EP2016277B1 - Solenoid valve with material armature connection - Google Patents

Abstract

The invention relates to a method for production of an armature assembly (24) and an armature assembly (24). The armature assembly (24) is of application in a solenoid VALVE (14) for operation of a fuel injector (10). The solenoid valve (14) comprises an energisable solenoid coil (22). An outer moulding (44; 54, 58, 60) is provided on The circumference (52) of an armature pin (28) or a hydraulic switch element (28). An armature plate (26) is produced in the region of The outer moulding (44; 54, 58, 60) by means of The MIM method (Metal Injected Molding).

Description

State of the art

DE 196 50 865 A1 refers to a solenoid valve whose magnet armature is designed in several parts and has an armature disk and an anchor bolt. The anchor bolt is guided in a slider. In order to avoid ringing of the armature disk after closing the solenoid valve, a damping device is provided on the armature. With such a device exactly the required short switching times of the solenoid valve can be maintained. The solenoid valve is intended for use in injection systems with a high-pressure accumulator injection system (common rail). As the next solution DE 196 50 865 A1 the anchor plate is guided on the anchor bolt. The armature plate is acted on the one hand by a return spring and on the other hand secured by a shim, which is inserted in a recess on the circumference of the anchor bolt.

According to the solution DE 199 32 781 A1 An armature assembly is proposed in which an anchor plate is attached via a guide pin on the anchor bolt. The guide pin is guided in a formed on the guide portion of the anchor plate on the anchor bolt elongated hole, so that the anchor plate with respect to the circumferential surface surface of the anchor bolt is added play.

WO 96/17166 A discloses an anchor produced by MIM (Metal Injection Molding) process.

Solenoid valves are used as actuators for cost and space reasons on high-pressure accumulator injection systems (common rail). The magnetic circuit of a solenoid valve consists of a magnetic coil received within a magnetic core and an armature which is connected to the switching element to be moved. There are several possibilities for the connection between the armature and the switching element. According to DE 196 50 865 A1 the anchor bolt of the anchor plate can be mounted over the already mentioned lock washer. Due to the inevitable play between the lock washer, a recess in the end face of the anchor plate and the recess made on the circumference of the anchor bolt for receiving the lock washer, there are adverse effects on the dynamics of the solenoid valve.

In one-piece anchor assemblies in which the anchor plate and the anchor bolt are made of one and the same material, there is the disadvantage that the selected material is a compromise between wear requirements to be observed and the magnetic circuit design of the magnetic circuit. Form-fitting two-part solutions of an anchor assembly in which the anchor group has a relative to the anchor bolt movable anchor plate, are in the pressing of the anchor plate on the anchor bolt or in the production of a Schälniet connection between the anchor plate and the peripheral surface of the anchor bolt. The disadvantage of this solution lies in the high demands on the fine geometry of the components anchor plate and anchor bolt before the positive connections. A possibility of connecting a two-part armature assembly between anchor plate and anchor bolt is also given by a cohesive joining method such as welding or gluing. The disadvantages of these connection options are on the one hand the cumbersome assembly, on the other hand in the low achievable strength and finally in the limited accuracy in which such a connection can be made.

For two-part anchor assemblies, d. H. the formation of the anchor assemblies from two separate assemblies, namely anchor plate and anchor bolt, there is generally the advantage that the materials for the magnetic circuit, d. H. the material of the anchor plate and the material of the sealing function, which takes over the anchor bolt, can be optimally selected to the particular requirement. Therefore, it is desirable, taking into account the above-described boundary conditions, to use two-piece anchor assemblies that are selected according to the respective functions, optimally with regard to the material.

Disclosure of the invention

According to the invention, it is proposed to form an armature plate belonging to the magnetic circuit of the magnetic valve by means of the MIM technique (Metal Injection Molding) between an anchor bolt or a switching element which directly releases or closes a pneumatic hydraulic connection. For this purpose, for example, at least one recess in the form of a groove or groove are attached to the circumference of an anchor bolt, for example, or on the circumference of a hydraulic switching element in the region of the connection point with the anchor plate. The recesses can be made in the region of the opening of the anchor plate, which are penetrated by the anchor bolt or by the hydraulic switching element, complementary to the outer geometry of the circumference of the anchor bolt or the hydraulic switching element.

