KR940011344B1 - Fuel injection valve - Google Patents

Abstract

The fuel injection valve has a ferromagnetic valve housing containing a magnetic coil surrounding a core to which the valve armature is attached. The valve armature supports a valve needle (27) cooperating with an annular valve seat (48). The seal between the valve needle (27) and the valve seat (48) is provided by a rounded surface (90) defined by a toroid (94) with a circular or elliptical cross-section in the outer surface of the valve needle (27). Oref. the toroid (94) has an elliptical cross-section with its major axis parallel to the longitudinal axis of the valve needle (27).

Description

[Name of invention]

Fuel injection valve

[Brief Description of Drawings]

Embodiments of the present invention are briefly shown in the drawings and are shown in detail in the following description.

1 shows a preferred embodiment of a fuel injection valve according to the present invention,

2 is an enlarged view of one section in FIG.

3 shows two other embodiments of the valve needle in the region of the sealing sheet in the form of two half sections.

Detailed description of the invention

[Private Technology]

The present invention relates to a fuel injection valve which belongs to the general manner of claims 1 or 6. Known fuel injection valves that cooperate with the valve needle as a closure have a conical sealing sheet at the tip of the valve needle that opens or closes the flow hole of the fuel in conjunction with a similar conical valve seat surface. For example, such fuel injection valves known from Federal Republic No. 3,502,410 have the disadvantage that burrs may be produced in which the sealing surface of the valve needle is ground, resulting in damage to the sealing effect and flow characteristics. . If such burrs are removed continuously, deformation and edge damage can occur in the sealing sheet.

Another known fuel injection valve cooperates with a spherical closure that is attached to the actual valve needle (Germany 3,318,486). With the exception of the additional manufacturing steps required at the time of manufacture, such valves develop the disadvantage of "attaching" hydraulically when the valves are away from the valve seat surface and thus delaying the reaction. This effect is based on a flatter contact between the closure and the valve seat surface due to the relatively large radius of the sphere, and short-term negative pressure is generated in the seal because the fuel flows slowly into the empty space as the two parts move away from each other.

In addition, a fuel injection valve is known from Federal Republic No. 3,301,501, wherein the pierced disc is located downstream of the valve seat to improve the injected fuel jet. Fuel is injected through a hole made in the inner side of the pierced disc in the inner wall of the processing sleeve. The actual injection end of such a fuel injection valve forms the closing collar of the processing sleeve. The disadvantage of this fuel injection valve is that the fuel jet generated by the pierced disk impinges at a steep angle on the inner wall of the treatment sleeve. The impact point is also upstream of the dispensing end of the treatment sleeve. The fuel flows to the injection end itself in a "spiral" along the inner wall of the treatment sleeve, and the injection takes place in a conical shape. The droplets injected during this process are relatively large and hinder the formation of an optimal fuel-air mixture.

Pegs are known from publication 3,301,501, which form part of a penetrated disc and partly protrude into the valve needle body and also form an annular duct towards the nozzle body. However, this annular duct is not advantageously designed with respect to flow. Fuel coming from the valve seat is not "informed" into the penetrated disk and can be collected in various voids. This prolongs the time period between the rise of the valve component away from the valve seat and the injection of fuel from the aperture, and the valve runs late.

Advantages of the Invention

The fuel injection valve according to the invention has the features of the features of claims 1 or 6 and, in contrast, has the advantage of being easy, accurate in production, and free of burrs and other impurities damaging the flow. In addition, the smooth surface contours of the valve needle and valve seat surface make a very good correlation between the stroke of the valve needle and the volume of fuel ejected. Since the valve needle is hydraulically attached to the valve seat surface greatly suppressed, the fuel injection valve operates in a short opening time.

In particular, there is an advantage of rounding the transition portion disposed downstream of the sealing sheet to achieve uniform fuel flow from the sealing sheet.

