DE10257896A1 - Valve body with elongated valve stem for fuel injector used in internal combustion engine, has armature near top attracted by electromagnetic coil and incorporating through-passage for fuel - Google Patents

Abstract

The valve stem for a fuel injector (3) is an elongated circular-section rod. The armature (20) is mounted near the top and is circular, with a through-passage (30) for fuel flowing toward the valve at the nozzle tip. A first clamping flange (21) engages the top surface of the armature and a second flange (34) engages the end of a tubular downward extension of the armature. A laser is used during manufacture to produce an intense beam of light (43) which cuts a slot (33) at the join between the end of the armature extension and the second clamping flange.

Description

State of technology

The invention is based on one Method of manufacturing a fuel injector according to the Genus of claim 1 and of a fuel injector according to the preamble of claim 8.

For example, from the DE 199 50 761 A1 a fuel injector is known in which a magnet armature engages a valve needle having a valve closing body at its spray-side end, which cooperates with a valve seat surface to form a sealing seat, the magnet armature being movable on the valve needle between a first stop of a first stop body and one on one second stop body formed second stop with a game which corresponds to the width of a gap is guided. The gap between the stops and the magnet armature decouples the inert masses of the magnet armature on the one hand and the valve needle and the valve closing body on the other hand. This improves the dynamics of the fuel injector, with small changes in the size of the gap having a major influence on the dynamics.

In conventional manufacturing processes for the above described or other generic fuel injection valves, will first one of the two stop bodies welded to the valve needle, then the gap is set, for example with the help of a gauge and the other stop body while maintaining that determined with, for example, an apprenticeship Gap welded to the valve needle.

A disadvantage of the described Manufacturing process or that from the above publication known manufactured by the described manufacturing process Fuel injector is particular that the manufacture of the fuel injector and the gap only with a multitude of manufacturing steps, Tools and components possible and also the manufacturing tolerances that can be achieved for an exact setting the dynamic properties of the fuel injector only can be achieved insufficiently.

The manufacturing method according to the Manufacture of the fuel injector with the characteristic In contrast, features of claim 1 have the advantage that the gap, which determines the play of the magnetic armature between the flanges, can be manufactured with very small manufacturing tolerances. The one there needed The number of manufacturing steps is significantly reduced. The manufacturing steps themselves are much easier and more precise to carry out.

The fuel injector according to the invention with the characterizing features of claim 8 has the advantage that the dynamic properties of the fuel injector in particular can be set precisely and easily. In particular, the Time between the activation of the magnetic circuit and the impact of the magnet armature on the first flange and thus the time span, between the activation of the magnetic circuit and the start of opening or the start of closing of the fuel injector passes, can be set precisely.

By the measures listed in the subclaims are advantageous developments of the specified in claim 1 Manufacturing method for manufacturing a fuel injector or the fuel injector according to the invention according to claim 8 possible.

By creating the gap one piece anchor designed with the second flange or an anchor made in one piece with the first flange, the manufacturing process continues simplified. Causes of errors caused, for example, by foreign bodies between the flanges and the anchor or unevenness on the components or tools or measuring tools are avoided.

It is also an advantage that the Gap nearby a recess on the valve needle and / or a recess the side of the armature facing the valve needle or one of the Flanges is produced. This can ensure the generation of the gap done so be that the Valve needle not prohibited processed or damaged in the manufacture of the gap. Furthermore, the recess for positioning the armature or a the flanges can be used.

In a further development of the Manufacturing method according to the invention become the joint connections between the flanges and the valve needle by soldering, welding or laser welding manufactured. As a result, particularly firm and heat-resistant joint connections can be produced can also be particularly advantageously inserted into the manufacturing process.

It is also advantageous if the process steps on hollow cylindrical flanges and hollow cylindrical shaped Anchor executed become. The process steps, in particular the play-free axial assembly and positioning the anchor and the first and second flange, particularly simple To run. In addition, hollow cylindrical components are easy and precise to manufacture.

Be further developed particularly advantageously can the manufacturing method according to the invention in that the gap is generated by a laser beam. The processing of a component by means of a laser beam minimizes the heating of the component, in particular at the processing point. Since the diameter of laser beams can be generated very small, very continuously in the course and with very small tolerances, the component to be machined with it can also be manufactured very precisely and with low manufacturing tolerances.

It is also advantageous if the side of the flanges and the anchor where the gap creates was generated, for example by a laser beam, hardened is. This reduces wear over the life of the fuel injector in this area, whereby the width of the gap remains constant. The dynamic properties of the fuel metering of the fuel injection valve according to the invention remain thereby constant.

An embodiment of the invention is shown in simplified form in the drawing and in the following Description closer explained. Show it:

1 a schematic section through an embodiment of a fuel injector designed according to the invention 1 .

2 an enlarged schematic section through the embodiment of the fuel injector 1 according to the invention in the region of the armature 20 and

3 a schematic representation of a partial step of the manufacturing method according to the invention.

description of the embodiment

An embodiment of the Invention described by way of example. Matching components are doing so in all figures with matching Provide reference numerals.

