EP2855914A1

EP2855914A1 - Fuel injector

Info

Publication number: EP2855914A1
Application number: EP13714636.1A
Authority: EP
Inventors: Michael Kurz
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2012-06-01
Filing date: 2013-04-04
Publication date: 2015-04-08
Anticipated expiration: 2033-04-04
Also published as: WO2013178386A1; EP2855914B1; CN104583575B; CN104583575A; DE102012209330A1

Abstract

The invention relates to a fuel injector (10), having an electrical actuator (28), particularly an electromagnet, for injecting fuel into the combustion chamber of an internal combustion engine. A closing element (44), which releases or closes an outlet (62) of a control chamber (60) can be operated by the actuator (28). An armature (20) operating the closing element (44) has openings (58, 94, 104) which are opened when the closing element (44) is closing and closed when the closing element (44) is opening.

Description

description

title

Fuel injector prior art

DE 10 2007 001 554 A1 relates 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. It is a

Control valve provided which the connection of the control room to a

Low pressure side either locks or releases. The control valve has a slidably guided in a bore of a guide piece between two valve positions

balanced force control piston on. 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, to the same extent as the pressure in the

Hochdrucksammeiraum (common rail) increases, also the Absteuermenge from the

Control room, which is under system pressure increases. It has been found that within the ballistic operating range of the fuel injector in the

Ansteuerdauerkennfeld a high armature opening speed adversely on the

Map slope and the scatter between individual anchor strokes affects. In a ballistic operating phase of a fuel! njektors is a slow opening of the valve and a quick closing of the valve an advantage. DESCRIPTION OF THE INVENTION Following the solution proposed according to the invention, an armature assembly of a fuel which can be actuated by an electric actuator, in particular a current-carrying electromagnet, is! Njektors constructed such that on the one hand sets a very high closing speed of the armature and on the other hand, a relatively slow

Anchor opening takes place.

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 a favorable bounce, especially a bounce avoidance of the anchor at the top

Hub stop allows. 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 allows the maturity of the map and the stroke to stroke spread of the invention

proposed fuel injector can be reduced.

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 with 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, for example as

Stepped holes can be executed. These stepped holes run through the

Basic anchor or its disc-shaped designed upper part, so that a passage of fuel is possible. The stepped bores comprise a portion which is formed in a larger diameter, which at a conical transition region in a

Bore portion of the stepped bore merges into a smaller diameter is executed. Within the stepped bores, for example, ball-shaped, gravity-actuated closure elements are arranged. A stop this

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, i. an electromagnet, the armature is attracted against the action of an armature spring, so that a closing element, which is received on the armature, releases the valve seat. During this upward movement of the armature to release the valve seat, the

Gravity-actuated closure elements 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, i. the Absteuermenge passes through slots, which may be carried out on the upper anchor plate and the anchor, in a central drainage hole. By closing the stepped holes is thus their

Flow through fuel prevented, which sets a slower opening of the armature.

The, for example, spherical 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, leading to the desired reduction in the opening speed of

Armature assembly leads. 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 spherical closure member formed on the underside of the armature assembly the valve seat in the valve body of the fuel! njektors closes. 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, for example, 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 spherically formed

Closure elements are caught by the upper anchor plate overlapping the stepped holes on the top plan side of the ground anchor which forms a stop so that the closure elements can not leave the upper enlarged diameter bore portions of the stepped bores.

Thus, the stepped holes are released and allow a faster

Pressure equalization between the upper anchor plate and the bottom of the base anchor. The armature assembly now learns the maximum possible closing speed, which significantly by the number of enabling in outflow of volume slots whose

Cross-sectional area and by the number of stepped holes in the disc-shaped portion of the armature is determined. 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 area, which runs between the two bore sections 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 can be guided to a guide diameter, which is the leading to the outflow of Absteuermenge

enabling slits to the center, so that on the whole the completion of the discharged 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 outlined regarding the opening and the

Closing described anchor assembly, can be in the stepped bores in the conical transition region between the bore sections arranged spherically shaped closure elements 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. That essentially

Disc-shaped running, flexible damping element can be pressed for example by a disc 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, i. a vertical upward movement of the

Armature assembly in the direction of the electromagnet in its energization against the action of the closing spring, is the disc-shaped, flexible

