EP3346121B1 - Magnetic valve for a fuel injection system and high pressure fuel pump - Google Patents

Description

The invention relates to a solenoid valve for a fuel injection system of an internal combustion engine, and a high-pressure fuel pump having such a solenoid valve.

In fuel injection systems in internal combustion engines, a fuel is usually subjected to a high pressure, wherein the pressure is for example in gasoline internal combustion engines in a range of 150 bar to 400 bar and in diesel engines in a 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.

The publication EP 2 574 768 A1 discloses a fuel injector for an internal combustion engine which opens and closes a fuel passage by means of an electromagnetically operable armature to achieve accurate fuel metering. For this purpose, the armature has a special shape with a through hole having a larger diameter portion and a smaller diameter diameter portion so as to improve responsiveness to magnetic flux and avoid sticking of the armature to adjacent components.

From the DE102010061810 A1 In addition, a valve device of a fuel pump according to the preamble of claim 1 is known.

In the fuel injection system, at various positions of the path the fuel takes from a tank to the respective combustion chamber of the internal combustion engine, valve arrangements can be made be provided, for example, as volume flow control valves, which are used for example in gasoline high-pressure pumps, which are designed as a reciprocating pump, and to vary the delivery rate of the fuel by the high-pressure fuel pump by selectively varying the closing or opening time relative to a position of the reciprocating piston of the high-pressure fuel pump , These flow control valves are often designed as solenoid valves and have a valve seat and a movably mounted closing element. The closing element is moved over an actuator region comprising a movable armature, which by means of electromagnetic forces can be moved relative to a pole piece. Due to the position of the armature at least one of the positions of the solenoid valve (open or closed) can be actively brought about or maintained for a certain period of time.

In order for the armature to be moved by means of electromagnetic force, the armature comprises a ferromagnetic material or consists entirely of such a material, and has a mass that is subject to the inertial laws. Due to this fact, a switching of the valve takes place with a certain time offset relative to the beginning of the actuation of the solenoid valve. It is desirable to minimize this skew in order to achieve good controllability, especially at high strobe frequencies. Furthermore, the anchor often strikes in at least one end position in other components. Depending on the impulse, which is linked directly to the mass of the armature via the speed, mechanical vibrations are generated when the armature strikes, which on the one hand leads to material wear, but on the other hand also to unwanted emission of structure-borne noise. It is therefore desirable to keep the moving masses as small as possible by constructive measures.

The object of the invention is therefore to reduce an armature mass in a solenoid valve for a fuel injection system.

This object is achieved with a solenoid valve with the feature combination of claim 1.

A high-pressure fuel pump in a fuel injection system having such a solenoid valve is the subject of the independent claim.

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

A solenoid valve for a fuel injection system includes a valve portion having a closure member and a valve seat which cooperate to close the solenoid valve. Further, the solenoid valve includes an actuator portion having a control pin for moving the shutter member along an axis of movement to an opening or closing position. The actuator portion includes a fixed pole piece having a pole piece bore disposed in the pole piece and a plunger armature movable relative to the pole piece along the axis of travel that is non-contact with the pole piece having a pole piece end in the pole piece bore. The plunger anchor forms the control pin.

So far, it has been known that the armature is formed as a movable block, which is connected to the control pin or otherwise coupled, wherein the control pin in turn acts on the closing element of the solenoid valve. The block-shaped armature has a very large compared to the control pin mass, with very high magnetic forces are necessary to comply with the required switching times of the solenoid valve at this high mass.

Therefore, it is now proposed not to perform the anchor as a block-shaped element, but as a plunger anchor. To further save mass, this plunger also forms the control pin, which moves the closing element along the axis of movement. Thus, the control pin is also the plunger anchor. By the execution of the anchor according to the plunger anchor principle, wherein the plunger armature forms the same time the control pin, the moving masses can be reduced to a minimum. Due to the lower moving masses, the pulses can be reduced when striking in an end position, resulting in less noise leads and at the same time reduces the material load. In addition, lower switching times can be achieved due to the reduced mass to be moved.

The valve region has a valve seat plate which forms the valve seat. The plunger armature is designed as a cylindrical pin which penetrates the valve seat plate contactlessly with a valve seat plate end, so that it can advantageously push away the closing element, for example in the form of the plate, from the valve seat by simple contact and does not have to be fixedly connected to the closing element. This in turn reduces the mass of both the closing element and the plunger anchor, since the two elements have no fixed connection to each other.

The closing element is preferably designed as a plate, which rests in the closed position of the solenoid valve on the valve seat plate. The pole piece and the plate are arranged in particular on opposite sides of the valve seat plate.

