WO2018028865A1 - Electromagnetically actuable intake valve and high-pressure fuel pump - Google Patents

Abstract

The invention relates to an electromagnetically actuable intake valve (1) for a high-pressure fuel pump (2), comprising an annular magnet coil (3) for acting on an armature (7) which is able to move in translation between two end stops (4, 5) and can be coupled to a valve tappet (6), which armature (7) is at least partially received in a cavity (8) of a valve body (9). According to the invention, the armature (7) has multiple eccentrically arranged through-bores (10) which are or can be hydraulically connected via at least one circumferential slot (11) created in the armature (7) and/or in a stop element (12) forming the first end stop (4). Furthermore, the invention relates to a high-pressure fuel pump (2) having such an intake valve (1).

Description

 Description title

 Electromagnetically operated suction valve and high-pressure fuel pump

The invention relates to an electromagnetically actuated suction valve for a high-pressure fuel pump with the features of the preamble of claim 1. The proposed electromagnetically actuated intake valve is used to supply a high-pressure fuel pump with fuel. The invention therefore further relates to a high-pressure fuel pump with such a suction valve.

State of the art

From DE 10 2014 200 339 AI an electromagnetically controllable suction valve for a high-pressure pump of a fuel injection system, in particular a common rail injection system is known which comprises an annular magnetic coil for acting on a liftable armature and a pole core, which together with the armature Working air gap limited. The armature is at least partially surrounded by a valve body which is designed as a screw plug and the attachment of the suction valve to the high-pressure pump is used. The pole core and the valve body are connected by means of a sleeve, wherein the connection of the sleeve with the pole core via a weld. Since striking the anchor at the pole core, the weld is heavily loaded, so that there is a risk that the component connection fails prematurely, it is proposed to relieve the weld, to axially bias the pole core in the direction of the armature. In this way, the robustness of the component connection and, as a consequence, the robustness of the suction valve should be increased.

The present invention has for its object to provide an electromagnetically actuated suction valve for a high-pressure fuel pump, whose Robustness is further increased. Furthermore, the dynamics of the armature movement should be optimized to reduce the valve switching time and / or to minimize valve timing variations. To solve the problem, the electromagnetically actuated suction valve with the features of claim 1 is proposed. Advantageous developments of the invention can be found in the dependent claims. Furthermore, a high-pressure fuel pump is specified with such a suction valve. Disclosure of the invention

The electromagnetically actuated suction valve proposed for a high-pressure fuel pump comprises an annular magnet coil for acting on a liftable between two end stops and can be coupled with a valve lifter anchor, at least in sections in a recess of a

Valve body is added. According to the invention, the armature has a plurality of eccentrically arranged through bores which are hydraulically connected or connectable via at least one circumferential groove formed in the armature and / or in a stop element forming the first end stop.

The plurality of through holes formed in the anchor allow a hydraulic pressure equalization in a stroke movement of the armature in fuel. Depending on the direction of movement of the armature, the fuel can flow via the passage bores from a pressure space located above the armature into a pressure space located below the armature or vice versa. The through holes thus promote rapid pressure equalization. In addition, they reduce the mass of the anchor so that its dynamics increase. This in turn leads to a reduction of the valve switching time.

Preferably, the plurality of through holes are arranged at the same angular distance from each other on an imaginary circular line, so that the armature is flowed through evenly in a lifting movement of fuel. For example, three, four or more through-holes may be formed in the armature. To further optimize the armature dynamics, it is important to prevent hydraulic bonding of the armature to the end stops. Hydraulic adhesive effects are due to the fact that a negative pressure forms between the armature and the respective end stop, which makes it difficult to release the armature from the end stop. At the same time due to the negative pressure increases the risk of cavitation, so that adjacent areas are exposed to increased wear by cavitation erosion. In order to counteract hydraulic adhesive effects in the region of the first end stop, the suction valve according to the invention has a circumferential groove formed in the armature or in the stop element, in particular annular groove, for the hydraulic connection of the through holes passing through the armature.

About a trained in the anchor circumferential groove a constant hydraulic connection of the through holes is made. About a formed in the stop element circumferential groove a hydraulic connection of the through holes is made at least at fitting anchor. For this purpose, the at least one circumferential groove formed in the armature and / or in the stop element has a common covering area with the through bores formed in the armature.

The at least one circumferential groove formed in the armature and / or in the stop element reduces the contact area of the armature with the stop element. Further, it forms a fuel-filled cavity between the armature and the stop element, which favors an underflow of the armature with fuel when the armature tries to release from the stop element. The passing over the groove between the armature and the stop element fuel counteracts the formation of local vacuum areas and thus prevents hydraulic bonding of the armature to the stop element. The anchor movement is thus highly dynamic. This in turn leads to short and little fluctuating valve switching times. Furthermore, the danger of cavitation decreases.

