GB2180887A

GB2180887A - Electromagnetically actuable fuel injection valve

Info

Publication number: GB2180887A
Application number: GB08622472A
Authority: GB
Inventors: Waldermar Hans; Wilhelm Kind
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1985-09-20
Filing date: 1986-09-18
Publication date: 1987-04-08
Also published as: DE3533521A1; DE3533521C2; JPS6270655A; GB8622472D0; JPH081161B2; GB2180887B

Abstract

An I.C. engine fuel injection valve comprises a nozzle body (9) with a valve needle (27), which is guided therein and has a shoulder (39) upstream of which is an abutment plate (12) having an opening (20) penetrated with radial play by the valve needle (27). A passage (37) extends between the opening (20) and the circumference of the abutment plate (12), the clear width of the passage being greater than the diameter of the needle (27) in the adjacent region (38). The wall of the opening (20) is interrupted by, apart from the passage (37), further recesses (42). Sticking between the abutment plate (12) and the needle shoulder (39), as can occur through adhesion forces and residual magnetic effects, is avoided through such a construction of the abutment plate. <IMAGE>

Description

SPECIFICATION Electromagnetically actuable fuel injection valve The present invention relates to an electromagnetic allyactuablefuel injection valve.

In a known fuel injection valve, the armature in the excited state of a magnet coil does not rest directly against a soft magnetic core ofthe valve, but an abut mentshoulder,which isformedatavalveneedle firmly connected with the armature, contacts an abutment fixed relative to the housing. In the valve described in DE-OS 29 05 099, this abutment is in the form of an abutment plate. Thus, a gap remains between armature and core even in the excited state of the magnet coil and magnetic sticking, as can arise duetoresidual magnetic effects, istherebyavoided.

Nevertheless, delays during lifting ofthe abutment shoulderfrom the abutment plate can arise afterthe switching-off of the magnet coil due to adhesion forces acting between the abutment shoulder and abutment plate. As a result of this sticking, erroneous metering by the fuel injection valve can occur.

According to the present invention there is provided an electromagnetically actuable fuel injection valve comprising a housing, a valve seat member connected to the housing and defining a valve seat, electro-magnetic-force generating means disposed in the housing, an armature arranged to be movable by such electromagnetic force, an elongate valve body connected to the armature and guided in the memberto co-operate with the valve seat, and an abutment plate arranged between the housing and the memberto define an end position ofthevalve body by contact with a shoulder thereof and having a central bore receiving a cylindrical portion ofthe valve body, a passage which is widerthan the diame terofthatportion and extends radiallyfrom the bore to the periphery of the plate, and at least one recess provided in the wall of the bore additional Iy to the passage.

Afuel injection valve embodying the present invention may have the advantage that sticking between the abutment plate and shoulder is largely avoided.

An embodiment of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which; Figure lisa sectional view of a fuel injection valve embodying the invention; and Figure2 is a plan view, to an enlarged scale, of an abutment plate ofthe valve of Figure 1.

Referring now to the drawings, there is shown in Figure 1 a fuel injection valve which is for a fuel injection system of a mixture-compressing, applied ignition internal combustion engine and comprises a housing 1 offerromagnetic material in which a magnet coil 3 is arranged on a coil carrier 2. The coil 3 has a currentfeed byway of a plug connection 4, which is embedded in a plastics material ring 5 partially encompassing the housing 1.

The carrier 2 ofthe coil 3 sits in a coil space 6 ofthe housing 1 on a connecting stub pipe 7, which feeds the fuel, for example petrol, and partially projects into the housing 1. The housing 1 remote from the stub pipe 7 partially encompasses a nozzle body 9.

Acylindrical armature 14 is disposed between an end face 11 ofthe stub pipe 7 and an abutment plate 12, which is placed on an internal shoulder 13 ofthe housing 1 and has a certain thickness for exact set- ting ofthevalve. The armature 14consists of a magnetic material not susceptible to corrosion and is disposed coaxially in the housing 1 art a small radial spacing from the housing 1,therebyforming a mag- netic gap. The armature 14 is provided with two coaxial blind bores 15 and 16, respectively, each extending from a respective one of its end faces, wherein the bore 16 opens out towards the body 9 and has a flat base which is provided with a coaxial bore 17 connecting the bores 15 and 16 together.The diameter ofthe bore 17 is smallerthan that ofthe bore 16.

