EP2746565B1 - Magnet module for a fuel injector, method for producing a magnet module and fuel injector - Google Patents

Description

State of the art

The invention relates to a magnet assembly for a fuel injector according to the preamble of claim 1. Furthermore, the invention relates to a method for producing a magnet assembly according to the invention and a fuel injector using a magnet assembly according to the invention.

A magnet assembly according to the preamble of claim 1 is known from DE 10 2010 001 486 A1 the applicant known. By means of the known magnet assembly, the fuel discharge from a control chamber is influenced in a fuel injector, whereby a stroke movement of a nozzle needle is controlled. For this purpose, a magnetic coil is inserted in a magnetic core, which are arranged on a front side in registration with a magnet armature. When the magnet coil is energized, the magnet armature is pulled in the direction of the magnet coil so that the magnet armature releases a sealing seat on the side opposite the magnet coil, via which fuel can flow out of the addressed control chamber. The disadvantage here is that both the armature and the magnetic coil and the magnetic core are arranged in a portion of the fuel injector, in which the fuel is located. The fuel thus comes into contact in particular with the magnetic coil, so that it must be specially designed. In particular, relatively high temperatures of the fuel, which may be up to 190 ° C. at a system pressure of, for example, 2000 bar, are a problem. In addition, the sealing of the bobbin or its connection pins in the direction of the electrical connections for controlling the Magnetic module critical. Although one could try to hydraulically separate by a corresponding separator, the magnetic coil of the armature, but the increased axial distance between the magnetic coil and the magnetic core, however, lowers the efficiency of the magnet assembly and makes it necessary to use a larger solenoid to achieve a certain magnetic force in turn, which in turn entails a number of disadvantages, in particular with regard to the installation space and the manufacturing costs of the magnet assembly.

From the DE 43 10 719 A1 a fuel injection valve is known with a solenoid valve, wherein a magnetic core and a magnetic coil are accommodated in a pole tube housing, which consists of a Innenporohr and a Außenpolrohr.

Disclosure of the invention

Based on the illustrated prior art, the present invention seeks to develop a magnetic assembly for a fuel injector according to the preamble of claim 1 such that in addition to the hydraulic separation between the area is arranged in the armature of the area in which the Magnetic coil and the magnetic core are, even when using relatively small or weak magnetic coils, a relatively high magnetic force can be achieved on the armature. This object is achieved in a magnetic assembly for a fuel injector with the features of claim 1, characterized in that the magnetic core and the magnetic coil are accommodated in a pole tube housing, which consists of a Innenpolrohr and a Außenpolrohr, which are arranged concentrically to each other, wherein between the inner pole tube and the outer pole tube on the magnet armature side facing a preferably arranged perpendicular to the longitudinal axis of the magnet armature partition is formed in which in at least partial overlap with the end face of the magnetic coil, a non-magnetic intermediate element is arranged, wherein the pole tube housing in the region of the partition in at least partial coverage with the magnet core has at least one magnetically active pole body, and wherein the partition wall forms a hydraulic seal between a pressure space for the magnet armature and a receiving space for the magnet coil and the magnet core. The invention thus makes it possible on the one hand, a hydraulic separation between the fuel-carrying region in which the magnet armature is located from the region of the magnetic coil and the Form magnetic core, and on the other hand by a magnetically formed region which is arranged in register with the end face of the magnetic coil on the side facing the armature, to influence the magnetic flux such that the magnetic field lines are guided over the magnetically active region of the partition, whereby the increases magnetic field strength and thus can achieve an increased magnetic force on the armature. As a result, despite the increased axial distance between the end face of the magnetic coil and the magnet armature on the magnet armature in comparison to the prior art, a sufficiently high magnetic force can be achieved, which makes it possible, for example, to use a magnet coil of the same size as in the prior art. According to the invention, the inner pole tube and the outer pole tube are made of nonmagnetic material, and the inner pole tube and the outer pole tube are connected in the region of the dividing wall with two magnetic ring bodies, between which the nonmagnetic intermediate element is arranged. Such a design has the advantage that the outer pole tube and the inner pole tube can be made of aluminum, for example, so that a particularly low weight of the magnet assembly is achieved.

To optimize the magnetic field strength or for orientation / deflection of the magnetic field lines, it may be provided that the non-magnetic intermediate element in the direction of the longitudinal axis of the armature has a tapered towards the magnet armature cross-section.

In a particularly preferred embodiment of the non-magnetic intermediate element, it is proposed that this consists of solder material. The solder material thus causes the connection and sealing in the region of the partition wall between the inner pole tube and the outer pole tube, and moreover has the advantage that it adapts particularly well when present component tolerances in its application by its temporary liquefaction.