The geometry on the outer peripheral surface of the anchor bolt or the hydraulic switching element can be easily manufactured in the output part with low tolerances. The residual air gap required for solenoid valves can be adjusted in the MIM tool and is created during metal injection molding, i. H. during the injection of a melt of a metallic material, without the need for reworking such as regrinding to adjust the residual air gap at the face of the anchor plate when joined to the anchor bolt or hydraulic switching element via the MIM process. Ideally, the armature plate is formed as part of the magnetic circuit with respect to the end face, which is usually designed plan, the anchor bolt or the hydraulic switching element reset, so that a step between the end face of the anchor plate passing through the anchor bolt and the hydraulic switching element results, which defines the residual air gap between the end face of the armature plate opposite the magnetic core and the front of the armature plate opposite magnetic core.

The material of the anchor bolt or the hydraulic switching element can be optimally selected according to the wear point. For the anchor plate, a magnetic material is preferably selected in order to apply high magnetic forces and to avoid eddy current losses. In the anchor plate openings or recesses can be formed in arbitrary geometry to reduce the mass and for flow optimization, which can be formed without reworking the anchor plate. About such openings or recesses in a fuel injector from a pressure-relieved control chamber diverted control volume flow to a low-pressure side return without major flow resistance, in the event that the inventively proposed solenoid valve is used on a fuel injector whose receiving the cavity valve as a low-pressure side return to the control of the Control room diverted fuel tax amount is used.

The connection between the anchor bolt or a hydraulic switching element and the integrally formed armature plate, produced by way of the MIM method, absorbs the acceleration forces which occur when the hydraulic switching element or the anchor bolt engages with the closing element received upon impact with the seat. Depending on the manufacturing process and amounts of acceleration forces occurring can have a plurality of recesses, grooves or a collar or multiple frets or a geometry with undercut on the anchor bolt or on the hydraulic switching element and complementary thereto on the inner circumferential surface of the anchor plate passing through opening or Be formed bore so that the acceleration forces are reliably absorbed. The use of the MIM method advantageously makes it possible to form a metallic component made of a metallic material on a component which is made of a different material, so that the individual components to be joined together take into account respectively optimized material properties matched to the application branch can be selected.

drawing

FIG. 1

1 shows a first embodiment variant of the connection proposed according to the invention in an armature assembly on a pressure-balanced 2 = 2 valve,

Figures 2.1, 2.2, 2.3 and 2.4

various embodiments of the MIM connection of the armature assembly,

FIG. 3

the use of the inventively proposed armature assembly on an outwardly opening valve (A-valve),

FIG. 4

the use of the inventively proposed MIM connection within an armature assembly on a sleeve valve sen.

variants

The representation according to FIG. 1 is a pressure balanced 2/2-valve refer, with a fuel injector is actuated and the armature assembly comprises an anchor plate and an anchor bolt or a hydraulic switching element and the anchor plate is integrally formed by means of a MIM connection to the anchor bolt.

The representation according to FIG. 1 It can be seen that a fuel injector 10, which is only partly shown here, has an injector body 12. The fuel injector 10 includes a solenoid valve 14. The solenoid valve 14 includes a magnet pot 16 in which a solenoid coil 22 is received. The magnet pot 16 is traversed by a passage opening 18, which serves to receive a closing spring 20.

Below the magnet pot 16 is an armature assembly 24 which includes an anchor plate 26. The anchor plate 26 may either be integrally formed on an anchor bolt or formed on a hydraulic switching element 28. The attachment between the anchor plate 26 and the anchor bolt 28 and the hydraulic switching element 28 takes place by means of an MIM connection 30 (Metal-Injected Molding).