Such an embodiment of the solenoid valve is particularly advantageous when the solenoid valve is to be operated as a normally open solenoid valve, in which the closing element in the de-energized state advantageously does not rest on the valve seat or the valve seat plate, but is kept away from it. If the closing element is additionally designed as a lightweight plate, the impulse for touching the plate with the valve seat can also be significantly reduced in this case compared to a closing element with a larger mass, such as a ball valve or a mushroom valve.

Advantageously, the closing element formed as a plate is firmly connected to the valve seat plate and designed to be flexible only in some areas, so that it releases valve openings when it comes from the Plunger armature is actuated. As a result, a displacement of the plate from its position can be prevented.

Advantageously, a stop for limiting the movement path of the plunger armature along the movement axis is formed on the plunger armature. As a result, the movement of the plunger armature in one direction can advantageously be limited.

It can be provided a single stop in a direction of movement of the plunger armature, but it can also be provided a plurality of stops that define two opposite end positions of the plunger armature.

In an exemplary embodiment, the stop is formed on a pole piece end of the plunger armature for cooperation with the pole piece. This means that the end of the plunger armature, which is arranged directed towards the pole piece, has the stop.

In an alternative embodiment, however, the stop may also be formed opposite to a valve seat plate end of the plunger armature and thus interact with the valve seat plate in order to limit the path of movement of the plunger anchor.

In a further advantageous embodiment, it is possible not to provide the stop itself on the plunger armature itself, but separated from this, for example in the Polstückbohrung in the form of a stop pin which limits the path of movement of the plunger armature in the Polstückbohrung.

Preferably, a return spring is provided to bias the plunger armature to an initial position. For example, the starting position is an opening position of the solenoid valve, in which the plunger anchor holds the closing element of the valve seat.

The magnetic forces of the actuator area then act just so strong to overpress the spring force of the return spring and, for example, to pull the plunger armature into a position in which the closing element returns to the valve seat.

In an advantageous embodiment, the return spring is disposed within the pole piece bore. With such a configuration, it is possible to use space twice, namely on the one hand as Polstückbohrung, in which the plunger anchor is immersed, but on the other hand as a space for the return spring itself.

In an alternative embodiment, the return spring is arranged outside of the pole piece bore and is supported, for example, on a stop on the plunger armature and on the pole piece. With such an arrangement, it is possible to use a larger spring with a stronger spring force.

If in a preferred embodiment, the stop is not formed directly on the plunger armature, but as a stop pin within the pole piece bore, it is preferred if the return spring is arranged around the stop pin, so as to save space.

In an embodiment in which the restoring spring is arranged outside the pole piece bore, the stop can also be arranged on the plunger armature such that it is located neither at the pole piece end of the plunger anchor nor at the valve seat plate end of the plunger rod, but centrally therebetween. In this case, the spring is supported on the pole piece and the stop in such a way that the stop does not come into contact with the pole piece during operation at any operating point.

In an advantageous embodiment, the solenoid valve is designed as a flow control valve.

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

For example, such a solenoid valve may be formed as a volume flow control valve, in particular as an inlet valve of the high-pressure fuel pump.

Fig. 1

eine schematische Übersichtsdarstellung eines Kraftstoffeinspritzsystems mit einer Kraftstoffhochdruckpumpe, an der als Einlassventil ein Magnetventil angeordnet ist;

Fig. 2

eine schematische Schnittdarstellung durch das Magnetventil aus Fig. 1 in einer ersten Ausführungsform;

Fig. 3

eine schematische Schnittdarstellung durch das Magnetventil aus Fig. 1 in zweiten ersten Ausführungsform;

Fig. 4

eine schematische Schnittdarstellung durch das Magnetventil aus Fig. 1 in dritten ersten Ausführungsform;

Fig. 5

eine schematische Schnittdarstellung durch das Magnetventil aus Fig. 1 in einer vierten Ausführungsform;

Fig. 6

eine schematische Schnittdarstellung durch das Magnetventil aus Fig. 1 in einer fünften Ausführungsform; und

Fig. 7

eine schematische Schnittdarstellung durch das Magnetventil aus Fig. 1 in einer sechsten Ausführungsform.

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

Fig. 1

a schematic overview of a fuel injection system with a high-pressure fuel pump to which a solenoid valve is arranged as an inlet valve;

Fig. 2

a schematic sectional view through the solenoid valve Fig. 1 in a first embodiment;

Fig. 3

a schematic sectional view through the solenoid valve Fig. 1 in the second first embodiment;

Fig. 4

a schematic sectional view through the solenoid valve Fig. 1 in the third first embodiment;

Fig. 5

a schematic sectional view through the solenoid valve Fig. 1 in a fourth embodiment;

Fig. 6

a schematic sectional view through the solenoid valve Fig. 1 in a fifth embodiment; and

Fig. 7

a schematic sectional view through the solenoid valve Fig. 1 in a sixth embodiment.