An in 1 illustrated first embodiment of a fuel injector according to the invention 1 is in the form of a high pressure fuel injector 1 designed for fuel injection systems of mixture-compressing, spark-ignited internal combustion engines. The fuel injector 1 is particularly suitable for injecting fuel directly 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 body 5 arranged valve seat surface 6 cooperates to form a sealing seat. At the fuel injector 1 in the exemplary embodiment, it is an inward opening fuel injector 1 which has a spray opening 7 features. The nozzle body 2 is through a seal 8th against an external pole 9 a solenoid 10 sealed. The solenoid 10 is in a bobbin case 11 encapsulated and on a bobbin 12 wound, which on an inner pole 13 the solenoid 10 is applied. The inner pole 13 and the outer pole 9 are due to a narrowing 26 separated from one another and to one another by a non-ferromagnetic connecting component 29 connected. The solenoid 10 is over a line 19 from one via an electrical plug contact 17 supplyable electric current excited. The plug contact 17 is from a plastic coating 18 surround that at the inner pole 13 can be molded.

The valve needle 3 is in a valve needle guide 14 led, which is disc-shaped. A paired adjusting disc is used for stroke adjustment 15 , On the other side of the shim 15 is the anchor 20 , This is above a first flange 21 non-positive with the valve needle 3 connected by a first joint connection 22 in the form of a weld 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 injector 1 through a sleeve 24 is brought under tension.

In the valve needle guide 14, in the armature 20 and on a guide element 36 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 rail, not shown, and through a further seal 37 sealed against a cylinder head, not shown.

On the spray side of the anchor 20 is between the anchor 20 and a second flange 34 A gap 33 provided which can accommodate an annular damping element, not shown, made of elastomer material. The anchor 20 is on the valve pin 3 axially movable between the second flange 34 and the first flange 21 guided. The second flange 34 is via a second joint 35 in the form of a weld with the valve needle 3 connected.

In the idle state of the fuel injector 1 becomes the anchor 20 from the return spring 23 acted against its stroke direction so that the valve closing body 4 on the valve seat 6 is kept in a sealing system. The gap 33 is closed, ie the anchor 20 and the second flange 34 touch, provided there is no ring-shaped damping element in the intermediate layer. With the gap closed 33 also occurs between the first flange 21 and anchor 20 an anchor free path 39 on, whose width in this state is the maximum width of the gap 33 equivalent. When the solenoid is excited 10 this builds up a magnetic field, which is the anchor 20 against the spring force of the return spring 23 moved in the stroke direction, the stroke by a in the rest position between the inner pole 12 and the anchor 20 working gap 27 is specified.

At the same time, an in 2 shown, on the first flange 21 attacking and at anchor 20 supporting spring element 38 excited, which in the rest position the anchor 20 with a slight preload against the second flange 34 presses against one of the first flange 21 trained shoulder 40 supported. On the shoulder 40 the return spring is also supported 23 starting with the shoulder 40 at the anchor 20 opposite side of the flange 21 is arranged.

This in 2 illustrated spring element 38 is also known as an AFW spring or an anchor free travel spring. The anchor 20 takes the first flange 21 which with the valve needle 3 is welded, also in the stroke direction. The one with the valve pin 3 related valve closing body 4 lifts from the valve seat 6 off, and that over the fuel channels 30 to 32 led fuel is through the spray opening 7 hosed.

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

2 shows an enlarged schematically illustrated section through the embodiment of the in 1 shown fuel injector according to the invention 1 in the area of the anchor 20 , The 2 shows the fuel injector 1 at rest with the sealing seat closed. Is clearly visible in this 2 the spring element 38 , which is in the illustrated state of the fuel injector 1 the anchor 20 against the second flange 34 presses and thus the gap 33 closes entirely. The anchor free way 39 is maximally trained in this state.

3 shows a schematic representation of a partial step of the manufacturing method according to the invention, wherein the anchor 20 , the first flange 21 and the second flange 34 already free of play on the valve needle 3 are assembled and positioned. Likewise are the first flange 21 and the second flange 34 already with the valve needle 3 through joint connections 22 . 35 connected in the form of welds. The anchor 20 is thus between the first flange 21 and the second flange 34 free of play on the valve needle 3 fixed.

To create the gap 33 becomes a beam source in this embodiment 42 , preferably a laser, positioned so that the (laser) beam emerging from it 43 perpendicular to the longitudinal axis of the valve needle 3 on the the second flange 34 facing end of the anchor 20 , the anchor 20 facing end of the first flange 21 or at the anchor's contact point 20 and second flange 34 incident. This will make the gap at each point 33 generated by the beam source 42 around the anchor 20 or the second flange 34 to be led. The anchor can also be used 20 with the second flange 34 be rotated, the beam source 42 remains in the same place. The anchor 20 will during the creation of the gap 33 , especially during the completion of the gap creation 33 , by suitable means in contact with the first flange 21 held. The width of the gap 33 between the anchor 20 and the second flange 34 can, especially by the properties of the laser beam 43 , can be set exactly. By creating the gap 33 by means of the laser beam 43 the faces of anchor facing each other 20 and second flange 34 hardened at the same time.

