JP2003505645A - Fuel injection valve - Google Patents

Abstract

SUMMARY OF THE INVENTION The present invention provides a fuel inlet at the supply end, an excitable operating device by which the valve needle (20) can be moved, and a valve seat (27) for opening and closing the valve. , 27 ') associated with a valve needle (20), and a fuel outlet provided at the injection end downstream of the valve seat (27, 27'). (32) and a fuel injector having a disk-shaped damping element (48) provided at the injection-side end for damping the movement of the valve needle (20). The damping element (48) is tightened between the torsion element (47) and the seat element (26), with the damping element (48) and the seat element (26) being closed when the valve is closed. Some fuel is pushed out of the wedge-shaped gap (79), so that the movement of the valve needle (20) is hydraulically damped.

Description

Detailed Description of the Invention

[0001]   Background technology   The invention starts from a fuel injection valve according to the preamble of the independent claims.

A magnet valve known from US-PS 5,236,173 has a buffer spring in the form of a disc spring between a valve seat body and a valve seat support to which the valve seat body is attached. There is. The disc spring is then clamped downstream of the valve seat between the valve seat and the shoulder of the valve seat support. The disc spring exerts a prestressing force on the valve seat body and presses it against the valve needle cooperating with the valve seat surface. Furthermore, the disc spring causes the valve closing body, which is formed integrally with the valve needle, to hit the valve seat surface softly and buffer the rebound of the valve needle on the valve seat body. However, this buffer type has the following drawbacks. That is, while the valve seat body bends in the injection direction after hitting the valve closing body,
The valve closure may either remain stationary or, on the contrary, by a pulse reversal, a return movement from the valve seat in the direction opposite to the injection direction. Valve bounce therefore occurs in the structure of this fuel injection valve on the contrary to a much greater extent.

Advantages of the invention The fuel injection valve according to the invention with the features of the independent claim has the advantage that an accidental bounce of the valve needle can be avoided more effectively.
In a particularly advantageous manner, the damping of the movement of the valve needle takes place hydraulically, in which case a hydraulic cushion between the damping element and the downstream element is pushed out. This hydraulic damping reduces noise generation during operation of the fuel injection valve. The buffered striking of the valve needle at the valve seat enhances continuous running resistance.

The damping element according to the invention can be manufactured in an advantageous manner simply and inexpensively and can be mounted on a fuel injection valve. Inexpensive fabrication of the cushioning element is possible by punching and stamping processes.

Advantageous embodiments and improvements of the fuel injection valve as defined in the independent claim are possible by the measures as defined in the dependent claims.

Advantageously, the damping element has a sealing edge, which cooperates for the axially movable valve closing member and the sealing seat. A ring-shaped line contact is produced by a damping element having a conical partition wall of the through hole which is penetrated by the valve needle.

It is particularly advantageous if the damping element is disc-shaped as a disc spring.

[0008]   Example description   Hereinafter, one embodiment of the present invention shown in the drawings will be described in detail.

An electromagnetically actuable valve in the form of an injection valve for a fuel injection device of a spark ignition type internal combustion engine, illustrated by way of example in FIG. 1, is at least partly surrounded by a magnet coil 1. It also has a tubular, substantially hollow cylindrical core 2 which serves as the inner pole of the magnetic circuit. This fuel injection valve is particularly suitable as a high pressure injection valve for directly injecting fuel into the combustion chamber of an internal combustion engine. A winding frame 3 made of, for example, stepped plastic, receives the windings of the magnet coil 1 and also comprises a core 2 and a magnet coil 1.
With a ring-shaped non-magnetic intermediate part 4 having an L-shaped cross section, which is partially surrounded by, a particularly compact and short injection valve construction in the region of the magnet coil 1 is possible.

A consistent slot 7 is provided in the core 2, which slot extends along the longitudinal axis 8 of the valve. The core 2 of the magnetic circuit also serves as a fuel inlet short pipe, in which case the long hole 7
Form a fuel supply passage. An outer metallic (for example ferrite) casing part 14 is rigidly connected to the core 2 above the magnet coil 1, which casing part serves as an outer pole or an external magnetizing element to close the magnetic circuit and The magnet coil 1 is completely surrounded at least in the circumferential direction. A fuel filter 15 is provided on the supply side in the elongated hole 7 of the core 2, and the fuel filter 15 filters the fuel components that block or damage the injection valve based on the size thereof. To do. The fuel filter 15 is fixed in the core 2 by pushing, for example.

