DE102005037951A1 - Housing for automotive fuel injection valve has heat-treated sleeve with modified magnetic characteristics - Google Patents

Abstract

In a process to manufacture a housing for an automotive electro-magnetic valve, on zone (58) in a sleeve of non-magnetic, paramagnetic material or duplex material is heated locally. The sleeve thereby acquires a magnetic section zone alongside the non-magnetized zones. The sleeve is then machined or fashioned to the desired housing (66) geometry.

Description

The The invention is based on a method for producing a solid housing according to the preamble of the main claim.

In the 1 a known fuel injection valve of the prior art is shown, which has a classic three-part construction of an inner metal flow guide member and at the same time housing component. This inner valve tube is formed from an inlet port forming an inner pole, a nonmagnetic intermediate part and a valve seat carrier receiving a valve seat, and in the description 1 explained in more detail.

From the DE 35 02 287 A1 is already a method for producing a hollow cylindrical metal housing with two magnetizable housing parts and an intermediate, the housing parts magnetically separating, non-magnetic housing zone known. This metal housing is in this case prefabricated from a magnetizable blank in one piece to an oversize in the outer diameter, wherein in the inner wall of the housing in the width of the desired central housing zone an annular groove is inserted. When the housing is rotating, a non-magnetisable filling material is filled into the annular groove while heating the annular groove area, and the rotation of the housing is maintained until solidification of the filling material. Subsequently, the housing is over-turned outside to the final dimension of the outer diameter, so that there is no longer any connection between the magnetizable housing parts. A valve housing produced in this way can be used, for example, in magnetic valves for anti-lock braking systems (ABS) of motor vehicles.

Are known further from the DE 42 37 405 C2 Method for producing a solid core for injection valves for internal combustion engines ( 5 of the document). The methods are characterized by providing, directly or through previous conversion processes, a one-piece sleeve-shaped magnetic martensitic workpiece that undergoes a local heat treatment in a central portion of the magnetic martensitic workpiece to convert that middle portion into a nonmagnetic, austenitic center portion , Alternatively, in the local heat treatment by laser, molten austenite-forming elements are added to the site of the heat treatment to form a nonmagnetic austenitic central portion of the solid core.

Advantages of invention

The inventive method for producing a solid housing with the characterizing features of the main claim has the advantage that housing in a particularly simple and cost-effective manner a magnetic separation of large scale technology reliably produced are.

Especially is due to the simplicity of the individual components only one opposite the known manufacturing process reduced effort on special tools necessary. As starting material can easily be produced strip material used with an austenitic or an austenitic-ferritic material structure be used, e.g. is brought into a sleeve shape by deep drawing. austenitic or austenitic-ferritic steels, as a material for the housing used, offer a very high corrosion resistance. Furthermore own these steels a much greater degree of deformation and higher Strengths as ferritic and martensitic steels. Of the Manufacturing process can be particularly cost-effective, reliable and reduced cycle time be designed.

From Another advantage is that a high degree of flexibility in the design of the Geometry of the housing itself, such as at length, Outer diameter, Gradations possible is.

By in the subclaims listed activities are advantageous developments and improvements of the main claim specified method possible.

Especially It is advantageous to join individual attachments with the solid housing and the ferromagnetic make individual zones of the housing make simultaneously so that certain assemblies of a valve or other aggregates very easily and with little time are manufacturable.

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 a fuel injection valve according to the prior art with a three-piece inner metal valve tube as a housing and 2 to 9 schematically method steps of a method according to the invention for producing a solid housing.

description the embodiments

Before using the 2 to 9 the method steps of the method for producing a solid housing according to the invention will be described, is based on 1 a fuel injection valve of the prior art as a possible input product for a housing produced according to the invention will be explained in more detail.