The anchor bolt 28 or the hydraulic switching element 28 of the armature assembly 24 is received in a bore 32 of the injector body 12. Depending on the embodiment variant, for example, in the event that the anchor plate 26 of the armature assembly 24 is connected to a hydraulic switching element 28, the lower end face of the hydraulic switching element 26 cooperate with a seat 36 formed in the injector body 12. In the injector body 12 there is a hydraulic chamber 40 into which, for example, a pressure relief line 38 is provided for pressure relief of an injection valve of the fuel injector 10 actuated control chamber.

When energizing the in FIG. 1 shown fuel injector 10, the anchor plate 26 which is integrally formed on the circumference of the anchor bolt 28 or a hydraulic switching element 28, attracted by the solenoid 22 and the seat 36 is opened at the lower end face of the anchor bolt 28 and the hydraulic switching element 28. This creates a pressure relief of the hydraulic chamber 40, so that a control amount via the discharge line 38, the hydraulic chamber 40 and the open seat 36 can flow into a low-pressure side return 34 of the injector 12.

If the energization of the solenoid 22, however, lifted, the armature assembly 24 is pressed by the solenoid cup 16 closing spring 20 in the seat 36, so that the flow connection between the control chamber relieving relief line 38 and the low-pressure side return 34 through the closed seat 36 in Injector body 12 is interrupted.

The representations according to the Figures 2.1, 2.2, 2.3 and 2.4 variants of the MIM connection can be seen within an armature assembly.

Figure 2.1 can be removed that the anchor bolt 28 and the hydraulic switching element 28 has a circumference 52. In the area in which the armature disk 36 of the anchor hole 24 is formed on the periphery 52 of the anchor bolt 28 and the hydraulic switching element 28, there is an outer contour 44. Depending on the selected configuration of the outer contour 44 on the periphery 52 of the anchor bolt 28 and the hydraulic Switching element 28, results in a positive connection 46 of the anchor plate 26 with the anchor bolt 28 or the hydraulic switching element 28. With the MIM process, a positive connection 46 is produced by the formation of the anchor plate 26 on the anchor bolt 28 or the hydraulic switching element 28 when forming the anchor plate 26. Preferably, the armature plate 26 of the armature assembly 24 is formed on the periphery 52 of the anchor bolt 28 and the hydraulic switching element 28, that between the end face 50 of the armature disk 26 and the end face of the anchor bolt 28 and the hydraulic switching element 28, a supernatant 48 results the residual air gap between the end face 50 of the armature disk 26 and the lower end face of the magnet coil 22 enclosed by the magnetic core 16 is defined.

While a magnetic material is preferably selected for the armature plate 26 in order to obtain high magnetic forces and small eddy current losses, the material from which the armature pin 28 and the hydraulic shifting element 28 are made is selected to be optimized for optimal wear is. The anchor plate 26 is formed by means of the MIM method to form a MIM connection 30 on the anchor bolt 28, wherein the Nachbearbeitungsaufwand takes a minimum.

The representation according to Figure 2.2 an alternative embodiment of the MIM connection of an armature assembly 24 can be seen.

From the illustration according to Figure 2.2 shows that at the periphery 52 of the anchor bolt 28 and the hydraulic switching element 28, a circumferential groove 54 extends. Complementary to the depth of the circumferential groove 54 on the circumference 52 of the anchor bolt 28 and the hydraulic switching element 28 is formed during the formation of the anchor plate 26, a projection 56. After the forming of the anchor plate 26 results between the projection 56 and the circumferential groove 54 on the periphery 52 of the anchor bolt 28 and the hydraulic switching element 28, the MIM connection 30. These components are joined together form-fitting manner.

Also in the in Figure 2.2 illustrated embodiment of the armature assembly 24 is located between the end face 50 of the anchor plate 26 and the end face of the anchor bolt 28 and the hydraulic switching element 28, a projection 48, which in the assembled state of the armature assembly 24, the residual air gap between the end face 50 of the anchor plate 26 and the end face of Magnetic coil 22 enclosed by the magnetic pot 16 is defined.

Figure 2.3 shows a further embodiment of an MIM connection having armature assembly.

