KR100339112B1 - Electromagnetically operable valve - Google Patents

Abstract

In the case of known fuel injection valves, wear components such as, for example, armatures and cores are equipped with wear resistant coatings made of, for example, chromium, molybdenum or nickel. When the coating of the component parts of the fuel injection valve is realized by electroplating, a certain wedge coating thickness distribution is obtained so that only a small impact area is produced. However, the coating thickness distribution is physically predefined and hardly affected.

The new valve has one or more components, ie armatures 27, with wedge faces, which in each case can be produced variously according to magnetic and hydraulic optimum conditions before application of the wear resistant coating. The annular impact segment 68 formed in the wedge shape has a limited impact surface width or contact width a which is kept constant throughout the service life since no wear of the impact surface leads to an enlargement of the contact width in continuous operation.

The valve is particularly suitable for use in fuel injection systems of explosive spark ignition internal combustion engines.

Description

Electromagnetically Operable Valve

Prior art

The present invention relates to an electromagnetically actuated valve according to the preamble of claim 1. Various electromagnetically actuated valves, in particular fuel injection valves, are known and wear resistant components are equipped with wear resistant coatings.

DE-A 29 42 928 discloses the application of wear-resistant diamagnetic material coatings to wear parts such as armatures and nozzle bodies. These applied coatings are applied to limit the lift of the valve needle, whereby the effect of residual magnetism across the moving parts of the fuel injection valve is minimized.

It is also known from DE-A 32 30 844 to have a wear resistant surface on the impact face of the armature and the fuel injection valve. These surfaces can be nitride cured by nickel plating or nitrogen impregnation with additional coating.

In addition, DE-A 37 16 072 is known to use thinly set molybdenum cured coatings on parts of injection valves that are prone to wear and corrosion and then to be processed into diamonds.

DE-A 38 10 826 has one or more impact surfaces designed in a spherical cap shape in order to obtain a very accurate air gap, which is made of a non-magnetic, highly rigid body round. body) A fuel injection valve is described in which an insert is formed centrally.

EP-A 0 536 773 is likewise known for fuel injection valves to which galvanization is applied to the armature. A light metal coating is applied to the cylindrical outer circumferential surface and the annular collision surface of the armature. Such chromium or nickel coatings have a thickness of, for example, 15-25 μm. As a result of the electroplating coating process, a slightly wedge-type coating thickness distribution is obtained, and the coating is at least thicker at the outer edge. As a result of the electroplated coating, the coating thickness distribution is physically predefined and hardly affected. After a certain operating time, the impact surface undesirably widens as a result of wear, thereby causing a change in the pull-in time and release time of the armature.

Advantages of the Invention

Electromagnetic actuated valves according to the invention having the features of claim 1 have the following advantages over them. At least one of the mutually impacted centripetal parts is not undesirably expanded due to wear of the impact surface even after prolonged operation once the wear resistant surface has been created, so that the pull-in and release times of the movable component are substantially constant. It is formed to be maintained. This is accomplished by having one or more of the components that collide with one another even before wear resistance is created. The wedge surface can be applied precisely in each case in different given situations in order to obtain magnetic and hydraulic optimum conditions.

The features described in the dependent claims make it possible to improve the electromagnetically actuated valves, in particular the fuel injection valves embodied in claim 1.

It is particularly good to make one or more of the impinging components into a very accurate surface shape by a mechanical method using a ground counterbore, whereby very accurate dimensions are obtained. Using a very precisely polished tool, narrower manufacturing tolerances than described above are contemplated so that very small changes in pull-in and in particular release time of the armature are obtained when the injection valve is operated.

As an additional advantage, with wedge armatures and / or cores, hydraulic sticking is completely eliminated because the shape of the wedge is always present, even when the coating is deposited evenly. The coating of one or more of the impinging component parts covers only a portion of the wedge shape of the component part itself.

It is also possible to apply uniform non-electroplating and magnetic abrasion resistant coatings so that the wedge surface shape of one or more components, i.e. the armature, meets the requirements of very small impact areas.

