EP2855914B1 - Fuel injector - Google Patents

Description

State of the art

DE 10 2007 001 554 A1 refers to a fuel injector. The fuel injector is provided for injecting fuel into the combustion chamber of an internal combustion engine and comprises a control chamber connected to a high-pressure side. The pressure in the control room controls the movement of a nozzle needle. A control valve is provided which either blocks or releases the connection of the control chamber to a low-pressure side. The control valve has a in a bore of a guide piece between two valve positions slidably guided force-balanced control piston. This blocks the connection of a coming from the control chamber and opening into the bore connection channel to the low pressure side in its closed valve position and releases it in his in the direction away from the nozzle needle shifted open valve position.

With increasing pressure level in high-pressure fuel injection systems, in particular in common-rail injection systems increases in a fuel injector, which is actuated by means of an electric actuator, such as a magnet, the required armature stroke. This is because, as the pressure in the high-pressure accumulation space (common rail) increases, the amount of exhaust from the control space, which is under system pressure, also increases. It has been found that within the ballistic operating range of the fuel injector in the drive duration map, a high armature opening speed adversely affects the map slope and the scatter between individual armature strokes. In a ballistic operating phase of a fuel injector, a slow opening of the valve and a quick closing of the valve is advantageous.

From the FR 2 954 806 A1 In addition, a fuel injection system with a solenoid valve is known which has a movable armature in which openings are formed.

Presentation of the invention

Following the solution proposed according to the invention, an armature assembly of an actuatable by an electric actuator, in particular a energizable electromagnet fuel injector is constructed such that on the one hand sets a very high closing speed of the armature and on the other hand, a relatively slow armature opening occurs.

Due to the slow opening movement of the armature, an advantageous behavior of the same can be achieved at the upper stroke stop, which represents a limitation of the armature travel. The reduction of the opening speed of the armature allows a reduction of the degree of damping on the upper stroke stop of the armature, which in turn allows a favorable bounce behavior, in particular a bounce avoidance of the armature at the upper stroke stop. By reducing the degree of damping, the residence time of the armature is reduced at the upper stroke stop in the fuel injector after switching off. This in turn allows a lower low pressure sensitivity of the armature. The significantly reduced low pressure sensitivity of the armature advantageously makes it possible to reduce the maturity of the characteristic diagram and the stroke to stroke spread of the fuel injector proposed according to the invention.

On the other hand, the proposed solution according to the invention allows a high closing speed of the armature, which in turn reduces the copy or the stroke to Hub scattering at one and the same fuel injector.

In one embodiment variant of the solution proposed according to the invention, the armature assembly of the fuel injector comprises, for example, a base anchor and an armature plate assigned to its upper side of the plan. The upper plan side of the anchor of the anchor assembly comprises a number of openings, which may be configured as stepped bores, for example. These stepped bores pass through the basic anchor or its disk-shaped upper part, so that a passage of fuel is possible. The stepped bores comprise a portion which is formed in a larger diameter, which merges at a conical transition region in a bore portion of the stepped bore, which in a smaller diameter is executed. Within the stepped bores, for example, ball-shaped, gravity-actuated closure elements are arranged. A stop of these closure elements is formed on the one hand by the conical transition region between the mentioned bore portions of the stepped bore, another stop by an upper anchor plate covering the upper bore portion of the stepped bore. Upon energization of the electric actuator for actuating the fuel injector, ie an electromagnet, the armature is attracted against the action of an armature spring, so that a closing element, which is accommodated on the armature, releases the valve seat. In this upward movement of the armature to release the valve seat, the gravity-operated closure elements are pressed by the acceleration force of the armature and the upcoming fuel pressure in the tapered transition of the stepped bore, so that the stepped holes are closed during the opening movement and therefore can not be traversed by the diesel fuel. When opening from the control room diverted amount, ie the Absteuermenge passes through slots that can be performed on the upper anchor plate and the anchor, in a central drain hole. By closing the stepped holes thus their flow through fuel is prevented, thereby setting a slower opening of the armature.

The spherically shaped closure elements remain in their position, i. remain placed in the tapered transition region during the opening movement until the armature assembly reaches an upper stroke stop formed by the lower face side of an electromagnet. When the upper stroke stop is reached, no acceleration forces or resistance forces due to the upcoming diesel fuel act on the basic anchor.

