EP0934461A1

EP0934461A1 - Fuel injection valve

Info

Publication number: EP0934461A1
Application number: EP98936192A
Authority: EP
Inventors: Ferdinand Reiter; Heinz-Martin Krause
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1997-08-22
Filing date: 1998-06-17
Publication date: 1999-08-11
Anticipated expiration: 2018-06-17
Also published as: KR20000068809A; DE59813774D1; BR9806192A; JP2001504912A; CN1104557C; DE19736548A1; TW358857B; CN1237226A; WO1999010650A1; EP0934461B1; US6598809B1

Abstract

The fuel injection valve is characterized in that a preparation attachment (40) consisting of a gas-surrounding element (35) and an insert (38) is provided on the downstream end of the fuel injection valve. The downstream end of the fuel injection valve with the preparation attachment (40) is totally encompassed by a tubular, thin-walled, metal gas-surrounding body (30) in the peripheral direction. The gas-surrounding body (30) is fixed to one of the valve housings (1)and encompasses at least partially the plastic tube (15) of the fuel injection valve by means of a non-material fitting snap-on, clamp or clip connector. The corresponding connector elements are configured in the form of noses (65) and latches (66). The inventive fuel injection valve is particularly suitable for injecting an intake pipe of a mixture-compressing, spark-ignited internal combustion engine.

Description

Fuel injector

State of the art

The invention relates to a fuel injector according to the preamble of the main claim.

There is already an electromagnetically actuated valve for injecting a fuel-gas mixture into a mixture-compressing spark-ignition internal combustion engine from DE-OS 195 05 886, in which a plastic gas encasing body partially surrounds the downstream end of the injection valve. A preparation attachment, which consists of a metal cup-shaped gas enclosure part and an insert body made of plastic, is provided within the gas enclosure body at the downstream end of the injection valve. The gas can flow in between the gas containment body and the valve housing (valve seat support), in order then to be supplied to the fuel in the preparation attachment. The gas encasing body made of plastic, which is sometimes quite thick-walled, is firmly connected to the actual plastic encapsulation of the valve through the use of a material-locking method, such as ultrasonic welding. From DE-OS 41 21 372 is already a

Fuel injection valve for injecting a fuel-gas mixture is known, in which a gas encasing sleeve surrounds a nozzle body of the valve at its downstream end. The metal gas encasing sleeve is designed so that its bottom part is shaped obliquely towards the valve end with a passage opening. In this way, a gas ring gap is formed between an orifice plate and the bottom part of the gas encasing sleeve. The gas encasing sleeve is attached to the metal nozzle body either by multiple welding points, by flanging, pressing, soldering or gluing. An annular groove-shaped receptacle for a sealing ring for sealing against a valve receptacle is achieved in that an additional complex U-shaped retaining ring is welded onto the outer circumference of the gas encasing sleeve.

Advantages of the invention

The fuel injector according to the invention with the characterizing features of the main claim has the advantage that a particularly inexpensive gas encasing body can be mounted on the spray-side end of the valve in a simple manner. For this purpose, the plastic injection molding customary on the known injection valves is advantageously used as a connection partner of the metal gas encasing body, which plastic injection molding only has to be minimally modified in the direct connection area compared to known injection valves. A simple, yet secure, attachment of the gas enclosing body is achieved by means of a non-integral connection technique. Problems that can occur when using integral connection techniques, such as negative heat effects, are completely avoided in the embodiment according to the invention. The measures listed in the subclaims allow advantageous developments and improvements of the fuel injector specified in the main claim.

It is advantageous to produce gas enclosures by means of deep drawing, since these components can be manufactured in large numbers in a simple manner.

It is particularly advantageous to design the non-material connection as a snap-in, snap-in or clip connection, in which lugs and tabs interact as corresponding connecting means.

The thin-walled and tubular gas enclosing body is very well suited for the immediate formation of annular grooves for receiving sealing rings which serve to seal the injection valve against a valve receptacle. On the outer circumference of the gas encasing body perpendicular to its axial extension outwardly standing annular beads can be produced very simply by folding. Additional U-shaped retaining rings can thus be dispensed with.

drawing

Embodiments of the invention are shown in simplified form in the drawing and explained in more detail in the following description. FIG. 1 shows the spray-side end of a fuel injector as a first example of a gas enclosure and FIG. 2 shows the spray-side end of a fuel injection valve as a second example of a gas enclosure with an upstream spray point. Description of the embodiments

1 shows a valve in the form of an injection valve for fuel injection systems of mixed-compression spark-ignition internal combustion engines, partially and in simplified form, in section. The injection valve has a metal, largely tubular valve seat support 1, at least partially forming a valve housing, in which a longitudinal opening 3 is formed concentrically with a longitudinal valve axis 2. In the longitudinal opening 3 there is e.g. tubular valve needle 5 arranged at its downstream end with a e.g. spherical valve closing body 7, on the circumference of which, for example, five flattenings 8 are provided, is connected.