Damping element completely in the recess on the upper plan side of the basic anchor. Thus, the flow holes that open into the circumferential distributor groove,

closed, the fuel can during the opening process of the anchor the

Holes do not pass, causing 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 dynamic 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, a reduction of

Opening speed of the armature assembly can also be achieved in that

Anchor 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 forms of the invention proposed solution, a slow opening movement of the

Anchor, i. a slow opening of the valve seat on the one hand sets and on the other hand there is a fast closing movement of the inventively proposed armature assembly. A reduction in the opening speed is achieved by generating a

Flow resistance is achieved while a quick closing is achieved in that just this generated flow resistance is released during the closing movement of the armature again. Significantly, by the invention

proposed solution the sample scattering, mainly during the ballistic armature stroke at very small quantities, i. the reproducibility of mass produced fuel injectors can be improved, on the other hand, at one and the same

Fuel! A significant reduction in stroke to stroke dispersion can be achieved. Another advantage is that with the slow opening movement a favorable bounce on the upper stroke stop, ie on the lower plan side of

Electromagnet can be achieved. 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.

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

FIG. 2 shows the armature assembly proposed according to the invention when opening the

Valve seat of the fuel injector,

Figure 3 shows the first embodiment of the invention proposed

Anchor assembly during the closing of the valve seat, Figure 4 is a plan view of the upper plan side of the ground anchor,

5 is a plan view of the upper plan side of the basic anchor with recessed ball-shaped closure elements, covered by an upper anchor plate,

Figure 6 shows the top view of a disc-shaped anchor with drain slots for the

Absteuermenge,

Figure 7 shows a further embodiment of the invention proposed

Anchor assembly with a deformable, substantially disc-shaped formed damping element during the opening movement of the

Valve seat,

Figure 8 shows the further embodiment of the present invention proposed

Armature assembly according to Figure 7 during the closing of the valve seat,

Figure 9 is a detail of the upper portion of the second embodiment of the

According to the invention proposed anchor assembly according to Figures 7 and 8, Figure 10 shows a third embodiment of the present invention proposed

Anchor assembly with slotted base anchor during the opening movement of the valve seat,

Figure 1 1, the third embodiment of the present invention proposed

Anchor assembly during the closing of the valve seat,

Figure 12 is a plan view of an armature assembly formed with a cruciform

deformable damping element, and Figure 13 shows the section line XIII - XIII as shown in Figure 12.

variants

The illustration according to FIG. 1 shows a first embodiment variant of the fuel injector proposed according to the invention with an armature assembly designed according to the invention.

FIG. 1 shows a fuel injector 10, which comprises a valve piece 12. The valve piece 12 is received in a holding body 14 via a valve clamping screw 16. The valve piece 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 collecting space (common rail) or a delivery unit with system pressure. The control chamber 60 in the valve piece 12 is over a

Outlet throttle 62 relieved of pressure, wherein a drainage channel is closed by a here spherically formed closing element 44. In the first embodiment of the fuel injector shown in Figure 1, 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 includes an armature assembly 18 that is essentially a

Base anchor 20 and arranged on the upper plan side upper anchor plate 22 includes.

FIG. 1 shows that the base anchor 20 here comprises spherically formed closure elements 24 which are located in passage openings 58 which extend from the lower plan side to the upper plan side of the disk-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, it is further apparent that the armature assembly 18 is acted on 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 is closed by a ball-shaped closing element 44, which in a cap 46 on the underside of a pressure surface 52 of the base anchor 20 of the armature assembly 18th

is included. 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.

Figure 2 shows the first embodiment of the invention proposed

Fuel injector with inventive armature assembly during the opening process of the valve seat.

FIG. 2 shows that, when the electric actuator is energized-here in the form of an electromagnet-the valve spring 12 moves upward in the vertical direction against the armature spring force 38. 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 basic anchor 20 is located on the tapered portion of the valve member 12, a further damping element 76 on a bottom 74 of the anchor 20 of the anchor assembly 18. As is apparent from the illustration in Figure 2, the valve seat 42 is open, so that fuel from the system under pressure Control chamber 60 via the outlet throttle 62 in the

Seat 48 flows out. The valve seat 42 is released by the spherical closure element 44, which in a cap 46 on the pressure surface 52 in the lower region of the

Base anchor 20 is received within the seat 48. In the sitting space prevails the seat pressure 50.