A unique advantage is that one or more of the surfaces of the mutually colliding components that are placed closest to their opposite components in the highest region of the surface are hardened by known processes, i.e., by nitriding processes such as plasma nitriding or gas nitriding. Wear resistance is created.

The illustrated embodiments of the invention are described in detail in the following description and illustrated in the accompanying drawings.

1 shows a fuel injection valve.

2 shows an enlarged stop of the injection valve in the core and armature regions.

3 shows a first embodiment of a wedge armature formed in accordance with the present invention.

4 shows a second embodiment of a wedge armature.

5 shows a third embodiment of a wedge armature.

Detailed description of the preferred embodiment

The electromagnetically actuated valve shown in the first drawing in the form of an injection valve for a fuel injection system of an explosive spark ignition internal combustion engine is surrounded by a magnetic coil (1) and acts as a fuel intake socket, tubular in shape and constant throughout its length. It has the core 2 which shows an outer diameter. A radially stepped coil form 3 receives the windings of the magnetic coil 1 with respect to the core 2 of constant outer diameter and provides a compact configuration of the injection valve in the region of the magnetic coil 1. Make it possible.

An airtight configuration, that is, a tubular intermetallic intermediate part 12 which partially encloses the core end 9 in the axial direction by welding, is connected to the lower core end 9 of the core 2 concentric with the valve longitudinal axis 10. It is connected. The stepped coil form 3 partially overlaps the core 2 and at least partly overlaps the intermediate part 12 in the axial direction with a large diameter step 15. To the coil form 3 and downstream of the intermediate part 12 is connected a tubular valve seat carrier 16 fixedly connected to the intermediate part 12, for example. The valve seat carrier 16 extends a longitudinal bore 17 formed concentrically on the longitudinal axis 10 of the valve. The longitudinal bore 17 is arranged at the downstream end 20 with tubular valve needles 19 connected to the spherical valve closing body 21, for example by welding, on the outer periphery of which five for passing fuel. Two flattening 22 are provided.

The action of the injection valve is realized in a known manner by electromagnetic means. The electromagnetic circuit comprising the magnetic coil 1 and the core 2 and the armature 27 moves the valve needle 19 axially to open against the spring force of the return spring 25 or It acts to close the injection valve. The armature 27 is connected to the end of the side not facing the valve needle 19 from the valve closing body 21 by a first weld seam 28 and aligned with the core 2. At the end of the valve seat carrier 16 located below the core 2, a cylindrical valve seat body 29 representing a fixed valve seat is fixed in a gas tight configuration by welding to the longitudinal bore 17. do.

The guide opening 32 of the valve seat body 29 is the valve closing body 21 during the axial movement of the valve needle 19 with the armature 27 along the valve longitudinal axis 10. Act to guide you. The spherical valve closing body 21 interacts with the valve seat of the valve seat body 29, which is tapered in a truncated cone shape in the flow direction. On the end side facing away from the valve closing body 21, the valve seat body 29 is concentrically and fixedly connected to a sprayhole disk 34, for example in the form of a pot. have. The lower part of the spray hole disk 34 is followed by one or more, for example four spray openings 39 formed by erosion or punching.

The insertion depth of the valve seat body 29 with the potted spray hole disk 34 determines a predetermined lift in accordance with the valve needle 19. One end setting of the valve needle 19 when the magnetic coil 1 is not excited is defined by the bearing contact of the valve closing body 21 to the valve seat of the valve seat body 29. On the other hand, when the magnetic coil 1 is excited, one end setting of the valve needle is precisely made by the support contact of the armature 27 to the core end 9, ie in the region set according to the invention. Generated and more strictly characterized by circles.

The adjustment sleeve 48 inserted into the flow bore 46 of the core 2 concentrically with the valve longitudinal axis 10 and formed by rolled spring-steel plating is the adjustment sleeve. It acts to adjust the spring bias of the return spring 25 which is supported with respect to 48, which is supported at its opposite side with respect to the valve needle 19.

The injection valve is largely surrounded by a plastic extrusion 50 extending axially across the magnetic coil 1 starting from the core 2 and extending to the valve seat carrier 16. have. The molded part of the plastic extrusion part 50 is an electrical connection plug 52 extruded together.