The injection valve is actuated electromagnetically in a known manner. An electromagnetic circuit with a magnetic coil 10, an armature 11 and a core 12 is used for the axial movement of the valve needle 5 and thus for opening against the spring force of a return spring 9 or closing the injection valve. The armature 11 is connected to the end of the valve body 7 facing away from the end Valve needle 5 by z. B. a weld seam connected by a laser and aligned with the core 12. The magnet coil 10 surrounds the core 12, which represents, for example, the end of an inlet connector which is enclosed by the magnet coil 10 and which serves to supply the medium to be metered by means of the valve, here fuel.

The electromagnetic circuit is closed, for example, with at least one bow-shaped guide element 14. The magnet coil 10 embedded in a coil former and the at least one guide element 14, as well as wide sections of the core 12 and the valve seat support 1, are one Surround outer jacket body of the injection molding plastic injection molding 15, at the same time an electrical connector, not shown, is also molded. In the area of the axial extent of the magnetic coil 10, the core 12 and the valve seat support 1 are firmly connected to one another, for example by means of a circumferential weld seam, a magnetic throttle point 13 connecting downstream of this connection point due to the thin-walled design of the valve seat support 1. Instead of the plastic encapsulation 15, another jacket body, which at least partially forms the outer valve circumference, can also be provided, which is designed, for example, as a jacket-shaped housing made of metal.

A cylindrical valve seat body 16 is tightly mounted in the longitudinal opening 3 in the downstream end of the valve seat carrier 1 facing away from the core 12. On its one lower end, which faces away from the valve closing body 7, the valve seat body 16 is connected concentrically and firmly to an injection cup disk 21, for example in the form of a pot. The connection of valve seat body 16 and spray orifice plate 21 takes place, for example, by a circumferential and tight, e.g. weld seam formed by a laser. This type of assembly avoids the risk of undesired deformation of the spray hole disk 21 in the region of its at least two, for example four, spray openings 25 formed by punching or eroding and which are located centrally in the spray hole disk 21. The spray plate 21 is also fixed to the valve seat support 1, for example, by a circumferential and tight weld.

The insertion depth of the valve seat part consisting of valve seat body 16 and cup-shaped spray orifice plate 21 in the longitudinal opening 3 determines the size of the stroke of the valve needle 5, since the one end position of the valve needle 5 is fixed when the solenoid 10 is not energized by the valve closing body 7 resting on a valve seat surface 29 of the valve seat body 16. The spherical

Valve closing body 7 interacts with the valve seat surface 29 of the valve seat body 16 that tapers in the shape of a truncated cone in the direction of flow. The other end position of the valve needle 5 is determined when the solenoid 10 is excited, for example by the armature 11 resting on the core 12. The path between these two end positions of the valve needle 5 thus represents the stroke.

At its downstream end, the injection valve and thus the valve seat support 1 are largely enclosed in the circumferential direction and at least partially axially by a sleeve-shaped, thin-walled gas-enclosing body 30. The e.g. Gas enclosing body 30 produced from a metal sheet by means of deep drawing is connected to the lower end of the plastic encapsulation 15. the

Upstream of the gas containment body 30 there is a gas inlet channel (not shown) which serves to supply the gas into the gas containment body 30. The gas enclosing body 30 has an inner passage opening 32, into which not only the downstream end of the valve seat carrier 1 with the

Valve seat body 16 protrudes, but in the further means for gas supply and supply in the direction of the spray openings 25 are provided. Thus, the gas enclosing body 30 surrounds, among other things, a cup-shaped gas enclosing part 35 in a between the

Gas enclosure body 30 and the valve seat support 1, which is directly connected to the gas inlet duct, is a space 36. This ensures the supply of the gas up to the fuel emerging from the spray openings 25 of the spray plate 21. Together with an insert body 38, the z. B. is made of plastic, the cup-shaped gas encasing part 35 as a sheet metal part is completely enclosed by the gas encasing body 30 in the axial direction