Fig. 1 shows a schematic overview of a fuel injection system 10 of an internal combustion engine, which promotes a fuel 12 from a tank 14 via a prefeed pump 16, a high-pressure fuel pump 18 and a high-pressure fuel storage 20 to injectors 22, which then inject the fuel 12 into combustion chambers of the internal combustion engine.

The fuel 12 is introduced via an inlet valve 24 into the high-pressure fuel pump 18, pressurized via an outlet valve 26 out of the high-pressure fuel pump 18, and fed to the high-pressure fuel accumulator 20.

The inlet valve 24 is designed as a solenoid valve 28, in particular as a volume flow control valve 30, and thus can actively regulate the delivery rate of fuel 12 in the high-pressure fuel pump 18 by targeted variation of a closing or opening time.

The solenoid valve 28 is in greater detail in each case in a schematic sectional view in various embodiments in the Fig. 2 to Fig. 7 shown.

The following is first on Fig. 2 Referenced.

The solenoid valve 28 has a valve region 32 with a closing element 34 and a valve seat 36, and an actuator region 38, which ensures that the closing element 34 can be moved along a movement axis 40.

For this purpose, the actuator region 38 comprises a control pin 42, which is coupled to the closing element 34. In the present embodiment, this coupling occurs without a fixed connection, so that the control pin 42 only touches the closure member 34 when the closure member 34 is to be moved.

The control pin 42 is moved along the movement axis 40 to interact with a fixed pole piece 44 as a coil 46 induces a magnetic field in the actuator region 38. The control pin 42 is simultaneously formed as a plunger armature 48, and immersed in a centrally arranged in the pole piece 44 pole piece bore 50 a. By magnetic interaction of the plunger armature 48 and the pole piece 44, the plunger armature 48 then moves along the axis of movement 40th

In all in Fig. 2 to Fig. 7 As shown, the closing element 34 is formed as a plate 52 and is arranged opposite to the pole piece 44 with respect to a valve seat plate 54, on which the valve seat 36 is formed. The control pin 42, which simultaneously forms the plunger armature 48, is formed as a cylindrical pin and immersed in the pole piece bore 50 with a pole piece end 56 which is arranged directed to the pole piece 44. It passes through a through-opening 60 in the valve seat plate 54 at the same time as a valve seat plate end 58 so as to be able to come into contact with the closing element 34.

The actuator portion 38 further includes a return spring 62 biasing the control pin 42 to an initial position, wherein in all of the illustrated embodiments, the home position is an opening position of the solenoid valve 28. Thus, the solenoid valve 28 is formed in the present embodiments as a normally open solenoid valve 28. However, it is also conceivable to form the solenoid valve 28 as a normally closed solenoid valve 28, wherein the starting position of the control pin 42 is then such that the plate 52 rests on the valve seat plate 54.

It is also conceivable to provide other valve shapes in the valve region 32, that is, instead of the plate 52, a ball valve or other forms, and that the closing element 34 is not disposed opposite to the pole piece 44 with respect to the valve seat plate 54, but on the same side.

In known solenoid valves 28 in fuel injection systems 10, normally no plunger anchors 48 are used, but the armature is formed as a block element and coupled to the control pin 42.

In the present case, however, it is now proposed to combine the functions of the control pin 42 and the normally provided block-shaped armature in the form of a plunger armature 48 so as to save mass in particular at the now no longer provided separately provided anchor.

Overall, this results in a lower moving mass, which means that impulses are reduced when striking in an end position, resulting in a lower noise. In addition, this has the advantage that the coil 46 and the associated electromagnet and possibly also the return spring 62 smaller due to the lower acting forces and thus can be designed more cost-effective, since lower forces are required for acceleration. Furthermore, lower switching times can be achieved than before.

The Fig. 3 to Fig. 7 show variations of with respect to Fig. 2 described solenoid valve 28 in the first embodiment, wherein in the following only the differences are to be described.

Fig. 3 shows a schematic sectional view of a second embodiment of the solenoid valve 28, wherein in contrast to the first embodiment, a stop 64 is now provided which is formed on the plunger armature 48 and is located in particular on the valve seat plate end 58 of the plunger armature 48. This stop 64 limits the path of movement of the plunger armature 48 in the direction of the opening position, in which the plate 52 is pushed away from the valve seat 36.

