WO2019063209A1

WO2019063209A1 - Electromagnetically actuatable inlet valve and high-pressure pump comprising an inlet valve

Info

Publication number: WO2019063209A1
Application number: PCT/EP2018/072630
Authority: WO
Inventors: Steffen Holm; Gabriel CICHON
Original assignee: Robert Bosch Gmbh
Priority date: 2017-09-29
Filing date: 2018-08-22
Publication date: 2019-04-04
Also published as: DE102017217489A1

Abstract

The invention relates to an electromagnetically actuatable inlet valve (24) for a high-pressure pump, in particular of a fuel-injection system. The inlet valve (24) has a valve member (34) which can be moved between an open position and a closed position. An electromagnetic actuator (60), by means of which the valve member (34) can be moved, is provided, wherein the electromagnetic actuator (60) comprises a solenoid coil (64), a magnetic core (66) and an armature (68) which acts at least indirectly on the valve member (34). The armature is displaceably guided in a recess (76) of a support element (78) in the direction of its longitudinal axis (69). The magnetic core (66) and the support element (78) are surrounded by a housing (70). In the housing (70), at least one sacrificial anode (96) is arranged in an intermediate space (94) between the housing (70) on the one hand and the support element (78) and/or the magnetic core (66) and/or a connecting element (92) connecting the magnetic core (66) and the support element (78) to one another. The at least one sacrificial anode (96) is electrically conductively connected to the support element (78) and/or the magnetic core (66) and/or the connecting element (92). The at least one sacrificial anode (96) consists of a less noble metal than the support element (78) and/or the magnetic core (66) and/or the connecting element (92).

Description

description

Title:

Electromagnetically actuated inlet valve and high-pressure pump with inlet valve

The invention relates to an electromagnetically operable inlet valve for a high pressure pump, in particular a fuel injection system, according to the preamble of claim 1. Furthermore, the invention relates to a high pressure pump with such an inlet valve.

State of the art

An electromagnetically operable inlet valve for a high-pressure pump of a fuel injection system is known from DE 10 2015 212 390 A1. The high-pressure pump has at least one pump element with one in one

Stroke driven pump piston limiting a pump working space. The pump working space can be connected to an inlet for the fuel via the inlet valve. The inlet valve comprises a valve member which cooperates with a valve seat for control and which is movable between an open position and a closed position. In its closed position, the valve member comes to rest against the valve seat. Furthermore, the inlet valve comprises an electromagnetic actuator, through which the valve member is movable. The electromagnetic actuator has a magnetic coil, a magnetic core and an at least indirectly acting on the valve member armature. The magnet armature is displaceably guided in a receptacle in a carrier element. When the solenoid is energized, the armature is movable against the force of a return spring. The carrier element and the magnetic core are connected to each other via a sleeve-shaped connecting element, wherein the connecting element can be welded to the carrier element and / or the magnetic core. The magnet core, the carrier element and the connecting element are surrounded by a housing. Between the magnetic core, the support element and the connecting element on the one hand and the housing on the other hand, a gap is present, which is filled with air. Upon heating and cooling of the actuator, moisture may enter the gap from the environment of the actuator. This can lead to corrosion of the carrier element, magnet armature and connecting element, wherein in particular the welded joint of the connecting element can be damaged, so that no secure connection of the magnetic core with the carrier element is more present. Even if sealing measures are provided on the housing, a reliable hermetic seal can not be ensured, so that corrosion can not be ruled out.

Disclosure of the invention

Advantages of the invention

The inlet valve according to the invention with the features of claim 1 has the advantage that the magnetic core and / or the carrier element and / or the connecting element are protected by the at least one sacrificial anode from corrosion. If moisture is present, there is corrosion of the sacrificial anode and not the components connected to it.

In the dependent claims advantageous refinements and developments of the inlet valve according to the invention are given. In the claims 3 to 6 particularly advantageous embodiments and arrangements of at least one sacrificial anode are given. In claim 7, an advantageous choice of material for the at least one sacrificial anode is specified.

drawing

Several embodiments of the invention are described below with reference to the accompanying drawings. 1 shows a schematic longitudinal section through a high pressure pump, Figure 2 shows an enlarged view of a designated in Figure 1 with II section with the inlet valve of the high-pressure pump with a sacrificial anode according to a first Ausführungsbeii- 3, the inlet valve with the sacrificial anode according to a second embodiment, Figure 4 shows the inlet valve with the sacrificial anode according to a third embodiment, Figure 5, the inlet valve with the sacrificial anode according to a fourth embodiment and Figure 6, the inlet valve with the sacrificial Ode de fifth embodiment.

