EP3270388A1 - Method for making a solenoid and solenoid - Google Patents

Abstract

The disclosure relates to a method for producing an air gap-reduced magnet coil (30) for a magnetic actuator (28), in particular for an injector (10), comprising the following steps providing a magnetic core (80) which is radially accessible at least in sections and has a receiving region ( 86) for directly receiving a coil winding (88), producing a coil winding (88) with a winding wire (90) placed directly around the magnetic core (80), the coil winding (88) being stabilized by the magnetic core (80) , and fixing the generated coil winding (88). The disclosure further relates to a corresponding magnetic coil (30).

Description

The invention relates to a method for producing an air gap-reduced magnetic coil for a magnetic actuator, in particular for an injector. Furthermore, the invention relates to a magnetic coil for a magnetic actuator, and an injector, in particular a fuel injection nozzle for an internal combustion engine, with such a magnetic actuator.

A fuel injector of general type is exemplified in EP 0 132 623 A2 known. The injection nozzle is provided with a magnetic actuator having a housing-fixed, encapsulated induction coil.

From the DE 10 2007 000 164 A1 For example, there is known a magnet coil having a magnet cup constructed for use with an injector, wherein a coil winding is received on an inner core, and wherein an outer core is provided surrounding the inner core and the coil. The connection between the inner core and the outer core is a core connector.

From the DE 28 09 975 A1 a solenoid actuator for an injection system is known, with a recorded on a core winding, which is surrounded by a hollow cylinder.

Injectors for supplying fuel to internal combustion engines are well known. These are commonly referred to as injectors. Modern injectors are equipped with mechatronic actuators, such as magnetic actuators, to control the opening and closing of the nozzles with high precision. Modern injection systems for diesel engines are designed for maximum injection pressures of several hundred bar up to over 1000 bar or even up to 2500 bar.

There are known injectors with so-called. Piezo actuators. Nevertheless, injectors with magnetic actuators are also used. Such injectors are usually provided with a solenoid which cooperates with a movable armature to drive the injector.

It is customary to provide a separate component, a so-called. Coil carrier on which the coil winding is produced. The bobbin is designed somewhat like a cable drum when the winding is created. Together with the bobbin, the coil winding can be supplied to a magnet pot or magnetic core to form a magnetic circuit. The bobbin on the one hand serves as an assembly aid. Furthermore, the coil carrier also secures the position of the generated coil winding. This applies at least temporarily until the coil winding is secured by a casting or encapsulation.

The function of the coil carrier as an assembly aid has the advantage that the coil winding produced can be introduced in a simple manner in a magnet pot, which provides a circumferential groove for receiving the coil winding.

However, it has been found that solenoids manufactured in accordance with this approach have a performance, in particular with regard to the power density, reach the limits. Any components which are made of a non-magnetizable material but which are located adjacent the flux-guiding region of the magnetic actuator or the flux-guiding region must be overcome by the magnetic fields generated by the coil. Thus, given the space available due to the required bobbin not the entire power potential of the magnetic circuit can be retrieved. In other words, the coil carrier increases the distance between the coil winding and the flux-conducting parts of the magnetic circuit. Accordingly, the introduction of a bobbin between the coil winding and the magnet pot or magnetic core has a similar effect as increasing the air gap. In other words, in practical terms, the bobbin increases the "imaginary" air gap. Specifically, the coil support defines a minimum distance between the coil winding and the magnetic pot or magnetic core.

Against this background, the present disclosure has the object to provide an air gap-reduced magnetic coil and a magnetic actuator with such a magnetic coil, which have a high power density for a given space and in particular allow a higher flux density than provided with coil carriers magnetic coils. Preferably, the magnetic coil is easy to produce even at the desired increased efficiency. In addition, the solenoid should be made sufficiently robust, in particular, the position and orientation of the coil winding should be stable. Furthermore, such a magnet coil preferably allows the generation of higher magnetic forces. The magnetic coil should be designed space-optimized.

Furthermore, advantageous embodiments of magnetic coils and provided with such a solenoid coils injectors are given.

• Bereitstellung eines Magnetkerns, der zumindest abschnittsweise radial zugänglich ist und einen Aufnahmebereich zur direkten Aufnahme einer Spulenwicklung umfasst,
• Erzeugung einer Spulenwicklung mit einem Wickeldraht, der direkt um den Magnetkern gelegt wird, wobei die Spulenwicklung durch den Magnetkern stabilisiert wird,
• Fixieren der erzeugten Spulenwicklung, und
• Erzeugung einer gebauten Magnettopfstruktur, umfassend:
  • Bereitstellung eines Umfangskörpers, der zur Flussführung ausgestaltet ist,
  • Fügen des Umfangskörpers mit dem Magnetkern,
    • wobei die Spulenwicklung zwischen dem Magnetkern und dem Umfangskörper angeordnet wird, und
    • wobei der Umfangskörper als Teil eines Gehäuses des magnetischen Aktors ausgebildet wird.

