EP3346122B1 - Electromagnetic switching valve and high-pressure fuel pump - Google Patents

Description

The invention relates to an electromagnetic switching valve for a fuel injection system of an internal combustion engine, as well as a high-pressure fuel pump having such an electromagnetic switching valve.

High-pressure fuel pumps in fuel injection systems in internal combustion engines are used to pressurize a high-pressure fuel, the pressure is for example in gasoline engines in the range of 150 bar to 400 bar and diesel engines in the range of 1500 bar to 2500 bar. The higher the pressure that can be generated in the respective fuel, the lower are emissions that occur during combustion of the fuel in a combustion chamber, which is particularly advantageous against the background that a reduction of emissions is increasingly desired.

In the fuel injection system, valve assemblies may be provided at various positions along the path that the fuel takes from a tank to the respective combustion chamber, for example as an intake valve on a high pressure fuel pump that pressurizes the fuel, but also as a relief valve at various positions of the fuel injection system, for example For example, on a common rail that stores the pressurized fuel before injection into the combustion chamber.

Frequently, fast-switching solenoid valves for volume flow and / or pressure control are used for this purpose. Depending on the flow rate and type, a spring holds a closing element of a valve region of such an electromagnetic switching valve open or closed against a volume flow or pressure. The associated actuator area, ie the magnetic actuator which opens or closes the closing element, is designed in such a way that that the spring can override the actuator force of the actuator in a certain time, thus switching the switching valve.

It is advantageous if the moving parts of the electromagnetic switching valve have two boundaries in an axial direction of movement, i. an actuator force acting direction, are given. Due to the contact between the moving parts and these limitations, however, there is in each case a pulse, which is emitted via the components of the fuel injection system, for example the high-pressure fuel pump, as sound. The sound radiation is perceived as noise.

So far, this problem has been addressed by a Bestromungsprofil the electromagnetic switching valve has been adapted so that a minimal impulse of the moving parts is formed on the limiting parts, while maintaining a necessary to be achieved function of the switching valve. Thus, a noise minimization could be achieved.

The object of the invention is to provide an electromagnetic switching valve, in which a sound radiation can be reduced to a minimum.

This object is achieved with an electromagnetic switching valve with the feature combination of claim 1.

A high-pressure fuel pump having such an electromagnetic switching valve is the subject of the independent claim.

Advantageous embodiments of the invention are the subject of the dependent claims.

An electromagnetic switching valve for a fuel injection system of an internal combustion engine has a valve portion having a closing member and a valve seat for closing of the switching valve cooperate, on. Furthermore, the electromagnetic switching valve has a spring with a spring force acting on the closing element for biasing the closing element into an open or closed position, and an actuator area for moving the closing element with an actuator force opposite to the spring force. The actuator region has an armature that is movable along an actuator force acting direction and that is coupled to the closing element for moving the closing element and a stationary pole piece. A pole piece approaching surface of the pole piece is disposed toward the armature, and an armature approaching surface of the armature is disposed facing the pole piece so that the pole piece approximation surface and the anchor approaching surface directly face each other. The pole piece has in the approach surface on a recess in which a plastic disc is fixed, which has a directed to the armature disc surface. The pole piece approaching surface and the disk surface are offset from each other. The spring is disposed between the armature and the pole piece and is supported with a spring end in the recess on the pole piece, wherein the plastic disc has a recess in which the spring is supported by the spring end, or the plastic disc has a through hole through which engages the spring with the spring end. Further, disc walls of the plastic disc, which form the recess or the through hole, are arranged inclined obliquely outwardly away from the central longitudinal axis of the pole piece.

During operation of the switching valve, the movable armature moves toward the fixed pole piece along the actuator force acting direction because the armature is attracted by the pole piece. At some point, the armature engages the pole piece with the pole piece approach surface and the anchor approach surface touching. It is now proposed to insert in the pole piece an additional plastic disc, but not flush with the Polstückannäherungsfläche concludes, but is arranged offset to her. Thereby, it is possible for the anchor approaching surface to strike the plastic disk without touching the pole piece approaching surface, so that the Plastic disc can decouple the components armature and pole piece metallic from each other. The momentum generated when the armature hits the pole piece is damped. By decoupling the metallic components from each other, the transmission to adjacent components is further reduced.

The staggered arrangement of pole piece approaching surface and disk surface also acts as a shock absorber so that upon impact of the armature in the pole piece, the pulse is first damped by the metallic armature striking the plastic disk.