That end portion of the armature 1 4which faces the nozzle body 9 is constructed as deformation region 18. This deformation region 18 has the task of mechanicallyconnecting the armature 14 with a valve needle 27 through embracing a retaining body which is part of the valve needle 27 and fills the bore 16. The embracing ofthe retaining body 28 by the deformation region 18 of the armature 14 is achieved through upsetting ofthe region 18.

Bearing on a flat face, facing the stub pipe 7, ofthe retaining body 28 is a compression spring 29, which is guidedthroughthe bore 17 ofthe armature l4and at the other side rests against a pipe insert 30, which is fastened in the stub pipe 7through drawing-in of the same,thespring thus acting on the armature 14 and valve needle 27 by a force directed away from the stub pipe7.

Let into the flat side, facing the stub pipe 7, ofthe retaining body 28 is a coaxial blind bore 31, which is of smaller diameter than the internal diameter of the spring 29 and at the bottom of which is disposed at least one, preferably obliquely arranged, through- flow opening 32, which produces a connection to an internal space 26 enciosed by the housing 1 and nozzle body 9. The space 26 receives the valve needle 27.

The valve needle 27 penetrates with radial play through a passage bore 20 in the abutment plate 12 and a guide bore 21 in the nozzle body 9 and has a needle spigot22 which projects outof an injection opening 23ofthe nozzle body 9. Formed between the guide bore 21 and the injection opening 23 is a conical valve seat surface 24, which co-operates with a conical sealing portion 25 ofthevalve needle 27. The length ofthevalve needle 27 and of the armature 14 is so dimensioned, starting from the sealing portion 25, that the armature 14 in the non-excited state of the coil 3 leaves a working gap free relative to the end face 11 of the stub pipe 7. When the coil 3 is excited, the thickness of this gap reduces without giving rise to direct contact of the armature 1 with stub pipe 7.

The valve needle 27 has two guide portions 33 and 34 which guidethevalve needle 27 in the bore 21 and leave an axial passage free forthe fuel, the guide por- tions being constructed with, for example, a rectangular cross-section.

In the excited state of the coil 3, the armature 14 is moved in opening direction ofthe valve needle 27 againsttheforce ofthe spring 29. The valve needle 27 then lies by a shoulder 39 against the flat side, facing the nozzle body 9, of the abutment plate 12.

Figure 2 shows one example ofthe abutment plate 12. Extending between the bore 20 and the circumference ofthe abutment plate 12 is a recess 37, the clear width ofwhich is greaterthan the diameter of the valve needle 27 in a cylindrical region 38 ofthevalve needle 27 between the retaining body 28 and the shoulder 39.

The bore 20 is interrupted at its circumference by, apartfrom the recess 37, at least one further, peferably part-circular, recess 42. The envelope surface of the bore 20 is thereby divided into at least two seg ments 43 and the contact area between shoulder 39 and abutment plate 12 is reduced.

Trials with such a valve have shown that the effect ofsticking between the shoulder 39 of the valve needle 27 and the flat side, resting against the nozzle body 9, of the abutment plate 12 can be appreciably reduced by the recesses 42. The optimum size of the recess 42 or ofthe recesses 42 may depend on different parameters, for example the diameter of the shoulder 39, the material property and surface ofthe valve needle 27 and abutment plate 12, the force on the valve needle 27, and the flow conditions.

The magneticflux is conducted through the sheli ofthehousing 1 bywayofa magneticfluxconduction step 40 to the armature 14 and from there byway ofthe stub pipe 7 serving as core with a conducting flage 50 backto the housing 1.

Claims

1. An electromagnetically actuable fuel injection valve comprising a housing, a valve seat member connected to the housing and defining a valve seat, electromagnetic-force generating means disposed in the housing, an armature arranged to be movable by such electromagnetic force, an elongate valve body connected to the armature and guided in the member to co-operate with the valve seat, and an abutment plate arranged between the housing and the member to define an end position ofthe valve body by contact with a shoulderthereof and having a central bore receiving a cylindrical portion ofthe valve body, a passage which is widerthan the diameter of that portion and extends radially from the bore to the periphery of the plate, and at least one recess provided in the wall ofthe bore addtionally to the passage.

2. Avalve as claimed in claim 1, wherein the at least one recess is part-circular in shape.

3. Avalveasclaimed in eitherclaim 1 or claim 2, wherein the abutment plate has two such recesses.

4. A valve substantially as hereinbefore described with reference to the accompanying drawings.

5. Afuel injection system for an internal combustion engine, the system comprising a valve as claimed in anyoneofthe preceding claims.