A bouncing, i. a strong abutment of the basic anchor in the implementation of its opening movement is prevented by a damper element which is disposed between the lower plan side, which forms the upper stroke stop, the electromagnet on the one hand and a corresponding abutment surface of the upper armature plate of the armature assembly.

By locking the stepped bore during the opening movement of the armature is a pressure equalization between the upper anchor plate and the bottom of the anchor complicates, which leads to the desired reduction in the opening speed of the armature assembly. The opening speed can also be influenced by the number of slots over which the Absteuermenge runs off and their cross-sectional area - to name two significant parameters.

When closing, i. a termination of the energization of the electric actuator in the form of an electromagnet, the armature assembly is driven by the action of the spring in the valve seat, as far as until the ball-shaped closure member on the underside of the armature assembly closes the valve seat in the valve housing of the fuel injector. The bouncing of the armature assembly upon reaching the bottom stop, i. the valve seat, can be avoided via a damping element. During the closing movement, the spherical closure elements are pressed by the pressure increase at the bottom of the base anchor from the tapered transition, so that the stepped holes are released during the closing movement and a flow of fuel is possible. The ball-shaped closure elements are caught by the stepped holes on the top plan side of the ground anchor covering upper anchor plate, which forms a stop, so that the closure elements can not leave the upper formed in an enlarged diameter bore portions of the stepped holes.

Thus, the stepped holes are released and allow a faster pressure equalization between the upper anchor plate and the bottom of the anchor. The armature assembly now experiences the maximum possible closing speed, which is largely determined by the number of slits allowing outflow in quantity, their cross-sectional area and by the number of stepped holes in the disk-shaped region of the armature. After closing the valve seat, the closure elements solve due to the impingement of the lower side of this overlapping upper anchor plate and thus return to the conical transition region extending between the two bore portions of the stepped bore.

In an advantageous embodiment variant, the upper anchor plate can be guided, for example, to a centrally arranged pin, which influences the geometry of the slots, which are designed to derive the Absteuermenge in the upper anchor plate.

Alternatively, the upper armature plate of the armature assembly may be guided to a guide diameter, which allows the leading of the Absteuermengen enabling slots to the center, so that on the whole the completion of the controlled from the pressure-relieved control chamber amount is facilitated.

In a further advantageous embodiment of the proposed solution according to the invention stepped bores can be released or closed by a flexible damping element. Analogous to the above-described with respect to the opening and closing described anchor assembly, which are arranged in the stepped holes in the conical transition region between the bore sections spherical closure elements can be replaced by a substantially formed as a thin disc flexible damping element. In this embodiment, the flexible, substantially disk-shaped damping element simultaneously forms a spacer of the armature assembly to the upper stroke stop, which is formed by the lower plan side of the electromagnet. The substantially disk-shaped, flexible damping element can be pressed for example by a disk to the anchor plate. The disk-shaped region of the basic anchor can have, in addition to through-flow bores, which are of untarred design, a circumferentially formed channel-shaped distributor groove, and a circumferential recess, which supports the essentially disk-shaped, flexible damping element. The depth of the recess formed in the upper plan side of the basic anchor defines a desired residual air gap. The residual air gap can also be defined by the thickness of the substantially disc-shaped damping element.

When opening the armature assembly, ie, a vertical upward movement of the armature assembly in the direction of the electromagnet during its energization against the action of the closing spring, the disc-shaped, flexible damping element lies completely in the recess on the upper plan side of the basic anchor. Thus, the flow holes, which open into the circumferential distributor, closed, the fuel can not pass through the holes during the opening process of the armature, whereby a slow opening of the armature, ie a slow release of the valve seat adjusts.

During the closing movement of the armature caused by the downward movement and the influx of fuel through the flow holes a back pressure in the circumferential distributor groove. Due to the flexibility of the damping element deforms this, so that a flow of fuel through the flow holes is possible because the damping element by the back pressure from the contact surface, i. the depression is pushed away from the anchor top. The armature moves substantially unthrottled to the valve seat, which sets a fast closing with a high closing speed.

In a further advantageous embodiment variant, a reduction in the opening speed of the armature assembly can also be achieved in that armature slots, which are usually provided on armatures, by a flexible damping element, which is for example cross-shaped and, for example, four anchor slots conceal or release, take place. By further anchor slots, or by further flow bores in the disc-shaped area of the basic anchor, which of the flexible, i. deformable designed damping element are not covered, the valve opening speed can be varied.