Particularly good spraying of fuel is possible if the fuel is injected through a number of holes in a thin platelet sandwiched between the nozzle body and the processing sleeve. Such platelets can be manufactured easily and inexpensively, and can also be manufactured in a shape capable of reliable centering by deep drawing.

It is advantageous to provide a peg that almost reaches the platelets in the valve needle. Due to the annular space formed between the peg and the nozzle body, the fuel flow is quiet and guided to the hole without disturbing the effective space. Flow optimization is also made possible by appropriately machining the valve needle in the region between the valve seat and the peg, for example by using a radius instead of an angled transition. In practice, this reduces the reaction time of the fuel injection valve between the rise of the valve needle in the valve seat and the injection of fuel in the aperture. Designing the pegs as part of the valve needle rather than as part of the platelet provides manufacturing gains.

Further development and refinement of the fuel injection valve as defined in claim 1 or 6 is made possible by the treatment means described in other claims.

Description of Example

The fuel injection valve, shown by way of example in the figure for use in a fuel injection system of a mixture compression external ignition internal combustion engine, has a valve housing 1 of ferromagnetic material having a magnetic coil 3 disposed therein. Have The magnetic coil 3 has a current supply via a plug connection 4 embedded in a plastic ring 5 which partially encloses the valve housing 1.

The winding frame 2 of the magnetic coil 3 is located in the coil space 6 of the valve housing 1 at a connection stop which supplies fuel, for example gasoline, and partially protrudes into the valve housing 1. . The valve housing 1 partially surrounds the nozzle body 9 remote from the connection stop 7.

Cylindrical armature 14 between the front face 11 of the connection stop 7 and the stop plate 12 which is arranged on the inner shoulder 13 of the valve housing 1 with a special thickness for precise adjustment of the valve. ) Is located. The armature 14 is made of a non-corrosive magnetic material and is located at a small radial distance from the magnetically conductive calculation of the valve housing 1, thus coaxial with the valve housing 1 between the armature 14 and the stairs. To form an annular magnetic gap. At two front surfaces, the cylindrical armature 14 has a coaxial first closing hole 15 and a second closing hole 16, and the second closing hole 16 is open toward the nozzle body 9. The first and second closing holes 15, 16 communicate with each other by coaxial holes 17. The diameter of the hole 17 is smaller than the diameter of the second closing hole 16. The end section of the armature 14 facing the nozzle body 9 is made as a deformation zone 18. This deformation zone 18 forms part of the valve needle 27 and connects the armature 14 with the valve needle 27 so as to be firmly fixed by surrounding the retaining body 28 filling the second closing hole 16. It plays a role. The enclosing of the retaining body 28 by the deformation region 18 of the armature 14 is accomplished by indenting the material of the deformation region 18 into the groove 29 located in the retaining body 28.

The compression spring 30 is placed at the bottom of the coaxial first closing hole 15 at one end, and at the other end tube insert 31 attached by screwing or fitting to the connection stop 7. There is a tendency for the armature 14 and the valve needle 27 to apply a load with a force away from the connection stop 7.

The valve needle 27 passes through the hole 34 in the stop plate 12 at a radial distance and is guided by the guide hole 35 of the nozzle body 9. The recess 37 provided in the ground plate 37 extends from the through hole 34 to the periphery of the stop plate 12, and the entire width of the recess is defined by the valve needle (in the region surrounded by the stop plate 12). 27) larger than the diameter.

The valve needle 27 has two guides 39 and 40 which guide the valve needle 27 in the guide hole 35 and provide a free axial passage for fuel and provide an example. For example, it is produced as a square.

The second guide 40 located downstream is accompanied by a cylindrical section 43 of smaller diameter. Cylindrical section 43 is then accompanied by a tapered conical section 44 ending in a coaxially good cylindrical peg 45.