This object is achieved according to the method according to the invention by a method for producing an air gap-reduced magnetic coil for a magnetic actuator, in particular for an injector, with the following steps:

• Providing a magnetic core which is radially accessible at least in sections and comprises a receiving region for directly receiving a coil winding,
• Producing a coil winding with a winding wire, which is placed directly around the magnetic core, wherein the coil winding is stabilized by the magnetic core,
• Fixing the generated coil winding, and
• Creation of a constructed magnet pot structure comprising:
  • Providing a peripheral body designed for flow guidance,
  • Joining the peripheral body with the magnetic core,
    • wherein the coil winding is disposed between the magnetic core and the peripheral body, and
    • wherein the peripheral body is formed as part of a housing of the magnetic actuator.

The object of the invention is completely solved in this way.

According to the invention, namely, the coil winding is generated directly on or on the core. This has the advantage that no separate coil support is required. In other words, the distance between the coil winding and the flux-guiding magnetic core can be significantly reduced. This reduces the magnetic resistance, ie the imaginary "air gap" between the coil winding and the magnetic core. Accordingly, the flux density can be significantly increased. Given the space available, a higher power density can be achieved. Conversely, it is possible to achieve desired characteristics, such as a defined magnetic force, with less space requirement.

Overall, the magnetic coil produced in this way can be referred to as air gap-reduced magnetic coil. The distances between the coil winding and flux-conducting regions, in particular the magnetic core and / or an armature, can be reduced both in the axial direction and in the radial direction.

Since the coil winding is fixed after the winding operation, it is not necessary to provide separate coil carriers or the like. The coil winding is preferably fixed in its wound position directly on the magnetic core. The fixing of the coil winding can be effected by various measures. It is essential that the fixing of the coil winding in particular secures the axial position and / or axial extent of the coil winding. In this case, it is not absolutely necessary to define the relative position between individual turns of the coil winding with high precision. It is essential that the coil winding assumes a desired overall position with respect to the magnet core. This applies in particular to the extent of the coil winding in the direction of a contact region in which the magnetic core interacts with a magnet armature.

Since the magnetic core is at least partially radially accessible, the winding process can be effected by simple means. In particular, it is not necessary to dive axially deep into an annular groove of a magnet pot for generating the coil winding.

According to an exemplary embodiment of the method, the coil winding is produced without a spool, wherein the magnetic core is at least partially rod-shaped and radially accessible to a winding tool. In other words, at least in the state in which the winding is generated, no peripheral wall spaced from the magnetic core is provided. Thus, a single-layer or multi-layer coil winding can be easily produced. The rod-shaped design of the magnetic core includes various cross-sectional shapes, in addition to round cross-sections as well as oval rectangular, square or triangular cross-sections.

The method comprises generating a built-up magnet pot structure by providing a peripheral body configured for flux guiding, wherein the peripheral body is joined to the magnetic core, and wherein the coil winding is disposed between the magnetic core and the peripheral body.

In other words, a built magnet cup is provided, which is generated from at least two flux-conducting parts, namely the magnetic core and the peripheral body. Thus, the flux-guiding surface of the magnetic coil can be increased. However, a good radial accessibility of the magnetic core is given for the winding process.

Another advantage of this measure is that in the magnetic core about axial slots are easily generated. Usually, such axial slots serve to reduce or avoid eddy currents. Due to the presence of an axial slot or a plurality of axial slots in the magnetic core, the expense for generating the coil winding directly on the magnetic core does not increase or only insignificantly.

The peripheral body is formed as part of a housing of the magnetic actuator. This has the advantage that overall the number of components to be assembled does not increase or does not rise excessively. It is conceivable to carry out the (flux-guiding) peripheral body as part of the housing of the actuator or at least to receive it on the housing of the actuator. Overall, even with a "built-in" magnetic pot, a radial space reduction can be achieved with constant or even increased performance of the magnetic actuator.

The magnetic core and the peripheral body can be suitably joined together. Preferably, the joining of the magnetic core takes place with the peripheral body such that no increase in the magnetic resistance occurs at the transition between the two components.

According to a further exemplary embodiment of the method, the coil winding has an axial extent along a longitudinal axis of the magnetic core up to a region in which the magnetic core interacts with a magnet armature. Preferably, the coil winding extends flush or almost flush to a frontal surface of the magnetic core, which is contacted by the magnet armature in the attracted state of the magnetic actuator. In this way, the space of the solenoid coil is maximally utilized for the coil winding. When using Coil carriers, which are usually provided at their axial ends each with a collar, it is not possible due to design, the coil winding axially so close to the contact area between the magnetic core and the armature lead.

According to a development of the above embodiment, the coil winding, the magnetic core and preferably also the peripheral body of the magnetic coil terminate axially in the direction of the magnet armature flush. This implies that, as far as possible, the coil winding does not protrude beyond the magnet core and / or the peripheral body in the direction of the magnet armature.

Furthermore, according to a further exemplary embodiment of the method, no separate, design-fixed component is provided which axially delimits the coil winding in the direction of the magnet armature. It goes without saying, however, that encapsulation or potting of the coil winding can nevertheless also be provided in this area.

According to a further exemplary embodiment of the method, an axial position securing in the form of a constriction or taper is formed on the magnetic core, which secures the axial position of the magnetic coil.

Alternatively or additionally, according to a further exemplary embodiment of the method, an axial position assurance for the coil winding in the form of guide grooves or a guide thread is formed on the magnetic core.