Advantages of the invention

Advantageously, can be achieved by the above outlined embodiments of the invention underlying idea that in all versions of the invention proposed solution slow opening movement of the armature, ie a slow opening of the valve seat on the one hand and on the other hand, a fast closing movement of the inventively proposed armature assembly , A reduction of the opening speed is achieved by generating a flow resistance, while a rapid closing is achieved by just that this generated flow resistance is canceled in the closing movement of the armature again. Significantly, the inventively proposed solution, the exemplar scattering, mainly during the ballistic armature stroke at very small quantities, ie the reproducibility of mass produced fuel injectors can be improved, on the other hand can be achieved with one and the same fuel injector, a significant reduction of the stroke to Hub scattering ,

Another advantage is that with the slow opening movement, a favorable bounce at the upper stroke stop, i. can be achieved on the lower plan side of the electromagnet. This in turn allows the reduction of the degree of damping at the upper stroke stop, whereby the residence time of the armature is reduced at the upper stroke stop after switching off the electromagnet. The consequence of this is a lower low pressure sensitivity of the armature associated with the positive side effect that the ripple of the map, in particular the map slope and the stroke to Hub scattering are reduced when operating one and the same fuel injector.

Brief description of the drawings

With reference to the drawing, the invention will be described below in more detail.

Figur 1

einen Schnitt durch einen erfindungsgemäß vorgeschlagenen Kraftstoffinjektor, dessen Steuerraum über eine Hochdruckquelle beaufschlagt ist,

Figur 2

die erfindungsgemäß vorgeschlagene Ankerbaugruppe beim Öffnen des Ventilsitzes des Kraftstoffinjektors,

Figur 3

die erste Ausführungsvariante der erfindungsgemäß vorgeschlagenen Ankerbaugruppe während des Schließvorgangs des Ventilsitzes,

Figur 4

eine Draufsicht auf die obere Planseite des Grundankers,

Figur 5

eine Draufsicht auf die obere Planseite des Grundankers mit in Stufenbohrung eingelassenen kugelförmig ausgebildeten Verschlusselementen, abgedeckt von einer oberen Ankerplatte,

Figur 6

die Draufsicht auf einen scheibenförmigen Grundanker mit Ablaufschlitzen für die Absteuermenge,

Figur 7

eine weitere Ausführungsvariante der erfindungsgemäß vorgeschlagenen Ankerbaugruppe mit einem verformbaren, im Wesentlichen scheibenförmig ausgebildeten Dämpfungselement während der Öffnungsbewegung des Ventilsitzes,

Figur 8

die weitere Ausführungsvariante der erfindungsgemäß vorgeschlagenen Ankerbaugruppe gemäß Figur 7 während des Schließens des Ventilsitzes,

Figur 9

ein Detail des oberen Bereiches der zweiten Ausführungsvariante der erfindungsgemäß vorgeschlagenen Ankerbaugruppe gemäß der Figuren 7 und 8,

Figur 10

eine dritte Ausführungsvariante der erfindungsgemäß vorgeschlagenen Ankerbaugruppe mit geschlitztem Grundanker während der Öffnungsbewegung des Ventilsitzes,

Figur 11

die dritte Ausführungsvariante der erfindungsgemäß vorgeschlagenen Ankerbaugruppe während des Schließvorganges des Ventilsitzes,

Figur 12

eine Draufsicht auf eine Ankerbaugruppe mit kreuzförmig ausgebildetem verformbaren Dämpfungselement, und

Figur 13

den Schnittverlauf XIII - XIII wie in Figur 12 eingezeichnet.

It shows:

FIG. 1

a section through a fuel injector proposed according to the invention, the control chamber is acted upon by a high pressure source,

FIG. 2

the armature assembly proposed according to the invention when opening the valve seat of the fuel injector,

FIG. 3

the first embodiment variant of the inventively proposed armature assembly during the closing operation of the valve seat,

FIG. 4

a plan view of the upper plan side of the basic anchor,

FIG. 5

a plan view of the upper plan side of the basic anchor with stepped in-formed spherical closure elements, covered by an upper anchor plate,

FIG. 6

the top view of a disc-shaped anchor with drain slots for the Absteuermenge,

FIG. 7

a further embodiment of the inventively proposed anchor assembly with a deformable, substantially disc-shaped formed damping element during the opening movement of the valve seat,

FIG. 8

the further embodiment of the inventively proposed anchor assembly according to FIG. 7 during the closing of the valve seat,

FIG. 9

a detail of the upper portion of the second embodiment of the inventively proposed anchor assembly according to the FIGS. 7 and 8 .