Processing attachment 40. The insert body 38, which is characterized by a largely conical shape, extends completely downstream of the valve seat body 16. In contrast, the gas-enclosing part 35, which is firmly connected to the insert body 38, is designed such that a base section 42 is at least partially surrounded by the material of the insert body 38 and protrudes radially from this, as seen in the center, for example over the axial length of the insert body 38. At the bottom portion 42 is a cylindrical, axially extending jacket portion 43, which the valve seat support 1 z. B. up to the level of the spherical equator of the valve closing body 7. The jacket section 43 of the gas containment part 35 extends in the space 36 formed between the gas containment body 30 and the valve seat support 1 and guarantees a defined gas supply due to its design. The jacket section 43 is not completely cylindrical in that it z. B. has four regions 44 of larger diameter and four regions 45 of smaller diameter, which alternate in the circumferential direction of the jacket section 43. In the installed state of the gas encasing part 35, it then looks that the annular space 36 is used in its entire radial width, since the areas 45 of smaller diameter abut the valve seat support 1 and z. B. are firmly connected to this by means of weld seams, while the regions 44 of larger diameter extend with play along the inner wall of the gas enclosing body 30 in the through opening 32. Between the valve seat support 1 and the areas 44 of larger diameter of the jacket section 43, the same number, for example four gas inlet channels 47 are formed corresponding to the number of these areas 44, which are arranged axially at equal intervals in the circumferential direction around the valve seat support 1. The bottom section 42 of the gas encasing part 35 extends at an axial distance from the downstream end face of the valve seat support 1, so that between the bottom section 42 and this end face an annular, radially extending flow channel 48 is formed, which connects to the gas inlet channels 47 and through which the gas flows radially becomes. Thereafter, the gas flows largely axially upstream into an annular channel 49 between the insert body 38, which has a conical shape upstream of the base section 42 and tapers toward the spray hole disc 21, and the wall of the longitudinal opening 3 in the valve seat carrier 1 until the flow on the spray disc 21 is deflected radially Direction.

The gas is metered for improved processing of the fuel emerging from the spray openings 25 of the spray plate 21 via a gas ring gap 50, the axial extent of which results from the distance of the insert body 38 from the spray plate 21. The axial dimension of the extent of the gas ring gap 50 forms the metering cross section for the gas flowing in from the ring channel 49, for example processing air. The supplied gas flows through the narrow gas ring gap 50 to one provided in the insert body 38 centrally and concentrically to the longitudinal valve axis 2 and near the spray orifice plate 21

Mixture spray opening 51 and there meets the fuel discharged through, for example, two or four spray openings 25. Due to the small axial extension of the gas ring gap 50, the gas supplied is accelerated greatly and atomizes the fuel particularly finely. A sealing ring 55 provides a seal between the gas encasing body 30 and the insert body 38 between the outer contour of the insert body 38 and the inner wall of the gas encasing body 30 below the bottom section 42, the bottom section 42 directly delimiting an annular groove necessary for receiving the sealing ring 55. The insert body 38 is characterized by a drip geometry at the downstream end of the preparation attachment 40. One adjoining the lower end face downstream

Draining crowns 56 with a multitude of serrations ensure an improved draining of the fuel (especially when operating without gas), since the fuel cannot converge to form large drops. The serrations of the drip-off crowns 56 are, for example, in the form of triangular teeth which taper to a point in the downstream direction, whereas the free areas which arise between the serrations are reversely triangular, that is to say become wider in the downstream direction.

From the aforementioned gas supply device, not shown, which is designed, for example, in the form of a gas inlet channel, the gas enters the intermediate space 36 formed between the valve seat support 1 and the gas casing body 30 in the through opening 32 via a plurality of inlet openings 58 which completely penetrate the wall of the gas casing body 30. For sealing between the circumference of the fuel injector and a valve seat, not shown, for example an intake manifold of the internal combustion engine, two sealing rings 60 are provided on the outer circumference of the spray-side end, for example. The upper sealing ring 60 facing the magnetic coil 10 is arranged in an annular groove 61 made in the plastic encapsulation 15. Against that is Lower sealing ring 60 facing the preparation attachment 40 is provided directly on the gas encasing body 30. For example, the deep-drawn gas encasing body 30 made of sheet metal has in its central axial extension region two circumferential annular beads 62, which are formed by folding and are perpendicular to the axial tubular extension. Together with the outer wall of the gas encasing body 30, the two annular beads 62 form a further annular groove 63 in this area.