In the illustrated in Figure 2 opening movement of the armature assembly 18 in a vertical upward direction in the arrow direction against the action of the spring force 38, the upper armature plate 22 and made of magnetic material ground anchor 20 moves upwards. The spherical shaped closure elements 24 are characterized by the

Acceleration force of the basic anchor 20 or by the fuel which the

Anchor assembly 18 in operation of the fuel injector, pressed into tapered transitional regions 56, so that the through holes 58, which extend from the bottom 74 to the top surface of the ground anchor 20, are closed when opening the armature assembly 18. 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 through more detailed in Figures 4 to 6, slit-shaped channels in the direction of a central drain hole 68, which passes through the magnet 28 from. By in the opening movement of the armature assembly 18 in the conical

Transition regions 56 pressed spherical closure elements 24, the flow resistance, which acts on the armature assembly in passing through the fuel in the direction of the upper stroke stop, increases, so that the opening movement of the armature is delayed accordingly. The spherically formed

Closure elements 24 remain in the position shown in FIG. closing the stepped holes 58 until the armature group 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 can be seen from the illustration according to FIG. 2, a top is located above the upper anchor plate 22

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.

By resulting from Figure 2 obstruction of the stepped holes 58, the pressure equalization between the abutment surface 72 of the upper anchor plate 22 and the

Underside 74 of the base anchor 20 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 significantly influenced by the number of slots 64, as shown in Figures 4 to 6, as well as their cross-sectional area.

FIG. 3 shows the first embodiment of the proposed invention

Armature assembly when closing the valve seat.

From the illustration according to FIG. 3, it can be seen that according to the arrow indicated there, when the energization of the electric actuator in the form of a magnet 28 is removed, the armature spring 36 shown in FIG. 1, the armature assembly 18 in the direction of

Valve seat 42, i. 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 - received by the cap 46 - on the pressure surface 52 of the

Basic anchor 20 placed 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. From Figure 3 it is further apparent that during the closing movement the

Closure elements 24 by the pressure increase at the bottom 74 of the base anchor 20 from the conically shaped transition region 56 within the respective

Stepped bore 58 are pushed out so that fuel through the now

released stepped holes 58 flows. The closure members 24 are now captured by the underside 78 of the upper anchor plate 22 and remain in that position until the anchor assembly 18 in the lower stroke stop, i. has arrived in the valve seat 42.

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 is largely determined by the number of slots 64 to be described, compare FIGS. 4, 5, 6 and their cross-sectional through areas, and, on the other hand, by the number of stepped bores 58 formed in the base anchor 20. After striking 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

Hole sections of the stepped holes. The illustration according to FIG. 4 shows a plan view of the basic anchor of the anchor assembly proposed according to the invention.

Figure 4 shows that, for example, in a 90 ° division at the top of the

Base anchor 20 are an outflow of the controlled tax amount favoring slots 64. 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 exemplary embodiment the base anchor 20 has a multiplicity of stepped bores 58.

FIG. 5 shows a basic anchor with sunken into its stepped bore

Closure elements which are covered by the upper anchor plate.

FIG. 5 shows that a number of slots 64 are formed on the circumference of the basic anchor 20 analogously to the illustration according to FIG. In the stepped bores 58, compare

Representation of Figure 4, are a number of spherical

Inserted locking elements 24. 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 can also be seen from the plan view according to FIG. 5, 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 case of that shown in FIG

Closing movement of the inventively proposed armature assembly can not leave the stepped holes 58, but remain trapped in these. FIG. 5 shows that a number of others are also on the upper side of the upper anchor plate 22 Slots 66 is executed, which allow easier discharge of the discharged from the control chamber 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 embodiment in which the upper anchor plate 22 has the shape of a ball which is trapped in the stepped bores 58 (not shown in FIG. 6)

Closure elements 24 completely covered. Due to the absence of the pin 82, the further slots 66 in the upper lift plate 22 are continuous, i. These form a cross-shaped pattern, so that the Absteuermenge from the control chamber 60 in comparison with the embodiment shown in Figure 5 with tightly continuous slots, can be better controlled. From each of the illustration according to FIGS. 4 to 6, it can be seen that the base anchor 20 is distributed on its edge-here approximately in a 90 ° pitch-which has slots 64 for the purpose of controlling the amount of deduction. Instead of the number of slots 64 shown in the embodiment variants of FIGS. 4, 5 and 6, slots 64 having a larger or smaller cross-section may also be provided in any desired configuration on the circumference of the slot

Base anchor 20 may be formed.