FIG. 10

a third embodiment of the invention proposed anchor assembly with slotted anchor during the opening movement of the valve seat,

FIG. 11

the third embodiment variant of the inventively proposed armature assembly during the closing operation of the valve seat,

FIG. 12

a plan view of an armature assembly with cross-shaped deformable damping element, and

FIG. 13

the section XIII - XIII as in FIG. 12 located.

variants

The representation according to FIG. 1 is a first embodiment of the inventively proposed fuel injector according to the invention designed according to anchor assembly.

FIG. 1 shows a fuel injector 10, which includes a valve piece 12. The valve piece 12 is received in a holding body 14 via a valve clamping screw 16. The valve member 12 defines a control chamber 60 which is acted upon by an inlet throttle from a high-pressure source 84, for example a high-pressure accumulator (common rail) or a delivery unit with system pressure. The control chamber 60 in the valve piece 12 is pressure-relieved via an outlet throttle 62, wherein a flow channel is closed by a here spherically formed closing element 44. In the in FIG. 1 shown first embodiment of the fuel injector is a valve seat 42 through the spherical trained closing element 44 is closed, consequently, the control chamber 60 of the fuel injector 10 is not relieved of pressure, but is at system pressure level.

The fuel injector 10 comprises an armature assembly 18, which essentially comprises a base anchor 20 and an upper anchor plate 22 arranged on the upper plan side thereof.

FIG. 1 shows that the base anchor 20 here comprises spherical closure elements 24 which are located in through holes 58 which extend from the lower plan side to the upper plan side of the disc-shaped head of the basic anchor 20. An upper stroke stop for limiting the armature stroke is identified by reference numeral 26 and given by a magnet bottom 30 of the electric actuator 28 designed as a magnet for actuating the fuel injector 10. An outlet nozzle 34, the electric actuator in the form of a magnet are enclosed by a magnetic sleeve 32 and screwed to the holding body 14 by a magnetic clamping nut.

From the illustration according to FIG. 1 Furthermore, it can be seen that the armature assembly 18 is acted upon by an armature spring 36 which exerts an armature spring force 38 in the direction of the valve seat 42. The armature spring 36 is supported on a bearing surface 40 on the inside of the drain nozzle 34. Reference numeral 42 denotes the valve seat, after the opening of the control chamber 60 of the fuel injector 10 is pressure relieved. The valve seat 42 can be closed by a ball-shaped closing element 44, which is accommodated in a cap 46 on the underside of a pressure surface 52 of the basic armature 20 of the armature assembly 18. The closure member 44 and the cap 46 are located within a seat 48 in which the valve seat 42 is located. Seat space pressure 50 prevails in the seat space 48.

FIG. 2 shows the first embodiment of the inventively proposed fuel injector with inventive armature assembly during the opening process of the valve seat.

FIG. 2 shows that when energized the electric actuator - here in the form of an electromagnet - within the valve member 12 in vertical direction upwards against the armature spring force 38 moves up. The base anchor 20 approaches the magnet bottom 30, which represents the upper stroke stop 26. On the base anchor 20, the upper anchor plate 22 is received, on which in turn a damper element 70 is arranged, which is the Magnet bottom 30 of the magnet 28 is opposite. Below the base anchor 20 is located on the tapered portion of the valve member 12, a further damping element 76 on a bottom 74 of the base armature 20 of the armature assembly 18. As shown in the illustration FIG. 2 shows, the valve seat 42 is open, so that fuel from the system under pressure pressure control chamber 60 via the outlet throttle 62 flows into the seat 48. The valve seat 42 is released by the spherical closing element 44 which is accommodated in a dome 46 on the pressure surface 52 in the lower region of the basic anchor 20 within the seat space 48. In the sitting space prevails the seat pressure 50.