According to this embodiment, a collar 58 is embodied on the circumference 52 of the anchor bolt 28 or of the hydraulic shift element 28. The raised above the circumference 52 of the anchor bolt 28 and the hydraulic switching element 28 projecting collar 58 forms during molding of the anchor plate 26 has a correspondingly configured recess on the inside of the armature plate 26. Also in the in Figure 2.3 illustrated embodiment of the armature assembly 24, the supernatant 48 is set between the end face of the anchor bolt 28 and the hydraulic switching element 28 and the end face 50 of the anchor plate 26 in the MIM tool so that in the formation of the anchor plate 26 on the anchor bolt 28 and the hydraulic Switching element 28 by corresponding axial arrangement of the collar 58, a residual air gap between the armature plate 26 and the magnetic coil 22 results.

In Figure 2.4 a variant embodiment of the invention proposed anchor assembly is shown in which at the periphery 52 of the anchor bolt 28 and the hydraulic switching element 28 at least one undercut 60 is executed. The undercut 60 on the periphery 52 of the anchor bolt 28 and the hydraulic switching element 28 is in the molding of the anchor plate 26 by means of the MIM method of the material from which the anchor plate 26 is made, surrounded. It forms a positive connection 46 between the anchor plate 26 and the anchor bolt 28 or the hydraulic switching element 28, which also withstands high acceleration forces.

The in the Figures 2.1 to 2.4 illustrated embodiments of the armature assembly 24 are all characterized by an MIM connection 30 between the anchor plate 26 and the anchor bolt 28 and the hydraulic switching element 28. The outer contour 44 of the circumference 52 of the anchor bolt 28 and the hydraulic switching element 28 can be easily made in the output part of the low demands on the tolerances. The formation of the residual air gap is adjusted by appropriate dimensioning of the supernatant 48 between the end face 50 of the anchor plate 26 and the end face of the anchor bolt 28 and the hydraulic switching element 28 in the MIM tool and the MIM process, ie the injection or the introduction of a liquid metallic Material, produced during the manufacture of the MIM connection 30 during the molding of the anchor plate 26. While the material of the anchor bolt 28 and the hydraulic switching element 28 is optimally designed with respect to the wear characteristics, the armature plate 26 to be formed on the anchor bolt 28 or of the hydraulic shift element 28 is optimally selected with regard to the magnetic properties of the material. Although in the Figures 2.1 to 2.4 not shown, to reduce the mass of the anchor plate 26 may be provided with through holes, through holes or recesses, on the one hand, a reduction in the mass of the anchor plate 26 achievable is and with which on the other hand, a flow of controlled from the control room tax amount can be optimized.

FIG. 3 shows the inventively proposed armature assembly on an outwardly opening valve (A-valve).

The representation according to FIG. 3 It can be seen that the fuel injector 10 includes in the injector 12, in which the solenoid valve 14 is received. The armature assembly 24 as shown in FIG FIG. 3 includes the anchor plate 26 which is positively connected via a MIM connection 30 with the anchor bolt 28 and the hydraulic switching element 28. At the periphery of the anchor bolt 28 and the hydraulic switching element 28, a seat surface is formed, which cooperates with the seat 36 of the injector 12. The armature assembly 24 as shown in FIG FIG. 3 opens when energizing the solenoid 22, which is enclosed by the magnetic pot 16, to the outside. For this purpose, a circumferential taper 66 is formed on the circumference 52 of the anchor bolt 28 and the hydraulic switching element 28, in the region of the relief line 38 for pressure relief of a in FIG. 3 not shown, but formed in the injector 12 control chamber opens. When the seat 36 is opened when the magnet coil 22 is energized and the armature assembly 24 is moved upwards, the control volume flows via the relief line 38, the cavity formed by the circumferential taper 66 on the circumference of the anchor bolt 28 and the hydraulic switching element 28 and the opened seat 36, respectively low-pressure side return 34 from. Another return over the guide leakage is located at the lower end of the bore 32 in the injector body 12, in which the anchor bolt 28 and the hydraulic switching element 28 is guided narrow tolerances. The embodiment according to FIG. 3 can also be seen that the upper end face of the anchor bolt 28 and the hydraulic switching element 28 cooperates with a stop 62 which limits the opening stroke of the armature assembly 24. In the illustration according to FIG. 3 the stroke stop 62 is formed on the lower end side of the magnet pot 16.