The electromagnetic switching valve may be provided to a high-pressure fuel pump of the fuel injection system as an intake valve or as an exhaust valve, but it is also possible to provide the electromagnetic switching valve, for example, on a common rail for pressure control in the fuel injection system.

Depending on the arrangement of spring, armature and pole piece to each other, the electromagnetic switching valve can be designed as normally open or normally closed switching valve.

The spring is arranged between the armature and the pole piece and is supported by a spring end in the recess on the pole piece. It can be provided, for example, that the plastic disc has a recess in which the spring is supported by the spring end. Alternatively, however, it is also possible that the plastic disc has a through hole through which the spring engages with the spring end.

The spring is disposed between the armature and the pole piece to keep the armature in the de-energized state at a distance from the pole piece, wherein the spring force of the spring counteracts the Aktuatorkraft, and is suppressed in energized state, so that armature and pole piece toward each other move. To save space, it is particularly preferred if the spring at least at one of the two elements anchor or pole piece can support. It is advantageous if the area where the spring is supported, and should usually be provided as a guide for a spring end, at the same time takes on another function. This is the case when the recess serves both for accommodating or securing the plastic disk, as well as a guide region for the spring between the armature and pole piece.

The arrangement of the spring and the plastic disc together in the recess can be realized by a variety of embodiments. For example, it is possible to provide in the recess a shoulder on which the disc rests, whereby the disc has a smaller disc thickness than the recess is deep. However, it is also possible to form the disc thickness somewhat thicker than the recess is deep, so that the plastic disc is flush with a recess bottom, where the spring end of the spring is supported.

The disc walls of the plastic disc, which form the recess or the through hole, are inclined obliquely outwardly away from the central longitudinal axis of the pole piece. As a result, the plastic disk has a somewhat greater stability upon impact of the armature, since a base of the plastic disk, which lies opposite the point of impact, is somewhat wider than the region of the impact itself.

In an advantageous embodiment, the plastic disc is fastened with a projection of the disc surface directed towards the armature to the pole piece approaching surface in the recess.

In an alternative embodiment, the plastic disc is secured in the recess with a disc surface recessed from the armature with respect to the pole piece approaching surface, the anchor at the anchor approaching surface in particular having a projection facing the pole piece which engages the recess as the armature and pole piece approach ,

It is therefore possible to mount the plastic disc with a projection or reset with a corresponding mating contour on the armature in the pole piece. Both supernatant and recessed arrangement are designed so that the contact of the armature takes place with the pole piece on the plastic disc.

The plastic disc can be fastened by injection of plastic cohesively in the recess on the pole piece, however, it is also possible to press an already finished plastic disc in the recess and thus to attach via a frictional connection or to fix positively over advantageous geometries.

The plastic disk has a disk thickness along the actuator force acting direction, wherein the disk surface is arranged offset in one embodiment by at least 10% of the disk thickness, in particular by at least 25% of the disk thickness, to the pole piece approaching surface. That is, with respect to its overall thickness, the plastic disk, when inserted with a projection in the recess, projects beyond the pole piece approaching surface by at least 10%, preferably at least 25%. Conversely, when the plastic disc is set back in the recess, the offset is at least 10% of the total disc thickness of the plastic disc, in particular at least 25% of the disc thickness.

The recess is advantageously arranged symmetrically directly around a central longitudinal axis of the pole piece arranged parallel to the actuator force acting direction, wherein in particular a cross-sectional area of the recess perpendicular to the actuator acting direction is at least 50%, in particular at least 65% of the cross-sectional area of the pole piece perpendicular to the actuator force acting direction. As a result, the recess is applied in particular in the middle region of the pole piece, while the outer region is formed only by the pole piece approaching surface in order to weaken the magnetic field lines as little as possible. The forces that occur through the impact of the anchor in the plastic disc, thereby advantageously taken in the middle of the pole piece and discharged to the outside. As a result, the formation of noise can be advantageously counteracted.

Preferably, the plastic disc is formed of an elastomeric material and therefore deforms under impact forces upon impact of the armature in the plastic disc.

Preferably, the plastic disc on additional particles such as fibers or magnetic particles. The fibers can advantageously also be magnetic. Magnetically, all materials are to be understood that can react to forces of a magnetic field.

A high-pressure fuel pump for a fuel injection system of an internal combustion engine advantageously has an electromagnetic switching valve described above.

