DE4421935A1 - Electromagnetically operated valve esp. for IC engine fuel-injection valve - has one of facing end faces of armature or core elements having wedge section which is inclined to valve longitudinal axis - Google Patents

Abstract

The electromagnetically operated valve has a valve longitudinal axis, a core (2) of ferromagnetic material, a magnetic coil and an armature (27). The armature operates a valve closing member which combines with a fixed valve seat and is pulled against a stop face of the core when the magnetic coil is excited. At least one of the two end faces (67) of the armature and core elements, which the directed towards the other opposite element, has a wedge section (73) that is inclined to the valve longitudinal axis.

Description

State of the art

The invention is based on an electromagnetic betä valve according to the genus of the main claim. It are already different electromagnetically operated Valves, in particular fuel injection valves, in which components subject to wear with wear solid layers are provided.

DE-OS 29 42 928 already knows wear Most diamagnetic layers of material on wear bean wanted to apply parts such as anchors and nozzle body. These applied layers serve to limit the Stroke of the valve needle, reducing the impact of the rest magnetism on the moving parts of the fuel spray valve can be minimized.

From DE-OS 32 30 844 is also known anchor and Stop surface of a fuel injector with ver to provide wear-resistant surfaces. These surfaces can be nickel-plated, for example, with an additional be provided layer, or nitrided, ie by Storage of nitrogen must be hardened.  

It is also known from DE-OS 37 16 072 for particularly stressed by wear and corrosion Parts of a fuel injector to ver molybdenum layers turn, which are thinly formed and subsequently with Diamonds can be edited.

In DE-OS 38 10 826 is a fuel injector described, in which at least one stop surface is designed to be extremely spherical to achieve an exact air gap, centered on the An a round body insert made of non-magnetic, high-strength material is formed.

EP-OS 0 536 773 is also a fuel Spray valve is known, in the case of the armature on the cylinder cal peripheral surface and annular stop surface Hard metal layer is applied by electroplating. This layer of chrome or nickel has, for example a thickness of 15 to 25 µm. As a result of the galvanic Coating results in a slightly wedge-shaped layer thickness distribution, with a minimal on the outer edges thicker layer is reached. By galvanically abge different layers, the layer thickness distribution is phy sical and hardly influenced. After a ge know operating time the stop surface widens due to wear and tear in an undesirable manner, causing Changes in the armature's pull-in and fall-out times were observed ben.

Advantages of the invention

The electromagnetically actuated valve according to the invention with the characterizing features of the main claim on the other hand the advantage that at least one of the one other striking components is designed so that after guarantee the creation of a wear-resistant surface It is steady that the stop surface even after a long time  Operating time is not undesirable due to wear is increased so that the pull-in and fall times of movable component remain almost constant. It will be there achieved by at least one of the one another striking components before generating the ver wear resistance has a wedge-shaped surface. These wedge-shaped surface can be used to achieve a magneti and hydraulic optimums to different ones Adjust conditions exactly.

By the measures listed in the subclaims are advantageous developments and improvements of specified in the main claim electromagnetically actuated Ren valve, especially fuel injector possible Lich.

It is particularly advantageous to have the extremely precise upper at least one of the striking components mechanically with a ground countersink tool put. In this way, very precise dimensions can be achieved. With Using the very precisely ground tools can be tighter Manufacturing tolerances are adhered to so far, so that it becomes very low when operating the injector spread of the suit and especially fall time of the Anchor is coming.

It is also advantageous that a wedge anchor and / or core a hydraulic gluing completely out is closed, since even largely largely isolated Layers the wedge is definitely present.

The layers on at least one of the striking construction namely parts have only a fraction of the wedge of the components themselves.

The wedge-shaped surface shape of at least one building partly, e.g. B. the anchor, it also allows that not galvanic and magnetic wear-resistant layers can be applied without the need for  in a very small impact area remains unfulfilled.

