DE102005036950A1 - Multiple part metallic molding, especially valve seat component for combustion engine injection valve, is obtained by multistage metal injection molding process allowing variation of properties of the parts - Google Patents

Abstract

Production of a metallic molding (40) with at least two parts (40a, 40b) involves: (a) forming a first part (40a) by a metal injection molding (MIM) process, involving mixing and homogenizing a metal powder and binder, injection molding, removing the binder and sintering the metal structure; and (b) forming the second part (40b) directly on the surface of the first, by a similar MIM process. An independent claim is included for a metallic component (40) having at least two parts (40a, 40b), produced independently but directly on each other by MIM processes.

Description

The The invention is based on a method for producing a metallic Component according to the preamble of claim 1 and of a metallic Component, in particular a valve seat component according to the species of Claim 8.

From the DE 42 30 376 C1 already a fuel injection valve is known, the valve needle is produced by the so-called metal injection molding (MIM) method. In the valve needle, a tubular operating member consisting of an armature portion and a valve sleeve portion is manufactured by injection molding and then sintering. Subsequently, the actuating part is connected by means of a welded connection with a valve closing member section, so that the valve needle is composed only of two individual components. In the anchor portion and valve sleeve portion while a continuous inner longitudinal opening is provided, can flow in the fuel in the direction of the valve closure member portion, which then exits near the valve closure member portion by transverse openings of the valve sleeve portion. In the manufacture of the valve needle with the MIM method so slide tools are needed to form the transverse openings.

From the DE 40 33 952 C1 is already a binary binder system known in the manner of solid polymer solutions for the technique of metal injection molding. It is characterized by the use of physiologically harmless low molecular weight binder components and by dispensing with wetting agents. In this way, can be made of metal powders dense molded parts easily by injection molding and remove them from the binder, without causing shrinkage or distortion occurs.

Advantages of invention

The inventive method for producing a metallic component with the characterizing ones Features of claim 1 has the advantage that by a suitable adaptation and repetition of the process steps of Metal Injection Molding (MIM) in conjunction with at least one thermal pressing the thermal conductivity largely modified in the metallic component to be produced and this can be adapted to a theoretical optimum.

By the procedure of the multistage MIM process can be found in The individual process steps produce component areas, the different Densities and other thermal conductivities exhibit. about a material variation of the metal powder used is a very greater Property range of the resulting component possible. Compared to one known coating e.g. a rotating part are these special Component properties with significantly lower production engineering Effort can be generated.

By in the subclaims listed activities are advantageous developments and improvements of the claim 1 specified method possible.

At the Use of a product according to the invention Component, e.g. as a valve seat component in a fuel injection valve It is advantageous that the temperature balance in the area of the downstream end the fuel injection valve around the valve seat component targeted is adjustable.

The metallic according to the invention Component with the characterizing features of claim 8 has the Advantage that over a multi-layer or a multi-layer structure with respect to its density and its magnetic properties and its thermal conductivity properties optimal set component can be generated. The component can be easy and inexpensive build up so that the heat conduction in individual parts is greatly reduced and thus an insulating effect across from one from the outside flowing to the component heat flow is reachable.

drawing

embodiments The invention are shown in simplified form in the drawing and explained in more detail in the following description. Show it

1 FIG. 2 shows a schematic section through an exemplary embodiment of a fuel injection valve with a valve seat component produced according to the invention, FIG.

2 a valve seat component after performing a multi-stage MIM process in a first embodiment,

3 a valve seat component after performing a multi-stage MIM process in a second embodiment,

4 the section IV in the region of a spray opening in 3 in an enlarged view,

5 a valve seat component after performing tion of a multi-stage MIM process in a third embodiment and

6 a valve seat component after performing a multi-stage MIM process in a fourth embodiment.

description the embodiments

An in 1 illustrated embodiment of a fuel injection valve 1 with a metallic component according to the invention and produced according to the invention as a valve seat component 40 is in the form of a fuel injector 1 designed for fuel injection systems of mixture-compression, spark-ignited internal combustion engines. The fuel injector 1 is particularly suitable for direct injection of fuel into a combustion chamber, not shown, of an internal combustion engine.