In addition, a structural design of the magnet assembly is particularly preferred, in which the outer pole tube forms part of the receiving space for the magnet armature, and that the pole tube housing is at least partially encapsulated by plastic on the side facing away from the magnet armature, which simultaneously forms a connector connection region. Such a design has the advantage that no separate housing part for radial sheathing of the magnet assembly must be provided, but that this function is primarily fulfilled by the outer pole tube. As a result, it is possible to form a fuel injector which is particularly compact in terms of diameter and, moreover, can be produced in a particularly simple and cost-effective manner due to the reduced number of components (lack of external housing in this area).

The invention also encompasses a method according to claim 5 for producing a magnet assembly according to the invention, wherein a non-magnetic intermediate element is arranged between an inner pole tube and an outer pole tube in a partition wall. According to the invention, it is provided that the dividing wall is machined, at least in the region of the nonmagnetic intermediate element, by a cutting material removal. Such a design makes it possible using a solder material production-related unevenness of the surface at the two end faces (on the magnetic coil and on the magnet armature side facing) particularly easy to compensate and to realize flat surfaces.

Further, the use of non-magnetic components for the outer pole tube and the inner pole tube is provided, wherein between the outer pole tube and the inner pole tube each consisting of magnetic solder ring body are formed, between which the existing non-magnetic solder intermediate element is arranged.

In order to arrange the solder at the desired (circular or annular) areas and at the same time to propose a particularly advantageous production process, it is provided that a one-piece component is used to form the inner pole tube and the outer pole tube, that in the region of the partition in an end face of Component is formed at least one radially encircling annular groove, that the at least one annular groove is filled with solder material, and that then at least on the at least one annular groove opposite end of the component material removal takes place, such that the material of the component into the region of the solder Will get removed. Such a design has the particular advantage that a positioning of the Außenpolrohrs to Innenpolrohr is not required, since the two components are realized by a one-piece component, which is processed only in the course of the manufacturing process by the cutting material removal such that from the one-piece component the two outer pole tube and the inner pole tube forming areas arise.

The invention also includes a fuel injector using a magnet assembly according to the invention. Such a fuel injector has the advantage that it does not require high requirements with respect to its magnetic coil, in particular that it can be used even at relatively high system pressures or fuel temperatures, the magnet assembly, despite the use of a relatively small magnetic coil, the required forces for actuating the magnet armature applies.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing.

Fig. 1

einen Teilbereich eines Kraftstoffinjektors unter Verwendung einer nicht erfindungsgemäßen Magnetbaugruppe in einem Längsschnitt,

Fig. 2

einen Teillängsschnitt im Bereich einer nicht erfindungsgemäßen Magnetbaugruppe,

Fig. 3

eine gegenüber der Fig. 1 abgewandelte Magnetbaugruppe unter Verwendung eines nicht magnetischen Außenpolrohrs und eines nichtmagnetischen Innenpolrohrs, ebenfalls im Längsschnitt und

Fig. 4 und Fig. 5

jeweils Teillängsschnitte zur Verdeutlichung eines möglichen Herstellungsverfahrens der Magnetbaugruppe gemäß Fig. 1 im Bereich einer Trennwand zwischen der Magnetspule und einem Magnetanker.

This shows in:

Fig. 1

a portion of a fuel injector using a non-inventive magnetic assembly in a longitudinal section,

Fig. 2

a partial longitudinal section in the region of a non-inventive magnetic assembly,

Fig. 3

one opposite the Fig. 1 modified magnetic assembly using a non-magnetic Außenpolrohrs and a non-magnetic Innenpolrohrs, also in longitudinal section and

4 and FIG. 5

each partial longitudinal sections to illustrate a possible manufacturing method of the magnetic assembly according to Fig. 1 in the region of a partition wall between the magnet coil and a magnet armature.

The same elements or elements with the same function are provided in the figures with the same reference numerals.

In the Fig. 1 a fuel injector 100 is shown in some areas, as it is used as part of a common rail injection system in a self-igniting internal combustion engine. Such a fuel injector 100 is designed, for example, to a system pressure of 1800 bar and more.

Within the fuel injector 100, a switching valve with a magnet assembly 10 according to the invention is arranged, which serves for actuating a magnet armature 11 designed as a flat armature. The armature 11 is arranged in a pressure chamber 12 filled with fuel and connected to a pin-shaped valve element 13, which regulates a fuel drain from a control chamber, not shown in the figures. By influencing the fuel outflow of the control chamber, the movement of a nozzle needle which opens or closes injection openings formed in the fuel injector 100 can be influenced in a known manner.