Description of the embodiments

In Figure 1, a high pressure pump is shown in fragmentary form, which is provided for the production of fuel in a fuel injection system of an internal combustion engine. The high-pressure pump has at least one pump element 10, which in turn has a pump piston 12, which is driven by a drive in a lifting movement, is guided in a cylinder bore 14 of a housing part 16 of the high pressure pump and in the cylinder bore 14 a pump working space 18 limited. As a drive for the pump piston 12, a

Drive shaft 20 may be provided with a cam 22 or eccentric on which the pump piston 12 is supported directly or via a plunger, for example a roller tappet. The pump working chamber 18 can be connected to a fuel inlet 26 via an inlet valve 24 and via an outlet valve 28 to a reservoir 30. During the suction stroke of the pump piston 12, the pump working chamber 18 can be filled with fuel when the inlet valve 24 is open. During the delivery stroke of the pump piston 12, fuel is expelled from the pump working chamber 18 and conveyed into the reservoir 30 when the inlet valve 24 is closed.

In the housing part 16 of the high-pressure pump, as shown in FIG. 2, a through-bore 32 with a smaller diameter than the cylinder bore 14, which opens on the outside of the housing part 16, adjoins the cylinder bore 14 on its side facing away from the pump piston 12. The inlet valve 24 has a piston-shaped valve member 34, the one in the through hole

32 slidably guided shaft 36 and a diameter in relation to the shaft 36 larger head 38 which is arranged in the pump working chamber 18. At the transition from the cylinder bore 14 to the through hole 32, a valve seat 40 is formed on the housing part 16, with which the valve member 34 cooperates with a formed on its head 38 sealing surface 42. In a subsequent to the valve seat 40 portion, the through hole 32 has a larger diameter than in the shaft 36 of the valve member 34 leading section, so that the shaft 36 of the valve member 34 surrounding annular space 44 is formed. In the annular space 44 open one or more inlet bores 46, on the other hand open on the outside of the housing part 16.

The shaft 36 of the valve member 34 protrudes on the pump working chamber 18 side facing away from the housing part 16 out of the through hole 32 and on this a support member 48 is attached. On the support member 48, a valve spring 50 is supported, on the other hand supported on a shaft 36 of the valve member 34 surrounding region of the housing part 16. By the valve spring 50, the valve member 34 is acted upon in a direction A in its closing direction, the valve member 34 in its closed position with its sealing surface 42 abuts the valve seat 40. The valve spring 50 is for example as

Formed helical compression spring.

The inlet valve 24 is actuated by an electromagnetic actuator 60, which is shown in particular in Figures 2 and 3. The actuator 60 is controlled by an electronic control device 62 as a function of operating parameters of the internal combustion engine to be supplied. The electromagnetic actuator 60 has a magnetic coil 64, a magnetic core 66 and a magnet armature 68. The electromagnetic actuator 60 is arranged on the pump working chamber 18 side facing away from the inlet valve 24. The magnetic core 66 and the magnetic coil 64 are surrounded by an actuator housing 70 which is on the housing part

16 of the high-pressure pump can be fastened. The actuator housing 70 is made of plastic and in this the magnetic coil 64 is received. By way of example, the actuator housing 70 can be fastened to the housing part 16 by means of a screw ring 72 that engages over it and which is screwed onto a collar 74 of the housing part 16 provided with an external thread.

The armature 68 is at least substantially cylindrical in shape and slidably guided over its outer jacket in a receptacle in the form of a bore 76 in a support member 78 in the direction of its longitudinal axis 69. The bore 76 in the carrier element 78 extends at least approximately coaxially to

Through hole 32 in the housing part 16 of the high-pressure pump and thus to Valve member 34. The bore 76 is followed in the support member 78 to the inlet valve 24 through a further bore 77 with a smaller diameter than the bore 76 at.

The magnet armature 68 has an at least approximately coaxial to the longitudinal axis 69 of the armature 68 arranged central blind bore 81 into which a on the valve member 34 remote from the armature 68 disposed return spring 82 projects, which is supported on the armature 68. The return spring 82 is supported at its other end at least indirectly on the magnetic core 66, which has a central blind bore 84 into which the return spring 82 protrudes. In the bore 84 of the armature 66, a support member 85 may be inserted for the return spring 82, for example, be pressed. The magnet armature 68 has one or more through openings 91 to allow passage of fuel during the movement of the magnet armature 68.

In the bore 76, an annular shoulder 88 is formed by the diameter reduction to the further bore 77. Between the annular shoulder 88 and the magnet armature 68 may be arranged a stop element 90, by which the movement of the armature 68 is limited to the inlet valve 24. The stop element 90 is sleeve-shaped and through this the magnet armature 68 protrudes toward the inlet valve 24 and comes at least indirectly on the valve member 34 to the plant. The magnetic core 66 and the carrier element 78 are connected to one another via a sleeve-shaped connecting element 92, which on the magnetic core 66 and on the carrier element 78 by means of a respective one

Welded joint 93 is attached.