A particular advantage is that the surface in its highest, closest to the opposite component lying area of at least one of the adjoining components is made wear-resistant in that them by means of a method known per se, e.g. B. one Nitriding processes such as plasma nitriding or gas nitriding or the like is hardened.

drawing

Embodiments of the invention are shown in simplified form in the drawing and explained in more detail in the description below. In the drawings Fig. 1 is a Brennstoffein injection valve, Fig. 2 is an enlarged stop of the injection valve in the region of the core and the armature, Fig. 3 shows a first embodiment of an inventive wedge-shaped from formed anchor, Fig. 4 shows a second exporting approximately example of a wedge-shaped armature and Fig. 5 shows a third exemplary embodiment of a wedge-shaped anchor.

Description of the embodiments

The in Fig. 1, for example depicted electromag netic operable valve in the form of an injection valve for fuel injection systems of gemischverdich Tenden, spark-ignition internal combustion engine has a space surrounded by a magnet coil 1, serving as a fuel inlet fitting core 2 is formed from, for example, here a tubular shape and its entire length has a constant outer diameter. A coil body 3 , which is stepped in the radial direction, takes up a winding of the magnetic coil 1 and, in conjunction with the core 2 having a constant outer diameter, enables a particularly compact structure of the injection valve in the area of the magnetic coil 1 .

With a lower core end 9 of the core 2 is a tubular metal lenes intermediate part 12 connected, for example by welding, concentrically to a longitudinal valve axis 10 and surrounds the core end 9 partially axially. The stepped bobbin 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 . In the Ven tilsitzträger 16 runs a longitudinal bore 17 which is formed con centrically to the valve longitudinal axis 10 . In the longitudinal bore 17 , for example, a tubular Ven valve needle 19 is arranged, which is connected at its downstream end 20 with a spherical valve closing body 21 , on the circumference 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 Magnetspu le 1 , the core 2 and an armature 27th The armature 27 is connected to the valve closing body 21 facing away from the end of the valve needle 19 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.

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 , a guide opening 32 of the Ven valve seat body 29 is used . The spherical valve closing body 21 interacts with the valve seat of the valve seat body 29 which tapers in the shape of a truncated cone in the direction of flow. On its end facing away from the valve closing body 21 , the valve seat body 29 is connected concentrically and firmly to an injection-orifice disk 34 , for example, in the form of a pot. At least one runs in the base part of the spray perforated disk 34 , for example four spray openings 39 formed by eroding or stamping.

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 19th The one end position of the valve needle 19 is fixed when the solenoid 1 is not energized by the contact of the valve closing body 21 on the valve seat of the valve seat body 29 , while the other end position of the valve needle 19 when the magnet coil 1 is excited by the contact of the armature 27 at the core end 9 it gives, ie exactly in the area that is formed according to the invention and is characterized in more detail by a circle.

A in a concentric to the longitudinal axis axis 10 flow hole 46 of the core 2 inserted an adjusting sleeve 48 , which is formed, for example, from a rolled spring steel sheet, is used to adjust the spring preload on the adjusting sleeve 48 restoring spring 25 , which in turn is with its opposite side supported on the valve needle 19 .

The injection valve is largely enclosed with a plastic injection 50 , which extends from the core 2 in the axial direction over the solenoid 1 to the valve seat carrier 16 . This plastic encapsulation 50 includes, for example, an injection-molded electrical connector 52 .

A fuel filter 61 protrudes into the flow bore 46 of the core 2 at its inlet end 55 and provides for the filtering out of those fuel components which, due to their size, could cause blockages or damage in the injection valve.

In Fig. 2, the marked in Fig. 1 with a circle marked area of an end position of the valve needle 19 , in which the armature 27 strikes the core end 9 of the core 2 , is shown on a different scale. It is already known to apply metallic layers 65 to the core end 9 of the core 2 and to the armature 27 , for example with chrome or nickel layers, by means of galvanizing. The layers 65 are applied both to an end face 67 running perpendicular to the longitudinal valve axis 10 and at least partially to a peripheral face 66 of the armature 27 . These layers 65 are particularly wear-resistant and, with their small surface area, reduce hydraulic adhesion of the striking surfaces, but without being able to reliably prevent it. The layer thickness of these layers 65 is generally between 10 and 25 microns.