In FIG. 2, which shows the section in FIG. 1, the transition between the cylindrical section 43 and the conical section 44 is rounded, for example in the form of a semi-circle, forming a sealing sheet 47, which sealing sheet The fuel injection valve is opened and closed in cooperation with the conical valve seat surface 48 formed in the nozzle body 9. The conical valve seat surface 48 of the nozzle body 9 extends to a length approximately equal to the length of the peg 45 such that an annular gap of constant cross section remains between the cylindrical nozzle body hole 49 and the cylindrical peg 45. It continues in the direction away from the armature 14 in the cylindrical nozzle body hole 49. The transition between the conical valve seat surface 48 and the cylindrical nozzle body hole 49, or between the conical section 44 of the valve needle 27, or between the peg 45 ensures a good flow pattern. To round. The end of the nozzle body 9 in the direction away from the armature 14 is formed with a flat surface 51 which is blocked by the nozzle body hole 49.

The length of the peg 45 is such that the peg 45 does not protrude directly from the nozzle body hole 49 when the fuel injection valve is closed, i.e. the peg 45 is defined by the flat surface 51 of the nozzle body 9. It is dimensioned to end just in front of the face.

While confined internally by the nozzle body opening 49 of the flat surface 51 of the nozzle body 9, the flat surface is constrained from the outside by a conical region 52 that expands in the direction facing the armature 14. Can be.

The platelet 55 that anchors to the flat surface 51 of the nozzle body 9 provides a rising edge 56 that roughly follows the contour of the conical region 52 of the nozzle body 9. The corners 56 of the platen 55 may be manufactured, for example, by deep drawing of the platen 55. The attachment of platelets 55 on the flat surface 51 is ensured by the treatment sleeve 58. Platelet 55 is compressed to flat surface 51 by bottom 60 of coaxial closing hole 61 of treatment sleeve 58 surrounding platelet 55 in the outer region. Thus, the platen 55 is sandwiched between the bottom 60 of the closing hole 61 of the processing sleeve 58 and the flat surface 51 of the nozzle body 9. In this arrangement, the platelet 55 is centered by the edges 56 of the platelet 55 which settle on the conical region 52 of the nozzle body 9 and no longer provide clearance. In particular, good centering of the platen 55 can be achieved if the edge 56 of the platen 55 expands when pressed against the conical region 52, ie if radial clamping is performed.

The platen 55 is clamped between the nozzle body 9 and the processing sleeve 58 by a processing sleeve 58 having a female thread 64 coupled with a male screw 65 formed around the nozzle body 9. do. In order to secure the position of the treatment sleeve with respect to the nozzle body 9 after complete screwing, the treatment sleeve 58 can be fitted into the outer slot 68 of the nozzle body 9 by a fixed nose 66. have. The edge of the treatment sleeve 58 facing the armature 14 is used as the fixed nose 66. The edge of the treatment sleeve is bent into the outer slot 68 of the nozzle body 9 to fix it. Between the edges forming the fixed nose 66 and the bottom 60 of the treatment sleeve 58 the surface area of the closing hole 61 extends and a female thread 64 is formed over almost the entire length. The female screw 64 and the male screw 65 are preferably made of a fine pitch screw. At the same time, the treatment sleeve 58 can be used to axially fix the sealing ring 69 which radially surrounds the nozzle body 9 as shown in FIG.

The processing holes 70 of the preferred cylindrical cross section open coaxially at the bottom 60 of the processing sleeve 58 and on the other hand at the sharp processing edge 71. The treatment edge 71 is surrounded by the annular groove 73. In the illustrated embodiment, the cross section of the annular groove 73 is approximately an isosceles square, ie the inner wall 74 of the annular groove 73 and the outer wall 75 of the annular groove 73 are inclined. The treatment edge 71 is formed at an acute angle between the inclined inner wall 71 of the annular groove 73 and the treatment hole 70. This acute angle should be between 10 ° and 20 °. At the same time the outer wall 75 of the annular groove 73 forms the inner surface of the collar 77. The collar 77 represents the part of the fuel injection valve that protrudes farthest in the direction away from the armature 14. The collar 77 surrounds the treatment edge and at the same time protrudes past the edge. The collar 77 serves to protect the treatment edge 71 from being damaged by retreating backwards during assembly of the fuel injection valve, for example in an internal combustion engine.