The gap 33 can also between the first flange 21 and anchor 20 be generated. It is also possible to use the gap 33 between one with the anchor 20 integrally formed second flange 34 or one piece with the anchor 20 integrally formed first flange 21 to create. To further simplify the manufacturing process, it is also conceivable to use the gap 33 on one piece with the first flange 20 and the second flange 34 trained anchor 20 between the anchor 20 and the first flange 21 and the anchor 20 and the second flange 34 to create.

A recess 41 that are radial around the valve needle 3 prevents damage to the valve needle 3 through the laser beam 43 , The recess 41 can also be on the anchor 20 , the first flange 21 and / or on the second flange 34 be arranged. The recess 41 can continue to position anchor 20, second flange 34 and first flange 21 serve.

The invention is not based on the illustrated embodiments limited and Z. B. also for after outside opening Fuel injectors can be used.

Claims (12)

Method of manufacturing a fuel injector ( 1 ), in particular for the direct injection of fuel into a combustion chamber of an internal combustion engine, with a valve needle ( 3 ) that have a valve closing body ( 4 ) with a valve seat surface ( 6 ) on a valve seat body ( 5 ) is formed, cooperates to form a sealing seat, a downstream of the Sealing seat provided spray opening ( 7 ) and one on the valve needle ( 3 attacking anchor ( 20 ), where on the valve needle ( 3 ) a first flange ( 21 ) and a second flange ( 34 ) are arranged and the anchor ( 20 ) according to the width of a gap ( 33 ) between the first flange ( 21 ) and the second flange ( 34 ) on the valve needle ( 3 ) is arranged to be axially movable in the following process steps: - Backlash-free axial assembly of the armature ( 20 ), the first flange ( 21 ) and the second flange ( 34 ) on the valve needle ( 3 ), - positioning the anchor ( 20 ), the first flange ( 21 ) or the second flange ( 34 ) on the valve needle ( 3 ), - Establish a joint connection ( 35 ) between the second flange ( 34 ) and the valve needle ( 3 ), - Establish a joint connection ( 22 ) between the first flange ( 21 ) and the valve needle ( 3 ), - creating a gap ( 33 ) between the anchor ( 20 ) and the second flange ( 34 ) or between the anchor ( 20 ) and the first flange ( 21 ). A method according to claim 1, characterized in that the second flange ( 34 ) and the anchor ( 20 ) are initially made in one piece and by creating the gap ( 33 ) be separated. Method according to claim 1 or 2, characterized in that the first flange ( 21 ) and the anchor ( 20 ) are initially made in one piece and by creating the gap ( 33 ) be separated. Method according to one of the preceding claims, characterized in that the gap ( 33 ) near a recess ( 41 ) on the valve needle ( 3 ) and / or a recess ( 41 ) on the valve needle ( 3 ) facing side of the anchor ( 20 ) or one of the flanges ( 21 . 34 ) is produced. Method according to one of the preceding claims, characterized in that the generation of the gap ( 33 ) by a laser beam ( 43 ) he follows . Method according to one of the preceding claims, characterized in that the joint connections ( 22 . 35 ) are made by soldering, welding or laser welding. Method according to one of the preceding claims, characterized in that the method steps on hollow-cylindrical flanges ( 21 . 34 ) and hollow cylindrical shaped anchor ( 20 ) are carried out. Fuel injector ( 1 ), in particular for the direct injection of fuel into a combustion chamber of an internal combustion engine, with a valve needle ( 3 ) that have a valve closing body ( 4 ) with a valve seat surface ( 6 ) on a valve seat body ( 5 ) is configured, cooperates to form a sealing seat, a spray opening provided downstream of the sealing seat ( 7 ) and one on the valve needle ( 3 attacking anchor ( 20 ), where on the valve needle ( 3 ) a first flange ( 21 ) and a second flange ( 34 ) are arranged and the anchor ( 20 ) according to the width of a gap ( 33 ) between the first flange ( 21 ) and the second flange ( 34 ) on the valve needle ( 3 ) is axially movable, characterized in that the armature ( 20 ) and / or one of the flanges ( 21 . 34 ) by creating a gap ( 33 ) are shortened. Fuel injection valve according to Claim 8, characterized in that the gap ( 33 ) by a laser beam ( 43 ) is generated. Fuel injection valve according to Claim 8 or 9, characterized in that the flanges ( 21 . 34 ) are hollow cylindrical, in particular sleeve-shaped. Fuel injection valve according to one of Claims 8 to 10, characterized in that the armature ( 20 ) is shaped as a hollow cylinder. Fuel injection valve according to one of Claims 8 to 11, characterized in that the side of the flanges ( 21 . 34 ) and the anchor ( 20 ) at which the gap ( 33 ) was generated by the generation is hardened.