For the function of the injection valve, it is necessary that the core 2 and armature 27 abut only in a relatively small area, for example only in the outer, from the valve axis 10 region of the upper end face of the armature facing away from the 27th This requirement is met by the galvanic coating. In the gal vanic coating occurs at the edges of the parts to be coated, here core 2 and anchor 27 , a field line concentration, which leads to the fact that a wedge-shaped layer thickness distribution, as indicated in Fig. 2, occurs. The applied wedge-shaped layer 65 is thus only used in a small area during operation of the injection valve. In continuous operation, however, there is no longer a defined stop surface, since parts of the layer 65 are worn away by several million stops, so that the stop surface is continuously increased and thus the wedge is continuously reduced.

In contrast, part of the armature 27 according to the invention in the region of its upper end face 67 is shown in FIG. 3, which has a wedge section 73 with an inclined, oblique profile with respect to the valve longitudinal axis 10 even before the coating or the generation of the wear resistance of the surface , so that the armature 27 has a wedge shape there. The inclination of the wedge portion 73 of the end face 67 of the armature 27 extends in the embodiment example in FIG. 3 inwards, wherein a Keilab section 73 of the end face 67 can be inclined outward ausgebil det ( Fig. 4). The wedge shape of the armature 27 in the region of the end face 67 is already produced during mechanical processing, for example by a correspondingly ground countersink tool.

While the layer thickness distribution that arises in the case of electrodeposited layers 65 is physically predetermined and can hardly be influenced, the wedge nature of the armature 27 can be determined and manufactured before the coating or the generation of the wear resistance in accordance with the required values, so that when in use each one magnetic and hydraulic optimum is achieved. Hydraulic bonding of the armature 27 to the core 2 is now completely ruled out by the wedge-shaped armature, since even with largely flat (also magnetic) layers 65, the wedge-shape is definitely present. With the help of very precisely ground countersinking tools, tighter manufacturing tolerances can be maintained for the wedge than previously, so that when the injection valve is operated, there is even less scatter in the pull-in and fall-out times of the armature 27 . The inclined wedge section 73 of the end face 67 also allows non-galvanic, wear-resistant layers, which may also be magnetic, to be applied without the requirement for a very small stop area remaining unfulfilled.

In addition, the end face 67 , at least in the region of its highest point, can be made wear-resistant by treating the surface by means of a hardening process. As a hardening process z. B. the known nitriding processes such as plasma nitriding or gas nitriding.

In the embodiment according to FIG. 3, starting from the peripheral surface 66 of the armature 27 , a stop section 68 of the end face 67 is first provided, which extends over a width a radially inward perpendicular to the valve longitudinal axis 10 and serves as a stop surface. This stop section 68 represents an almost completely constant width a ring surface over the entire operating time. The stop surface wear during continuous operation is thus precisely defined. In order to achieve a hydraulic and magnetic optimum, the wedge section 73 is ideally inclined at an angle between <0 ° and <= 1 ° with respect to the stop section 68 . The minimally wedge-shaped, e.g. B. layer formed of chromium 65 , which is deposited on the end face 67 , has only a fraction of the inclination of the section of the stop 68 adjoining inward, inclined Keilab section 73 of the armature 27th Consequently, the inclination of the wedge section 73 provided before coating on the armature 27 is completely retained or is minimally reinforced.

Since the stop surface width, which corresponds to the width a of the stop section 68 , remains constant even when worn, there is a constant contact width during the stop of the core 2 and armature 27 over the entire service life, which also means the hydraulic conditions in the gap between the Core 2 and anchor 27 remain constant, which is a particular advantage. As already mentioned, at least the surface of the impact section 68 can also be made wear-resistant by a hardening process, so that no additional layer 65 has to be applied to the end face 67 .