Since no separate coil support is used for fixing the position of the coil winding, it is conceivable to provide a corresponding position assurance directly on the magnetic core. It is essential that the axial position of the coil winding is defined at least sufficiently accurate. This can be limited in time in at least some embodiments of the method, if an encapsulation or encapsulation of the coil winding is provided.

If the axial position assurance for the coil winding is designed in the form of guide grooves or guide threads, it is not necessary to provide a separate guide element, for example a separate guide passage in the guide thread, for each separate turn of the coil winding. Rather, it is about a global position assurance or anti-skid device for the coil winding.

According to a further exemplary embodiment of the method, the receiving area on the magnetic core is provided at least in sections with an insulating layer, preferably with a plastic coating, prior to the generation of the coil winding.

The insulation layer is not a separate component. The insulation layer is not comparable to a coil carrier. The insulating layer may be, for example, a thin plastic coating. The insulating layer serves on the one hand for electrical insulation, but also for mechanical insulation.

Although it is customary to use coated wires to produce the coil winding, in particular with thin-walled coated wires, it can not always be ruled out that the coating breaks or breaks. Accordingly, an insulating layer directly on the receiving area of the magnetic core may be advantageous. It is understood that the insulating layer can also be designed as a lacquer layer. In principle, it is also conceivable to produce the insulating layer by wrapping the magnetic core with an insulating tape.

According to a development of the abovementioned embodiment of the method, the insulation layer is also used for fixing the coil winding when the winding wire deforms the insulation layer at least in sections. This measure makes use of the fact that the insulating layer is soft and deformable compared to the wire material and the material of the magnetic core. Accordingly, the coil winding can be generated so tightly that the winding wire at least partially cuts into the insulating layer. In other words, the winding wire sits with Preload on the receiving area. Furthermore, it is conceivable that the winding wire displaces the insulation layer at least in sections.

The above measures have the advantage that the risk of axial slippage of the coil winding relative to the magnetic core can be significantly reduced.

According to a further exemplary embodiment of the method, the winding wire is coated or painted, wherein the winding wire acts after the generation of the coil winding adhesive or connecting to fix the coil winding. Preferably, the winding wire is heated to fix the coil winding.

By way of example, the winding wire may be a so-called baked enamel wire. Preferably, the winding wire is designed such that on the one hand individual turns of the wire are connected to one another. In addition, the winding wire is preferably designed such that a connection / adhesion between the coil winding and the magnetic core results.

By way of example, the composite of magnetic core and coil winding can be baked when a defined heating takes place on the winding process. By way of example, the winding wire can be provided with a varnish which softens at about 200 ° C. (Celsius) and can thus be baked. This preferably includes a cohesive connection of adjacent turns. Furthermore, preferably results in a cohesive connection of at least some turns of the coil winding with the magnetic core. This may in particular also relate to an insulating layer of the magnetic core.

Typical application temperatures for the magnetic actuator are approximately in the range of 160 ° C (Celsius), at most up to about 180 ° C. Accordingly, the risk of re-softening the coating or coating of the winding wire is very low.

According to a further exemplary embodiment of the method, this further comprises at least partially encapsulating or encapsulating the coil winding with a filling material. This is done in the wound state after the coil winding has been generated on the magnetic core. According to an exemplary embodiment, the encapsulation or encapsulation of the coil winding takes place when the magnetic core has already been joined to the peripheral body in order to form a built magnet cup. However, it is also conceivable to encase the coil winding prior to joining with the peripheral body or to encapsulation. In this way, the coil winding is already protected and fixed in this manufacturing step.

The encapsulation can also be referred to as potting. The Umgießen or encapsulation may contribute to fixing and to secure the position of the coil winding.

According to a further exemplary embodiment of the method, the coil winding is secured at least temporarily with a hold-down, wherein the hold-down is preferably removed when the coil winding is fixed. The hold-down device may be, for example, a disk-like or ring-shaped holding-down device which defines an axial stop surface for the coil winding on the magnetic core. The hold-down can be removed if the coil winding is adequately secured and fixed, that is, if, for example, the cohesive position assurance has been brought about by heating. Furthermore, the hold-down can be removed approximately when the encapsulation or encapsulation of the coil winding has been performed. Accordingly, the hold-down can also be used for such a method, for example, to define an area to be overpainted or encapsulated.

• einen Magnetkreis mit einer gebauten Magnettopfstruktur, umfassend einen Magnetkern und einen Umfangskörper, der mit dem Magnetkern gefügt ist, und
• eine Spulenwicklung mit einem Wickeldraht, der direkt um den Magnetkern gelegt ist,

wobei die Spulenwicklung zwischen dem Magnetkern und dem Umfangskörper angeordnet ist,
wobei die Spulenwicklung spulenträgerlos erzeugt ist, und
wobei der Umfangskörper als Teil eines Gehäuses des magnetischen Aktors ausgebildet ist,
wobei die Spulenwicklung entlang einer Längsachse des Magnetkerns vorzugsweise eine axiale Erstreckung bis zu einem Bereich aufweist, in dem der Magnetkern und der Umfangskörper mit einem Magnetanker zusammenwirken.As regards the magnetic coil, the object of the invention is achieved by a magnetic coil for a magnetic actuator, in particular for an injector, wherein the magnetic coil has the following:

• a magnetic circuit having a magnetic cup structure constructed, comprising a magnetic core and a peripheral body joined to the magnetic core, and
• a coil winding with a winding wire placed directly around the magnetic core,

wherein the coil winding is disposed between the magnetic core and the peripheral body,
wherein the coil winding is produced spoolless, and
wherein the peripheral body is formed as part of a housing of the magnetic actuator,
wherein the coil winding along a longitudinal axis of the magnetic core preferably has an axial extent up to a region in which the magnetic core and the peripheral body cooperate with a magnet armature.