At the in FIG. 2 illustrated opening movement of the armature assembly 18 in a vertical upward direction in the direction of arrow against the action of the spring force 38 moves the upper armature plate 22 and the base made of magnetic material anchor 20 upwards. The ball-shaped closure elements 24 are pressed into tapered transitional regions 56 by the acceleration force of the base anchor 20 or by the fuel surrounding the armature assembly 18 during operation of the fuel injector, so that the through-bores 58 extending from the underside 74 to the top of the plan Base anchor 20 extend, 18 are closed when opening the armature assembly. Thus, during the opening movement of the armature assembly, the stepped bores 58 are closed, so that the fuel is unable to flow through them. The effluent when opening the valve seat 42 from the control chamber 60 amount flows over in the FIGS. 4 to 6 shown in more detail, slit-shaped channels in the direction of a central drain hole 68, which passes through the magnet 28, from.

As a result of the spherically shaped closure elements 24 pressed into the conical transition regions 56 during the opening movement of the armature assembly 18, the flow resistance which acts on the armature assembly when passing through the fuel in the direction of the upper stroke stop increases, so that the opening movement of the armature is correspondingly delayed , The spherically shaped closure elements 24 remain in the in FIG. 2 shown position, ie the stepped holes 58 occlusive until the armature assembly 18 has reached the upper stroke stop 26 and thus no acceleration force or resistance force by the upcoming fuel on the closure elements 24 acts more. As shown in the illustration FIG. 2 shows, located above the upper anchor plate 22, a damper element 70, which between the bottom 30 of the magnet 28 and a Stop surface 72 of the upper anchor plate 22 is located. This is needed to avoid bouncing of the armature assembly 18 at the upper travel stop 26.

Through the out FIG. 2 resulting obstruction of the stepped holes 58, the pressure equalization between the abutment surface 72 of the upper anchor plate 22 and the bottom 74 of the base anchor 20 is difficult, resulting in the desired reduction of the opening speed of the valve seat 42 and the armature stroke.

In addition, the opening speed of the armature assembly 18 is governed by the number of slots 64, as shown in FIG FIGS. 4 to 6 , and their cross-sectional area influenced.

FIG. 3 shows the first embodiment of the inventively proposed anchor assembly when closing the valve seat.

From the illustration according to FIG. 3 shows that according to the arrow shown there in abolition of the energization of the electric actuator in the form of a magnet 28, the in FIG. 1 illustrated armature spring 36, the armature assembly 18 in the direction of the valve seat 42, that is moved in the closing direction. The base anchor 20 and the recorded thereon upper anchor plate 22 move in a vertical direction downwards; In this case, the closing element 44 - accommodated by the cap 46 - placed on the pressure surface 52 of the base anchor 20 in the valve seat 42, so that a pressure build-up in the control chamber 60, which is continuously pressurized with system pressure takes place.

Out FIG. 3 Furthermore, it is apparent that, during the closing movement, the closure elements 24 are pushed out of the conically formed transitional area 56 within the respective stepped bore 58 by the increase in pressure on the underside 74 of the base anchor 20, so that fuel flows through the stepped bores 58 which are now released. The closure elements 24 are now caught by the underside 78 of the upper anchor plate 22 and remain in this position until the anchor group 18 in the lower stroke stop, ie in the valve seat 42 has arrived.

During the closing movement, the stepped bores 58 are thus released and lead to a more rapid pressure equalization between the stop surface 72, the upper anchor plate 22 and the underside 74 of the basic anchor 20. The anchor assembly 18 experiences the maximum possible closing speed, which significantly by the number of slots 64 to be described, compare FIGS. 4, 5, 6 and their cross-sectional area and on the other hand by the number of stepped holes 58 which are formed in the base anchor 20 is determined. After the impact of the armature assembly 18 and the closing element 44 in the valve seat 42, the closure elements 24 detach from the underside 78 of the upper anchor plate 22 by the impact impulse and thus return to the conical transition of the region 56 between the different bore portions of the stepped bores.

The representation according to FIG. 4 is a plan view of the basic anchor of the inventively proposed anchor assembly can be seen.

FIG. 4 shows that, for example, in a 90 ° division at the upper edge of the basic anchor 20, a discharge of the controlled tax amount favoring slots 64 are. As already mentioned, the cross-sectional area of the slots 64 and their number at the circumference of the basic anchor 20 can influence the outflow velocity of the removed quantity in the direction of the central drainage hole 68. FIG. 4 shows that in this embodiment, the basic anchor 20 has a plurality of stepped holes 58.