The core 2, together with the casing part 14, forms the supply-side end of the fuel injection valve, the upper casing part 14 extending, for example, just beyond the magnet coil 1 when viewed axially. . Closely and immovably connected to the upper casing part 14 is a lower tubular casing part 18, which is, for example, an axially movable armature 19 and a rod-shaped valve needle 20. It surrounds or receives the valve portion or elongated valve seat support 21. Both casing parts 14
And 18 are rigidly connected to each other, for example by annular weld seams.

In the embodiment shown in FIG. 1, the lower casing part 18 and the generally tubular valve seat support 21 are rigidly connected to each other by screwing. However, welding, brazing or flange joining are also possible joining methods. Casing part 18 and valve seat support 21
The seal between the two is provided by, for example, a seal ring 22. Valve seat support 2
1 has an inner through hole 24 over its entire axial extension, which extends concentrically to the valve longitudinal axis 8.

At the same time, its lower end 25 forms the downstream closure of the entire fuel injection valve.
The valve seat support 21 encloses a disc-shaped valve seat element 26 fitted in the through hole 24, the valve seat element tapering towards the downstream side in a frustoconical shape. Has 27. A valve needle 20 having a substantially circular cross section, for example rod-shaped, is arranged in the through hole 24 and has a valve closing section 28 at its downstream end. . This valve closing section 28, for example spherically or partially spherically or rounded or conically tapering, is provided in a known manner with a valve seat surface 27 provided in the valve seat element 26. Collaborate with. At least one valve seat element 26 is provided downstream of the valve seat surface 27.
An outlet hole 32 for one fuel is formed. The outlet hole 32 extends concentrically to the valve longitudinal axis 8 in the embodiment of FIG. 1 and terminates in the flat lower end face of the valve seat element 26 which extends perpendicularly to the valve longitudinal axis 8. .

The operation of the injection valve is carried out electromagnetically in a known manner. However, piezoelectric actuators or magnetostrictive actuators are likewise conceivable as excitable operating elements. Operation via a controlled and pressure-loaded piston is also conceivable. The valve needle 20 is moved in the axial direction, and by extension, the long hole 7 of the core 2 is moved.
Electromagnetic with a magnet coil 1, a core 2, casing parts 14 and 18 and an armature 19 for opening the injection valve against the spring force of a return spring 33 arranged therein or for closing the injection valve. Circuits are useful. The armature 19 is connected to the end of the valve needle 20 on the side opposite to the valve closing section 28, for example by means of a weld seam, and is aligned with the core 2. The valve needle 20 along the valve longitudinal axis 8,
A guide hole 34 is provided on one side at the end of the valve seat support 21 towards the armature 19 and on the other side the valve seat element 26 for guiding during its axial movement with the armature. A disk-shaped guide element 35 arranged upstream of the guide element 35 serves, the guide element having a precisely sized guide hole 55. The armature 19 is surrounded by the intermediate part 4 during its axial movement.

Between the guide element 35 and the valve seat element 26, another two disc-shaped elements, also a torsion element 47 and a damping element (48), are arranged and thus all four elements. 35, 47, 48 and 26 are positioned one above the other and are received in the valve seat support 21. The four disc-shaped elements 35, 47, 48 and 26 are rigidly connected to each other by means of a material connection,
This is done, for example, by welding seams 60 mounted on the outer circumference of the elements 35, 47, 48 and 26 or by a plurality of welding points or short welding seams 60 distributed along the outer circumference.

The adjusting sleeve 38, which is pushed into the elongated hole 7 of the core 2 and is fitted or screwed in, has a spring pre-load of the return spring 33 which is supported by the adjusting sleeve 38 on the upstream side thereof via the centering piece 39. Helps regulate stress. The other side of the return spring is supported by the armature 19. A single or a plurality of hole-shaped flow passages 40 are provided in the armature 19, and fuel is formed from the elongated holes 7 in the core 2 to the downstream side of the flow passage 40 through these flow passages. It can reach into the through hole 24 via the connection passage 41 near the guide hole 34 of the valve seat support 21.

The stroke of the valve needle 20 is defined by the mounting position of the valve seat element 26. When the magnet coil 1 is not excited, the end position of the valve needle 20 is
The valve closing section 28 is defined by contacting the valve seat surface 27 of the valve seat element 26, whereas the other end position of the valve needle 20 when the magnet coil 1 is energized is the armature 19. Is generated by contacting the downstream end face of the core 2. The surface of the structural part in the latter contact area is, for example, chrome-plated.