FIG. 7 shows a further second embodiment of the invention

proposed solution, in which instead of the spherically shaped

Closing a substantially disc-shaped deformable formed flexible damping element is used.

In Figure 7, the opening movement of the armature assembly according to the second

Embodiment shown, according to which analogously to the first embodiment of the valve seat 42 is released during the opening movement of the armature assembly 18 by the closing element 44. In this case, there is an outflow of fuel from the

System pressure acted upon control chamber 60 via the outlet throttle 62 in the armature space of the fuel injector 10th

In the embodiment variant shown in FIG. 7, the closure elements 24 according to the first embodiment variant illustrated in FIGS. 1, 2, 3 and 5 are characterized by FIG flexible disc-shaped damping element 90 replaced. The

Damping element 90 covers flow holes 94, which are executed in the basic anchor 20. The flexible damper 90 is secured over the disc 92 on top of the base anchor 20. Analogous to the embodiment variant shown in FIG. 4, according to which the stepped bores 58 open into a distributor groove 54, the through-bores 94 open in a circumferentially formed distributor groove 96, cf. illustration according to FIG. 9. During the upward movement, the flexible damping element 90 is replaced by the flexible damping element 90

Anchor space applied fuel present, so that the flexible damping element 90, the flow holes 94 closes. 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 is 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, in the

Opening movement closed. As is apparent from Figure 9, lies the flexible

Damping element 90 completely in the recess 100 at. The depth of this recess 100 depends on a residual air gap 98 and a thickness 1 14, in which the flexible damping element 90 is executed.

Figure 8 shows the closing movement of the second embodiment of the inventively proposed armature assembly when canceling the energization of the magnet.

FIG. 8 shows that the spring force 38 in FIG

Anchor spring 36 is 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 valve closing occurs by the influx of fuel through the flow holes 94 a back pressure in the distribution groove 96. The deformability of the substantially disc-shaped damping element 90 allows a flow of the fuel, since the flexible

Damping element 90 in its edge regions of the contact surface, i. of the

Groove 100 is pushed away, see deflected representation 106 in Figure 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 piece 12 moves until the bottom 74 of the base anchor 20 through the other

Damping element 76 is achieved to avoid bouncing. It can also be seen from the illustration according to FIG. 8 that the flexible damping element 90-shown here in its deflected position 106-passes through the disk 92, which partially dips into the central drainage bore 68, at the upper end

Plan page of the basic anchor 20 is fixed. FIG. 8 shows that the control chamber 60 is relieved of pressure into the seat space 48 via the outlet throttle 62 as long as the valve seat 42 is not closed by the ball-shaped closing element 44 held in the dome 46.

The illustration according to FIG. 9 shows, on an enlarged scale, how the non-deformed flexible damping element 90 with its outer edge dips into the recess 100 on the upper plane side of the basic anchor 20. The depth of the recess 100 at the

Anchor plate top 102 depends on the desired residual air gap 98 and the thickness 1 14 of the flexible damping element 90. Figure 9 further shows that the

Through 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 invention

proposed armature assembly with reduced opening and increased

Closing speed. In contrast to the embodiments described above, the

Basic anchor 20 of the armature assembly according to Figures 10 and 1 1 anchor slots on.

Magnetic armature, which are used in Magnetaktuatoren usually have, for reasons of magnetic flux, slots, so that the third

Variant of the solution proposed by the invention for application to such anchors offers.

As can be seen from FIG. 10, on the upper plan side of the basic anchor 20 of the armature assembly 18, analogously to the second variant of the solution proposed by the invention, there is the flexible disc-shaped damping element 90. This covers slits 104, of which in the drawing plane two are shown in FIG. Depending on the number of anchor slots 104 in the basic anchor 20, see illustration of FIG 12, the flexible decreases

Damping element 90, for example, a cross-shaped appearance 1 12 as shown in Figure 12 a, or may also be formed as a full-round damping element, just in disk 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 disc 92 protrudes partially into the central drainage hole 68 of the

Fuel injector 10 into it. Another damping element 76 is located below the bottom 74 of the base anchor 20 and forms a lower damping for the

To c eagle.

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, as in the armature space fuel from the gap between the magnet bottom 30 and the top of the flexible

Damping element is displaced, so that the opening speed of the

Armature assembly 18 is lowered.