The same effects can also be achieved if both the armature 27 and the core 2 are cut with wedges 73 of the end faces 67 before the coating or the generation of a wear-resistant surface. This ensures an even higher level of security against the impact and prevents hydraulic gluing. If it is expedient, the wedge portion of the end face can of course also be attached only to the core 2 , the armature 27 keeping, for example, a flat end face.

Further embodiments of the present invention ausgebil Deten anchors 27, Figs. 4 and 5. In FIG. 4, an anchor 27 is shown, in which the wedge portion 73 of the end inclined surface 67 is carried to the outside.

An exemplary embodiment of the armature 27 according to the invention, in which the end face 67 is formed only by the wedge section 73 , is shown in FIG. 5. Here, the stop section 68 is completely dispensed with at least a slight radial extension; rather, there is a wedge on the entire end face 67 , so there is no region of the end face 67 running perpendicular to the longitudinal axis 10 of the valve. Especially at very small angles of the wedge section 73 there is also a stable stop, so that a defined stop surface remains even during continuous operation. In addition to the possibility shown in FIG. 5 of the course of the inclination of the wedge section 73 in the direction of the valve longitudinal axis 10 , an exemplary embodiment analogous to the embodiment shown in FIG. 4 is also conceivable, in which the wedge section 73 intersects Direction away from the longitudinal axis 10 of the valve he stretches, that is to say it is inclined outwards.

Since the wedge section 73 already exists on at least one end face 67 of armature 27 and / or core 2 , which was previously achieved only by the application of chrome or nickel layers, now, as already mentioned, other methods for increasing quality by improvement can also be achieved the wear resistance of the end face 67 are used. Through the use of hardening processes such. B. plasma nitriding, gas nitriding or carburizing, through which the surface structure of the armature 27 and / or core 2 is changed, methods for immediate coating can even be dispensed with entirely.

Claims (9)

1. Electromagnetically actuated valve, in particular fuel injection valve for fuel injection systems of internal combustion engines, with a valve longitudinal axis, with a core made of ferromagnetic material, with a magnetic coil and with an armature which actuates a valve closing body interacting with a fixed valve seat and, when the magnetic coil is excited, against a stop surface of the Core is drawn, characterized in that at least one of the two end faces ( 67 ) of the components armature ( 27 ) and core ( 2 ), which are each directed towards the other opposite the component, at least one wedge section extending obliquely to the valve longitudinal axis ( 10 ) ( 73 ) sits. 2. Valve according to claim 1, characterized in that we at least one of the two end faces ( 67 ) of the components armature ( 27 ) and core ( 2 ) in a stop section ( 68 ) and the at least one to the valve longitudinal axis ( 10 ) oblique wedge section ( 73 ) is divided and the at least one stop section ( 68 ) has a defined width (a). 3. Valve according to claim 2, characterized in that the at least one stop portion ( 68 ) on armature ( 27 ) and / or core ( 2 ) has a width (a) which is only a fraction of the diameter of the end face ( 67 ). 4. Valve according to claim 1, characterized in that the at least one to the valve longitudinal axis ( 10 ) obliquely extending wedge section ( 73 ) extends over the entire end face ( 67 ). 5. Valve according to claim 2 or 4, characterized in that the at least one wedge portion ( 73 ) on the core ( 2 ) and / or armature ( 27 ) in the direction of the valve longitudinal axis ( 10 ) is inclined. 6. Valve according to claim 2 or 4, characterized in that the at least one wedge section ( 73 ) on the core ( 2 ) and / or armature ( 27 ) in the direction of the valve longitudinal axis ( 10 ) is inclined away. 7. Valve according to claim 1, characterized in that the core ( 2 ) and / or armature ( 27 ) in the region of the end face ( 67 ) are coated. 8. Valve according to claim 7, characterized in that the layer ( 65 ) applied by the coating is magnetic. 9. Valve according to claim 1, characterized in that the core ( 2 ) and / or armature ( 27 ) in the region of the end face ( 67 ) are treated by means of a hardening process.