EP0900333A1

EP0900333A1 - Electromagnetically operated valve

Info

Publication number: EP0900333A1
Application number: EP98902943A
Authority: EP
Inventors: Clemens Willke; Jürgen GRANER; Dieter Maier
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1997-03-26
Filing date: 1998-01-09
Publication date: 1999-03-10
Anticipated expiration: 2018-01-09
Also published as: KR20000015943A; WO1998042976A1; CN1220722A; JP2000511616A; CN1089856C; ES2199419T3; DE19712590A1; DE59808230D1; BR9804798A; EP0900333B1; US6045116A

Abstract

The invention relates to an electromagnetically operated valve which has an axially displaceable valve needle (13), said valve needle comprising at least one armature (17) and one spherical valve closing body (18). Said armature (17) forms a closing body support which holds said valve closing body (18) with an end area (46) situated downstream, said end area (46) encompassing said valve closing body (18) in such a way that at least one channel (49) which is directly connected to a longitudinal bore (23) in said armature (17) is formed on the surface of said valve closing body (18). The valve is especially suitable for use in fuel injection devices of mixture-compressing internal combustion engines with externally supplied ignition.

Description

Electromagnetically actuated valve

State of the art

The invention relates to an electromagnetically actuated valve according to the preamble of the main claim.

An electromagnetically actuated valve is already known from DE-PS 38 31 196, in which a valve needle is formed from an armature, a tubular connecting part and a spherical valve closing body. The armature and the valve closing body are connected to one another via the tubular connecting part, the connecting part with which the valve closing body is firmly connected by means of a weld seam serving as the direct closing body carrier. The connecting part has a multiplicity of flow openings through which fuel exit from an inner through opening and outside of the

Connection part can flow to the valve closing body or to a valve seat surface interacting with the valve closing body. In addition, the connecting pipe has a longitudinal slot running over the entire length, through which fuel can flow very quickly coming from the inner through opening due to its large hydraulic flow cross section. The Most of the fuel to be sprayed flows out of the connecting part over the length of the connecting part, while a small remaining amount only emerges from the connecting part at the ball surface.

From DE-OS 195 03 224 an electromagnetically actuated injection valve is already known, which has a valve needle, the closing body carrier serving as a connecting part is formed from plastic. The spherical valve closing body and the closing body carrier are firmly connected to one another by a snap connection. A plurality of transverse openings are provided in the closing body support, through which fuel can emerge from an inner opening upstream of the valve closing body. The fuel subsequently flows outside of the closing body carrier in the direction of a valve seat surface, wherein it flows through flow channels formed on the outer circumference of the closing body carrier shortly before the valve seat surface.

It is well known, as can be seen from DE-OS 40 08 675, fixed connections of individual components of valve needles cohesively, for. B. to achieve by means of welds.

Advantages of the invention

The electromagnetically actuated valve according to the invention with the characterizing features of the main claim has the advantage that it can be produced inexpensively in a particularly simple manner. It is particularly advantageous that an extremely simple and inexpensive connection between a closing body carrier and a spherical valve closing body can be achieved. The closing body carrier is in an end region for reaching around formed of the valve closing body in such a way that it forms one or more channels directly on the surface of the valve closing body, through which fuel can flow unhindered coming from an inner longitudinal bore towards a valve seat surface. Optimal inflow to the metering area of the valve is achieved with little manufacturing effort. Compared to known valves, there are no transverse openings and slots in the closing body carrier and, on the other hand, grinding on the valve closing body or flow-through grooves in the valve seat body.

The measures listed in the subclaims allow advantageous developments and improvements of the electromagnetically actuated valve specified in the main claim.

It is particularly advantageous to use a non-material joining method, e.g. B. by pressing or flanging to fasten the striker. It is advantageous if the end region of the closing body carrier still protrudes in the downstream direction beyond a spherical equator of the spherical valve closing body.

In a particularly advantageous manner, the armature itself can serve directly as a closing body carrier, so that a two-part valve needle is present together with the valve closing body. Such a valve needle is particularly simple and inexpensive to manufacture and, due to the reduced number of parts, has only a single connection point. The longitudinal bore of the armature is advantageously designed with flow arms which merge directly into the channels in the end region of the closing body carrier. Especially such flow arms and the channels can be effectively shaped by means of spaces.

The anchor can advantageously be designed as a cold-pressed part. A connecting part serving as a closing body support can also be extruded. In extrusion molding, the channel-forming recesses can be formed very easily. The recesses no longer have to be deburred. The armature can advantageously be designed as a sintered part or MIM part.

drawing

Embodiments of the invention are shown in simplified form in the drawing and in the following

Description explained in more detail. 1 shows a first electromagnetically actuated valve according to the invention, FIG. 2 shows a first exemplary embodiment of a valve needle, FIG. 3 shows a section through the valve needle according to FIG. 2 along the line III-III, FIG. 4 shows a second

Embodiment of a valve needle and Figure 5 shows a third embodiment of a valve needle.