Fig. 4 shows a schematic sectional view of a third embodiment of the solenoid valve 28, in which the stopper 64 is not formed on the plunger 48 itself, but is arranged separately from the plunger 48 in the Polstückbohrung 50, within the return spring 62, located in the Polstückbohrung 50 is located. The stopper 64 is formed here as a stop pin 66.

Fig. 5 shows a schematic sectional view of a fourth embodiment of the solenoid valve 28, the second embodiment in Fig. 3 corresponds only to the stop 64, as in Fig. 3 shown at the valve seat plate end 58, but at the pole piece end 56 of the plunger armature 48 is formed. This means that here the movement path of the plunger armature 48 is limited in the direction of the closing position of the solenoid valve 28, by an interaction between pole piece 44 and stop 64 takes place.

Fig. 6 shows a schematic sectional view of a fifth embodiment of the solenoid valve 28, wherein not, as in the first four embodiments, the return spring 62 is disposed within the pole piece bore 50, but outside of the pole piece bore 50, and on the one hand on the stopper 64 and on the other hand on the pole piece 44 supported.

Fig. 7 shows a schematic sectional view of a sixth embodiment of the embodiment in Fig. 6 corresponds, wherein only the stopper 64 is not at one end, namely the valve seat plate end 58 of the plunger 48, but centrally, so that the stopper 64 comes into contact with the valve seat plate 54 and the pole piece 44, but only via the return spring 62nd is coupled to Wegbegrenzung with the pole piece 44.

Claims (10)

1. A solenoid valve (28) for a fuel injection system (10), having

   - a valve region (32) with a closing element (34) and a valve seat (36) which interact in order to close the solenoid valve (28); and

   - an actuator region (38) with a control pin (42) for moving the closing element (34) along a movement axis (40) into an open or closed position,

   wherein the actuator region (38) has a stationary pole piece (44) with a pole piece bore (50) which is arranged in the pole piece (44), and a solenoid plunger (48) which is movable relative to the pole piece (44) along the movement axis (40), said solenoid plunger being arranged with a pole piece end (56) in the pole piece bore (50) in a contactless manner with respect to the pole piece (44),
   wherein the solenoid plunger (48) forms the control pin (42) and the valve region (32) has a valve seat plate (54) which forms the valve seat (36), and wherein the solenoid plunger (48) is configured as a cylindrical pin,
   characterized in that
   the solenoid plunger (48) penetrates the valve seat plate (54) with a valve seat plate end (58) in a contactless manner.
2. The solenoid valve (28) according to Claim 1,
   wherein the closing element (34) is configured as a small plate (52) which rests on the valve seat plate (54) in the closed position of the solenoid valve (28).
3. The solenoid valve (28) according to Claim 2, wherein the pole piece (44) and the small plate (52) are arranged on opposite sides of the valve seat plate (54).
4. The solenoid valve (28) according to any one of Claims 1 to 3,
   characterized in that a stop (64) for limiting the movement travel of the solenoid plunger (48) along the movement axis (40) is configured on the solenoid plunger (48).
5. The solenoid valve (28) according to Claim 4, characterized in that the stop (64) is configured at a pole piece end (56) of the solenoid plunger (48) for interaction with the pole piece (44) or the stop (64) is configured at a valve seat plate end (58) of the solenoid plunger (48) for interaction with the valve seat plate (54).
6. The solenoid valve (28) according to any one of Claims 1 to 3, characterized in that a stop pin (66) for limiting the movement travel of the solenoid plunger (48) along the movement axis (40) is arranged in the pole piece bore (50).
7. The solenoid valve (28) according to any one of Claims 1 to 3,
   characterized in that a restoring spring (62) is provided in order to prestress the solenoid plunger (48) into a starting position, wherein the starting position is preferably an open position of the solenoid valve (28), in which open position the solenoid plunger (48) holds the closing element (34) away from the valve seat (36).
8. The solenoid valve (28) according to Claim 7, characterized in that a stop (64) for limiting the movement travel of the solenoid plunger (48) along the movement axis (40) is configured on the solenoid plunger (48), and the restoring spring (62) is arranged within the pole piece bore (50) or the restoring spring (62) is arranged outside of the pole piece bore (50) and is supported on the stop (64) and on the pole piece (44).
9. The solenoid valve (28) according to any one of Claims 1 to 8,
   characterized in that the solenoid valve (28) is configured as a volumetric flow regulating valve (30).
10. A fuel high-pressure pump (18) for a fuel injection system (10) of an internal combustion engine, having a solenoid valve (28) according to any one of Claims 1 to 8.

Images