Also in this way the object of the invention is completely solved.

According to an exemplary embodiment, the coil winding extends axially to an axial end face or almost to an axial end face in which the magnetic core and / or the peripheral body in the tightened state of the magnetic actuator contact the magnet armature.

According to an exemplary embodiment of the magnetic coil, the coil winding, the magnetic core and preferably also the peripheral body terminate axially in the direction of the magnet armature flush.

According to an exemplary embodiment of the magnetic coil, an axial position assurance for the coil winding is formed on the magnetic core.

Preferably, a solenoid coil according to one of the above aspects is used in a magnetic actuator which is part of an injector, in particular part of a fuel injection nozzle for an internal combustion engine.

It is understood that the features of the invention mentioned above and those yet to be explained not only in the respectively specified Combination, but also in other combinations or alone, without departing from the scope of the present invention.

Fig. 1

einen Längsschnitt durch eine exemplarische Ausgestaltung eines Injektors;

Fig. 2

eine vereinfachte Seitenansicht eines Spulenträgers für eine Magnetspule, auf dem eine Spulenwicklung erzeugt wird;

Fig. 3

einen vereinfachten Längsschnitt durch einen Magnettopf für eine Magnetspule;

Fig. 4

einen vereinfachten Längsschnitt durch eine Spulenbaugruppe, die auf Basis des Spulenträgers gemäß Fig. 2 und des Magnettopfes gemäß Fig. 3 erzeugt wurde;

Fig. 5

eine schematisch stark vereinfachte Ansicht eines Magnetkerns, bei dem in direkter Weise eine Spulenwicklung erzeugt wird;

Fig. 6

einen Längsschnitt durch einen Umfangskörper, der mit dem Magnetkern gemäß Fig. 5 verbindbar ist;

Fig. 7

einen vereinfachten Längsschnitt durch eine Magnetspule, die auf Basis des Umfangskörpers gemäß Fig. 6 und des mit der Spulenwicklung versehenen Magnetkerns gemäß Fig. 5 erzeugt wurde;

Fig. 8

eine schematische Seitenansicht einer ersten Ausführungsform eines Magnetkerns mit einem Aufnahmebereich für eine Spulenwicklung;

Fig. 9

eine schematische Seitenansicht einer zweiten Ausführungsform eines Magnetkerns mit einem Aufnahmebereich für eine Spulenwicklung;

Fig. 10

eine schematische Seitenansicht einer dritten Ausführungsform eines Magnetkerns mit einem Aufnahmebereich für eine Spulenwicklung;

Fig. 11

einen vereinfachten schematischen Längsschnitt durch eine Magnetspule, die mit einem Magnetanker zusammenwirkt; und

Fig. 12

ein schematisch stark vereinfachtes Blockdiagramm zur Veranschaulichung einer beispielhaften Ausgestaltung eines Verfahrens zur Herstellung einer Magnetspule für einen magnetischen Aktor.

Further features and advantages of the invention will become apparent from the following description of several preferred embodiments with reference to the drawings. Show it:

Fig. 1

a longitudinal section through an exemplary embodiment of an injector;

Fig. 2

a simplified side view of a coil carrier for a magnetic coil on which a coil winding is produced;

Fig. 3

a simplified longitudinal section through a magnet pot for a magnetic coil;

Fig. 4

a simplified longitudinal section through a coil assembly, based on the bobbin according to Fig. 2 and the magnet pot according to Fig. 3 was generated;

Fig. 5

a schematically simplified view of a magnetic core, in which a coil winding is directly generated;

Fig. 6

a longitudinal section through a peripheral body, with the magnetic core according to Fig. 5 is connectable;

Fig. 7

a simplified longitudinal section through a magnetic coil, based on the peripheral body according to Fig. 6 and the magnetic core provided with the coil winding according to Fig. 5 was generated;

Fig. 8

a schematic side view of a first embodiment of a magnetic core having a receiving area for a coil winding;

Fig. 9

a schematic side view of a second embodiment of a magnetic core having a receiving area for a coil winding;

Fig. 10

a schematic side view of a third embodiment of a magnetic core having a receiving area for a coil winding;

Fig. 11

a simplified schematic longitudinal section through a magnetic coil, which cooperates with a magnet armature; and

Fig. 12

a schematically highly simplified block diagram illustrating an exemplary embodiment of a method for producing a magnetic coil for a magnetic actuator.