Description of the embodiments

The electromagnetically actuated valve according to the invention in the form of an injection valve for fuel injection systems of mixture-compressing, spark-ignited internal combustion engines, shown by way of example and partially in simplified form in FIG. 1, has a largely tubular core 2 surrounded by a magnetic coil 1, serving as the inner pole and partially as fuel flow an upper, disk-shaped cover element 3, the core 2 enables a particularly compact structure of the injection valve in the region of the Magnetic coil 1. The magnetic coil 1 is surrounded by an outer, ferromagnetic valve jacket 5 as the outer pole, which completely surrounds the magnetic coil 1 in the circumferential direction and at its upper end firmly with the cover element 3 z. B. is connected by a weld 6. To close the magnetic circuit, the valve jacket 5 is designed stepped at its lower end, so that a guide section 8 is formed, which axially encloses the magnet coil 1 similar to the cover element 3 and which represents the boundary of the magnet coil region 1 downwards or in the downstream direction .

The guide section 8 of the valve jacket 5, the magnet coil 1 and the cover element 3 form an inner opening 11 or 58, which extends concentrically to a longitudinal valve axis 10 and in which an elongated sleeve 12 extends. An inner longitudinal opening 9 of the ferritic sleeve 12 partially serves as a guide opening for a valve needle 13 that is axially movable along the longitudinal axis 10 of the valve. The sleeve 12 is therefore made to precise dimensions with respect to the inner diameter of the inner opening 9. The sleeve 12 ends viewed in the downstream direction, for example in the region of the guide section 8 of the valve jacket 5, with which it is fixedly connected, for example, with a weld seam 54. In addition to the axially movable valve needle 13, the fixed core 2 is also arranged in the longitudinal opening 9 of the sleeve 12. In addition to guiding the armature 17 or receiving the core 2, the sleeve 12 also fulfills a sealing function, so that a dry magnet coil 1 is present in the injection valve. This is also achieved in that the disc-shaped cover element 3 completely covers the magnet coil 1 on its upper side. The inner opening 58 in the cover element 3 allows the sleeve 12 and thus also the core 2 to be elongated, so that both Components protrude beyond the cover element 3 through the opening 58.

A valve seat body 14 adjoins the lower guide section 8 of the valve jacket 5 and has a fixed valve seat surface 15 as a valve seat. The valve seat body 14 is fixedly connected to the valve jacket 5 by means of a second weld 16, for example generated by a laser. The valve needle 13 is formed by a tubular armature 17 and a spherical one

Valve closing body 18 is formed, the armature 17 serving directly as a closing body carrier. On the downstream end face of the valve seat body 14 is, for. B. in a recess 19 a flat spray plate 20, the fixed connection of

Valve seat body 14 and spray plate 20 z. B. is realized by a circumferential dense weld 21. The tubular armature 17 is fixedly connected at its downstream end facing the spray orifice plate 20 to the spherical valve closing body 18, for example by flanging, grooves or channels being provided in the connection area, so that fuel flowing through the armature 17 in an inner longitudinal bore 23 comes out and can flow directly along the valve closing body 18 to the valve seat surface 15.

The injection valve is actuated electromagnetically in a known manner. For the axial movement of the valve needle 13 and thus for opening against the spring force of a return spring 25 or closing the injection valve, the electromagnetic circuit with the solenoid 1, the inner core 2, the outer valve jacket 5 and the armature 17 is used. The armature 17 is connected to the the valve closing body 18 facing away from the core 2. The spherical valve closing body 18 interacts with the valve seat surface 15 of the valve seat body 14 which tapers in the shape of a truncated cone and is formed in the axial direction downstream of a guide opening 26 in the valve seat body 14. The spray plate 20 has at least one, for example four, spray openings 27 formed by erosion or stamping.

The insertion depth of the core 2 in the injection valve is, among other things, decisive for the stroke of the valve needle 13. The one end position of the valve needle 13 when the solenoid coil 1 is not energized is determined by the valve closing body 18 bearing against the valve seat surface 15 of the valve seat body 14, while the other The end position of the valve needle 13 when the solenoid coil 1 is excited results from the contact of the armature 17 at the downstream end of the core 2. The stroke is adjusted by axially displacing the core 2 in the sleeve 12, which is subsequently firmly connected to the sleeve 12 in accordance with the desired position, laser welding being useful for achieving a weld seam 22.