Fig. 1

eine schematische Darstellung eines Kraftstoffeinspritzsystems einer Brennkraftmaschine, das an verschiedenen Positionen ein elektromagnetisches Schaltventil aufweisen kann;

Fig. 2

eine Schnittdarstellung durch ein Ausführungsbeispiel eines elektromagnetischen Schaltventiles aus Fig. 1;

Fig. 3

eine schematische Schnittdarstellung eines Teilbereiches des elektromagnetischen Schaltventiles aus Fig. 2 in einer ersten Ausführungsform;

Fig. 4

eine schematische Schnittdarstellung eines Teilbereiches des elektromagnetischen Schaltventiles aus Fig. 2 in einer zweiten Ausführungsform;

Fig. 5

eine schematische Schnittdarstellung eines Teilbereiches des elektromagnetischen Schaltventiles aus Fig. 2 in einer dritten Ausführungsform;

Fig. 6

eine schematische Schnittdarstellung eines Teilbereiches des elektromagnetischen Schaltventiles aus Fig. 2 in einer vierten Ausführungsform.

Advantageous embodiments of the invention will be explained in more detail with reference to the accompanying drawings. It shows:

Fig. 1

a schematic representation of a fuel injection system of an internal combustion engine, which may have an electromagnetic switching valve at various positions;

Fig. 2

a sectional view through an embodiment of an electromagnetic switching valve Fig. 1 ;

Fig. 3

a schematic sectional view of a portion of the electromagnetic switching valve Fig. 2 in a first embodiment;

Fig. 4

a schematic sectional view of a portion of the electromagnetic switching valve Fig. 2 in a second embodiment;

Fig. 5

a schematic sectional view of a portion of the electromagnetic switching valve Fig. 2 in a third embodiment;

Fig. 6

a schematic sectional view of a portion of the electromagnetic switching valve Fig. 2 in a fourth embodiment.

Fig. 1 shows a schematic representation of a fuel injection system 10, with which an internal combustion engine fuel 12 is supplied from a tank 14 for combustion. The fuel 12 is pumped from a backing pump 16 via a low pressure line 18 to a high-pressure fuel pump 20, where the fuel 12 is subjected to high pressure. From the high-pressure fuel pump 20, the pressurized fuel 12 is then conveyed to a so-called. Common rail 22 and injected from there via injectors 24 into the combustion chambers of the internal combustion engine.

In various places of the fuel injection system 10, valves, in particular electromagnetic switching valves 26, are provided to control the fuel flow through the fuel injection system 10.

For example, the high-pressure fuel pump 20 may have an electromagnetic switching valve 26 as the inlet valve 28, but it is also possible for such a switching valve 26 to be provided as an outlet valve 30 on the high-pressure fuel pump 20. In addition, it is also conceivable that such an electromagnetic switching valve 26 is provided as a pressure reducing valve 32 on the common rail 22 in order to regulate the pressure in the common rail 22.

Fig. 2 shows a sectional view of such an electromagnetic switching valve 26th

The electromagnetic switching valve 26 has a valve region 34, which comprises a closing element 36 and a valve seat 38. The closure member 36 cooperates with the valve seat 38 to close the switching valve 26. When the closing element 36 lifts off the valve seat 38, the switching valve 26 is in its open position. In the illustrated embodiment, the closing element 36 is formed as a plate 40, which rests flat on the valve seat plate 42 of the valve seat 38 in the closed position of the switching valve 26. The closing element 36 in this case comprises a pin 44 which pushes the plate 40 away from the valve seat plate 42 and thus opens the switching valve 26.

The switching valve 26 further includes a spring 46 which in the present embodiment biases the closing member 36 with a spring force FF toward the open position and thus keeps the switching valve 26 in its open position.

The switching valve 26 further includes an actuator portion 48 which is formed as a magnetic actuator and the closing member 36 can move with an actuator force FA, which is opposite to the spring force FF. For this purpose, the switching valve 26 has an armature 50, which is movable along an actuator force acting direction RA, and a fixed pole piece 52. In addition, the actuator region 48 comprises a coil 54, by means of which a magnetic field can be established in the actuator region 48 when a voltage is applied from the outside. By this magnetic field, the armature 50 is attracted by the pole piece 52 and moves in the direction of the pole piece 52 along the Aktuatorkraftwirkung RA. As the armature 50 and the pin 44 are coupled together, the pin 44 is thus pulled away from the armature 50 by the closing element 36, so that the closing element 36 can rest against the valve seat plate 42 and thus comes into its closed position.