Between the support member 78, the magnetic core 66 and the connecting element 92 on the one hand and the surrounding actuator housing 70 on the other hand, a gap 94 is present. The gap 94 extends in the radial direction with respect to the longitudinal axis 69 of the magnet armature 68 between the carrier element 78, the connecting element 92 and the magnetic core 66 on the one hand and the actuator housing 70 on the other. In the direction of the longitudinal axis 69 of the magnet armature 68, the intermediate space 94 extends along the carrier element 78, the connecting element 92 and the magnetic core 66 up to the end of the magnetic core 66 facing away from the carrier element 78. According to the invention, at least one sacrificial anode 96 is arranged in the intermediate space 94, which is electrically conductively connected to the carrier element 78 and / or the connecting element 92 and / or the magnetic core 66 and which consists of a less noble metal than the carrier element 78 and / or the connecting element 92 and / or the magnetic core 66. The carrier element 78, the connecting element 92 and the magnetic core 66 are usually made of ferrous alloys or steel. The at least one sacrificial anode 96 is made, for example, of magnesium or aluminum or an alloy containing at least one of these metals.

2, the inlet valve 24 is shown with the sacrificial anode 96 according to a first embodiment. In this case, the sacrificial anode 96 is sleeve-shaped and surrounds the connecting element 92 at least over part of its circumference, preferably over its entire circumference. In the direction of the longitudinal axis 69 of the magnet armature 68, the sacrificial anode extends over almost the entire length of the connecting element 92. The sacrificial anode 96 is inserted into the actuator housing 70, in particular pressed into its outer jacket in this. The sacrificial anode 96 is preferably connected to the carrier element 78 or alternatively electrically connected to the connecting element 92 or the magnetic core 66. The electrically conductive connection of the sacrificial anode 96 to the carrier element 78, the connecting element 92 or the magnetic core 66 can be effected by direct contact or for example via at least one of the sacrificial anode 96 radially inwardly protruding preferably resilient contact arm 97. When placing the actuator housing 70 on the carrier element 78 and the magnetic core 66, the electrically conductive connection of the sacrificial anode 96 is produced. Since the magnetic core 66 is connected to the carrier element 78 via the connecting element 92 and these parts consist of electrically conductive material results from the sacrificial anode 96 corrosion protection for these parts regardless of which of the parts sacrificial anode 96 is electrically conductively connected.

FIG. 3 shows the inlet valve 24 with the sacrificial anode 96 according to a second exemplary embodiment, wherein the sacrificial anode 96 is arranged in the region of the magnetic core 66. The sacrificial anode 96 is ring-shaped and surrounds the magnetic core 66 at least over part of its circumference, preferably over its entire circumference. The sacrificial anode 96 is preferred way electrically conductively connected to the magnetic core 66. The extent of the annular sacrificial anode 96 in the direction of the longitudinal axis 69 is less than the extension of the sleeve-shaped sacrificial anode 96 according to the first embodiment.

FIG. 4 shows the inlet valve 24 with the sacrificial anode 96 according to a third exemplary embodiment, wherein the sacrificial anode 96 is arranged in the region of the carrier element 78 and has a ring shape. The support member 78 has an at least approximately frusto-conical portion 79 connecting a cylindrical portion of the smaller diameter support member 78 on which the connection member 92 is disposed to a cylindrical portion of the larger diameter support member 78 facing the housing part 16 of the pump is arranged. The sacrificial anode 96 according to the third embodiment is adapted to the portion 79 of the support member 78 is also frusto-conical and surrounds the portion 79 at least on a part of the circumference, preferably over the entire circumference, and is electrically conductively connected to the portion 79.

FIG. 5 shows the inlet valve 24 with the sacrificial anode 96 according to a fourth exemplary embodiment, wherein the sacrificial anode 96 is arranged in the region of the magnetic core 66. The sacrificial anode 96 is arranged on the carrier element 78 facing away from the end face of the magnetic core 66 and formed disc-shaped. The sacrificial anode 96 is electrically conductively connected to the magnetic core 66.

In an embodiment shown in Figure 6, the sacrificial anode 96 is not designed as a form-containing component but introduced in the form of a powder or granules in the space 94. The sacrificial anode 96 fills the gap 94 at least partially and is electrically conductively connected to the carrier element 78 and / or the connecting element 92 and / or the magnetic core 66. The sacrificial anode 96 is symbolized in Figure 6 by a plurality of points. The function of the solenoid-operated intake valve will be described below

24 explained. During the suction stroke of the pump piston 12, the intake valve til 24 opened by the valve member 34 is in its open position, in which this is arranged with its sealing surface 42 away from the valve seat 40. The movement of the valve member 34 in its open position is effected by the prevailing between the fuel inlet 26 and the pump working chamber 18 pressure difference against the force of the valve spring 50. The magnetic coil 64 of the actuator 60 may be energized or de-energized. When the solenoid 64 is energized, the armature 68 is pulled by the resulting magnetic field against the force of the return spring 82 to the magnetic core 66 out. When the solenoid 64 is deenergized, the armature 68 is urged toward the inlet valve 24 by the force of the return spring 82. The magnet armature 68 abuts at least indirectly on the end face of the shaft 36 of the valve member 34.