Fig. 1 shows a longitudinal section through an exemplary embodiment of an injector 10. The design of the injector 10 is merely exemplary in nature and is here merely representative of a variety of other conceivable embodiments. The injector 10 has a housing 12. The housing 12 is provided with a port 14 through which fuel or fuel can be supplied. A nozzle-side end of the injector 10 is provided with a valve nozzle 16. Further, a nozzle needle 18 is received in the housing 12, via which an injection quantity can be controlled. The nozzle needle 18 is coupled to a control piston 20, which is acted upon by a closing spring 22 in the direction of a closed position. At the end of the control piston 20, which faces away from the valve nozzle 16, a control bore 24 is formed, to which an electromagnetic actuator 28 connects.

The actuator 28 comprises a solenoid coil 30 provided with a coil winding 32. The actuator 28 is further associated with an armature 24, which is acted upon by a spring 36 in the direction of a rest position. By activating the actuator 28, the armature 34 can be attracted or lifted. At its end remote from the valve nozzle 16, the housing 12 has a reflux connection 38, via which excess fuel can be dispensed. Further, a control terminal 40 is provided, via which the electromagnetic actuator 28 can be controlled by the coil winding 32 is selectively energized.

Other embodiments of injectors are conceivable without further ado. Regularly, the injectors 10 are provided with an actuator 28, which is often configured as an electromagnetic actuator 28 and provided with a coil winding 32. The coil winding 32 is regularly encapsulated or encapsulated. In this way, the coil winding 32 can be effectively protected from environmental influences.

With reference to the embodiments explained in more detail below, advantageous embodiments of magnetic coils 30 for such electromagnetic actuators 28 and in particular advantageous method aspects for their production are illustrated and described in more detail.

Based on FIGS. 2, 3 and 4 the production of a coil assembly 70 (see. Fig. 4 ) comprising a coil winding 54 wound around a bobbin 50. In basically known manner, a winding wire denoted by 52 can be wound in single-layer or multi-layer onto the coil carrier 50, more like a cable drum. A significant advantage of the use of the bobbin 50 is the simplified handling of the coil winding 54. The bobbin 50 provided with the coil winding 54 is designed to fit in an in Fig. 3 to be introduced with 58 designated magnetic pot. Fig. 4 illustrates the joined state.

The in Fig. 3 illustrated magnetic pot 58 has a basically rotationally symmetrical design. The magnetic pot 58 comprises a circumferential groove or annular groove 60 into which the coil carrier 50 can be inserted, cf. the sectional view of the bobbin 50 in Fig. 4 , In the center of the magnet pot 58, a designated 64 core is formed. The core 64 includes a central bore 66 which serves as a guide for an anchor. Outwardly, the annular groove 60 is bounded by an outer wall 62. In addition, the magnet pot 58 has an end wall 68, which forms a front end and connects the core 64 and the outer wall 62 with each other. The in Fig. 3 shown magnet pot 58 is designed in one piece.

The in Fig. 4 1 shows that the coil winding 54, which is accommodated on the coil carrier 50, can not contact the core 64 or can not be arranged in the immediate vicinity of the core. Between the coil winding 54 and the core 64, a cylinder wall of the bobbin 50 extends.

With reference to the FIGS. 5 to 11 illustrate alternative configurations of solenoids 30 in which the coil winding is directly producible on the core.

Fig. 5 FIG. 16 illustrates a magnetic core, designated 80, that includes a shaft 82. At one end of the shaft 62, a flange 84 is formed. The in Fig. 7 shown sectional view can be taken that the magnetic core 80 is provided with a central armature guide 126, that is about with a through hole.

The shaft 82 extends along a longitudinal axis 92. A coil winding 88 is formed on the shaft 82 and is wound directly onto the shaft 82 in a receiving region 86. The receiving area 86 indicates the portion of the shaft 82 in which the coil winding 88 contacts the shaft 82. The receiving area 86 is provided according to a further embodiment with a coating or paint, which acts insulating.

The coil winding 88 consists of a winding wire 90, which is wound around the longitudinal axis 92 and forms a plurality of turns. The coil winding 88 may be single-layered or multi-layered. In the Fig. 7 shown coil winding 88 includes, by way of example, a three-layer design.

Fig. 5 further illustrates schematically in greatly simplified form a generally designated 98 winding unit. The winding unit 98 comprises a winding tool designated 100. The winding tool 100 may, for example, comprise a wire dispenser and / or a wire feed. Furthermore, in Fig. 5 exemplified a designated 102 changing table. The wrapping table 102 and the winding tool 100 may suitably cooperate to produce the coil winding 88. This may, for example, comprise a defined rotation of the shank 82, cf. a curved arrow labeled 104 in FIG Fig. 5 , Furthermore, the generation of the winding 88 comprises a defined relative lifting movement (see the double arrow in FIG Fig. 5 ) between the shaft 82 and the winding tool 100.

The receiving region 86 of the shaft 82, which is designed to receive the coil winding 88, is radially accessible. This greatly simplifies the generation of the coil winding 88.

In addition, in this context, the Fig. 3 which shows an integrally formed magnet pot 58, in which the core 64 just is not radially accessible. A winding directly on the core 64 of the magnet pot 58 according to Fig. 3 could at best be generated directly only with great effort.

Fig. 5 further illustrates a downholder designated 108. The hold-down 108 is in Fig. 5 still spaced from the shaft 82. The hold-down 108 is exemplarily placed on the shaft 82 to limit or define an axial extent of the winding 88 to be generated. However, it is preferred if the hold-down 108 is configured as an assembly aid, that is before or in connection with the completion of the magnetic coil 30 (see. Fig. 7 ) Will get removed.