The valve element 13 is accommodated radially inside a valve housing 14, which has a stepped receiving bore 15 for receiving an outer pole tube 16. The outer pole tube 16 is part of a Polrohrgehäuses 19 and hydraulically sealed received in the receiving bore 15 via a arranged in an annular groove 17 sealing ring 18 and axially clamped by means of a union nut 20 with the valve housing 14.

The magnetic pole outer pole tube 16 has a ring-shaped and concentric with the longitudinal axis 21 of the fuel injector 100 and the armature 11 arranged first wall portion 22 in which the annular groove 17 is formed. At the first portion 22 is followed on the side facing away from the valve housing 14 on a radially inwardly projecting, perpendicular to the longitudinal axis 21 arranged wall portion 23 at. On the side opposite the wall portion 23 of the first portion 22, a concentric with the longitudinal axis 21 arranged, annular second section 24 connects. The pressure chamber 12 is bounded radially by the first wall section 22 of the outer pole tube 16.

Concentric with the outer pole tube 16, the magnet assembly 10 has an inner pole tube 25 made of magnetic material. The substantially sleeve-shaped Innenpolrohr 25 has a through hole 26 for receiving a compression spring 27, which is axially indirectly supported on a step 28 of the through hole 26 and the armature 11 in the direction of the valve housing 12 subjected to force. The through hole 26 opens into a return pipe 29 which is connectable to the low pressure region of the fuel system. About the through hole 26 and the return pipe 29 can flow out of the control chamber fuel flowing, which is located within the pressure chamber 12, via at least one formed in the armature 11 hole 30.

On the side facing the valve housing 14, the inner pole tube 25 has a radially outwardly projecting wall section 31, which is located at the same axial height as the wall section 23 of the outer pole tube 16, wherein both wall sections 23, 31 have the same thickness. Between the two wall sections 23, 31, an annular intermediate region 32 is formed, which consists of non-magnetic material, in particular non-magnetic solder consists. The cross section of the intermediate region 32 is V-shaped or has two conically arranged side surfaces, such that the width of the intermediate region 32 decreases in the direction of the magnet armature 11. The two wall sections 23, 31 form, together with the intermediate region 32, a closed partition wall 35, which forms an axial boundary of the pressure chamber 12.

On the opposite side of the pressure chamber 12 of the partition wall 35 of the outer pole tube 16 and the inner pole tube 25, an annular receiving space 36 is formed. In the receiving space 36, a likewise annular magnetic core 37 is arranged, which has an annular groove-like opening 38 for receiving a magnetic coil 40 on the side facing the partition wall 35. The magnet coil 40 is connected via contact pins 41 (in the illustration of FIG Fig. 1 only a single contact pin 41 can be seen) connected to plug lugs 42 for the electrical control of the solenoid coil 40, which is arranged in a plastic connector connection portion 43. In addition, an axial portion of the magnetic core 37, the Innenpolrohr 25, the return port 29 and the upper axial end portion of the second portion 24 of the Außenpolrohrs 16 surrounded by plastic of the male connection portion 43, which thus forms part of the housing of the fuel injector 100.

In the Fig. 2 a partial longitudinal section of the magnet assembly 10 in the region of the partition 35 is shown enlarged. In particular, it can be seen that the nonmagnetic intermediate region 32 is arranged in alignment with and overlapping the end face 44 of the magnet coil 40 and has the same ring width on the side facing the magnet coil 40 as the magnet coil 40. The lines 45 indicate the flux of the magnetic field lines in the magnet assembly 10 shown. It can be seen that both the inner pole tube 25 and the outer pole tube 16 are penetrated by the lines 45, that is, that both are part of the magnetic circuit. In particular, it can be seen that the lines 45 on the side facing the magnet armature 11 are deflected by the two wall sections 23, 31.

In the Fig. 3 is one opposite the Fig. 1 modified magnetic assembly 10a shown. In the magnet assembly 10a, the wall portion 23a of the Außenpolrohrs 16a formed in its radial extent reduced in size, and the inner pole tube 25a has no radially outwardly projecting portion at the level of the wall portion 23a. In addition, both the outer pole tube 16a and the inner pole tube 25a are made of non-magnetic material such as aluminum. The partition wall 35 is formed by two annular, consisting of magnetic material, in particular of magnetic solder material pole body 46, 47, between which the non-magnetic material existing intermediate region 32a is arranged. The two pole bodies 46, 47 assume the function of the (magnetic) wall sections 23, 31 of the magnet assembly 10.