FIG. 5 shows a basic anchor with embedded in the stepped bore closure elements, which are covered by the upper anchor plate.

FIG. 5 shows that analogous to the representation according to FIG. 4 a number of slots 64 are formed on the circumference of the base anchor 20. In the stepped holes 58, see illustration according to FIG. 4 , a number of spherical closure elements 24 are embedded. The number of closure elements 24 corresponds to the number of stepped bores 58, so that each of the stepped bores 58 receives a spherically formed closure element 24 actuated by gravity and the surrounding pressure. As seen from the top view FIG. 5 Furthermore, due to the geometry of the upper anchor plate 22, the closure elements are partially covered by them, so that the closure elements in the in FIG. 3 illustrated closing movement of the inventively proposed armature assembly can not leave the stepped holes 58, but remain trapped in these. FIG. 5 shows that also at the top of the upper anchor plate 22 a number of others Slots 66 is executed, which allow easier discharge of the discharged from the control room amount of fuel in the direction of the central drain hole 68.

The upper anchor plate 22 is guided on a pin 82, which determines the radial length of the here arranged in 90 ° division further slots 66 in the upper anchor plate 22.

FIG. 6 shows a variant in which the upper anchor plate 22 in the in. In FIG. 6 not shown stepped bores 58 trapped, spherical shaped closure elements 24 completely covered. Due to the absence of the pin 82, the other slots 66 in the upper lifting plate 22 are continuous, ie they form a cross-shaped pattern, so that the Absteuermenge from the control chamber 60 in comparison to in FIG. 5 illustrated embodiment with tightly continuous slots, can be better controlled.

From each of the presentation according to FIGS. 4 to 6 shows that the base anchor 20 distributed on its edge - here about 90 ° division - the slots 64 for Absteuern the Absteuermenge has. Instead of in the variants of the FIGS. 4, 5 and 6 shown number of slots 64 may also be larger or smaller cross-section slots 64 may be formed in any configuration on the circumference of the base anchor 20.

FIG. 7 shows a further second embodiment of the proposed solution according to the invention, in which instead of the spherically shaped closure elements, a substantially disc-shaped deformable formed flexible damping element is used.

In FIG. 7 the opening movement of the armature assembly according to the second embodiment is shown, according to which, analogously to the first embodiment, the valve seat 42 is released during the opening movement of the armature assembly 18 by the closing element 44. In this case, an outflow of fuel from the pressurized with system pressure control chamber 60 via the outlet throttle 62 takes place in the armature space of the fuel injector 10th

In the in FIG. 7 illustrated embodiment, the closure elements 24 according to the first in the FIGS. 1 . 2 . 3 and 5 illustrated embodiment by the flexible disc-shaped damping element 90 replaced. The damping element 90 covers through-flow bores 94, which are embodied in the basic anchor 20. The flexible damper 90 is secured over the disc 92 on top of the base anchor 20. Analogous to in FIG. 4 illustrated embodiment, according to which the stepped holes 58 open in a distribution groove 54, open the flow holes 94 in a circumferentially formed distribution groove 96, see illustration according to FIG. 9 , In the upward movement, the flexible damping element 90 is acted upon by the fuel present in the armature space, so that the flexible damping element 90 closes the through-flow bores 94. Due to the higher flow resistance in the armature space, the base anchor 20 and thus the entire armature assembly 18 travel at a reduced speed toward the magnet bottom 30 of the magnet 28, the magnet bottom 30 representing the upper stroke stop 26 of the armature assembly 18. The flexible damping element 90 can simultaneously serve as a spacer with respect to the upper stroke stop 26, given by the magnet lower side 30. The damping element 90 represents a non-magnetic component. Since the flexible damping element 90 completely immersed in the opening movement of the armature assembly 18 in a recess 100 which is located on the anchor plate top 102, the flow holes 94, which open into the circumferential distribution groove 96, at closed the opening movement. How out FIG. 9 As can be seen, the flexible damping element 90 is completely in the recess 100 at. The depth of this depression 100 depends on a residual air gap 98 and on a thickness 114 in which the flexible damping element 90 is embodied.

FIG. 8 shows the closing movement of the second embodiment of the invention proposed anchor assembly when canceling the energization of the magnet.