The armature 50 has an armature approaching surface 56 disposed facing the pole piece 52, and the pole piece 52 has a pole piece approaching surface 58 disposed facing the armature 50. Thus, pole piece approach surface 58 and anchor approach surface 56 directly oppose each other.

In operation, anchor approach surface 56 and pole piece approach surface 58 move toward each other.

The pole piece 52 has in the pole piece approaching surface 58 a recess 60 in which a plastic disk 62 is attached. This has a disk surface 64 directed towards the armature 50.

In the present embodiment in Fig. 2 For example, the plastic disk 62 is secured in the recess 60 with a protrusion 66 of the disk surface 64 facing the armature 50 with respect to the pole piece approaching surface 58. That is, the pole piece approaching surface 58 and the disk surface 64 are offset from each other of the actuator force acting direction RA.

Fig. 3 shows a sectional view of a portion of the switching valve 26 in the region in which the armature 50 and pole piece 52 opposite, in a first embodiment.

In Fig. 3 It can be seen that the plastic disk 62 has a disk thickness DS along the actuator force acting direction RA, wherein the protrusion 66 is so large that the disk surface 64 is offset by about 25% of the disk thickness DS to the pole piece approaching surface 58.

It can also be seen that the recess 60 has a shoulder 68 in which the plastic disk 62 is fastened. The spring 46 of the switching valve 26 is also supported in the recess 60, to which the plastic disc 62 has a through hole 70 through which the spring 46 can reach through with a spring end 72, with which it is supported in the recess 60. Disc walls 74 of the plastic disc 62, which form the through hole 70 are obliquely inclined away from a central longitudinal axis AM of the pole piece 52 so as to absorb forces acting upon impact of the armature 50 in the plastic disc 62, better within the plastic disc 62 and the Spring 46 can be mounted better.

Fig. 4 shows a sectional view of a second embodiment of the switching valve 26 in the region of armature 50 and pole piece 52. Here it can be seen that the plastic disc 62 is not secured with a projection 66 in the recess 60, but is set back from the armature 50 with respect to the pole piece approaching surface 58. The armature 50 has at its anchor approaching surface 56 a to the pole piece 52 facing projection 76. This projection 76 engages in the approach of armature 50 and pole piece 52 in the recess 60 and strikes on the plastic disk 52. Otherwise, the structure of the switching valve 26 and in particular the arrangement of spring 46 and plastic disc 62 substantially corresponds to the first embodiment in FIG Fig. 3 ,

Fig. 5 shows a third embodiment of a switching valve 26 in a sectional view in the region of armature 50 and pole piece 52. Here it can be seen that the plastic disc 62 has a disc thickness DS, which is greater than the depth T of the recess 60 along the Aktuarorkraftwirkrichtung RA. The plastic disk 62 is fixed to the same surface on which also the spring end 72 of the spring 46 is supported. In the other features of the switching valve 26 corresponds to in Fig. 5 shown embodiment of the first embodiment in Fig. 3 ,

Fig. 6 shows a sectional view of a fourth embodiment not according to the invention, in which the plastic disc 62 has a recess 78 in which the spring 46 is supported. Therefore, the spring 46 does not penetrate the plastic disk 62 through a provided through hole 70, but the recess 60 is completely filled with the plastic disk 62nd

The individual features of the different embodiments can, as long as this is technically possible, all be combined.

In all embodiments, it can be seen that the recess 60 is arranged symmetrically immediately about the central longitudinal axis AM, which extends parallel to the Aktuarorkraftwirkrichtung RA. In this case, a cross-sectional area FQ of the recess 60 and thus also a cross-sectional area FQ of the plastic disc 62 is at least 50% of the cross-sectional area of the pole piece 52 perpendicular to the Aktuatorkraftwirkrichtung RA. The means that the plastic disc 62 is disposed in the center of the pole piece 52, and so forces acting on the impact of the armature 50 in the pole piece 52 and the plastic disc 62 can be discharged from the center to the outside.

In order to further dampen the impact of the armature 50 in the plastic disk 62 and the pole piece 52, the plastic disk 62 may be formed, for example, of an elastomer. In order to mitigate an interruption of the magnetic circuit by providing a non-magnetic plastic disk 62, 62 additional particles may be provided in the plastic disk, which are magnetic, such as magnetic particles or magnetic fibers. In addition, 62 fibers may be provided to support the power dissipation in the plastic disc, which are arranged in the direction of force flow and thus facilitate the dissipation of impact forces.