That in the 1 For example, shown electromagnetically operable valve in the form of an injection valve for fuel injection systems of mixture-compression, spark-ignited internal combustion engines has one of a magnetic coil 1 surrounded, serving as a fuel inlet nozzle and inner pole tubular core 2 which has, for example, a constant outer diameter over its entire length. A bobbin stepped in the radial direction 3 takes a coil of the solenoid 1 on and allows in conjunction with the core 2 a compact design of the injector in the field of solenoid 1 ,

With a lower core end 9 of the core 2 is concentric to a valve longitudinal axis 10 tightly a tubular metal non-magnetic intermediate part 12 connected by welding and surrounding the core end 9 partially axial. Downstream of the bobbin 3 and the intermediate part 12 extends a tubular valve seat carrier 16 Fixing with the intermediate part 12 connected is. In the valve seat carrier 16 is an axially movable valve needle 18 arranged. At the downstream end 23 the valve needle 18 is a spherical valve closing body 24 provided on the circumference, for example, five flats 25 are provided for flowing past the fuel.

The actuation of the injection valve takes place in a known manner electromagnetically. For the axial movement of the valve needle 18 and thus to open against the spring force of a return spring 26 or for closing the injection valve is the electromagnetic circuit with the solenoid 1 the core 2 and an anchor 27 , The tubular anchor 27 is with a valve closing body 24 opposite end of the valve needle 18 firmly connected by, for example, a weld and onto the core 2 aligned. In the downstream, the core 2 opposite end of the valve seat carrier 16 is a cylindrical valve seat body 29 who has a tight valve seat 30 has, tightly assembled by welding.

The spherical valve closing body 24 the valve needle 18 acts with the valve seat tapering frustoconically in the flow direction 30 of the valve seat body 29 together. At its lower end face is the valve seat body 29 with an example cup-shaped spray perforated disc 34 tight and tight by a z. B. connected by means of a laser weld. In the spray-disk 34 are at least one, for example four formed by eroding or punching injection orifices 39 intended.

To the magnetic flux for optimal operation of the armature 27 with energization of the solenoid 1 and thus for safe and accurate opening and closing of the valve to the anchor 27 to conduct, is the magnetic coil 1 of at least one, for example, designed as a bracket and serving as ferromagnetic element guide element 45 Surrounded by the magnetic coil 1 circumferentially at least partially surrounds and with its one end to the core 2 and its other end to the valve seat carrier 16 is present and with these z. B. is connected by welding, soldering or gluing. An inner metal valve tube as the basic framework and thus also the housing of the fuel injection valve form the core 2 , the non-magnetic intermediate part 12 and the valve seat carrier 16 , which are fixedly connected to each other and extend over the entire length of the fuel injection valve. All other functional groups of the valve are arranged inside or around the valve tube. In this arrangement, the valve tube is the classic three-part construction of a housing for an electromagnetically actuated unit, such as a valve, with two ferromagnetic or magnetizable housing areas, which are effective for the management of the magnetic circuit lines in the armature 27 by means of a nonmagnetic intermediate part 12 are magnetically separated from each other or at least connected to each other via a magnetic throttle point.

The injection valve is largely with a plastic extrusion 51 enclosed, separate from the core 2 starting in the axial direction via the magnetic coil 1 and that at least one guide element 45 to the valve seat carrier 16 extends, wherein the at least one guide element 45 completely axially and circumferentially covered. To this plastic extrusion 51 For example, a mitangespritzter electrical connector belongs 52 ,

With the in the 2 to 9 schematically indicated process steps of the method according to the invention for producing a solid housing, it is possible in an advantageous manner, particularly simple and inexpensive thin-walled housing 66 for a variety of purposes, including preferably to produce electromagnetically operable valves that can replace a three-piece valve tube described above.

In a first process step ( 2 ) becomes a sleeve-shaped basic body 55 bereitge represents, wherein the main body 55 consists of a non-magnetic or paramagnetic or partially magnetic material and, for example, has an austenitic or austenitic-ferritic material structure. In this base body to be provided 55 it is for example a deep-drawn, precisely worked and customized sheet metal sleeve or a machined component. For example, the austenitic material 1.4301 or a duplex steel 1.4462 can be used as base material. These materials either have no or only moderate magnetic properties with very low saturation induction. For a low saturation, the material may be subjected to a heat treatment before or after shaping in order to eliminate, for example, forming martensite formed during the forming.

Instead of providing the body 55 in sleeve form, it is also conceivable, the main body 55 as a solid cylinder, so in solid material to use as a starting component, the inventive method steps on this body 55 to perform and subsequently create a sleeve shape.

