EP0681104A1 - Fuel injection valve - Google Patents

Abstract

A fuel injection valve (1) includes a valve nozzle body (5), valve closure piston (10) and a valve seating (15) downstream of which is an injection orifice (33) and a two part separate head (50). The head (50) comprises a tubular body (51) of non-reinforced polyamide with a slot for installation of a flat insert (52), made of PPS, at right angles to the valve axis (2). The insert (52) is downstream of the injection orifice (33) and has a gas feed zone leading to a central opening. <IMAGE>

Description

State of the art

The invention relates to a fuel injector according to the preamble of the main claim. An electromagnetically actuated valve for injecting a fuel-gas mixture into a mixture-compressing spark-ignition internal combustion engine is already known from US Pat. No. 4,957,241, in which a spacer plate for influencing the air quantity is installed between a nozzle body and a protective cap. The spacer plate between the nozzle body and the protective cap has a central opening into which the downstream pin end of a valve needle is immersed. The air supply to the fuel emerging from a fuel channel takes place via air channels and air chambers. The radial air supply for tapping the valve needle is determined by the height of the spacer knobs. Ultimately, however, the amount and the composition of the fuel-air mixture is determined by the size of the annular gap extending in the axial direction between the pin of the valve needle and the circumference of the opening in the spacer plate.

Also known are injection valves (US Pat. No. 4,982,716) in which an adapter is provided at the downstream end, in which air supply ducts are formed. Downstream of a single spray opening, an impact surface is provided in the adapter, which the sprayed fuel jet strikes and is guided in the form of a film into two spray ducts, air from the air supply ducts being aimed specifically at the fuel films formed after the impact. The air can only be metered in via the air supply ducts and is inevitably determined by their cross sections.

In addition, it is also known from DE-OS 41 08 279 to arrange an attachment body downstream of a valve seat. The fuel emerging from a nozzle in the form of a column passes directly into an atomizing hole in the attachment body, where it is struck and processed by air flowing out of the support air channels introduced into the side walls.

In known injection valves with gas supply in an attachment body, it is the case that the functions of air supply or metering and the attachment to the injection valve are solved together, so that an optimum of both functions is hardly possible due to the integration.

Advantages of the invention

The fuel injector according to the invention with the characterizing features of the main claim has the advantage that a functional separation of gas supply and metering compared to the sealing of the fuel injector to an intake line and the attachment of the attachment body to the fuel injector is made so that each function is better guaranteed for itself. In addition, a large variety of variants results from the structural design, which can be achieved very easily and inexpensively.

It is particularly advantageous to form the attachment body in two parts, namely from a tubular base body and a flat insert part that can be inserted into at least one slot opening of the base body. While the basic body serves to seal the fuel injection valve to an intake line and to attach the attachment body to the fuel injection valve, the insert part is mainly responsible for the gas supply and metering.

The measures listed in the subclaims allow advantageous developments and improvements of the fuel injector specified in the main claim.

In addition, a beam splitter can be provided in the base body in an advantageous manner, which maintains or amplifies a dual jet of the fuel injector.

In order to ensure a clear installation position of the insert part in the base body, it is favorable if the insert part has a trapezoidal cross section. By designing inflow areas and boundary areas on the insert part with different geometries, the inflow cross section and thus the gas throughput can be influenced very easily and adjusted to an optimum in accordance with the requirements. A large variety of variants can be achieved very easily in that only the insert parts are exchanged for different specific applications be, while the basic body is reusable. So there is a modular system.

The use of "tailor-made" plastics for the various components results in further advantages. The use of a non-glass fiber reinforced polyamide for the base body and a very precisely sprayable, highly reinforced plastic, such as polyphenylene sulfide, for the insert part is particularly advantageous.

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 a partially illustrated fuel injection valve, FIG. 2 shows an attachment body according to the invention, FIG. 3 shows a section along the line III-III in FIG. 2, FIG. 4 shows a section along the line IV-IV in FIG. 3 according to a first exemplary embodiment, FIG Section through the attachment body according to a second embodiment and Figure 6 is a perspective view of the attachment body.

Description of the embodiments

In FIG. 1, a valve in the form of a fuel injection valve for fuel injection systems of mixture-compressing spark-ignition internal combustion engines is partially shown as a first exemplary embodiment. Together with an attachment body according to the invention, the fuel injection valve serves to inject a fuel-gas mixture into an intake pipe or directly into the combustion chamber of the internal combustion engine.