The fuel filter 61 protrudes into the flow bore 46 of the core 2 at the suction side end 55 of the core, and the fuel constituents that may cause blockage or damage in the injection valve are filtered according to their size. To ensure that

In FIG. 2, the area of one end setting of the valve needle 19 characterized in FIG. 1 in a circle and the armature 27 impinges against the end 9 of the core 2. Are shown on different scales. The application of a metal coating 65, for example a chromium or nickel coating, to the armature 27 and the end 9 of the core 2 by electroplating is already known. In this case the coating 65 is applied to both the end face 67 extending perpendicular to the longitudinal valve shaft 10 and at least a portion of the outer circumferential face 66 of the armature 27. These coatings 65 are particularly wear resistant and their small surface reduces hydraulic sticking of the impact surface but does not completely prevent it. The coating thickness of these coatings 65 is generally measured from 10 to 25 mu m.

With respect to the action of the fuel injection valve, the core 2 and the armature 27 are only in relatively small areas, for example, of the upper end face of the armature 27 facing away from the valve longitudinal axis 10. Only collide in the outer zone. This condition is particularly satisfied by the electroplating coating process. During the electroplating coating, in the case of the core 2 and the armature 27 a field line concentration appears at the edge of the part to be coated, and a wedge coating thickness distribution as shown in FIG. Is formed. The applied wedge coating 65 is therefore only applied to a small area when the injection valve is actuated. However, during continuous operation, the limited impact surface no longer exists because the coated 65 parts wear as a result of millions of collisions, so that the impact surface grows larger and the wedge shape is constantly further reduced.

In contrast to the above, in FIG. 3 a portion of the upper end face 67 area of the armature 27 according to the invention is shown, wherein the end face has the valve length prior to the coating process or the creation of surface wear resistance. It is a wedge segment 73 with a slanted course inclined with respect to the direction axis 10. Although the wedge segment 73 of the end face 67 is inclined outwardly in FIG. 4, in the embodiment of FIG. 3, the wedge segment 73 of the end face 67 of the armature 27 is formed. The slope extends inwardly. The wedge shape of the armature 27 in the region of the end face 67 is formed by mechanical work, ie by suitable abrasive counterboring.

While the coating thickness distribution formed in the case of an electroplated coating 65 is physically predefined and hardly affected, the wedge shape of the armature 27 has a magnetic and hydraulic optimum during use. Depending on the values required to be achieved in the case, the coating process or the production of the abrasion resistance is previously defined and produced in advance. Hydraulic sticking of the armature 27 to the core 2 is present in the wedge shaped armature since the wedge shape is present in any case even where the coating (including magnetic coating 65) is widely and evenly deposited. Are completely excluded. Using a very accurate polishing counter boy, the manufacturing tolerance for the wedge shape is narrower than described above so that the pull-in and release times of the armature 27 change smaller when the injection valve is actuated. The inclined wedge portion 73 of the end face 67 is capable of application of a non-electroplating, wear resistant coating (which may be oily) while meeting the requirements for very small impact areas.

In addition, the end face 67 at least in its highest region can be abrasion resistant by surface treatment using a curing process. Known nitriding processes such as, for example, plasma nitriding or gas nitriding are suitable for this purpose.

In the embodiment according to FIG. 3, a collision segment 68 of the end face 67 arising from the outer circumferential surface 66 of the armature 27 is provided, the collision segment being the valve longitudinal axis 10. Perpendicular to and extend radially inwardly across width a and act as a collision surface. The impact segment 68 consists of an annular surface which remains almost completely constant in width a through its working period. Therefore, the wear of the impact surface during the continuous operation is precisely defined. To achieve inflow and magnetic optimum. The wedge segment 73 is ideally inclined with respect to the impact segment 68 at an angle between greater than 0 degrees and less than 1 degrees. The minimum wedge coating 65, for example formed of chromium, deposited on the end face 67 is an inclined wedge segment 73 of the armature 27 inwardly adjoining the impact segment 68. Occupies only a portion of the inclined portion of. Accordingly, the inclination of the wedge segment 73 provided prior to the coating of the armature 27 is maintained completely or increased to a minimum.