The platen 55 includes a plurality of holes 80 extending from the upstream side to the downstream side of the platen 55. On the upstream side of the platen 55, the hole 80 is opened into an annular space formed between the nozzle body hole 49 and the peg 45. The central axis 81 of the hole 80 advances directly towards the treatment edge 71 or towards an almost upstream side of this edge. With respect to the longitudinal axis of the fuel injection valve, the central axis 81 of the hole 80 has radial and tangential components. The angle formed between the central axis 81 of the hole 80 and the surface of the processing hole 70 is determined to be very small, i.e., the jetting jet ejected from the hole 80 is very small at the processing hole 70. It is supposed to collide. This collision angle should be less than 10 °.

The shape of the valve needle 27 in the region of the sealing sheet 47 is shown in FIG. The portion of the valve needle 27 which, together with the conical valve seat surface 48, causes the injection valve to open and close, is made as a round 90 through which the cylindrical section 43 of the valve needle 27 is formed. It is successively changed to conical section 44. The transition from the cylindrical section 43 to the round 90 and the transition from the round 90 to the conical section 44 are good in tangential direction when viewed in the flow direction.

The contour of the round 9 can be formed with a radius R as shown in the half section on the left side of FIG. Assuming that the radius R representing the round 90 extends into the circle 93 (shown in dashed lines), all the circles 93 forming the sealing sheet 47 together represent the toroid 94.

The right half section of FIG. 3 shows a second embodiment. In this arrangement, the round 90 follows the contour of the ellipse 96 most. In the illustrated embodiment, the arrangement of the ellipse 96 is selected such that the longer radius of the two ellipse radii a, b extends in the axial direction of the injection valve. However, this is not limited and can arbitrarily position the shape of the ellipse 96 with respect to the longitudinal valve shaft.

Round 90 may also not be represented by radius R or radius a, b but may follow any other shape that forms a toroid as a whole.

The round 90 is well manufactured by appropriately grinding the valve needle 27 rotating about the longitudinal axis. In this process, grinding of the entire point of the valve needle 27 from the cylindrical section 43 to the peg 45 can occur in a single machining step. In contrast to known machining techniques for fuel injection valves, no burr remains, and removal of the burr frequently damages and deforms the appearance of the sealing sheet.

The best correlation between the valve needle stroke and the outflowing fuel volume due to the round 90 is particularly advantageous in the fuel injection valve described. Since the relatively small radius of the round 90 leads to an apparent linear contact between the valve needle 27 and the conical valve seat surface 48, the valve needle 27 is hydraulically "attached" to the valve seat surface 48. The tendency to do so is greatly reduced for injection valves having spherical closures, for example with flatter sealing sheets.

The fuel injection valve works as follows.

When current flows through the magnetic coil 3, the armature 14 is attracted in the direction of the connection stop 7. The sealing sheet 47 of the valve needle 27 tightly connected to the armature 14 rises away from the conical valve sheet surface, the flow cross section is discharged between the sealing sheet 47 and the conical valve sheet surface 48, and the fuel Can reach the hole 80 through an annular space located between the nozzle body hole 49 and the peg 45. The fuel flows through the hole with a high pressure drop because the holes 80 form the narrowest flow cross section in the fuel injection valve. Thus, the size of the aperture 80 determines the volume flow of injected fuel, which the skilled artisan calls " metering. &Quot; The fuel jet blowing out of the hole 80 advances toward the processing hole 70 such that the jet impinges directly on or directly upstream of the processing edge 71. At the same time, the collision speed is large enough to be called "shock". Due to the high kinetic energy, individual fuel droplets are dispersed and sprayed when impinging on the processing hole 70. As a result, fuel mist remains in the fuel injection valve downstream of the treatment edge 71. This fuel mist mixes well with the intake air of the internal combustion engine.