The fuel injector 1 consists of a nozzle body 2 in which a valve needle 3 is arranged. The valve needle 3 stands with a valve closing body 4 in operative connection with one on a valve seat component 40 arranged valve seat surface 6 cooperates to a sealing seat. In the fuel injection valve 1 In the exemplary embodiment, this is an inwardly opening fuel injection valve 1 which has at least two spray openings 7 features. The nozzle body 2 is through a seal 8th against a valve housing 9 sealed. The drive is, for example, an electromagnetic circuit, which is a magnetic coil 10 includes, in a coil housing 11 encapsulated and placed on a coil carrier 12 is wound, which at an inner pole 13 the solenoid 10 is applied. The inner pole 13 and the valve housing 9 are through a narrowing 26 separated from each other and each other by a non-ferromagnetic connecting member 29 connected. The magnetic coil 10 is over a line 19 from one via an electrical plug contact 17 energized electric current. The plug contact 17 is from a plastic casing 18 surrounded by the inner pole 13 can be injected.

The valve needle 3 is in a valve needle guide 14 guided, which is designed disk-shaped. For stroke adjustment is a paired shim 15 , On the other side of the dial 15 there is an anchor 20 , This is about a first flange 21 non-positively with the valve needle 3 in connection, which by a weld 22 with the first flange 21 connected is. On the first flange 21 a return spring is supported 23 from, which in the present design of the fuel injection valve 1 through an adjusting sleeve 24 is brought to bias.

In the valve needle guide 14 , in anchor 20 and on a guide body 5 run fuel channels 30 . 31 and 32 , The fuel is supplied via a central fuel supply 16 fed and through a filter element 25 filtered. The fuel injector 1 is through a seal 28 against a fuel distribution line, not shown, and through another seal 36 sealed against a cylinder head, not shown.

On the downstream side of the anchor 20 is an annular damping element 33 , which consists of an elastomer material, arranged. It lies on a second flange 34 on which over a weld 35 non-positively with the valve needle 3 connected is.

At rest of the fuel injection valve 1 becomes the anchor 20 from the return spring 23 contrary to its stroke direction so acted upon, that the valve closing body 4 on the valve seat surface 6 is held in sealing contact. Upon energization of the solenoid 10 builds up this a magnetic field, which is the anchor 20 against the spring force of the return spring 23 moved in the stroke direction, wherein the stroke by a in the rest position between the inner pole 12 and the anchor 20 working gap 27 is predetermined. The anchor 20 takes the first flange 21 , which with the valve needle 3 is welded, also in the stroke direction with.

The with the valve needle 3 related valve closing bodies 4 lifts from the valve seat surface 6 and the fuel gets through the spray holes 7 hosed.

If the coil current is switched off, the armature drops 20 after sufficient degradation of the magnetic field by the pressure of the return spring 23 from the inner pole 13 which causes the valve needle 3 related first flange 21 moved against the stroke direction. The valve needle 3 is thereby moved in the same direction, whereby the valve closing body 4 on the valve seat surface 6 touches down and the fuel injector 1 is closed.

According to the invention, the valve seat component 40 produced by multi-stage MIM process. The valve seat component described in more detail here 40 is exemplary of metallic components that can be manufactured as moldings. Based on 2 to 6 are different embodiments of the valve seat member according to the invention produced 40 explained. The already known and also referred to as metal injection molding (MIM) method comprises the production of moldings from a metal powder with a binder, for. As a plastic binder, which are mixed together and homogenized, for example, on konventio nelle plastic injection molding machines and the subsequent removal of the binder and sintering of the remaining metal powder scaffold. The composition of the metal powder can be tuned in a simple manner to optimum magnetic and thermal properties.