Since the impact surface width corresponding to the width a of the impact segment 68 remains constant even when wear occurs, a constant contact width during the collision of the core 2 with the armature 27 is present for the useful life. In this way, the hydraulic ratio in the gap between the core 2 and the armature 27 is also kept constant, which represents a particular advantage. As mentioned above, at least the surface of the segment 68 may also be wear resistant by the curing process, thereby eliminating the need for an additional coating 65 applied to the end face 67. The same effect is similarly obtained if both the armature 27 and the core 2 have a wedge segment 73 of the end face 67 prior to the production or coating process of the wear resistant surface. This can ensure higher collision reliability or prevention of hydraulic sticking. The wedge segment of the end face is formed only on the core 2. The armature 27 may, for example, maintain a flat end face.

Another embodiment of the armature 27 constructed in accordance with the invention is shown in FIGS. 4 and 5. The armature 27 is shown in FIG. 4 and the wedge segment 73 of the end face 67 is inclined outwardly.

An embodiment of the armature 27 according to the invention in which the end face 67 is formed by the wedge segment 73 is shown in FIG. 5. The impact segment 68 representing one or more small radial extensions is in this case completely withdrawn and the wedge shape is present throughout the end face 67, ie extending perpendicular to the valve longitudinal axis 10. There is no area of the end face 67. In particular, even when the wedge segment 73 angle is very small, a stable collision surface also exists so that a limited collision surface is maintained even during continuous operation. In addition to the selection in which the slope of the wedge segment 73 continues in the direction of the valve longitudinal axis 10 shown in FIG. 5, an embodiment similar to the embodiment shown in FIG. 4, that is, the wedge segment 73 ) May also take into account a design extending in a direction away from the valve longitudinal axis 10, ie outwardly inclined.

The end face 67, since the wedge segment 73 already obtained by application of a chromium or nickel coating only on the armature 27 and / or one or more end faces 67 of the core 2 already exists. Other processes for quality improvement by improving the wear resistance of the are also used as described above. By using a curing process such as, for example, a plasma nitriding, gas nitriding or carburizing process, it is possible to completely withdraw the direct coating procedure by changing the surface structure on the armature 27 and / or the core 2.

Claims (9)

A valve longitudinal axis, a core made of ferromagnetic material, a magnetic coil, and an armature that actuates the valve closing body cooperating with the fixed valve seat and is pulled against the impingement surface of the core when the magnetic coil is excited In an electromagnetically actuated valve, in particular a fuel injection valve for a fuel injection system of an internal combustion engine, At least one of the two end faces 67 of the component armature 27 and the core 2, each guided towards the opposite component part, is at least one wedge segment running obliquely with respect to the valve longitudinal axis 10. 73. An electromagnetically actuated valve, comprising: 73). The method of claim 1, One or more wedge segments 73 divided into impingement segments 68 and one of the two end faces 67 of the component armature 27 and the core 2 run obliquely to the valve longitudinal axis 10. And at least one impact segment (68) has a finite width (a). The method of claim 2, And said at least one wedge segment (68) on said armature (27) or core (2) has a width (a) representing only a portion of said end face (67) diameter. The method of claim 1, At least one wedge segment (73) running obliquely to the valve longitudinal axis (10) extends throughout the end face (67). The method according to claim 2 or 4, The one or more wedge segments (73) on the core (2) or armature (27) run inclined in the direction of the valve longitudinal axis (10). The method according to claim 2 or 4, And said at least one wedge segment (73) on said core (2) or armature (27) runs inclined in a direction away from said valve longitudinal axis (10). The method of claim 1, Electromagnetic actuated valve, characterized in that the core (2) or armature (27) is coated in the region of the end face (67). The method of claim 7, wherein Electromagnetic actuated valve, characterized in that the coating (65) applied by the coating process is magnetic. The method of claim 1, Electromagnetic actuated valve, characterized in that the core (2) or armature (27) is treated in the end face region by a hardening process.