FIG. 8 can be seen that by the spring force 38 of in FIG. 1 armature spring 36 is shown a vertical downward movement of the base anchor 20 of the armature assembly 18 in the direction of the valve seat 42 in the valve piece 12. When the valve is closed by the influx of fuel through the flow holes 94 a back pressure in the distribution groove 96. The deformability of the substantially disk-shaped damping element 90 allows a flow of the fuel, since the flexible damping element 90 in its edge regions of the contact surface, ie Well 100 is pushed away, see deflected representation 106 in FIG. 8 so that the flow holes 94 are released. This means that the basic anchor 20 in the Substantially unthrottled until it reaches its valve seat 42 in the valve member 12 moves until the bottom 74 of the base anchor 20 is achieved by the further damping element 76 to avoid bouncing.

The representation according to FIG. 8 It can also be seen that the flexible damping element 90 - shown here in its deflected position 106 - through the disc 92, which is partially immersed in the central drain hole 68, is fixed to the upper plan side of the basic anchor 20. FIG. 8 shows that the control chamber 60 as long as in the seat 48 is relieved of pressure via the outlet throttle 62, as long as the valve seat 42 is not closed by the spherical closure member 44, held in the cap 46.

The representation according to FIG. 9 It can be seen on an enlarged scale how the undeformed flexible damping element 90 with its outer edge dips into the recess 100 on the upper plan side of the basic anchor 20. The depth of the recess 100 on the anchor plate top 102 depends on the desired residual air gap 98 and the thickness 114 of the flexible damping element 90th FIG. 9 shows that the flow holes 94 in the circumferential distribution groove 96, which extends in the anchor plate top 102 circumferentially open.

FIG. 10 shows a further, third embodiment of the inventively proposed armature assembly with reduced opening and increased closing speed.

In contrast to the embodiments described above, the base anchor 20 of the armature assembly according to the FIGS. 10 and 11 Anchor slots on. Magnetic armature, which are used in Magnetaktuatoren usually have, for reasons of magnetic flux, slots, so that the third embodiment of the proposed solution according to the invention for application to such anchors offers.

How out FIG. 10 shows, is on the upper plan side of the basic anchor 20 of the armature assembly 18 analogous to the second embodiment of the solution proposed by the invention, the flexible substantially disc-shaped damping element 90. This covers slots 104, of which in the plane according to FIG. 10 two are shown. Depending on the number of anchor slots 104 in the basic anchor 20, see illustration according to FIG. 12 For example, the flexible damping element 90 assumes a cross-shaped appearance 112 as in FIG FIG. 12 shown, or may also be formed as a full-round damping element, just in disc form. When the magnet 28 is energized, the basic armature 20 of the armature assembly 18 moves upward in the vertical direction according to the arrow and approaches an upper stroke stop 26 given by the magnet lower side 30 of the magnet 28. The flexible damping element 90 is connected to the base anchor 20 through the disc 92. The disk 92 protrudes partially into the central drainage hole 68 of the fuel injector 10. Another damping element 76 is located below the underside 74 of the base anchor 20 and forms a lower damping for the Ankerhubbewegung.

Analogous to the above-described embodiments of the solution proposed according to the invention, the basic anchor 20 comprises the pressure surface 52 on which the dome 46 is located. The cap 46 partially surrounds the here spherically formed closing element 44, with which the valve seat 42 in the valve piece 12 is closed. As a result, an outflow of fuel from the control chamber 60 via the outlet throttle 62 and the flow channel, which opens into the seat 48, prevented.

In the upward movement, i. the opening movement of the base anchor 20, the anchor slots 104 are closed by the upper plan side of the base anchor 20 covering flexible damping element 90, since there is fuel in the armature space, which is displaced from the gap between the magnet bottom 30 and the top of the flexible damping element, so that the Opening speed of the armature assembly 18 is reduced.

In contrast, at the in FIG. 11 illustrated closing movement of the armature assembly in the third embodiment achieves a similar effect, as already above in connection with the second embodiment in their closing movement in FIG. 8 has been described.