The use of a plastic component such as the plastic disk 62 in the pole piece 52 of the switching valve 26, the metallic components, namely the armature 50 and the pole piece 52 are decoupled from each other and the impact of the moving armature 50 in the limiting component, namely the pole piece 52, attenuated. The forwarding of the pulse or the excitation of adjacent parts is thereby prevented or reduced, which leads to a lower sound emission and thus to a reduction of the noise emission.

Claims (11)

1. An electromagnetic control valve (26) for a fuel injection system (10) of an internal combustion engine, having:

   - a valve area (34) with a closing element (36) and with a valve seat (38), which interact to close the control valve (26) ;

   - a spring (46) with a spring force (FF) acting on the closing element (36) for preloading the closing element (36) in an opening or closing position;

   - an actuator area (48) for moving the closing element (36) with an actuator force (FA) opposing the spring force (FF); where the actuator area (48) has an armature (50) movable along an actuator force direction (RA), which is coupled with the closing element (36) to move the closing element (36), and a fixed pole piece (52), wherein a pole piece approach area (58) of the pole piece (52) is arranged facing the armature (50), and where an armature approach area (56) of the armature (50) is arranged facing the pole piece (52), so that the pole piece approach area (58) and the armature approach area (56) are directly opposite each other,

   wherein the pole piece (50) has a recess (60) in the pole piece approach area (58), in which a plastic disk (62) is fixed, which has a disk area (64) directed towards the armature (50), wherein the pole piece approach area (58) and the disk area (64) are arranged offset from each other,
   characterized in that
   the spring (46) is arranged between the armature (50) and the pole piece (52) and is supported by having one end of the spring (72) in the recess (60) in the pole piece (52),
   wherein the plastic disk (62) has an indentation (78), in which the spring (46) is supported by one end of the spring (72), or the plastic disk (62) has a through hole (70), through which the spring (46) reaches with the spring end (72), and
   wherein disk walls (74) of the plastic disk (62), which form the indentation (78) or the through hole (70), are arranged slanted towards the exterior and inclined away from the central longitudinal axis (AM) of the pole piece (52).
2. The electromagnetic control valve (26) according to claim 1, characterized in that the plastic disk (62) is fixed in the recess (60) by a protrusion (66) of the disk area (64) to the pole piece approach area (52) directed toward the armature (50) .
3. The electromagnetic control valve (26) according to Claim 1, characterized in that the plastic disk (62) having a disk area (64) set back from the armature (50) in relation to the pole piece approach area (58) is fixed in the recess (60), wherein the armature (50) in particular has a projection (76) on the armature approach area (56) facing the pole piece (52), which engages in the recess (60) on approaching the armature (50) and pole piece (52).
4. The electromagnetic control valve (26) according to any one of the Claims 1 to 3,
   characterized in that the plastic disk (62) has a disk thickness (DS) along the actuator force direction (RA), wherein the disk area (64) is arranged offset from the pole piece approach area (58) by at least 10% of the disk thickness (DS), in particular by at least 25% of the disk thickness (DS).
5. The electromagnetic control valve (26) according to any one of the Claims 1 to 4,
   characterized in that the recess (60) is arranged directly in the pole piece (52) symmetrically about a central longitudinal axis (AM) of the pole piece (52) parallel to the actuator force direction (RA), wherein a cross-sectional area (FQ) of the recess (60) perpendicular to the actuator force direction (RA) equals at least 50% of the cross-sectional area of the pole piece (52) perpendicular to the actuator force direction (RA).
6. The electromagnetic control valve (26) according to Claim 5, where a cross-sectional area (FQ) of the recess (60) perpendicular to the actuator force direction (RA) equals at least 65% of the cross-sectional area of the pole piece (52) perpendicular to the actuator force direction (RA).
7. The electromagnetic control valve (26) according to any one of the Claims 1 to 6,
   characterized in that the plastic disk (62) is formed from an elastomeric material.
8. The electromagnetic control valve (26) according to any one of the Claims 1 to 7,
   characterized in that the plastic disk (62) has additional particles.
9. The electromagnetic control valve (26) according to Claim 8, characterized in that the additional particles comprise fibers.
10. The electromagnetic control valve (26) according to Claim 8 or 9,
    characterized in that the additional particles comprise magnetic particles.
11. A high-pressure fuel pump (20) for a fuel injection system (10) of an internal combustion engine, having an electromagnetic control valve (26) according to any one of the Claims 1 to 10.

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