The electrical contact connection of the magnet coil 1 and thus its excitation is effected via a contact element 43, which has a plastic coating 44 on the outside of the winding frame 3. The plastic cladding 44 can also extend through other structural parts of the fuel injector (eg casing parts 14 and 18). An electrical connection cable 45 extends from the plastic covering portion 44, and current is supplied to the magnet coil 1 via this connection cable. The plastic cover 44 projects through the upper casing part 14, which is interrupted in this area.

FIG. 2 shows a configuration in which the guide range and the valve seat range are enlarged and slightly changed with respect to FIG. 1, in which case the same portion or the same action as in FIG. 1 is performed. The same symbols are attached to the parts to be performed. In the example shown in FIG. 2, the valve seat element 26 has an annular flange 64, which engages below the downstream end of the valve seat support 21. The outlet hole 32 is formed, for example, obliquely with respect to the longitudinal axis 8 of the valve, the outlet hole terminating in an injection range 66 which is convex on the downstream side.

The guide element 35 has a precisely dimensioned inner guide bore 55 through which the valve needle 20 moves during its axial movement. From the outer circumference, the guide element 35 has a plurality of circumferentially distributed cutouts 56 which allow the fuel flow along the outer circumference of the guide element 35 into the torsion element 47 and further towards the valve seat surface. Guaranteed.

The damping element, which is clamped between the torsion element 47 and the valve seat element 26, is of disc-shaped design with a small thickness and is substantially similar to a disc spring. The cushioning element 48 is fixed in a material connection, for example by a plurality of outer peripheral welding points or welding seams 60, which also provide a rigid connection of the guide element 35, the torsion element 47 and the valve seat element 26. The cushioning element 48 is made of a wear-resistant, spring-acting, stainless steel metallic material. The valve seat element 26 and the cushioning element 48 are configured as follows. That is, the damping element 48 is designed such that it can perform a slight axial movement in the partial range when the valve is opened and closed. This will be described later with reference to FIGS.

FIG. 3 shows the damping element 48 in a plan view. The buffer element 48 is a ring disk having an inner through hole 70. This through hole 70 is penetrated by the valve closing section 28 of the valve needle 20. From the inner through hole 70, the damping element 48 has a plurality of radially successive sections. The through hole 70 is directly surrounded by the sealing section 71. The partition wall 72 of the through hole 70 is formed in a slightly conical shape, and the opening diameter of the through hole 70 decreases toward the downstream side. The partition wall 72 here has a different cone angle than the valve closing section 28 in this region, so that there is a difference angle between both adjacent facing surfaces 28, 72. Extending from the partition wall 72 together with the sealing section 71 is a curved, S-shaped section 73 of cross section, to which a radially outer flat fastening section 74 is connected. The S-shaped section 73 also has an axially extending component, so that a bowl-shaped cushioning element 48 with a submerged inner extent results. The through-hole 70 with the partition wall 72 and the sealing section 71 is axially offset with respect to the fixed section 74, while the section 73 joins the sections 71 and 74 together.

The valve seat element 26 has an upper end surface 77 facing the torsion element 47, which does not extend exactly perpendicular to the valve longitudinal axis 8 but is slightly inclined. . In this way, an intermediate chamber is formed between the torsion element 47 and the valve seat element 26, which intermediate chamber increases its axial extension towards the valve longitudinal axis 8 and thus the damping element 48. Can move axially.
In order to be able to receive the cushioning element 48, the valve seat element 26 is formed in its central region with a recess 78 upstream of the valve seat surface 27, which recess is substantially in the region of the cushioning element 48. It has the contours of section 73 and seal section 71.

FIG. 4 shows a portion indicated by IV in FIG. 2 in a state where the valve is open, and FIG. 5 shows a portion indicated by V in FIG. 2 in a state where the valve is closed. When the valve is open, the damping element 48 has its locking section 74 in direct flat contact with the lower end face of the torsion element 47. There is a small angle of difference between the damping element 48 and the valve seat element 26, which results in a wedge-shaped gap 79 between the elements 48 and 26. This gap 79 is filled with fuel by capillary action. The damping element 48 is not in contact with the valve closing section 28 with its partition wall 72 of the through hole 70, so that there is a narrow ring gap 80 which expands downstream due to the difference angle between the partition wall 72 and the valve closing section 28. Has occurred in the meantime.