Fig. 6 illustrates a longitudinal section through a cylindrical or tubular-shaped peripheral body 114, which forms an interior 116. The magnetic core 80 according to Fig. 5 and the peripheral body 114 according to FIG Fig. 6 can be connected together to a design similar to the magnet pot 58 according to Fig. 3 train. However, this design is a "built" magnet pot.

In this way, a magnet pot structure 120 can result, which in Fig. 7 is shown schematically simplified in longitudinal section. The magnetic pot structure 120 is similar in shape to the magnetic pot 58 in accordance with its external appearance Fig. 3 , However, the magnetic pot structure 120 is formed by a plurality of components, in particular by the peripheral body 114 according to FIG Fig. 6 and the magnetic core 80 according to Fig. 5 ,

Together, the magnetic core 80 and the peripheral body 114 form a circumferential groove or annular groove 124, in which the coil winding 88 is arranged. The groove 124 is designed as an axially extending circumferential groove on an end face of the magnet pot structure 120. At one end of the magnet pot structure 120, the flange 84 is arranged, which connects the shaft 82 of the magnetic core 80 with the peripheral body 114. It is understood that embodiments of magnet pot structures 120 are conceivable in which the flange 84 on the peripheral body 114 (as inner flange) instead of the magnetic core 80 (as outer flange) is formed.

The magnet pot structure 120 provides an armature guide 126 along the longitudinal axis 92. At the end, which faces away from the flange 84, an end face 130 is formed. The face 130 defines a contact area in which the magnet pot structure 120 contacts a magnet armature when it is tightened. It is advantageous to design the coil winding 88 without a carrier since in this way it is possible to maximize the area of the annular groove 124 that can be used for the coil winding 88. In particular, the coil winding 88, the flange 84, the shaft 82 and the peripheral body 114 respectively - spatially - contact. In this way, a larger number of turns can be accommodated in the annular groove 124, as would be the case with a carrier-based winding. Another advantage is that the coil winding 88 can extend as far as the end face 130.

Overall, the magnetic resistance in the magnetic circuit, to which the magnet coil 30 is assigned, can be significantly minimized in this way.

Based on FIGS. 8, 9 and 10 Various alternative embodiments of magnetic cores 180, 280, 380 are illustrated, each having a shaft 82 and a flange 84. Similar to in Fig. 5 As already shown with reference to the magnetic core 80, the magnetic cores 180, 280, 380 can also be directly wound or wrapped in order to form a coil winding directly in the respective receiving region. However, the magnetic cores 180, 280, 380 are each provided with design features that cause a positional fixation, in particular an axial positional fixation of the coil winding 88.

The magnetic core 180 according to Fig. 8 has a taper or constriction 140 that extends over a defined portion of the shaft 82.

The magnetic core 280 according to Fig. 9 has a conical configuration with a cone 144 which tapers in the direction of the flange 84.

The magnetic core 380 according to Fig. 10 has guide grooves or guideways 148, which are designed approximately similar to a screw thread.

Each of the configurations 140, 144, 148 of the position assurance according to improves the axial retention of the coil winding 88 in the respective receiving area 86. It is understood that combinations of the in the FIGS. 8, 9 and 10 embodiments shown are conceivable.

Furthermore, fundamentally different designs are also conceivable. By way of example, a position assurance can be provided with guide grooves, which, however, does not provide a guide element for each turn which bears against the shaft 82. Even if only every second, third or X-th winding is guided accordingly, - given a global perspective - a sufficient axial position fixation is given. Also, the grooves do not have to completely rotate the shaft 82.

In addition to those in the FIGS. 8, 9 and 10 shown embodiments of the magnetic cores 180, 280, 380, it is noted that the axial position assurance can also be generated by the coil winding 88 itself. This is the case in particular when the winding wire 90, from which the coil winding 88 is produced, is painted and / or coated. By way of example, the winding wire 90 may be a so-called baked enamel wire. Other types of coatings and / or coatings of the wire 90 are conceivable. A coated wire 90 can be wound in a basically known manner around the receiving region 86 on the magnetic core 80, 180, 280, 380. Then, the coating / coating of adjacent turns can be materially connected to each other. This is, for example, associated with a temporary heating of the coil winding 88. In this way, the coating / coating can soften, so that connections with adjacent coatings / coatings can be received.

Likewise, it is conceivable to coat or coat the receiving region 86 on the shaft 82 of the magnetic cores 80, 180, 280, 380 at least in sections. In this way, a cohesive connection with a coating / coating of the wire 90, if present, be brought about.

An alternative position assurance with painted / coated shank 82 of the magnetic core 180, 280, 380 can be generated if the winding process generates a sufficiently tight winding of the wire 90 with sufficient pretensioning. In such a case, the wire 90 at least partially penetrate into the coating / painting of the shaft 82. Also in this way, at least a sufficient axial position assurance can be effected.

It is understood that combined configurations for securing the position are conceivable that use at least some of the aforementioned aspects.