The fuel injection valve 1, which can be actuated electromagnetically, for example, extends concentrically along a longitudinal axis 2 of the valve. As part of a valve housing, the fuel injection valve 1 has a nozzle body 5 which extends at the downstream end. In the nozzle body 5, a stepped longitudinal bore 7 is formed, which runs concentrically to the longitudinal valve axis 2 and in which a z. B. needle-shaped valve closing part 10 is arranged. The valve closing part 10 has, for example, two guide sections 11, 12 which, together with a guide region 13 of the wall of the longitudinal bore 7 of the nozzle body 5, serve to guide the valve closing part 10. The longitudinal bore 7 of the nozzle body 5 has at its downstream end a fixed valve seat 15 tapering in the direction of the fuel flow, which together with a sealing section 17 of the valve closing part 10 tapering in the fuel flow direction forms a seat valve.

At its end facing away from the sealing section 17, the valve closing part 10 is connected to a tubular armature 20, which has a magnetic coil 22 partially surrounding the armature 20 in the axial direction and a tubular core 23 of the fuel injector 1 opposite the armature 20 in the fixed valve seat 15 cooperates. At the end of the valve closing part 10 connected to the armature 20 there is a return spring 25 with one end which tends to move the valve closing part 10 in the direction of the fixed valve seat 15. With its other end, the return spring 25 is supported on a z. B. non-magnetic adjusting sleeve 27.

On an end face 30 of the nozzle body 5 of the fuel injector 1 facing away from the core 23, there is an injection orifice disk 32 which is fixedly connected to the nozzle body 5, for example, by means of a weld seam produced by means of laser welding. The spray orifice plate 32 has, for example, four spray openings 33 through which the fuel flowing past the valve seat 15 when the valve closing part 10 is lifted off is sprayed off.

For the supply and metering of a gas, which is used to improve the preparation and atomization of the fuel, an attachment body 50, for example made of plastic, is provided at the downstream end of the fuel injection valve 1. As a gas z. B. the by a bypass in front of a throttle valve in a suction pipe of the internal combustion engine suction air required by an additional fan, but also recirculated exhaust gas from the internal combustion engine or a mixture of air and exhaust gas can be used. The use of recirculated exhaust gas enables a reduction in the pollutant emissions of the internal combustion engine. The supply of the gas to the attachment body 50 is not shown in more detail in FIG. 1.

The attachment body 50 is formed in two parts, a tubular base body 51 radially surrounding the downstream end of the nozzle body 5 and being fastened to it, for example, by snapping it into place. The base body 51 also extends in the axial direction downstream of the spray hole disk 32. A flat insert part 52 which can be pushed into the base body 51 is arranged immediately downstream of the spray hole disk 32 in the installed state. The insert part 52 is designed so that a gas coming from outside the attachment body 50 into the interior of the attachment body 50 directly downstream of the Spray plate 32 can flow. In addition to supplying the gas, the insert 52 also takes on the function of metering the gas throughput through the resulting free flow cross section. The flow cross section for the gas in the insert part 52 tapers from the outer circumference to the valve longitudinal axis 2, so that the gas is accelerated strongly and the fuel exiting the spray openings 33 and axially flowing through the insert part 52, which the gas strikes vertically, atomizes particularly finely becomes.

In FIG. 2, the attachment body 50 is again shown in section separately from the injection valve as an independent component. The attachment body 50 is formed by two individual parts, namely by the tubular base body 51 and by the flat disc-shaped insert part 52, which can be inserted into the base body 51. The base body 51 is composed of an upstream support section 54 and a downstream beam splitting section 55. While the carrier section 54 has a completely cylindrical contour with a constant outside diameter, the beam splitting section 55 has three ring-shaped regions of different outside diameters, which run concentrically to the valve longitudinal axis 2 and follow one another axially. Two ring regions 57 projecting radially to the same extent beyond the carrier section 54 serve to form an annular groove 58 into which a sealing ring 59 can be used for sealing between the circumference of the injection valve and a valve receptacle, not shown, for example the intake line of the internal combustion engine. The annular groove 58 is delimited axially by the two ring regions 57 and radially by a groove base 60 which has a smaller diameter than the outer diameter of the carrier section 54, but for example in the same way is the same as the diameter of the inner wall of the tubular support section 54.

The entire base body 51 is fastened on the injection valve, in particular on the nozzle body 5, by snapping in a bead 62 formed in the circumferential groove 64 on the nozzle body 5 in a circumferential groove 64 that extends circumferentially in the carrier section 54 and extends radially from the inner wall in the direction of the longitudinal axis 2 of the valve that there is no risk of the connection becoming loose due to vibrations or the effects of temperature. A suitable selection of the bead 62 and the groove 64 can also ensure complete security against rotation. With e.g. interlocking and interacting depressions or elevations on the bead 62 and in the groove 64, the anti-rotation is achieved. In addition, other types of connection of the attachment body 50 to the nozzle body 5 are conceivable instead of snapping in or snapping in, e.g. Gluing or shrinking, which, however, result in permanent connections. Furthermore, the attachment body 50 can be prevented from rotating by means of a knurl or surfaces in the groove base of the groove 64 on the nozzle body 5.

