EP1339970A2

EP1339970A2 - Fuel injection valve

Info

Publication number: EP1339970A2
Application number: EP01999741A
Authority: EP
Inventors: Guenter Dantes; Detlef Nowak
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2000-12-05
Filing date: 2001-11-30
Publication date: 2003-09-03
Also published as: WO2002046604A3; US20030132322A1; KR20020072298A; WO2002046604A2; JP2004515691A; DE10060290A1

Abstract

A fuel injection valve (1), especially for direct injection of fuel into a combustion chamber of a mixture-compression, spark ignition internal combustion engine, comprises an actuator (10) and a valve needle (3) which is actuated by said actuator (10) and which activates a valve closing body (4). Said valve-closing body forms a sealed seat, together with a valve seat surface (6) which is configured on a valve seat body (5). The inventive valve also comprises several injection openings (7) which are configured in the valve seat body (5), and a damping element (37) is located in a recess (36) of the valve-closing body (4) on the off-flow side.

Description

Fuel injection entil

State of the art

The invention is based on a fuel injection valve according to the preamble of the main claim.

From DE 33 14 899 AI an electromagnetically actuated fuel injection valve is already known, in which an armature interacts with an electrically excitable solenoid for electromagnetic actuation and the stroke of the armature is transmitted to a valve closing body via a valve needle. The valve closing body interacts with a valve seat surface to form a sealing seat. The armature is not rigidly attached to the valve needle, but is arranged axially movable thereon. A first return spring acts on the valve needle in the closing direction and thus keeps the fuel injection valve closed when the solenoid coil is de-energized and not energized. The armature is acted upon in the stroke direction by means of a second puck spring so that the armature in the rest position rests against a first stop provided on the valve needle. When the solenoid is energized, the armature is pulled in the stroke direction and takes the valve needle with it at the first stop. When the current exciting the solenoid coil is switched off, the valve needle becomes its closed position by means of the first return spring m accelerates and carries the anchor over the described stop. As soon as the valve closing body hits the valve seat, the closing movement of the valve needle is abruptly ended. The movement of the armature, which is not rigidly connected to the valve needle, continues counter to the stroke direction and is absorbed by the second return spring, ie the armature swings through against the second return spring, which has a substantially lower spring constant than the first return spring. The second return spring accelerates the armature again in the stroke direction.

A disadvantage of the fuel injection valve known from DE 33 14 899 AI is in particular the incomplete debouncing. If the armature hits the stop of the valve needle, this can cause the valve closing body connected to the valve needle to be briefly lifted again from the valve seat and thus to an undesired brief opening of the fuel injection valve, which falsifies the spray pattern and increases the amount of fuel injected, which in turn leads to a This results in higher fuel consumption and increased knocking of the internal combustion engine due to afterburning.

A damping between the valve seat body and the valve seat support is known from US Pat. No. 5,236,173.

Advantages of the invention

The fuel injection valve according to the invention with the characterizing features of the main claim has the advantage that the rebound of the valve closing body from the sealing seat through a recess of the valve closing body arranged

Damping element is prevented without having to increase the spring constant of the return spring and thereby having to buy longer opening times. Furthermore, a multi-hole concept can be implemented in a simple manner, without restrictions, for example when using standard components.

The measures listed in the subclaims allow advantageous developments and improvements of the fuel injector specified in the main claim.

The low-cost and easy-to-manufacture cylindrical shape of the damping element made of any elastic material, for example rubber, silicone or foam, or the design of the damping element as a liquid cushion enclosed by a sheath is particularly advantageous.

It is also advantageous to form several rings of spray openings, which are partially covered by the damping element. This measure enables the mixture cloud injected into the combustion chamber of the internal combustion engine to be adapted to the operating state of the internal combustion engine.

This is advantageously supported by a different inclination of the spray openings with respect to a longitudinal axis of the fuel injector.

Another advantage is the design of the damping element in the form of a spring connected to a damping body, which is arranged in the recess of the valve closing body. In this case, the damping body which oscillates freely when the fuel injector is open can also consist of metal, since the damping effect is achieved by the spring. In this case, the cost-effective production, which makes no special demands on the material of the damping element, is particularly advantageous. drawing

Exemplary embodiments of the invention are shown in simplified form in the drawing and are explained in more detail in the following description

1 shows an axial section through a first exemplary embodiment of a fuel injection valve according to the invention,

2A shows an enlarged detail of FIG. 1, the first exemplary embodiment of a fuel injection valve according to the invention in the area IIA in FIG. 1,

Fig. 2B em second exemplary embodiment of a fuel injection valve according to the invention in the same area as Fig. 2A, and

Fig. 2C em third exemplary embodiment of a fuel injection valve according to the invention in the same area as Fig. 2A and 2B.