During the delivery stroke of the pump piston 12 is determined by the actuator 60, whether the valve member 34 of the inlet valve 24 is in its open position or closed position. When energized solenoid 64, the armature 68 is pressed by the return spring 82 in the direction of arrow B in Figure 2, wherein the valve member 34 is pressed by the armature 68 against the valve spring 50 in the direction of adjustment B in its open position. The force of the force acting on the armature 68 return spring 82 is greater than the force of the valve member 34 acting on the valve spring 50. In the direction of adjustment B, the armature 68 acts on the valve member 34 and the armature 68 and the valve member 34 are together in the direction of adjustment B emotional. As long as the solenoid coil 64 is not energized can thus be promoted by the pump piston 12 no fuel in the memory 30 but displaced by the pump piston 12 fuel is fed back into the fuel inlet 26. If during the delivery stroke of the pump piston 12 fuel is to be conveyed into the reservoir 30, the magnetic coil 64 is energized, so that the magnet armature 68 is pulled toward the magnetic core 66 in a direction opposite to the direction of adjustment B as indicated by arrow A in FIG. By the armature 68 thus no force is exerted on the valve member 34, wherein the armature

68 is moved by the magnetic field in the direction of adjustment A and the valve member 34 is moved independently of the armature 68 due to the valve spring 50 and the pressure prevailing between the pump chamber 18 and the fuel inlet 26 pressure difference in the direction of adjustment A in its closed position. By opening the inlet valve 24 during the delivery stroke of the pump piston 12 by means of the electromagnetic actuator 60, the delivery rate of the high pressure pump can be set variably in the memory 30. When a small fuel delivery amount is required, the intake valve 24 is kept open by the actuator 60 during a large part of the delivery stroke of the pump piston 12, and when a large fuel delivery amount is required, the intake valve 24 becomes only for a small part or not at all during the delivery stroke the pump piston 12 is kept open.

Claims

5 claims

An electromagnetically actuated inlet valve (24) for a high pressure pump, in particular a fuel injection system, having a valve member (34) movable between an open position and a closed position, with an electromagnetic actuator (60) through which the valve member (34) is movable is, wherein the electromagnetic actuator (60) comprises a magnetic coil (64), a magnetic core (66) and an at least indirectly on the valve member (34) acting armature (68) in a receptacle (76) of a support member (78) in Direction of its longitudinal axis (69) ver-5 is slidably guided, wherein the magnetic core (66) and the carrier element

(78) surrounded by a housing (70), characterized in that in the housing (70) in a gap (94) between the housing (70) on the one hand and the support member (78) and / or the magnetic core (66) and / or at least one of the magnetic core (66) and the carrier element (78) together with the connecting connecting element (92)

Sacrificial anode (96) is arranged, which is electrically conductively connected to the carrier element (78) and / or the magnetic core (66) and / or the connecting element (92) and which consists of a less noble metal than the carrier element (78) and / or the magnetic core (66) and / or the connection 5 element (92).

2. Inlet valve according to claim 1, characterized in that the connecting element (92) by means of at least one welded connection (93) with the carrier element (78) and / or the magnetic core (66) is connected.0

3. inlet valve according to claim 1 or 2, characterized in that the at least one sacrificial anode (96) is at least approximately sleeve-shaped or annular and the support member (78) and / or the magnetic core (66) and / or the connecting element (92) at least part of 5 surrounds its circumference.

4. inlet valve according to claim 1 or 2, characterized in that the at least one sacrificial anode (96) on the carrier element (78) facing away from the end face of the magnetic core (66) is arranged and preferably at least approximately disc-shaped.

5. inlet valve according to one of the preceding claims, characterized in that the at least one sacrificial anode (96) inserted into the housing (70), in particular is pressed.

6. inlet valve according to claim 1 or 2, characterized in that the at least one sacrificial anode (96) in powder or granular form in the intermediate space (94) is introduced and at least partially fills it.

7. Inlet valve according to one of the preceding claims, characterized in that the at least one sacrificial anode (96) consists of magnesium or aluminum or a magnesium or aluminum-containing alloy.

8. Pump, in particular high-pressure fuel pump, with at least one

Pump element (10), which has a pump piston (12) delimiting a pump working chamber (18), wherein the pump working chamber (18) can be connected to an inlet (26) via an inlet valve (24), characterized in that the inlet valve (24) according to one of the preceding claims is formed.