The carrier section 54 has slot openings 65 with a trapezoidal cross section at two regions of its circumference offset by 180 ° and thus exactly opposite, through which the flat insert part 52 is inserted. The slot openings 65 are made in the downstream end of the carrier section 54 in such a way that the insert part 52 is placed on a shoulder 67 which extends radially inwards from the upper ring region 57 and which, viewed in the axial direction, thus exactly in the plane of the transition from the carrier section 54 to the beam splitting section 55 is moved along when inserted and then lies there.

The insert part 52 also has a trapezoidal cross section corresponding to the slot openings 65 with two flat side surfaces 68 in order to guarantee a defined installation position. However, the insert 52 can be inserted identically from the two slot openings 65. In addition to the two flat side surfaces 68 of the insert part 52, through which the trapezoidal cross section is formed, two rounded side surfaces 69 are provided on the insert part 52, which complete the outer contour of the insert part 52 between the flat side surfaces 68. These rounded side surfaces 69 are designed in such a way that they have the same radius as the base body 51 and thus, when pushed in, make the base body 51 flush with the outside. The shape of the insert 52 is particularly evident in FIGS. 4 to 6.

For example, if a two-jet fuel injector 1 for injecting fuel in the direction of two intake valves is to be achieved or maintained, it is expedient to provide a beam splitter 72 in the beam splitting section 55 of the base body 51. The beam splitter 72 can have a wide variety of configurations, which can be selected as a function of the desired beam angle and images. In FIGS. 1 and 2, the beam splitter 72 is shown by way of example with a pointed cutting edge 73, which is directed toward the spray orifice plate 32, while starting from the cutting edge 73, the beam splitter 72 widens in cross section in the downstream direction, so that it has a triangular cross section . The two-beam radiation, which is already generated by the spray openings 33 of the spray plate 32, but can be impaired by the gas supply interposed, is retained by the beam splitter 72 reinforced. The valve longitudinal axis 2 runs exactly in the center through the beam splitter 72, the beam splitter 72 being formed in one piece with the base body 51 and thus running from a peripheral region of the beam splitting section 55 to a circumferential region lying opposite one another, as shown in FIG. 3. The beam splitter 72 divides an inner circular spray chamber 75 of the beam splitting section 55 into two subspaces of the same size if a symmetrical beam splitting is required. The radial extension direction of the beam splitter 72 is, for example, identical to the insertion direction of the insert part 52. A beam splitter 72 in the base body 51 can of course also be dispensed with if the fuel does not need to have multiple beams.

FIG. 3 shows a section along the line III-III in FIG. 2, so that the attachment body 50 can now be seen rotated by 90 ° with respect to FIG. 2. In this view it is clear that the beam splitter 72 completely divides the spray chamber 75 and is formed in one piece with the base body 51. It can also be seen that the insert part 52 has regions which extend to different extents in the axial direction. Starting from the rounded side surfaces 69, two tapering inflow regions 78, which have a smaller axial extent than from the flat side surfaces 68 to the opening 77, run to a central circular opening 77 Inflow areas 78 are completely surrounded channels for the gas supply, which are delimited laterally by flanks 80 of the delimitation areas 79 and axially by an inflow floor 81 and the support section 54 or the spray-perforated disk 32. It is also possible to replace the initially open inflow areas 78 to provide already completely enclosed inflow channels in the insert part 52.

The geometry of the inflow regions 78 or of the delimitation regions 79 with their flanks 80 is particularly illustrated by FIGS. 4 to 6. In FIG. 4, which is a representation of a section along the line IV-IV in FIG. 3, the inflow regions 78 are largely triangular, so that the outer contour of the insert part 52, which has already been described, also has a largely triangular shape for the boundary regions 79 results. Immediately on the rounded side surfaces 69, the two inflow regions 78, which are designed symmetrically to one another, have their largest inflow cross section, which guarantees that the supplied gas can flow well into the insert part 52. The width of the inflow region 78 on the rounded side surface 69 is slightly smaller than the width of the entire insert 52. Towards the central opening 77 through which the fuel-gas mixture emerges, the straight flanks 80 of the delimitation regions 79 run towards one another, so that the inflow cross-section of the inflow areas 78 is becoming smaller and the velocity of the gas is increasing.