When the valve is closed, the valve needle 20 moves in the direction of the valve seat surface 27 along the valve longitudinal axis 8. The spring-loaded damping element 48 is then slightly entrained, which also at least causes the valve closing section 28 of the valve needle 20 to contact the ring-shaped upper edge of the partition wall 72, which forms the sealing edge 27 ′. Will be taken to. The volume of the gap 79 is reduced in this manner during this closing process. By pushing the fuel out of the gap 79, the bounce of the valve needle 20 of the festival hitting the valve seat surface is effectively prevented. In short, the buffer element 48
The hydraulic buffering by The cushioning element 48 is molded by the cushioning element 4
8 makes it possible to perform a complete sealing function when the valve is closed. When the valve is closed, the damping element 48 is not in contact with the recess 78 in the valve seat element 26, as shown in FIG. Partition wall 72 having valve seat surface 27 and sealing edge 27 '
Is precisely configured, for example, as follows, i.e. both together to perform the valve sealing function when the valve closing section 28 is in close contact.

[Brief description of drawings]

[Figure 1]   1 shows a cross section of one embodiment of a fuel injection valve according to the present invention.

[Fig. 2]   The guide range on the injection side and the valve seat range are shown on different scales.

[Figure 3]   Figure 3 shows a cushioning element according to the invention in plan view.

[Figure 4]   The part indicated by IV in FIG. 2 is shown with the valve open.

[Figure 5]   The part indicated by V in FIG. 2 is shown with the valve closed.

[Explanation of symbols]

1 magnet coil, 2 cores, 3 winding frame, 4 middle part, 7 long hole,
8 longitudinal axis of valve, 14 upper casing part, 15 fuel filter, 1
8 Lower casing part, 19 Armature, 20 Valve needle, 21 Valve seat support, 22 Seal ring, 24 Through hole, 25 Lower end, 2
6 valve seat element, 27 valve seat surface, 27 'sealing edge, 28 valve closing section, surface, 32 outlet hole, 33 return spring, 34 guide hole, 35 guide element, 38 adjusting sleeve, 39 concentric piece, 40 flow passage , 41 connecting passages, 43 contact elements, 44 plastic enclosures,
45 connection cable, 47 torsion element, 48 cushioning element,
55 guide hole, 56 notch, 60 weld seam, 64 flange,
66 injection range, 70 through hole, 71 seal section, 72 partition wall, surface, 73 section, 74 fixed section, 77 end surface, 78 recess, 79 gap, 80 ring gap

Claims (10)

[Claims] 1. A fuel inlet (2) at the supply end and an excitable actuating device (1, 2, 19) by which a valve needle (20) can be moved.
), A valve closing member (28) connected to the valve needle (20) cooperating with the valve seat (27, 27 ') for opening and closing the valve, and downstream of the valve seat (27, 27'). A fuel outlet (32) at the injection end and a damping element (48) at the injection end to cushion the movement of the valve needle (20). In the fuel injection valve, the buffer element (48) has an upstream element (47).
Between the valve and the downstream element (26), the valve needle (20)
A fuel injection valve characterized in that a variable hydraulic cushion existing between a buffer element (48) and a downstream element (26) when the valve moves. 2. The damping element (48) has a sealing edge (27 '), which cooperates for the valve closing member and the sealing seat. Fuel injection valve. 3. Fuel injection valve according to claim 1, characterized in that the damping element (48) is in the form of a disc and is designed as a disc spring. 4. The damping element (48) has the shape of a ring disc, which has an inner through hole (70) with a partition wall (72), the through hole being provided. 4. Fuel injection valve according to claim 1, 2 or 3, characterized in that (70) is penetrated by a valve needle (20). 5. The partition wall (72) of the through-hole (70) is slightly conical and has a sealing edge (27 ') at its upstream end. The fuel injection valve according to claim 4. 6. The damping element (48) is configured in the shape of a pot, the sealing section (71), the section having a curved cross-section having an S-shape (in the radial direction outward from the partition wall). 73) Fuel injection valve according to claim 4 or 5, characterized in that a fixed section (74) which is radially outwardly connected is connected to this. 7. The downstream element (26) has a recess (78) in its central region.
7. The fuel injection valve according to claim 6, characterized in that the recess has substantially the contours of the section (73) and the sealing section (71) of the damping element (48). . 8. A damping element (48) having its fixed section (74) in contact with an upstream element (47) when the valve is open, so that the damping element (48) and the downstream element (47) are Fuel injection valve according to claim 7, characterized in that a wedge-shaped gap (79) is formed between it and 26). 9. The upstream element is a torsion element (47) in the form of a torsion disc and the downstream element is a valve seat element (26) having a valve seat (27). Item 9. The fuel injection valve according to any one of items 1 to 8. 10. The damping element (48) is characterized in that its radially outer edge is rigidly connected to the torsion element (47) and the valve seat element (26) by a material connection. 9. The fuel injection valve according to item 9.