Fig. 11 illustrates a magnetic coil 30, which basically the already in Fig. 7 shown solenoid 30 is designed at least similar. The solenoid 30 according to Fig. 11 cooperates with a magnet armature 158. Depending on the current supply to the coil winding 88 of the magnetic coil 30, the armature 158 is occasionally tightened or not. The armature 158 includes, by way of example, an armature plate 160 received on an armature shaft 162. Accordingly, the armature 158 may also be referred to as a plate anchor. A movement of the anchor, a so-called Ankerhub, is in Fig. 11 indicated by a double arrow marked 164. The armature shaft 162 is movably received in the armature guide 126 in the magnetic core 80 of the magnet pot structure 120. In the manner already described above, the magnetic pot structure 120 comprises not only the magnetic core 80 but also a peripheral body 114. Together, the peripheral body 114 and the magnetic core 80 arranged in the peripheral body 114 form an annularly extending annular groove 124, in which the coil winding 88 is received. The coil winding 88 is approximately in accordance with the in Fig. 5 illustrated manufacturing step directly wound on a receiving portion 86 of the magnetic core 80.

As mentioned above, the annular groove 124 is not affected by a bobbin or the like. Rather, the coil winding 88 can claim the entire or almost the entire space of the annular groove 124. This also includes exemplary embodiments in which the coil winding 88 up to an air gap 166 between the armature plate 160 and the end face 130 of Magnet pot structure 120 extends. Thus, for a given space a maximum power output and a maximum magnetic force can be achieved.

In the Fig. 11 Magnet coil 30 shown further includes, for example, a potting 152, which is introduced into the annular groove 124 and closes any remaining cavities around the coil winding 88. Also in this way, the coil winding 88 can be securely fixed.

Fig. 12 1 illustrates, on the basis of a schematically greatly simplified block diagram, an exemplary embodiment of a method for producing a magnet coil for an electromagnetic actuator, in particular for an injector of an internal combustion engine. The method preferably allows the production of an air gap-reduced and magnet flux-optimized magnet coil with a high power density.

The method comprises a step S10 relating to the provision of a magnetic core. Preferably, the magnetic core comprises a shaft on which a receiving region for a coil winding is formed.

Another step S12 relates to the provision of a winding wire for generating the coil winding. The winding wire may in particular be designed as a coated winding wire, for example as a so-called baked enamel wire. Alternative coatings, in particular multilayer coatings are conceivable.

The step S10 is followed by a step S14, which relates to the generation of a holding contour or position securing contour for the coil winding in the receiving region of the magnetic core. The receiving area can be provided with elements for securing the position of the coil winding, for example with a constriction or taper, an at least partially conical design, guide grooves, guide elevations, thread-like aisles, or the like.

The step S14 may alternatively or additionally be an at least partial coating of the magnetic core or at least in sections Painting of the magnetic core include. A coating / coating of the magnetic core can be provided on the one hand for isolation purposes. Furthermore, the coating / coating itself can also serve as a position assurance, in particular as an axial position assurance, for the coil winding. On the one hand, a coating / coating of the magnetic core increases the coefficient of friction when pairing coil winding / receiving area. Furthermore, the coating / coating itself may, however, be soft enough so that the winding wire of the coil winding can at least partially penetrate into the coating / coating or deform it. Also in this way can result in a position assurance for the coil winding.

There follows a step S16 concerning an arrangement of the magnetic core and the winding wire in a winding device provided for the winding operation. The receiving region of the magnetic core is radially accessible, so that the coil winding can be generated directly on a circumferential surface of the magnetic core. It is understood that any coating / coating of the magnetic core does not conflict with the term "direct wrapping". It is essential that no separate component, such as a separate coil support, between the coil winding and the magnetic core is arranged. Such a separate component is regularly movable relative to the magnetic core. A coating / coating of the magnetic core is firmly connected to the magnetic core itself or forms part of the magnetic core.

This is followed by the actual winding step S18, which involves the production of a single-layer or multi-layer coil winding in the receiving region of the magnetic core by direct winding. The step S18 involves generating a coupled motion between the supplied winding wire and the magnetic core, which includes a relative rotation and a lifting / advancing movement to wind the magnetic core in a desired manner.

The step of winding S18 may in principle be coupled with optional steps S20, S22. Between steps S18, S20 and S22 there may also be a temporal coupling / overlapping. It would also be conceivable to execute steps S20 and S22 before step S18. Step S20 relates to the provision of a hold-down. Step S22 relates to the placement of the hold-down on the magnetic core. The hold-down device can provide an axial position assurance / position limitation for the coil winding. The hold-down is preferably designed as a mounting auxiliary component. Accordingly, the hold-down is removed after the assembly and fixation of the coil winding from the magnetic core.

Additional steps S24, S26 may follow. Step S24 relates to the provision of a shell or perimeter body. The jacket is preferably designed as a hollow cylinder. The cladding is adapted to the magnetic core such that the magnetic core and the cladding together can form a structure corresponding to an integrally formed magnetic pot, but provided as a built-up magnetic pot structure. The jacket is exemplarily coupled to a housing of the electromagnetic actuator or designed as part of the housing.

In a step S26, a joining process takes place in which the magnetic core and the jacket are joined together. In this way, the coil winding, which is already accommodated on the magnetic core, disposed between the magnetic core and the shell.