In addition to the return spring 25, an adjusting sleeve 29 is inserted into a flow bore 28 of the core 2, which runs concentrically with the valve longitudinal axis 10 and serves to supply the fuel in the direction of the valve seat surface 15. The adjusting sleeve 29 is used to adjust the spring preload of the return spring 25 abutting the adjusting sleeve 29, which in turn is supported with its opposite side on the armature 17, the dynamic injection quantity also being adjusted using the adjusting sleeve 29.

Such an injection valve is characterized by its particularly compact construction, so that a very small, Handy injection valve is formed, the valve jacket 5 of which, for example, has an outer diameter of only approximately 11 mm. The components described so far form a preassembled independent assembly, which can be referred to as functional part 30. The fully set and assembled functional part 30 has z. B. on an upper end face 32, for example, two contact pins 33 protrude. The electrical contacting of the magnetic coil 1 and thus its excitation takes place via the electrical contact pins 33, which serve as electrical connecting elements.

With such a functional part 30, a connection part (not shown) can be connected, which is distinguished above all by the fact that it comprises the electrical and the hydraulic connection of the injection valve. A hydraulic connection between the connection part (not shown) and the functional part 30 is achieved in the fully assembled injection valve in that flow bores of both assemblies are brought together so that an unimpeded flow of fuel is ensured. It is then z. B. the end face 32 of the functional part 30 directly to a lower end face of the connecting part and is firmly connected to this. When the connection part is mounted on the functional part 30, the part of the core 2 and the sleeve 12 projecting beyond the end face 32 can protrude into a flow bore of the connection part in order to increase the connection stability. In the connection area for secure sealing z. B. a sealing ring 36 is provided, which rests on the end face 32 of the cover 3, the sleeve 12. The contact pins 33 serving as electrical connecting elements go with a secure electrical connection in the fully assembled valve corresponding electrical connecting elements of the connecting part.

Figure 2 shows the valve needle 13 on an enlarged scale compared to Figure 1. The tubular armature 17 is designed as a turned part, which has a multi-step outer contour. On the outer circumference of the armature 17, for example, two annular guide surfaces 40 and 41 are formed, which serve on the one hand to guide the axially movable valve needle 13 in the sleeve 12 and on the other hand to guide the valve seat body 14. The armature 17, for example made of a ferritic material (chrome steel), has an upper stop surface 42 facing the core 2, which is provided with a wear protection layer, e.g. B. is chrome-plated.

The inner longitudinal bore 23 in the armature 17 has a largely circular cross section, but the z. B. is interrupted after 120 ° in circumference, since three flow arms 44 extend from it. The flow arms 44, introduced for example by broaching, run over the entire axial length of the armature 17. The profiled inner contour of the armature 17 can be produced by means of so-called inner broaching, the broaching tool having a plurality of staggered cutting edges and a straight line

Performs cutting movement in the longitudinal bore 23. At its lower end facing the valve closing body 18, the inner longitudinal bore 23 has a conical shoulder 45, through which the longitudinal bore 23 widens in the downstream direction and which serves as a stop for the valve closing body 18. Starting from the shoulder 45, an end region 46 of the armature 17 extends along the outer circumference of the spherical valve closing body 18, the flow arms 44 also ensuring corresponding interruptions in the end region 46. The spherical valve closing body 18 has a spherical equator 48 running perpendicular to the longitudinal axis 10 of the valve, up to or over which the end region 46 extends as seen in the downstream direction. In other words, at least one hemisphere and thus the radius of the spherical valve closing body 18 are encompassed by the armature 17. The end region 46 has a larger outer diameter than the valve closing body 18. The firm connection of the armature 17 serving as the closing body carrier and the valve closing body 18 is achieved, for example, by flanging or pressing or by pressing in and subsequent flanging, the encompassing region downstream of the ball equator 48 being one of them secure connection guaranteed. The flow arms 44 of the longitudinal bore 23 merge in the region of the valve closing body 18 into narrow channels 49 which are open towards the circumference of the end region 46 and through which the fuel supplied in the longitudinal bore 23 and flowing along the spherical surface is passed in the direction of the valve seat surface 15. These channels 49 are formed, for example, in the same broaching process as the flow arms 44. This design of the valve needle 13 enables a very simple inflow of the fuel to the metering area of the injection valve. Figure 3 is a sectional view of a section along the

Line III-III in FIG. 2. It mainly clarifies the contour of the inner longitudinal bore 23 in the armature 17 with its three flow arms 44 which are each formed at 120 ° and run radially outward.