In contrast, a similar effect is achieved in the closing movement of the armature assembly shown in Figure 1 1 in the third embodiment, as already described above in connection with the second embodiment in their closing movement in Figure 8.

In the vertical downward movement in the closing direction to the valve seat 42 to bend, reaches, for example, complementary to the number of armature slots 104 formed, for example, a cross shape 1 10 accepting 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 the ground anchor 20 at its

Downward movement, i. experienced during 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 is much faster than its opening movement, see illustration of Figure 10, in which the flow resistance in the armature space by the locked anchor slots 104 is considerably larger.

FIG. 12 is a plan view of a basic anchor with armature slots 104, wherein in this third variant of the solution proposed according to the invention, the flexible damping element has a cross shape 1 10 complementary to the number of armature slots 104. Other flow holes 108 present in the base anchor 20 are continuously open, i. are not of a deflectable bendable

Damping element 90 covered. Instead of the plan view according to FIG. 12

illustrated cross shape 1 10, the deformable flexible damping element complementary to the number of anchor slots 104 in the basic anchor also have a different geometry.

The illustration in FIG. 13 shows the sectional profile XIII-XIII as shown in FIG. From Figure 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 individual arms 1 12 of the cross-shaped 1 10 formed, flexible damping element 90 so that the anchor slots 104 - as shown in 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 at corresponding

High pressure performance in this application requires a functional range where the armature stroke is in the ballistic operating range.

The solution proposed according to the invention can also be used in addition

pressure balanced solenoid valve injectors are used because with constantly increasing rail pressure, i. constantly increasing system pressure also in this, by the

According to the invention proposed solution eliminated problems may occur.

Claims

claims

1 . Fuel injector (10) for injecting fuel into the combustion chamber of a

Internal combustion engine with an electric actuator (28), in particular an electromagnet, with which a closing element (44) can be actuated, which releases or closes a drain (62) of a control chamber (60), characterized in that an armature actuating the closing element (44) (18, 20) has openings (58, 94, 104) which, when the closing element (44) is closed, are opened and upon opening of the

Closing element (44) are closed.

2. Fuel injector according to claim 1, characterized in that the openings are designed as stepped bores (58), as through holes (94) or as anchor slots (104).

3. Fuel injector according to one of the preceding claims, characterized

characterized in that in the openings (58) gravity-actuated closure elements (24) are accommodated in spherical form.

4. Fuel injector according to one of the preceding claims, characterized

in that the armature (20) is acted upon by an armature spring (36) in the closing direction of a valve seat (42).

5. Fuel injector according to one of the preceding claims, characterized

characterized in that the openings (58, 94) of the armature (20) open into a circumferentially running distribution groove (54, 96).

6. Fuel injector according to one of the preceding claims, characterized

in that the openings embodied as stepped bores (58) comprise a conically shaped transition area (56) between borehole sections having diametrically different diameters.

7. Fuel injector according to one of the preceding claims, characterized

in that the armature (20) has at least one drain slot (64) which a quantity diverted from the control chamber (60) when opening the valve seat (42) flows to a central outlet (34, 68).

8. Fuel! A njector according to claim 3, characterized in that the spherical closure elements (24) are at least partially covered by a stop (72) representing armature plate (22).

9. Fuel injector according to one of the preceding claims, characterized

in that the openings (94, 104) can be released or closed by a disc-shaped, flexible damping element (90) accommodated on an anchor plate upper side (102).

10. Fuel injector according to the preceding claim, characterized in that the depth of a depression (100) on the anchor plate upper side (102) defines a residual air gap (98) between the armature (20) and the stroke stop (26) of the armature (20).

1 1. Fuel injector according to one of claims 1 to 9, characterized in that the residual air gap (98) by a thickness (1 14) of the flexible damping element (90) is defined.

12. Fuel injector according to one of the preceding claims, characterized

in that the anchor slots (104) in the armature (20) can be released or closed by a flexible damping element (90) having a cross shape (110).

A fuel injector according to the preceding claim, characterized in that the armature (20) comprises a number of flow bores (108) allowing continuous passage of fuel during the lifting movement of the armature (20).

14. Fuel injector according to one of the preceding claims, characterized

characterized in that the upper anchor plate 22 has continuous slots (66), which allows an improved discharge from the control chamber (60) of controlled amount.