According to a preferred embodiment of the invention, the stop element is at least partially plate-shaped and at one in the Recess projecting annular collar of the valve body axially supported. For example, the stop element may be formed as a simple plate, which rests on the annular collar of the valve body. The plate-shaped portion of the stop element or the plate-shaped stop member forms the first end stop and also allows adjustment of the stroke of

Anchor. If the stop element is made of a non-magnetic or non-magnetizable material, it can also be used for magnetic separation of the armature from the valve body. In addition, a material for forming the stop element can be selected, which is particularly resistant to wear and thus contributes to the increase in robustness of the suction valve.

It is also proposed that the stop element has a collar portion embracing the annular collar of the valve body. About the collar portion, the radial position of the stop element can be predetermined. Preferably, the stop element is pressed over the collar portion in the valve body. In this case, the stop element is fixed in position both in the radial and in the axial direction. The axial position fixation prevents the stop element from sticking to the armature when it moves away from the first end stop in the direction of the further end stop. The interference fit of the stop element thus promotes a high anchor dynamics.

In addition, the stop element preferably has a central recess which is hydraulically connected to the through holes formed in the armature independently of the stroke of the armature. This means that the central recess of the stop element also has a covering area with the through-holes. Accordingly, the armature movement space formed in the valve body is connected to a further pressure space via the central recess of the stop element, into which fuel can be displaced or can flow out of the fuel in order to produce the required pressure equalization during a stroke movement of the armature.

Advantageously, at least one circumferential groove is formed in the armature, which is completely covered by the stop element at adjacent anchor. The contact area of the armature with the stop element is therefore reduced by a maximum, namely by the groove width. Accordingly, the driving a hydraulic bonding of the armature to the stop element. In addition, the at least one groove formed in the armature reduces the mass of the armature, which also has a favorable effect on the dynamics of the armature.

Alternatively or additionally, it is proposed that at least one circumferential groove is formed within an end face of the stop element facing the armature, so that the groove is bounded radially inward and radially outward by the end face. In this arrangement too, the groove reduces the contact area between the armature and the stop element, so that hydraulic adhesive effects are counteracted.

Advantageously, the second end stop is formed by a pole core, which defines a working air gap together with the armature. On the position of the pole core to the valve body and thus the stop element, the stroke of the armature can be adjusted.

The pole core is preferably fixedly connected to the valve body via a sleeve, so that the once set stroke of the armature undergoes no change due to a relative movement of the pole core relative to the valve body. Preferably, the sleeve is welded to the pole core and / or the valve body. In this way, a particularly robust and also fluid-tight connection can be achieved.

Further, a high-pressure fuel pump for a fuel injection system is proposed with a suction valve according to the invention. The suction valve is preferably integrated in a housing part of the high-pressure fuel pump. This means that the valve stem of the suction valve is guided over a bore of the housing part of the high-pressure fuel pump and / or cooperates with a valve seat formed in the housing part of the high-pressure fuel pump. By integrating the suction valve in the high-pressure fuel pump, a particularly compact structure can be created.

Preferred embodiments of the invention are explained below with reference to the accompanying drawings. These show: 1 shows a schematic longitudinal section through an inventive suction valve, which is integrated in a fuel high pressure pump,

Fig. 2 a) an enlarged detail of Figure 1 in the region of the first end stop, and b) a plan view of the cooperating with the first end stop surface of the armature, and

Fig. 3 a) shows a schematic longitudinal section through an inventive suction valve according to another preferred embodiment, and b) a plan view of the stop element.

Detailed description of the drawings

The electromagnetically actuated intake valve 1 shown in FIG. 1 serves to supply a high-pressure fuel pump 2 with fuel. The suction valve 1 is for this purpose integrated in a housing part 20 of the high-pressure fuel pump 2, in such a way that a valve stem 6 of the suction valve 1 is guided in a liftable manner via a bore 21 formed in the housing part 20. The bore 21 opens via a valve seat 25 into a high-pressure element chamber 22 of the high-pressure fuel pump 2, so that when the intake valve 1 is open, fuel flows from a low-pressure chamber 26 via inlet bores 27 and the valve seat 25 into the high-pressure element chamber 22. When the intake valve 1 is closed, the fuel present in the high-pressure element space 22 is compressed by means of the lifting movement of a pump piston 29 and subsequently fed via an outlet valve 23 to a high-pressure accumulator (not shown).