FIG. 4 shows a further embodiment of the inventively proposed anchor assembly on a sleeve valve.

The representation according to FIG. 4 is the fuel injector 10 can be seen, which has a sleeve valve to relieve the pressure of a discharge line 38 of a control chamber in the injector 12. The armature assembly 24 includes in this embodiment a valve sleeve 68 which is joined to the anchor plate 26 via an MIM connection 30. Within the valve sleeve 38 is acted upon by the closing spring 20 cylindrical valve body 70th added. About the closing spring 20 of the cylindrically shaped valve body 70 is acted upon.

When current is applied to the magnetic coil 22 of the magnet pot 16, the end face 50 of the armature plate 26 is tightened, so that the valve sleeve 68 lifts off from the seat 36 at the top of the injector body 12. As a result, an orifice 74 of the discharge line 38 of the control chamber formed in the injector body 12 is depressurized, since a biting edge 76, which is formed on the lower end face of the valve sleeve 68, is lifted off the plan side of the injector body 12. The discharge point 74 of the discharge channel 38 may, for example, in a dome-shaped elevation 72 on the plan side of the injector body 12 of the fuel injector 10 according to the embodiment in FIG. 4 lead. If the biting edge 76 of the valve sleeve 68 is set back from the dome-shaped elevation 72, the control quantity flowing out of the relief channel 38 flows laterally in the direction of a low-pressure-side return 34 from the injector body 12 of the fuel injector 10.

Claims (10)

1. Method for the production of an armature subassembly (24) for a solenoid valve (14) which contains a current-activatable magnetic coil (22), with the following method steps:

   a) an external contouring (44; 54, 58, 60) is generated on the circumference (52) of an armature bolt (28) or of a hydraulic switching element (28),

   b) an armature plate (26) is formed in the region of the external contouring (44, 54, 58, 60) by means of the MIM method (metal-injected moulding).
2. Method according to Claim 1, characterized in that, according to method step a), at least one slot (54) or one groove is formed on the circumference (52) of the armature bolt (28) or of the hydraulic switching element (28).
3. Method according to Claim 1, characterized in that, according to method step a), at least one collar (58) or one undercut (60) is formed on the circumference (52) of the armature bolt (28) or of the hydraulic switching element (28).
4. Method according to Claim 1, characterized in that, according to method step b), a positive connection is generated between the material of the armature disc (26) and the external contouring (44; 54, 58, 60) of the circumference (52) of the armature bolt (28) or of the hydraulic switching element (28).
5. Method according to Claim 1, characterized in that, according to method step b), a projection (48) defining a residual air gap is generated between the end face of the armature bolt (28) or of the hydraulic switching element (28) and one end face (50) of the armature plate (26).
6. Method according to Claim 1, characterized in that, according to method step b), through-orifices or clearances are generated in the armature disc (26).
7. Armature subassembly (24) for a solenoid valve (14) with an armature plate (26) and with an armature bolt (28) or with a hydraulic switching element (28), characterized in that the armature plate (26) is integrally formed, in the region of an external contouring (44; 54, 58, 60), on the circumference (52) of the armature bolt (28) or of the hydraulic switching element (28) by means of the MIM method.
8. Armature subassembly (24) according to Claim 7, characterized in that the circumference (52) of the armature bolt (28) or of the hydraulic switching element (28) has at least one groove or at least one slot-shaped depression (54).
9. Armature subassembly (24) according to Claim 7, characterized in that at least one elevation (58, 60) projecting in a raised manner beyond the circumference (52) is formed on the circumference (52) of the armature bolt (28) or of the hydraulic switching element (28).
10. Armature subassembly (24) according to Claim 7, characterized in that the armature plate (26) is manufactured from a magnetic material and the armature bolt (28) or the hydraulic switching element (28) is manufactured from a wear-optimized material.

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