Description of the exemplary embodiments

Before exemplary embodiments of a fuel injection valve 1 according to the invention are described in more detail with reference to FIGS. 2A to 2C, the fuel injection valve 1 m according to the invention and its overall components are briefly explained with reference to FIG. 1 in order to better understand the invention.

The fuel injection valve 1 is in the form of a fuel injection valve for fuel injection systems of mixture-compressing, externally ignited

Internal combustion engines executed

Fuel injection valve 1 is particularly suitable for dxrect injection of fuel a combustion chamber, not shown, of an internal combustion engine.

The fuel injection valve 1 comprises a nozzle body 2, in which a valve needle 3 is arranged. The valve needle 3 is in operative connection with a valve closing body 4, which cooperates with a valve seat surface 6 arranged on a valve seat body 5 to form a sealing seat 7 has. The nozzle body 2 is sealed by a seal 8 against an outer pole 9 of a magnetic circuit. A magnet coil 10 is encapsulated in a coil housing 11 and wound on a coil carrier 12 which bears against an inner pole 13 of the magnetic circuit. The inner pole 13 and the outer pole 9 are separated from one another by a gap 26 and are supported on a connection component 29. The magnet coil 10 is excited via a line 19 by an electrical current that can be supplied via an electrical plug contact 17. The plug contact 17 is surrounded by a plastic sheath 18, which can be molded onto the inner pole 13.

The valve needle 3 is guided in a valve needle guide 14, which is disc-shaped. A paired adjusting disk 15 is used for stroke adjustment. An armature 20 is located on the other side of the adjusting disk 15. This anchor is non-positively connected via a first flange 21 to the valve needle 3, which is connected to the first flange 21 by a weld seam 22. A restoring spring 23 is supported on the first flange 21, which in the present design of the fuel injection valve 1 is preloaded by a sleeve 24

A second flange 31, which is connected to the valve needle 3 via a weld 33, serves as the lower one Armature stop. An elastic intermediate ring 32, which rests on the second flange 31, prevents bouncing when the fuel injection valve 1 is closed.

In the valve needle guide 14 and in / armature 20 run fuel channels 30a to 30b. In the preferred exemplary embodiment, the spherical valve closing body 4 has at least one bevel 34, via which the fuel flows around the valve closing body 4 and is led to the spray openings 7. The fuel is supplied via a central fuel supply 16 and filtered through em filter element 25. The fuel injection valve 1 is sealed by a seal 28 against a fuel line, not shown.

The valve closing body 4 has a recess 36 on an injection-side end 35, which is preferably cylindrical or pot-shaped. In the recess 36 em damping element 37 is arranged, which abspr tzse tig is supported on the valve seat 5. In the present first exemplary embodiment, the damping element 37 is arranged in such a way that it rests on the valve seat body 5 within the spray openings 7 formed in the valve seat body 5. A detailed description of the first exemplary embodiment of the fuel injection valve 1 according to the invention and its mode of operation is given with reference to FIG. 2A.

In the idle state of the fuel injection valve 1, the armature 20 is acted upon by the return spring 23 against its stroke direction in such a way that the valve closing body 4 is held in a sealing arrangement on the valve seat 6. When the magnetic coil 10 is excited, this magnetic field builds up, which moves the armature 20 counter to the spring force of the return spring 23 m in the stroke direction, the stroke being predetermined by a working gap 27 between the inner pole 13 and the armature 20 in the rest position. The armature 20 also carries the flange 21, which is welded to the valve needle 3, in the stroke direction. The one with the Valve needle 3 Actively connected valve closing body 4 lifts off the valve seat surface 6 and the fuel is sprayed off.

If the coil current is switched off, the armature 20 drops from the inner pole 13 after the magnetic field has been sufficiently reduced by the pressure of the return spring 23, as a result of which the flange 21, which is operatively connected to the valve needle 3 m, moves counter to the stroke direction. The valve needle 3 is thereby moved in the same direction, as a result of which the valve closing body 4 rests on the valve seat surface 6 and the fuel injection valve 1 is closed. A rebound of the valve closing body 4 from the valve seat body 5 is prevented by the damping element 37, which absorbs the kinetic energy of the valve needle 3.

FIG. 2A shows an excerpted sectional view of the area marked IIA in FIG. 1. Matching components are provided with matching reference numerals for easier orientation.

As already briefly described with reference to FIG. 1, the valve closing body 4 of the fuel injection valve 1 designed according to the invention has an almost spherical shape. This results in an offset-free, cardanic valve needle guidance, which ensures that the fuel injection valve 1 functions exactly. This is particularly important with regard to the prevention of bouncing by the damping element 37 when the fuel injection valve 1 is closed.