By alloying in an additive in at least one area of the non-magnetic basic body 55 becomes at least one ferromagnetic zone 58 in the main body 55 generated. In 3 is a basic body 55 ' shown the five consecutive zones 57 . 58 having alloyed by creating ferromagnetic zones 58 each of an austenitic or austenitic-ferritic zone 57 of the basic body 55 are alternately surrounded. The additive can by means of an additional wire 61 or a powder in the respective desired area of the base body 55 are introduced, in such an amount that a magnetic or a magnetizable microstructure arises. The welding technical melting of the additional wire 61 or powder for alloying the additive is done for example by means of a welding system 62 , Alternatively, the additive can also by a previous coating on the body 55 be applied. As a method of melting, laser welding, electron beam welding, plasma welding or the like can be used. come into use. The material and the dosage of the additive must be chosen so that the austenitic structure or the duplex structure is ferritic or martensitic. For example, the additive can consist of a ferritic or martensitic steel or can be composed of the ferrite-stabilizing alloying elements chromium and iron.

By double alloying in the body 55 arise five longitudinal zones 57 . 58 , each of which has different magnetic properties immediately following each other due to the melted material. Here are the two outer zones 57 and the middle zone 57 of the basic body 55 ' the same austenitic or duplex structural properties, while the intervening alloyed zones 58 assume a ferromagnetic or magnetizable, in particular ferritic or martensitic material structure and magnetically from the other three zones 57 are separated.

Before installing the body 55 ' in a valve or other aggregate is the main body 55 ' if necessary, undergone a finish to ultimately make the solid housing 66 to be present in a desired geometry. In the case of use of a housing produced according to the invention 66 in a fuel injector, it may be advantageous to have the housing 66 by specific manufacturing measures such as stretching, rolling, swaging, crimping and / or Auftulpen specifically. You may also need the alloyed zones 58 be reworked. With the housing 66 is a component that in a known fuel injection valve according to 1 the sum of the functions of the valve tube consisting of core 2 , Intermediate part 12 and valve seat carrier 16 can take over completely and thus extends, for example, over the entire axial length of a fuel injection valve.

4 shows a schematic section of a fuel injection valve with a housing made according to the invention 66 , which is installed as a thin-walled sleeve in the valve and thereby the core 2 and the anchor 27 radially and circumferentially surrounds and even from the solenoid 1 is surrounded. The magnetic coil 1 is in turn surrounded by an outer magnetic circuit component, for example, instead of the in 1 shown bow-shaped guide element 45 also as a rotating stepped magnet pot 46 can be trained. Out 4 It becomes clear that the zones changed in their magnetic properties and made magnetizable 58 of the housing 66 eg in the axial extension region between the core 2 and one above the solenoid 1 arranged cover element 48 of the magnetic circuit and in the axial extent of the armature 27 , in particular in the axial guide region, lie in order to guide the magnetic circuit lines optimally and effectively in the magnetic circuit. The three non-magnetic zones 57 of the housing 66 act as magnetic separation in the magnetic circuit.

Based on 5 to 9 a method of production modified from the method described above is explained. An assembly of a non-magnetic sleeve-shaped body 55 and one or more ferromagneti or ferritic attachments, such as the cover element 48 ( 5 and 6 ) or the magnet pot 46 ( 7 and 8th ), is pre-assembled. For the purpose of simultaneous joining and ferromagnetic machining of the body 55 become the (ferro) magnetic attachments 46 . 48 with the main body 55 optionally welded with the introduction of an additive.

By alloying in an additive in the joining region to be welded to the base body 55 becomes a ferromagnetic zone 58 in the main body 55 generated. The additive can by means of an additional wire 61 or a powder in the respective joining region of the base body 55 are introduced, in such an amount that a magnetic or a magnetizable microstructure arises. The welding technical melting of the additional wire 61 or powder for alloying the additive is done for example by means of a welding system 62 , As a method of melting, laser welding, electron beam welding, plasma welding or the like can be used. come into use. The material and the dosage of the additive must be chosen so that the austenitic structure or the Dup1ex microstructure is ferritic or martensitic. For example, the additive can consist of a ferritic or martensitic steel or can be composed of the ferrite-stabilizing alloying elements chromium and iron.