The annular groove 73 surrounding the treatment edge 71 has a fuel edge which can be deposited on the inner wall 74 of the annular groove 73 and is piggybacked on the secondary vortex inside the annular groove 73 to treat the treatment edge 71. Toward the center and offers the advantage of spraying from its corners. The fuel injection valve having the annular groove 73 made by the present invention shows that the fuel injection valve without the annular groove 73 has a much less tendency toward drop formation. The causes of these consequences are not yet fully explained.

The fuel injection valve according to the present invention achieves a very good fuel treatment. The best result is achieved with a 0.3 mm thick platelet 55 when the diameter of the processing hole 70 is 2.2 mm and the length is 5 mm. The diameter of the hole 80 depends on the respective application state and is within a range between 0.15 and 0.35 mm.

Claims (12)

The core has a valve housing made of ferromagnetic material and a core surrounded by a magnetic coil, and is firmly connected to a valve needle that provides a sealing sheet made in a rounded shape, each of which cooperates with the valve seat surface to open and close the fuel injection valve. In a fuel injection valve for a fuel injection system of an internal combustion engine having an armature operating in connection with the arm, the round 90 forming the sealing sheet 47 is formed by a portion of the outer surface of the virtual toroid 94. A fuel injection valve characterized in that. 2. The round 90 is defined by a first circular peripheral section 43 passing tangentially in one face and a second circular peripheral section 44 passing tangentially in the other face. A fuel injection valve characterized in that. A fuel injection valve according to claim 1, characterized in that the cross section of the toroid (94) represents the shape of the circle (93) (left half section in FIG. 3). The fuel injection valve according to claim 1, wherein the cross section of the toroid (94) represents the shape of the ellipse (94 right half section in FIG. 3). 5. The fuel injection valve according to claim 4, wherein the longer radius (a) of the ellipse (96) extends parallel to the longitudinal axis of the fuel injection valve. It has a valve housing made of ferromagnetic material, a core surrounded by a magnetic coil, and is firmly connected to a valve needle which controls the opening and closing of the fuel injection valve, respectively, in cooperation with the valve seat surface manufactured in the nozzle body, to operate in relation to the core. A fuel injection valve for a fuel injection system of an internal combustion engine having an armature having an armature, a platelet provided with a hole installed between the nozzle body and the processing sleeve, and having a processing sleeve providing a central processing hole ending at the corner. A fuel injection valve characterized in that it ends at (45). 7. The fuel injection valve according to claim 6, wherein the peg (45) ends in the vicinity of the platelet (55) when the fuel injection valve is closed. 7. The valve needle (27) according to claim 6, characterized in that the valve needle (27) provides a conical section (44) upstream of the peg (45), and the transition between the conical section (44) and the peg (45) is rounded. Fuel injection valve. 9. The valve seat surface (48) of claim 8, wherein on the downstream side, the valve seat surface (48) passes through the nozzle body hole (49) surrounding the peg (45), and the transition between the valve seat surface (48) and the nozzle body hole (49) is rounded. A fuel injection valve characterized in that the. 7. The center axis 81 of the hole 80 of the platelet 55 intersects the generation surface of the processing hole 70 near the upstream side of the edge of the processing hole 70 or near the upstream side. A fuel injection valve, characterized in that. 7. The fuel injection valve according to claim 6, characterized in that the platelets (55) provide edges (56) which settle in the conical region (52) of the nozzle body (9). 12. The fuel injection valve according to claim 11, wherein the processing sleeve (58) is screwed into the nozzle body (9) and a portion of the processing sleeve (58) is fixed to the nozzle body (9).

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