To secure the insert 52 against slipping in the base body 51, the flat side surfaces 68, which run obliquely to the longitudinal axis 2 of the valve, are designed such that a minimal projection 83 exists in their central region. This projection 83 is, for example, 0.1 mm opposite the side surfaces 68, as are present in the slot openings 65 of the carrier section 54 in the installed state. When inserting insert 52 through slot opening 65, a narrower area is thus first immersed followed by a slightly wider area of the insert part 52 through the projections 83, which can only be pushed through the slot opening 65 while overcoming resistance and therefore leads to a slight deformation of the base body 51, and then again a narrower area. The area which is wider as a result of the projections 83 is therefore in the installed state in the interior of the carrier section 54, with the result that there is a latching and centering. The insert 52 can now be replaced only with effort.

In a further exemplary embodiment according to the invention, which is shown in FIG. 5, the inflow regions 78 and the limiting regions 79 differ from those of the exemplary embodiment illustrated in FIG. In order to generate a swirl in the gas, which flows largely tangentially into the opening 77, the flanks 80 of the delimitation regions 79 are designed spirally. Here, too, the inflow area 78 tapers from a large cross section on the rounded side surfaces 69 to a very small cross section directly at the opening 77. The swirling gas is thus greatly accelerated and hits the one coming from the spray plate 32 in the opening 77 Fuel so that a swirl component is also contained in the fuel-gas mixture.

FIG. 6 shows a perspective view of the exemplary embodiment of the attachment body 50 already illustrated in FIGS. 2 to 4 with sectional views.

The constructive solution of this attachment body 50 makes an advantageous functional separation of gas supply, metering and metering compared to the sealing of fuel injector 1 into an intake line and Attachment of the attachment body 50 on the fuel injector 1 reached. In addition, a large variety of variants can be achieved simply and inexpensively with the front body 50 described, by only replacing the insert parts 52 for specific applications, while the base body 51 can still be used, so that a modular system is present. In addition to the variants for forming the inflow region 78, the gas throughput can also be calibrated by changing the diameter of the opening 77 in the insert part 52.

Another important factor is the optimal choice of materials. The use of "tailor-made" plastics for the corresponding functions results in further advantages. For example, the base body 51 is made of a non-glass fiber reinforced polyamide, which has sufficient ductility. In contrast, the insert 52 z. B. made of a thermally stable, very precisely sprayable, highly reinforced plastic, such as polyphenylene sulfide. Such a pairing of materials proves to be favorable, particularly when inserting insert 52 into base body 51. In addition to the exemplary embodiments already described, further inflow geometries in insert 52 are conceivable.

Claims (10)

Fuel injection valve for injecting a fuel-gas mixture for fuel injection systems of internal combustion engines, with a valve longitudinal axis, with a movable valve closing body, with a nozzle body, which has a valve seat interacting with the valve closing body, with at least one spray opening downstream of the valve seat, with one at the downstream end of the valve seat Injection valve arranged attachment body, which has at least one means for gas supply and from which a fuel-gas mixture emerges, characterized in that the attachment body (50) from an axially extending, tubular base body (51) with at least one slot opening (65) and a flat insert part (52) which is insertable into the base body (51) through the at least one slot opening (65) approximately transversely to the longitudinal valve axis (2), the insert part (52) being arranged downstream of the at least one spray opening (33) and i At least one inflow region (78) for the gas leading to an opening (77) is formed in the insert part (52). Fuel injection valve according to Claim 1, characterized in that both the base body (51) and the insert part (52) are made from a plastic. Fuel injection valve according to Claim 2, characterized in that the base body (51) is made from a non-reinforced polyamide and the insert (52) is made from polyphenylene sulfide. Fuel injection valve according to Claim 1, characterized in that the base body (51) has slot openings (65) on its circumference, which have a trapezoidal cross section and through which the insert part (52) can be inserted. Fuel injection valve according to Claim 1, characterized in that a beam splitter (72) is arranged in one piece with the base body (51) downstream of the insert part (52). Fuel injection valve according to Claim 1 or 4, characterized in that the insert (52) has a trapezoidal cross section and is delimited by flat side surfaces (68) and rounded side surfaces (69). Fuel injection valve according to Claim 1, characterized in that the insert (52) has inflow regions (78) and at least partially delimiting boundary regions (79) which have a different extent in the direction of the valve longitudinal axis (2). Fuel injection valve according to Claim 1 or 7, characterized in that the inflow regions (78) for the supply and metering of gas are triangular and taper radially towards the longitudinal valve axis (2). Fuel injection valve according to Claim 1 or 7, characterized in that the inflow regions (78) for supplying and metering gas are designed in a spiral shape and taper radially towards the longitudinal valve axis (2). Fuel injection valve according to Claim 1, characterized in that the insert part (52) is fixed by a catch in the base body (51).

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