The gas encasing body 30 is fastened to the lower, downstream end of the plastic encapsulation 15 by means of a snap, snap or clip connection. For this purpose, the plastic encapsulation 15 at its lower end facing the gas encasing body 30 is e.g. designed in such a way that a circumferential or a plurality of lugs 65 which are distributed around the circumference and project outwardly like a saw tooth are provided. As the connecting means corresponding to the lugs 65, the gas-enclosing body 30 has a plurality of inward distributions distributed over the circumference above the inlet openings 58

Valve seat support 1 standing on elastic tabs 66 which engage behind the lugs 65. No tightness has to be achieved at this connection point, so that the specified connection options can be used very well due to their simplicity. The connection area can also be made modified, however, the metal gas encasing body 30 is always attached to the plastic encapsulation 15 by a non-material joining process with corresponding connecting means. The tabs 65 can e.g. in openings or windows of the

Snap the gas enclosure body 30 into place. Special securing hooks, not shown, can also be formed on the gas enclosing body 30. As FIG. 2 shows, the length of the gas enclosing body 30 can be varied very easily. Correspondingly, the two folded annular beads 62 can also be molded on at another point on the gas enclosing body 30. A very elongated gas enclosing body 30 is advantageous if a far-reaching spray point is to be provided. According to the length of the gas encasing body 30, only the valve seat support 1 and the valve needle 5 need to be extended; all other components of the fuel injector can be used in an identical manner. The

Spray area (preparation attachment 40) is sufficient e.g. in the valve of Figure 2 into the intake duct of the internal combustion engine clearly into it. Wall wetting of the intake duct can be avoided in a simple manner by a targeted spraying onto one or more inlet valves, as a result of which the exhaust gas emission of the internal combustion engine and the fuel consumption are reduced.

Claims

claims

1. Fuel injection valve for fuel injection systems of internal combustion engines, with a valve longitudinal axis, with a valve housing which is at least partially surrounded by a casing body, with an axially movable valve closing body, with a valve seat body which has a valve seat surface interacting with the valve closing body, with at least one downstream of the valve seat surface provided spray opening, with means arranged at the downstream end of the injection valve for generating a fuel-gas mixture, and with a means surrounding the means for generating a fuel-gas mixture completely in the circumferential direction, characterized in that the

Gas enclosing body (30) is metallic and is not materially connected to the jacket body (15).

2. Fuel injection valve according to claim 1, characterized in that the outer jacket body as one

Plastic injection molding (15) is executed.

3. Fuel injection valve according to claim 1 or 2, characterized in that the gas enclosing body (30) can be produced by deep drawing from a sheet metal.

4. Fuel injection valve according to one of the preceding claims, characterized in that the gas enclosing body (30) is sleeve-shaped or tubular with an inner through opening (32).

5. Fuel injection valve according to claim 1, characterized in that the non-material connection between the gas enclosing body (30) and the jacket body (15) is a snap, snap or clip connection.

6. Fuel injection valve according to claim 2 and 5, characterized in that the plastic extrusion coating (15) at its end facing the gas encasing body (30) is designed in such a way that a circumferential or a plurality of peripherally distributed, outwardly directed, sawtooth-like lugs (65) protrude .

7. Fuel injection valve according to claim 6, characterized in that the gas enclosure body (30) is provided at its end facing the plastic encapsulation (15) with a plurality of circumferentially distributed, inwardly directed tabs (66) which act as corresponding connecting means for the lugs (65). reach behind.

8. Fuel injection valve according to one of the preceding claims, characterized in that in the gas enclosure body (30) at least one inlet opening (58) is provided for the inflow of a gas.

9. Fuel injection valve according to claim 4, characterized in that on the outer circumference of the

Gas enclosure body (30) perpendicular to the axial tubular

Extension of the gas encircling body (30) two circumferential annular beads (62) formed by folding stand outwards form an annular groove (63) together with the outer wall of the gas containment body (30).

10. Fuel injection valve according to claim 1, characterized in that the means for generating a

The fuel-gas mixture is designed as a preparation attachment (40) consisting of a cup-shaped metal gas encasing part (35) and an insert body (38) made of plastic and having a mixture spray opening (51).