It may be followed by a further step S28, which contributes to further fixing and securing the position of the coil winding. By way of example, step S28 may include heating the magnetic core, cladding, and coil winding assembly. If the winding wire, but possibly also the magnetic core, is provided with a coating / coating, a softening of the coating material or of the paint can be effected by the heating. In this way, a connection of adjacent paint layers can take place. In this way, when the coating / coating is solidified again, an increased strength and a position assurance for the coil winding can result. Alternatively or additionally, the step S28 may also comprise a casting or encapsulation of the magnetic pot structure formed from the magnetic core and the jacket. This relates in particular to an annular groove in which the coil winding is received. In this way, any remaining cavities can be filled, so that after hardening of the potting material or the softened plastic, which is used for encapsulation, an even higher strength and as well as a position fixation results for the coil winding.

It may be followed by another, optional step S30, which is coupled to the optional steps S20, S22. The step S30 relates to the removal of the hold-down. The hold-down preferably does not form a permanent component of the magnetic coil to be generated or of the actuator to be generated. Instead, the hold-down serves merely as an assembly aid or as a temporary positional fixation for the coil winding.

In a further step S32, the resulting magnetic coil is provided. The step S32 may include further assembly, such as completion of the magnetic actuator by mating the solenoid with an armature.

Claims (15)

Method for producing an air gap-reduced magnet coil (30) for a magnetic actuator (28), in particular for an injector (10), comprising the following steps: Providing a magnetic core (80) which is radially accessible at least in sections and comprises a receiving region (86) for directly receiving a coil winding (88), - generating a coil winding (88) with a winding wire (90), which is placed directly around the magnetic core (80), wherein the coil winding (88) is stabilized by the magnetic core (80), - Fixing the generated coil winding (88), and - creating a built magnetic pot structure (120), comprising: Providing a peripheral body (114) designed for flow guidance, - joining the peripheral body (114) with the magnetic core (80),
wherein the coil winding (88) is disposed between the magnetic core (80) and the peripheral body (114), and
wherein the peripheral body (114) is formed as part of a housing (12) of the magnetic actuator (10). The method of claim 1, wherein the coil winding (88) is produced without a spool, and wherein the magnetic core (80) at least partially rod-shaped and radially for a winding tool (100) is accessible. A method according to any one of the preceding claims, wherein the coil winding (88) has an axial extent along a longitudinal axis (92) of the magnetic core (80) to a region (130) in which the magnetic core (80) is provided with a magnetic armature (158) cooperates, wherein the coil winding preferably extends flush or nearly flush to a frontal surface of the magnetic core (80), which is contacted by the magnet armature (158) in the attracted state of the magnetic actuator (28). The method of claim 3, wherein the coil winding (88), the magnetic core (80) and preferably also the peripheral body (114) of the magnetic coil (30) terminate axially flush with the magnet armature (158). Method according to one of the preceding claims, wherein on the magnetic core (80) an axial position assurance (140, 144) in the form of a constriction or taper is formed, which ensures the axial position of the magnetic coil (30). Method according to one of the preceding claims, wherein on the magnetic core (80) an axial position assurance (148) for the coil winding (88) in the form of guide grooves or a guide thread is formed. Method according to one of the preceding claims, wherein the receiving region (86) on the magnetic core (80) is provided at least in sections with an insulating layer, preferably with a plastic coating, prior to the generation of the coil winding (88). The method of claim 7, wherein the insulating layer for fixing the coil winding (88) is used when the winding wire (90) deformed at least in sections, the insulating layer. A method according to any one of the preceding claims, wherein the winding wire (90) is coated or painted, the winding wire (90) being adhesive or connecting after formation of the coil winding (88) to fix the coil winding (88), and wherein the winding wire (90) is heated, in particular, to fix the coil winding (88). Method according to one of the preceding claims, further comprising at least partially encapsulating or encapsulating the coil winding (88) with a filling material (152). Method according to one of the preceding claims, wherein the coil winding (88) at least temporarily secured with a hold-down (108), wherein the hold-down (108) is preferably removed when the coil winding (88) is fixed. Magnetic coil (30) for a magnetic actuator (28), in particular for an injector (10), comprising a magnetic circuit having a built magnetic pot structure (120) comprising a magnetic core (80) and a peripheral body (114) joined to the magnetic core (80), and a coil winding (88) having a winding wire (90) placed directly around the magnetic core (80), wherein the coil winding (88) is disposed between the magnetic core (80) and the peripheral body (114),
wherein the coil winding (88) is produced without a spool,
wherein the peripheral body (114) is formed as part of a housing (12) of the magnetic actuator (10), and
wherein the coil winding (88) preferably has an axial extent along a longitudinal axis (92) of the magnetic core (80) to a region where the magnetic core (80) and the peripheral body (114) cooperate with a magnet armature (158). A magnetic coil (30) according to claim 12, wherein the coil winding (88), the magnetic core (80) and preferably also the peripheral body (114) terminate axially flush with the armature (158). Magnetic coil (30) according to claim 12 or 13, wherein on the magnetic core (80) an axial position assurance (148) for the coil winding (88) is formed. Injector (10), in particular fuel injection nozzle for an internal combustion engine, having a magnetic actuator (28) with an air gap-reduced magnetic coil (30) according to one of claims 12 to 14.

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