The valve seat body 5 of the fuel injection valve 1 is almost pot-shaped and contributes to the valve needle guidance through its shape. The valve seat body 5 is inserted into an injection-side recess 38 of the nozzle body 2 and is connected to the nozzle body 2 by means of a weld seam 39. The valve closing body 4 has at its spray-side end 35 a recess 36 which is cup-shaped or cylindrical and opens in an outflow direction. The above-mentioned damping element 37 is arranged in the recess 36. This preferably consists of an elastic rubber or plastic material and is dimensioned such that its axial length is somewhat larger than the axial length of the recess 36 in the valve closing body 4.

In the closed state of the fuel injection valve 1, the damping element 37 is compressed by the force of the return spring 23, which keeps the fuel injection valve 1 closed, so that the valve closing body 4 m sealing system is held on the valve seat surface 6 and the damping element 37 m is slightly reduced in its axial length ,

If the actuator 10 of the fuel injection valve 1, which is designed as a magnetic coil 10 in the exemplary embodiment, is actuated, the valve closing body 4 lifts off the sealing seat, as a result of which fuel flows to the spray openings 7 via the at least one bevel. The expansion of the damping element 37 makes an additional contribution during the opening movement for quick opening of the fuel injection valve 1 The damping element 37 can be fastened in the recess 36 of the valve closing body 4 and thereby also lift off the valve seat body 5 during the further opening movement, but it can also be arranged only loosely in the recess 36 and when the fuel injection valve 1 is opened remain on the valve seat body 5. In this case, it must be ensured that the opening stroke of the fuel injection valve 1 does not exceed the axial length of the damping element 37 in the relaxed state, since otherwise the damping element 37 can slip out of the recess 36. When the fuel injection valve 1 closes, the armature 20 drops from the inner pole 13 due to the force of the return spring 23 after sufficient reduction of the magnetic field, as a result of which the valve needle is moved 3 m downstream direction 37 is compressed and thereby exerts a force on the valve closing body 4, which acts counter to the closing direction and brakes the movement of the valve needle 3. As a result, the valve closing body 4 impinges on the sealing seat at a very low residual speed, as a result of which a further undesired, brief opening of the fuel injection valve 1 is counteracted.

2B shows an excerpted sectional illustration of a second exemplary embodiment of a fuel injection valve 1 designed according to the invention. The detail is the same as that in FIG. 2A. Matching components are provided with matching reference symbols.

In contrast to the first exemplary embodiment of the fuel injection valve 1 according to the invention shown in FIGS. 1 and 2A, the second exemplary embodiment shown in FIG. 2B has two, in particular, concentric rings 40 of spray openings 7. The inner spray openings 7a of an inner ring 40a are closed 1 covered by the damping element 37, while the outer spray openings 7b of an outer ring 40b are arranged analogously to the first exemplary embodiment described in FIG. 2A.

The damping element 37 can also be designed analogously to the exemplary embodiment described in FIG. 2A, wherein in the present second exemplary embodiment the damping element 37 must be fastened in the recess 36 so that the inner ring 40a is protected from inner spray openings 7a released when the fuel injection valve 1 is opened

So if the solenoid 10 is energized, the valve closing body 4 first lifts off the valve seat surface 6, whereby the outer spray openings 7b of the outer ring 40b are released only after passing through a certain stroke, the difference between the axial length of the damping element 37 relaxed state and the corresponds to the axial length of the recess 36, the damping element 37 also lifts off the valve seat body 5, as a result of which the inner spray openings 7a of the inner ring 40a are released

By means of the arrangement of the spray openings 7 described, it can be achieved that, depending on the stroke position of the valve needle 3, the fuel cloud injected into the combustion chamber consists only of fuel which was sprayed from the outer spray openings 7b of the outer ring 40b, or that a fuel oil is formed, contains the components both from the inner spray openings 7a of the inner ring 40a and from the outer spray openings 7b of the outer ring 40b

This is particularly advantageous for the design of the mixture cloud, since, for example, the shape of the mixture cloud and its stoichiometer can be influenced directly by a different inclination of the spray openings 7 with respect to a longitudinal axis 41 of the fuel injection valve 1. By switching the rings 40 on and off Spray openings 7 can be generated in a manner adapted to the continuous operating state of the fuel injection valve 1. The required lifting levels can be achieved using additional anchor stops, e.g. B. a driving sleeve or a fuel injection valve 1 with two actuators 10, for example by em double coil valve, can be achieved. If, for example, the outer spray openings 7b of the outer ring 40b are inclined at a small angle with respect to the longitudinal axis 41 of the fuel injection valve 1, in a first switching position of the fuel injection valve 1, when the spray openings 7a of the inner ring 40a are closed, a mixture cloud with a small beam opening angle and high combustion chamber penetration results, as required for the partial load range. The inner spray openings 7a of the inner ring 40a, on the other hand, are more inclined, so that a fuel cloud m is injected into the combustion chamber for full-load operation when the inner spray openings 7a of the inner ring 40a are open and the outer spray openings 7b of the outer ring 40b are open Has radial component, so that the beam opening angle is larger than in partial load operation and the mixture cloud thus fills the combustion chamber homogeneously.