In the vertical downward movement in the closing direction to the valve seat 42 to bend, reaches, for example, complementary to the number of anchor slots 104 formed, for example, a cross shape 110 assuming flexible damping element 90 in one deflected state 106. This allows fuel to flow through the armature slots 104, so that the flow resistance, which undergoes the ground anchor 20 during its downward movement, ie in its movement in the closing direction, is significantly reduced, so that the closing movement of the armature assembly 18 together with the basic anchor 20 substantially faster than its opening movement, see comparison according to FIG. 10 in which the flow resistance in the armature space is significantly greater due to the closed anchor slots 104.

FIG. 12 is to take a plan view of a basic anchor with anchor slots 104, wherein in this third embodiment of the solution proposed by the invention, the flexible damping element complementary to the number of anchor slots 104 has a cross shape 110. Further, in the basic anchor 20 existing flow holes 108 are continuously open, ie are not covered by a deflectable flexible damping element 90. Instead of in the plan view according to FIG. 12 illustrated cross shape 110, the deformable flexible damping element complementary to the number of anchor slots 104 in the basic anchor also have a different geometry.

The representation in FIG. 13 is the section XIII - XIII as shown in FIG. 12 refer to. Out FIG. 13 shows that in the anchor plate top 102 in the region of the anchor slots 104 each have a recess 100 is introduced into which dive individual arms 112 of the formed in cross shape 110, flexible damping element 90, so that the anchor slots 104 - FIG. 13 shown - are closed flat.

The proposed solution according to the invention according to its three embodiments shown above can be used in non-pressure balanced solenoid valve fuel injectors, which are operated at a very high system pressure level. The height of the armature stroke of the armature assembly 12 with appropriate high pressure capability requires in this application a functional area in which the armature stroke is in the ballistic operating range.

The proposed solution according to the invention can also be used in pressure balanced solenoid valve injectors, since with constantly increasing rail pressure, i. constantly increasing system pressure even in this, which can be solved by the solution proposed by the invention solved problems.

Claims (13)

1. Fuel injector (10) for injecting fuel into the combustion chamber of an internal combustion engine, having an electric actuator (28), in particular an electromagnet, by way of which a closing element (44) which opens up or closes off an outlet (62) of a control chamber (60) can be actuated, wherein an armature (18, 20) which actuates the closing element (44) has openings (58, 94, 104) which are opened during the closing of the closing element (44) and which are closed during the opening of the closing element (44), characterized in that gravitational-force-actuated closure elements (24) of spherical shape are received in the openings (58).
2. Fuel injector according to Claim 1, characterized in that the openings are in the form of stepped bores (58), passage bores (94) or armature slots (104).
3. Fuel injector according to one of the preceding claims, characterized in that the armature (20) is acted on in a closing direction of a valve seat (42) by an armature spring (36).
4. Fuel injector according to one of the preceding claims, characterized in that the openings (58, 94) of the armature (20) open into a distributor groove (54, 96) of encircling form.
5. Fuel injector according to one of the preceding claims, characterized in that the openings, which are in the form of stepped bores (58), comprise a conical transition region (56) between bore sections which have mutually different diameters.
6. Fuel injector according to one of the preceding claims, characterized in that the armature (20) has at least one outlet slot (64) via which a quantity discharged from the control chamber (60) upon opening of the valve seat (42) flows to a central outlet (34, 68).
7. Fuel injector according to Claim 1, characterized in that the spherical closure elements (24) are at least partially covered by an armature plate (22) which constitutes a stop (72).
8. Fuel injector according to one of the preceding claims, characterized in that the openings (94, 104) can be opened up or closed off by way of a disk-shaped, flexible damping element (90) which is held on an armature-plate top side (102).
9. Fuel injector according to Claim 8, characterized in that the depth of a depression (100) on the armature-plate top side (102) defines a residual air gap (98) between the armature (20) and the stroke stop (26) of the armature (20).
10. Fuel injector according to Claim 9, characterized in that the residual air gap (98) is defined by a thickness (114) of the flexible damping element (90).
11. Fuel injector according to one of the preceding claims, characterized in that the armature slots (104) in the armature (20) can be opened up or closed off by way of a flexible damping element (90) which has a cross shape (110).
12. Fuel injector according to Claim 11, characterized in that the armature (20) comprises a number of throughflow bores (108) which permit a continuous passage of fuel during the stroke movement of the armature (20).
13. Fuel injector according to one of the preceding claims, characterized in that the upper armature plate (22) has slots (66) which run all the way through and which allow the quantity discharged from the control chamber (60) to be conducted away in an improved manner.

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