For fuel injectors 1 for directly injecting fuel into the combustion chamber of an internal combustion engine, there is a significant risk of the formation of deposits on the downstream components, such as injection orifice plates, valve seat bodies, and even in the dead space between the downstream end of the valve needle 3 on the valve closing body 4 and the valve closing body 4 facing upper end face of the valve seat body. In particular, the injection openings 7 prone to coking of the free cross-section, so that it may disadvantageously come to reduced quantities compared to the desired spray rates. Accordingly, it is desirable, the temperature budget in the region of the downstream end of the fuel injection valve 1 around the valve seat component 40 targeted. In particular, it has been found that, in particular, the thermal conduction properties of the orifices commonly used on (gasoline) injectors have a significant influence on the temperatures in the critical areas of the fuel injector 1 , So at the dead volume and at the entrance to the spray orifices 7 to take.

According to the invention, therefore, the production and the use of a spray perforated disk are dispensed with and instead the heat conductivity in the valve seat component is compensated by suitable adaptation and repetition of the process steps of MIM in conjunction with at least one thermal pressing 40 largely modified and adapted to a theoretical optimum. In the method according to the invention for the production of a metallic component, the metal injection molding process (MIM) is applied at least twice, so that it is a multi-stage process in which additionally at least one thermal pressing operation is interposed or followed , In this way, the density of the component areas deposited in the last MIM process can be set between the value of the bulk density and the maximum achievable density. In this case, the structure of the component, here the valve seat component 40 , from the densest area to the less dense area. For the concrete valve seat component 40 this means that the area of high strength exposed to the high pressure of the fuel is produced in the first process step. Due to the procedure of the multi-stage MIM process, further component areas can now be produced in the following process steps which have a different density and different heat conduction properties. Advantageously, so the valve seat member 40 be generated by first a valve seat part 40a and subsequently directly on this valve seat part 40a an injection-molded part 40b is produced, wherein the injection hole part 40b as part of the valve seat component 40 replaced the classic spray perforated disc. About a material variation of the metal powder used is a very large range of properties of the resulting valve seat component 40 possible. In comparison to a known coating, for example a rotary part, these special component properties can be produced with significantly lower production-related expense.

In 2 is a valve seat component 40 after performing a multi-stage MIM process in a first embodiment. In a first MIM process, the outer shape and shape of the valve seat member to be manufactured 40 largely already generated. Only on the combustion chamber facing the downstream end face on which a spray hole disc is mounted in known fuel injection valves, the wall thickness is not created to the final extent, but only required for the component strength against the fuel pressure wall thickness is applied. In the subsequent thermal pressing process, the component density and thus the thermal conductivity of the material is adjusted. In a second MIM process is now on the valve seat part 40a sprayed on a further layer of the metal powder until the final desired wall thickness, with which a deposit formation should be largely avoided, is achieved. The in this way on the valve seat part 40a generated spray hole part 40b has a significantly lower component thickness than the valve seat part 40a on. By adjusting the density in the subsequent optional thermal pressing process, the density of this spray hole part can 40b to values between the bulk density after the MIM process, which is about 70% of the starting material, and the maximum attainable density of about 99%. This allows the heat conduction in this spray hole part 40b greatly reduce and thus achieve an insulating effect against the combustion chamber side incoming heat flow.

In the second MIM process for making the injection hole part 40b can be, for example, at the same time Abspritzöffnungsabschnitte 7 ' in the area later desired spray openings 7 produce. 3 illustrates a valve seat component 40 after performing a multi-stage MIM process in a second embodiment, wherein the valve seat part 40a is configured according to the first embodiment, while in the injection hole part 40b already Abspritzöffnungsabschnitte 7 ' are trained with. In this respect, therefore, not only the densities and the thermal properties of the can be during the process steps of the invention Set built components, but also educate opening contours targeted.

4 shows the detail IV in the region of a spray opening 7 in 3 in an enlarged view, wherein it is clear that it is particularly advantageous, the Abspritzöffnungsabschnitte 7 ' in the injection hole part 40b having a larger diameter than the Abspritzöffnungsabschnitte 7 '' in the valve seat part 40a , So can in a particularly simple and inexpensive way stepped spray openings 7 in the valve seat component 40 getting produced.