This exemplary embodiment thus combines the advantages of avoiding bouncing and thus reducing the scatter of the metered fuel closely with the possibility of modeling the spray pattern depending on the operating state of the fuel injection valve 1.

FIG. 2C shows a third exemplary embodiment of a fuel injection valve 1 designed according to the invention, which likewise has two rings 40a and 40b of spray openings 7a and 7b. The section is again chosen as in FIGS. 2A and 2B; matching components are provided with matching reference numerals.

In contrast to the first and second exemplary embodiments described in FIGS. 2A and 2B, in the present third exemplary embodiment the bounce avoidance is achieved by a combination of a damping body 43 and a spring 42, which is arranged between an end face 44 of the recess 36 and the damping body 43 , The combination of spring 42 and damping body 43 forms the damping element 37. In the closed state of the Fuel injection valve 1, the spring 42 is biased so that the damping element 37 is flush with the valve closing body 4. If the fuel injection valve 1 is actuated, the valve closing body 4 in turn lifts off the sealing seat, as a result of which the outer ring 40b is opened by external spray openings 7b, while the damping body 43 is initially held on the valve seat body 5 under the tension of the spring 42m sealing system. In the further course of the opening stroke, the spring 42 is increasingly relaxed until the damping body 43 also lifts off the valve seat body 5 and the inner ring 40a is thereby released from inner spray openings 7a.

When the fuel injection valve 1 is closed, the damping body 43 first touches the inner ring 40a of spray openings 7a. From this point in time, the closing movement is braked by the spring 42 arranged in the valve closing body 4, since the restoring force of the spring 42 also increases with increasing spring compression. As a result, bouncers are avoided.

The invention is not limited to the exemplary embodiments shown and can also be used in particular in fuel injection valves 1 with piezoelectric or magnetostrictive actuators 10 and for any shapes and materials of the damping element 37 and any number of spray openings 7.

Claims

Expectations

1. Fuel injection valve (1), in particular for the direct injection of fuel, a combustion chamber of a mixture-compressing, externally ignited internal combustion engine, with an actuator (10), an actuable by the actuator (10) valve needle (3) for actuating a valve closing body (4), the forms a sealing seat together with a valve seat surface (6) formed on a valve seat body (5), and at least one spray opening (7) formed in the valve seat body (5), characterized in that em. in a downstream recess (36) of the valve closing body (4) Damping element (37) is arranged.

2. Fuel injection valve according to claim 1, characterized in that the damping element (37) is formed in the shape of a cylinder

3. Fuel injection valve according to claim 1 or 2, characterized in that the damping element (37) consists of an elastic material.

4. Fuel injection valve according to one of claims 1 to 3, characterized in that the damping element (37) m is compressed in a closed state of the fuel injection valve (1).

5. Fuel injection valve according to one of claims 1 to 4, characterized in that the axial extent of the damping element (37) m an open state of the fuel injection valve (1) is longer than the axial extent of the recess (36) in the valve closing body (4).

6. Fuel injection valve according to one of claims 1 to 5, characterized in that the spray openings (7) in the valve seat body (5) are arranged in a ring (40) so that the spray openings (7) are not covered by the damping element (37) ,

7. Fuel injection valve according to claim 6, characterized in that em radial diameter of the damping element (37) is smaller than em radial diameter of the ring (40) of spray openings (7).

8. Fuel injection valve according to one of claims 1 to 7, characterized in that the valve seat body (5) em inner ring (40a) of inner spray openings (7a) and e outer ring (40b) of outer spray openings (7b) is formed.

9. Fuel injection valve according to claim 8, characterized in that that the inner ring (40a) of inner spray openings (7a) in the closed state of the fuel injector (1) is covered by the damping element (37).

10. Fuel injection valve according to claim 8 or 9, characterized in that the inner spray openings (7a) of the inner ring

(40a) of the fuel injector (1) and the outer

Spray openings (7b) of the outer ring (40b) are inclined differently with respect to a longitudinal axis (41).

11. Fuel injection valve according to claim 10, characterized in that the inclination of the inner spray openings (7a) is greater than the inclination of the outer spray openings (7b).

12. Fuel injection valve according to claim 1, characterized in that the damping element (37) consists of a spring (42) and a damping body (43) acted upon by the spring (42).

13. Fuel injection valve according to claim 12, characterized in that the spring (42) is supported on an end face (44) of the recess (36).

14. Fuel injection valve according to claim 12 or 13, characterized in that the spring (42) is compressed in the closed state of the fuel injection valve (1).

15. Fuel injection valve according to claim 14, characterized in that the spring (42) is relaxed in the open state of the fuel injection valve (1).