The valve stem 6 is acted upon in the closing direction by the spring force of a valve spring 24, so that the spring force of the valve spring 24 pulls the valve stem 6 into the valve seat 25. In order to open the suction valve 1 against the spring force of the valve spring 24 or to keep it open, another spring 28 is provided whose spring force is greater than that of the valve spring 24. The further spring 28 is supported on the one hand on an armature 7, on the other hand on a pole core 17 which defines a working air gap 18 together with the armature 7. If a solenoid coil 3 provided for acting on the armature 7 remains de-energized, the spring force of the spring 28 keeps the suction valve 1 open. To close the suction valve Tils 1, the solenoid coil 3 is energized. It forms a magnetic field whose magnetic force pulls the armature 7 in the direction of the pole core 17 in order to close the formed between the pole core 17 and the armature 7 working air gap 18. By the movement of the armature 7 of the valve stem 6 is relieved, so that the valve spring 24 is able to pull the valve stem 6 in the valve seat 25 and the

Suction valve 1 closes.

During operation of the suction valve 1, the armature 7 moves between two end stops 4, 5 back and forth. The upper end stop 5 is presently formed by the pole core 17. As a lower end stop 4 is a stop element 12 which is inserted into a recess 8 of a valve body 9 and supported on an annular collar 13 of the valve body 9. The axial distance between the pole core 17 and the stop element 12 thus determines the maximum stroke of the armature 7. To permanently fix the position of the pole core 17 relative to the valve body 9, the pole core 17 is fixedly connected to the valve body 9 by means of a sleeve 19.

The stop element 12 has a central recess 15 through which a bolt-shaped portion of the armature 7 is guided for contacting the valve stem 6. At a the recess 15 delimiting plate-shaped section, a collar portion 14 of the stopper member 12 connects, which surrounds the annular collar 13 of the valve body 9. Preferably, the stop element 12 is pressed over the collar portion 14 in the valve body 9. The interference fit prevents the abutment member 12 from following the anchor 7 as it moves from the lower end stop 4 toward the upper end stop 5.

In order to prevent at the same time a hydraulic bonding of the armature 7 on the stop element 12, the armature 7 has four through holes 10, which are connected via a frontally formed in the armature 7 circumferential groove 11 (see Figures 2a and 2b)). The four through holes 10 are for this purpose in the same

Angular distance from each other along a circular line arranged. The groove 11 is formed as an annular groove having a common overlap region with the through holes 10. During a lifting movement of the armature 7 in the direction of the upper end stop 5, the groove 11 facilitates the detachment of the armature 7 from the stop element 12, since fuel flows under the armature 7 via the groove 11 to flow, so that no local vacuum areas arise. In conjunction with the four through holes 10, a quick pressure equalization is also achieved via the groove 11, which allows a high armature dynamics. A modification of the suction valve 1 of Fig. 1 is shown in Figures 3a) and 3b). Here, the groove 11 is not formed in the armature 7, but in an armature 7 facing end face 16 of the stop element 12. When fitting anchor 7, the groove 11 connects formed in the anchor 7 through holes 10, since they have a common coverage area. During an upward movement of the armature 7 thus fuel can flow through the groove 11 under the armature 7, so that it is easier to release from the stop element 12. The mode of action therefore essentially corresponds to that described above, so that reference is made to this.

Claims

claims 1 . Electromagnetically operated suction valve (1) for a high pressure fuel pump (2), comprising an annular solenoid (3) for acting on a between two end stops (4, 5) liftable and with a valve lifter (6) coupled armature (7), at least is partially accommodated in a recess (8) of a valve body (9), characterized in that the armature (7) has a plurality of eccentrically arranged through holes (10), the at least one circumferential groove (11) in the armature (7) and / or in a first end stop (4) forming stop element (12) is formed, hydraulically connected or connectable. 2. Suction valve according to claim 1,  characterized in that the stop element (12) is at least partially plate-shaped and axially supported on a in the recess (8) projecting annular collar (13) of the valve body (9). 3. Suction valve according to claim 2,  characterized in that the stop element (12) has a collar (13) of the valve body (9) embracing collar portion (14) via which preferably the stop element (12) in the valve body (9) is pressed. 4. Suction valve according to one of the preceding claims, characterized in that the stop element (12) has a central recess (15) which is hydraulically connected independently of the stroke of the armature (7) with the through holes (10). 5. Suction valve according to one of the preceding claims, characterized in that in the armature (7) at least one circumferential groove (11) is formed, which is completely covered by the stop element (12) at adjacent armature (7). 6. Suction valve according to one of the preceding claims,  characterized in that at least one circumferential groove (11) within an armature (7) facing end face (16) of the stop element (12) is formed so that it is radially inwardly and radially outwardly of the end face (16) limited. 7. Suction valve according to one of the preceding claims,  characterized in that the second end stop (5) by a pole core (17) is formed, which defines a working air gap (18) together with the armature (7). 8. Suction valve according to claim 7,  characterized in that the pole core (17) via a sleeve (19) is fixedly connected to the valve body (9), wherein preferably the sleeve (19) to the pole core (17) and / or the valve body (9) is welded. 9. High-pressure fuel pump (2) for a fuel injection system with a suction valve (1) according to one of the preceding claims, wherein preferably the suction valve (1) in a housing part (20) of the high-pressure fuel pump (2) is integrated.