FIG. 4 shows a second exemplary embodiment of a valve needle 13, in which the parts that are the same or have the same effect as the exemplary embodiment shown in FIG. 2 are identified by the same reference numerals. The valve needle 13 according to FIG. 4 is characterized by a slightly differently shaped inner longitudinal bore 23. The anchor 17, now available as a cold pressed part, has a stepped longitudinal bore 23 which has a continuously circular cross section. In turn, guide surfaces 40 and 41 are provided on the outer circumference of the armature, which serve to guide the valve needle 13. Likewise, the end region 46 of the armature 17 extends beyond the spherical equator 48 of the valve closing body 18 in the downstream direction. Beginning in the region of the shoulder 45, at least one, for example three grooves or channels 49 are in turn formed in the end region 46, which have an axial extension component starting from the longitudinal bore 23 and through which the fuel flows in the direction of the valve seat surface 15. The spherical valve closing body 18 is, for example, pressed into the longitudinal bore 23 of the armature 17 and / or fastened in the end region 46 by flanging.

A further exemplary embodiment of a valve needle 13 is shown in FIG. 5. In this exemplary embodiment of the valve needle 13, the armature 17 and the valve closing body 18 are connected to one another via a sleeve-shaped connecting part 50. All connections on the valve needle 13 are made by means of non-integral joining processes. The ferritic anchor 17, which is for example an extruded part, is, for. B. pressed onto the upstream end of the connecting part 50 with a central holding area 53. An upper annular guide surface 40 for guiding the valve needle 13 during its axial movement results from the armature 17 having a dimensionally accurate

Ring leg 51 is formed. In the connection area with the armature 17 there is, for example, also extruded but austenitic connection part 50 with at least one axially extending slot-shaped recess 52 provided by which the assembly of the armature 17 on the connecting part 50 is improved.

At the downstream end of the connecting part 50, a guide ring 55 is pressed onto the outer circumference of the connecting part 50, which has an H-shaped cross section and has the lower guide surface 41 on its outer circumference. As already described, the spherical valve closing body 18 is in turn firmly connected by pressing or flanging, but here not with the armature 17, but with the connecting part 50 which now serves as a closing body carrier. The grooves or channels 49 required for the passage of fuel become open during the extrusion of the connecting part 50 cut out one or more times very easily. The spherical valve closing body 18 is introduced into the downstream end of the longitudinal bore 23 supplying the fuel, with a conical shoulder 45 again serving as a stop. Advantageously, the grooves or channels 49 or recesses 52 made during the extrusion of the connecting part 50 need not be deburred. Furthermore, no cuts are required on the valve closing body 18 for fuel to pass through, since coming from the longitudinal bore 23 it can flow freely through the channels 49 along the surface of the valve closing body 18.

In addition to the design of the closing body support 17, 50 as a turned part or cold pressed part, designs as a sintered part or MIM (metal injection molding) part are also possible.

Claims

claims

1. Electromagnetically actuated valve, in particular injection valve for fuel injection systems from

Internal combustion engines, with a longitudinal valve axis, with a core which is at least partially surrounded by a magnetic coil, with an axially movable valve needle, which comprises at least one closing body carrier and a spherical valve closing body, the valve closing body being fixedly connected to the closing body carrier and cooperating with a fixed valve seat, and the Closing body carrier has an inner longitudinal bore which extends to the surface of the valve closing body and has a downstream end region which has a larger outer diameter than the diameter of the valve closing body, characterized in that the closing body carrier (17, 50) has the valve closing body (18) with the end region (46) encompasses such that at least one channel (49) which is connected to the longitudinal bore (23) and has an axial extension component is formed along the surface of the valve closing body (18), which s I extends to the end of the end region (46) and at least up to a ball equator (48) of the valve closing body (18) in the downstream direction.

2. Valve according to claim 1, characterized in that the valve closing body (18) can be fastened by pressing into the longitudinal bore (23) in the end region (46) of the closing body carrier (17, 50).

3. Valve according to claim 1, characterized in that the valve closing body (18) by means of flanging in the longitudinal bore

(23) can be fastened in the end region (46) of the closing body carrier (17, 50).

4. Valve according to one of the preceding claims, characterized in that the closing body carrier (17) is designed as an anchor.

5. Valve according to one of claims 1 to 3, characterized in that an armature (17) and the valve closing body (18) connecting part (50) is provided, which serves as a closing body carrier.

6. Valve according to one of the preceding claims, characterized in that the closing body carrier (17, 50) in the longitudinal bore (23) has a shoulder (45) which serves as a stop for the valve closing body (18).

7. Valve according to claim 4, characterized in that in the longitudinal bore (23) of the armature (17) a plurality of flow arms (44) are provided which merge directly into the channels (49) in the axial direction.

8. Valve according to claim 7, characterized in that the flow arms (44) and the channels (49) can be formed by means of spaces in the armature (17).

9. Valve according to one of the preceding claims, characterized in that three channels (49) are provided in the end region (46).

10. Valve according to one of the preceding claims, characterized in that the closing body carrier (17, 50) represents a turned part or a cold pressed part.

11. Valve according to one of / claims 1 to 9, characterized in that the closing body carrier (17, 50) is a sintered part or a MIM part.