In 9 is a preassembled module consisting of basic body 55 , Cover element 48 and magnet pot 46 shown, in which also already the winding of the magnetic coil 1 is integrated. This preassembled module can in the 5 to 8th be processed in a corresponding manner by the joining of the joining partners at the same time two magnetic zones 58 be created.

Welding and the associated mixing of the weld metal create magnetic zones 58 in the main body 55 ' by which a magnetic circuit in a valve or other electromagnetically operated unit can be closed. An additive during welding can be completely dispensed with, if the material mixture of the joining partners, ie the materials of the body 55 and the attachments to be welded cover element 48 and / or magnet pot 46 , results in a ferromagnetic material mixture. The material mixture of the material of the body 55 and the material of the lid member 48 or the magnet pot 46 and optionally the additive may also be partially magnetic to cause a positive effect on the magnetic circuit.

To minimize the rework or even the elimination of any post-processing, the geometry of the welding partners can be adjusted by chamfers and / or grooves so that the accumulation of material in the magnetically made zones 58 is minimized by the additive or the Schweißaufwurf.

The invention is by no means limited to use in fuel injection valves or solenoid valves for anti-lock braking systems, but relates to all electromagnetically operable valves of different application areas and generally all fixed housing in units in which zones of different magnetism are sequentially required. In the inventive way are not only housing 66 with five consecutive zones 57 . 58 can be produced, but also housing 66 with more or less than five zones 57 . 58 ,

Claims (15)

Method for producing a solid housing ( 66 ), in particular a valve housing for an electromagnetically actuated valve, wherein the housing ( 66 ) has at least three zones and in each case two immediately consecutive zones have different magnetic properties, with the method steps: a) provision of a basic body ( 55 ) of a non-magnetic or paramagnetic material or duplex material, b) melting the base body ( 55 ) in at least one zone ( 58 ) to form a magnetic or magnetizable structure and c) finishing of the resulting base body ( 55 ' ) until a desired geometry of the housing ( 66 ). Method according to claim 1, characterized in that the basic body ( 55 ) has an austenitic or austenitic-ferritic material structure. Method according to claim 1 or 2, characterized in that the basic body ( 55 ) is provided as a deep-drawn, customized sheet metal sleeve or as a machined component. Method according to claim 1 or 2, characterized in that the basic body ( 55 ) hollow cylindrical sleeve-shaped or made of solid material, in particular fully cylindrical. Method according to one of the preceding claims, characterized in that the melting of the base body ( 55 ) takes place together with the alloying of an additive. A method according to claim 5, characterized in that as additives a ferritic or martensitic steel or chromium or iron individually or in combination in the basic body ( 55 ) are introduced. Method according to claim 5 or 6, characterized in that the additive is used as wire ( 61 ) or is supplied as a powder or predeposited. A method according to claim 5 or 6 or 7, characterized characterized in that the melting by means of laser welding, electron beam welding or plasma welding he follows. Method according to one of the preceding claims, characterized in that the basic body ( 55 ' ) in the molten zone ( 58 ) has a ferritic or martensitic material structure. Method according to one of the preceding claims, characterized in that the basic body ( 55 ) with a magnetic attachment ( 46 . 48 ) are added to a preassembled module and simultaneously at least one zone ( 58 ) of the basic body ( 55 ) is magnetized in the joining area. A method according to claim 10, characterized in that the joining of the base body ( 55 ) with the magnetic attachment, in particular a cover element ( 48 ) and / or a magnet pot ( 46 ), by means of laser welding. Method according to claim 10 or 11, characterized in that several add-on parts ( 46 . 48 ) on the base body ( 55 ) to a preassembled assembly and multiple zones ( 58 ) of the basic body ( 55 ) are magnetized. Method according to one of claims 10 to 12, characterized in that the materials of the base body ( 55 ) and the attachment to be attached ( 46 . 48 ) are selected so that when joining already a ferritic or martensitic material mixture in the main body ( 55 ). Method according to one of the preceding claims, characterized in that the basic body ( 55 ) in the area of the zone to be melted ( 58 ) is provided with chamfers and / or grooves. Method according to one of the preceding claims, characterized in that the finishing of the base body ( 55 ' ) by means of stretching, rolling, swaging, flanging, machining and / or Auftulpen done.