In the 5 is a valve seat component 40 after performing a multi-stage MIM process in a third embodiment. In addition to the two-stage design, it is also conceivable to connect further MIM process steps, so that a construction of a metallic MIM component with three to five or even more layers, layers or parts is possible if required. In 5 is a valve seat component 40 shown in addition to the valve seat part 40a and the injection hole part 40b another on the spray hole part 40b applied protective part 40c having.

By a suitable choice of material in the metal powders used, however, can also be an intermediate layer 40d with increased conductivity under an insulating, inert outer layer 40e realized from the base material with low density ( 6 ).

The invention is not limited to the illustrated embodiments and for any construction of metallic components, regardless of use in fuel injection valves 1 applicable.

Claims (16)

A method for producing a metallic component, characterized in that in a first process process, a Meta1 injection molding process with the method steps - mixing and homogenizing a metal powder and a binder, - subsequent injection molding, - removing the binder and - sintering of the metal powder scaffold to form of a first part ( 40a ) and, in a second process, a metal injection molding process comprising the steps of mixing and homogenizing a metal powder and a binder, subsequently injection molding, removing the binder, and sintering the metal powder framework to form at least a second part ( 40b ) directly on the surface of the first part ( 40a ) is applied, in which a molded part as a metallic component ( 40 ) consisting of at least two parts ( 40a - 40e ) is formed. A method according to claim 1, characterized in that after the first metal injection molding process and / or after the second metal injection molding process, a thermal pressing of at least one of the plurality of parts ( 40a - 40e ) he follows. A method according to claim 2, characterized in that by the thermal pressing the component density and the thermal conductivity of the corresponding part ( 40a - 40e ) is set. Method according to claim 3, characterized in that at least two of the several parts ( 40a - 40e ) are processed so that they have a different thermal conductivity. Method according to one of the preceding claims, characterized in that the metal powder for at least two of the several parts ( 40a - 40e ) is different. Method according to one of the preceding claims, characterized in that during the respective metal injection molding process an opening structure in the corresponding part ( 40a - 40e ) is provided with. Method according to one of the preceding claims, characterized in that after the first process process of the metal injection molding process, a metallic part ( 40a ) is formed as a molded part, onto which, with further metal injection molding process processes, thin layer-shaped parts ( 40b - 40e ) are applied. Metallic component, in particular valve seat component, characterized in that it comprises at least two parts ( 40a - 40e ), which are independent of each other by means of metal injection molding process, but directly to each other. Metallic component according to claim 8, characterized in that at least two of the several parts ( 40a - 40e ) have a different thermal conductivity. Metallic component according to claim 8 or 9, characterized in that the metal powder for at least two of the several parts ( 40a - 40e ) is different. Metallic component according to one of the claims 8 to 10, characterized in that in each of the parts ( 40a - 40e ) An opening structure is provided. Metallic component according to one of claims 8 to 11, characterized in that the metallic component as a valve seat component ( 40 ) for a fuel injection valve ( 1 ) is designed for fuel injection systems of internal combustion engines. Metallic component according to claim 12, characterized in that the valve seat component ( 40 ) at least one valve seat part ( 40a ) with a valve seat surface ( 6 ) and at least one injection opening ( 7 . 7 '' ) and a spray hole part ( 40b ) with at least one injection opening ( 7 . 7 ' ). Metallic component according to claim 13, characterized in that the at least one injection opening ( 7 ) in the valve seat component ( 40 ) two spray opening sections ( 7 ' . 7 '' ) having. Metallic component according to claim 14, characterized in that the spray-discharge opening section ( 7 '' ) in the valve seat part ( 40a ) has a smaller opening width than the opening width of the Abspritzöffnungsabschnitts ( 7 ' ) in the injection hole part ( 40b ), so that a stepped injection opening ( 7 ) is present. Metallic component according to one of claims 12 to 15, characterized in that the most downstream part ( 40b . 40c . 40e ) of the valve seat component ( 40 ) has an insulating effect against an external heat flow.