and 83 approach each other, so that the gap area 84a shortens and the gap areas 84b and 84c accordingly be extended. The contours of the groove 69 and the bead 67 always touch in a wide range of expansion or shrinkage of the holding section 62 at two common contact points 82 and 83. In the exemplary embodiment shown in FIG. 3, the function described above is achieved in that the cross-sectional contour of the wavy-curved bead 67 has at its apex a radius of curvature Ri which is greater than the radius of curvature R ₂ at the apex of the cross-sectional contour of the likewise 69-shaped groove 69.

However, the function according to the invention can also be achieved in the same or similar manner by other configurations of the cross-sectional contour of the bead 67 or the cross-sectional contour of the groove 69. Corresponding alternative exemplary embodiments are illustrated in FIGS. 4 to 6. In the alternative exemplary embodiments in FIGS. 4 to 6, elements which have already been described are provided with the same reference numerals, so that a description in this regard is unnecessary. The alternative embodiment shown in FIG. 4 differs from the embodiment already described with reference to FIGS. 1 to 3 in that the

Cross-sectional contour of the groove 69 is rectangular. This one too

In the exemplary embodiment, the holding section 62 bears against the two circumferential contact points 82 and 83 on the beveled flanks 80 and 81 of the bead 67.

The sealing effect at these contact points 82 and 83 is in this

Embodiment also maintained regardless of whether the fuel filter

61, in particular its holding section 62, due to the interaction with the

Fuel is subject to stretching or shrinking. The ratio of the depth a to the width b of the groove 69 can be adapted to the ratio of the axial and radial expansion or shrinkage depending on the material properties of the plastic used to form the fuel filter 61. The same applies to the ratio of the radii R _t and R ₂ of the embodiment shown in FIGS. 1 to 3.

5, the cross-sectional contour of the groove 69 is trapezoidal. In this exemplary embodiment too, the holding section 62 of the fuel valve 61 bears against the circumferential contact points 82 and 83. The ratio of the depth a to the width b of the groove 69 can also be adapted to the material properties in this embodiment.

In the embodiment shown in FIG. 6, the cross-sectional contour of the bead 67 is essentially trapezoidal with preferably, but not necessarily, rounded corners. In this exemplary embodiment, the bead 67 also has an upstream, beveled flank area 80, in which the opening cross section of the fuel inlet connector 60 continuously narrows in the flow direction of the fuel, and a downstream, beveled flank area 81, in which the opening cross section of the fuel inlet port 60 in the flow direction of the fuel continuously expanded. The length of the groove 69 is dimensioned such that the holding section 62 bears in a sealing manner at contact points 82 and 83 on the beveled flank areas 80 and 81 of the bead 67. Of course, the exemplary embodiments shown can be combined with one another as desired with regard to the formation of the bead 67 and the groove 69. It is also conceivable, for example, to design the cross-sectional contour of the bead 67 and / or the groove 69 in the form of a part circle, in particular a semicircle. Various other geometrical shapes are possible and, depending on the manufacturing process used, may be preferable for forming the bead 67 and for forming the groove 69.

Claims

EXPECTATIONS

1. Fuel injection valve, in particular injection valve for fuel injection systems of internal combustion engines, with a fuel inlet connection and with a fuel filter that can be inserted into the fuel inlet connection, wherein a bead provided on the inside of the fuel inlet connection engages in a groove provided on a holding section of the fuel filter, characterized in that the bead (67) has at least one beveled flank area (80, 81), in which the opening cross section of the fuel inlet connection (60) continuously narrows or widens, and that the groove (69) is shaped in such a way that the retaining section having the groove (69) (62) of the fuel filter (61) bears sealingly on the beveled flank area (80, 81) of the bead (67).

2. Fuel injection valve according to claim 1, characterized in that the bead (67) has an upstream, beveled flank region (80) in which the opening cross section of the fuel inlet connector (60) in

Flow direction of the fuel continuously narrowed, and a downstream, beveled flank region (81), in which the opening cross section of the Fuel inlet port (60) continuously expanded in the flow direction of the fuel.

3. Fuel injection valve according to claim 2, characterized in that between the holding section (62) of the fuel filter (61) and the fuel inlet connection (60) outside in the beveled flank areas (80, 81) located contact points (82, 83) a gap (84a , 84b, 84c) which compensates for radial expansion of the holding section (62).

4. Fuel injection valve according to one of claims 1 to 3, characterized in that the cross-sectional contour of the bead (67) is curved in a wave-like or part-circular manner and is curved with a first radius of curvature (RJ).

5. Fuel injection valve according to one of claims 1 to 4, characterized in that the cross-sectional contour of the groove (69) is curved in a wave-like or part-circular manner and is curved with a second radius of curvature (R ₂ ).

6. Fuel injection valve according to claim 4 and 5, characterized in that the second radius of curvature (R ₂ ) is smaller than the first radius of curvature (Rι).

7. Fuel injection valve according to one of claims 1 to 4, characterized in that the cross-sectional contour of the groove (69) is rectangular or trapezoidal.

8. Fuel injection valve according to one of claims 1 to 3, characterized in that the cross-sectional contour of the bead (67) is trapezoidal, in particular with rounded corners, is formed.

9. Fuel injection valve according to one of claims 1 to 8, characterized in that the bead (67) on the inside of the fuel inlet connector (60) and / or the groove (69) on the outside of the holding section (62) of the fuel filter (61) all around is or are trained.

10. Fuel injection valve according to one of claims 1 to 9, characterized in that the fuel inlet connection (60) consists of a metal and the bead (67) is formed by a non-cutting manufacturing process, in particular by rolling or squeezing.

11. Fuel injection valve according to one of claims 1 to 10, characterized in that at least the holding section (62) of the fuel filter (61) consists of a plastic material.