The magnet assembly 10 can be manufactured particularly easy to produce if, according to the representation of Fig. 4 an initially integrally formed member 50 is used, which consists of magnetically active material, and the outer pole tube 16 and the Innenpolrohr 25 forms after the now described finishing. For this purpose, in a first step, a V-shaped annular groove 52 is formed in a horizontally encircling annular wall region 51 on the side facing the receiving space 36, into which the (non-magnetic) solder material forming the intermediate region 32 is subsequently introduced. Subsequently, according to the Fig. 5 the wall region 51 is machined from both sides by machining material (in particular grinding), whereby the wall thickness of the wall region 51 is reduced and at the same time flat end faces 53, 54 are formed. By reducing the wall thickness of the wall region 51, the intermediate region 32 forms a part of the end faces 53, 54.

The magnetic assemblies 10, 10a or the fuel injector 100 described so far can be modified or modified in many ways without departing from the scope of the invention as defined in the claims. In particular, it is also conceivable that the magnetic assembly 10a with the in the 4 and 5 to manufacture then, for which purpose a plurality of annular grooves are formed, which are filled with the material of the intermediate region 32a and the pole body 46, 47.

Claims (7)

1. Magnet assembly (10; 10a) for a fuel injector (100), having a magnet coil (40) arranged in a magnet core (37), which magnet coil interacts with a magnet armature (11) which is arranged opposite a face side (44) of the magnet coil (40) and which serves at least indirectly for influencing a fuel flow, wherein the magnet core (37) and the magnet coil (40) are received in a pole tube housing (19) which is composed of an inner pole tube (25; 25a) and an outer pole tube (16; 16a) which are arranged concentrically with respect to one another, wherein, between the inner pole tube (25; 25a) and the outer pole tube (16; 16a), on the side facing toward the magnet armature (11), there is formed a partition (35) which is arranged preferably perpendicular to the longitudinal axis (21) of the magnet armature (11) and in which a non-magnetic intermediate element (32; 32a) is arranged so as to at least partially overlap the face side (44) of the magnet coil (40), wherein the pole tube housing (19) has, in the region of the partition (35), at least one magnetically active pole body (46, 47) at least partially overlapping the magnet core (37), and wherein the partition (35) forms a hydraulic seal between a pressure chamber (12) for the magnet armature (11) and a receiving chamber (36) for the magnet coil (40) and the magnet core (37),
   characterized in that
   the inner pole tube (25a) and the outer pole tube (16a) are composed of non-magnetic material, and in that the inner pole tube (25a) and the outer pole tube (16a) are connected, in the region of the partition (35), to two ring-shaped pole bodies (46, 47) which are composed of magnetically active material and between which the non-magnetic intermediate element (32a) is arranged.
2. Magnet assembly according to Claim 1,
   characterized
   in that the non-magnetic intermediate element (32; 32a) has, in the direction of the longitudinal axis (21) of the magnet armature (11), a cross section which narrows toward the magnet armature (11).
3. Magnet assembly according to either of Claims 1 and 2,
   characterized
   in that the non-magnetic intermediate element (32; 32a) is composed of solder material.
4. Magnet assembly according to one of Claims 1 to 3,
   characterized
   in that the outer pole tube (16; 16a) forms a part of the receiving chamber for the magnet armature (11), and in that the pole tube housing (19) is, on the side averted from the magnet armature (11), at least regionally encapsulated by plastic, which simultaneously forms a plug connector region (42).
5. Method for producing a magnet assembly (10; 10a) according to one of Claims 1 to 4,
   in which method a non-magnetic intermediate element (32; 32a) is arranged between an inner pole tube (25; 25a) and an outer pole tube (16; 16a) in a partition (35), wherein the partition (35) is machined, at least in the region of the non-magnetic intermediate element (32; 32a), by means of a cutting material removal process, characterized
   in that pole bodies (46, 47) composed in each case of magnetic solder are formed between the outer pole tube (16a) and the inner pole tube (25a), between which pole bodies the intermediate element (32a) composed of non-magnetic solder is arranged.
6. Method according to Claim 5,
   characterized
   in that a unipartite component (50) is used to form the inner pole tube (25; 25a) and the outer pole tube (16; 16a), in that at least one radially encircling ring-shaped groove (52) is formed into a face side of the component (50) in the region of the partition (35), in that the at least one ring-shaped groove (52) is filled with solder material, and in that, subsequently, at least on that face side of the component (50) which is situated opposite the at least one ring-shaped groove (52), material removal is performed such that the material of the component (50) is removed as far as into the region of the solder.
7. Fuel injector (100) having a magnet assembly (10; 10a) according to one of Claims 1 to 4.

Images