CN111486038A

CN111486038A - Valve for metering a fluid and fuel injection device

Info

Publication number: CN111486038A
Application number: CN202010076700.4A
Authority: CN
Inventors: J·珀尔曼; J·格拉纳; K·加尔滕; M·米勒; S·塞尔尼; P·劳申贝格尔
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2019-01-29
Filing date: 2020-01-23
Publication date: 2020-08-04
Also published as: KR20200094101A; DE102019201087A1

Abstract

The invention relates to a valve (1) for metering a fluid, in particular a fuel injection valve for an internal combustion engine, the valve comprises an armature (4) of an electromagnetic actuator (2) and a valve needle (8) which can be actuated by the armature (4), the valve needle is used for operating a valve closing body (9) which cooperates with a valve seat surface (10) to form a sealing seat, wherein the armature (4) is guided movably on the valve needle (8), wherein at least one stop element (11) is provided, which is arranged fixedly on the valve needle (8), which is delimited in relation to the actuating valve needle (8) by a relative movement between the armature (4) and the valve needle (8), an armature free travel spring (18) is provided, which is supported at least indirectly on the stop element (11) on one side and at least indirectly on the armature (4) on the other side. The armature free travel spring (18) is configured as a disk spring and/or a wave spring (18).

Description

Valve for metering a fluid and fuel injection device

Technical Field

The present invention relates to a valve for metering a fluid, in particular a fuel injection valve for an internal combustion engine. In particular, the invention relates to the field of injectors for motor vehicle fuel injection systems, in which fuel is preferably injected directly into the combustion chamber of an internal combustion engine.

Background

DE 102015217513 a1 discloses a fuel injection valve for a fuel injection system of an internal combustion engine. Known fuel injection valves comprise a valve needle which interacts with a valve seat surface to form a sealing seat and an armature which is arranged on the valve needle and is acted upon by a return spring in the closing direction and interacts with an electromagnetic coil. In this case, the armature is mounted on the valve needle in a floating manner between two stops.

Disclosure of Invention

In this case, a valve for metering a fluid, in particular a fuel injection valve for an internal combustion engine, is proposed, having an armature of an electromagnetic actuator and a valve needle which can be actuated by the armature and which serves for actuating a valve closing body which, in cooperation with a valve seat surface, forms a sealing seat, wherein the armature is guided movably on the valve needle, wherein at least one stop element is provided which is arranged in a stationary manner on the valve needle and which, in conjunction with the actuation of the valve needle, delimits a relative movement between the armature and the valve needle, wherein an armature free-travel spring is provided which is supported at least indirectly on the stop element on one side and on the armature at least indirectly on the other side. According to the invention, the armature free travel spring is configured as a disk spring and/or a wave spring.

The valve of the invention has the following advantages: improved configuration and functional manner can be achieved. Furthermore, the manufacturing can be simplified and a lower cost production can be achieved.

In valves for metering fluids, the armature (solenoid armature) is not fixedly connected to the valve needle, but rather is mounted in a floating manner between stop elements. These stop elements can be realized as stop sleeves, stop rings or the like. If necessary, the stop element can also be molded on the valve needle. In the rest state, the armature is adjusted by at least one armature free travel spring to a stop which is fixed in position relative to the valve needle, so that the armature rests there. The entire free travel of the armature can be provided as an acceleration path during actuation of the valve.

In the case of a floating arrangement of the armature on the valve needle, the following advantages are also obtained for a fixed connection of the armature to the valve needle or for a one-piece valve needle: by means of the armature pulse generated during the opening with the same magnetic force, the valve needle can be reliably opened even at high pressures, in particular fuel pressures, which can be referred to as dynamic mechanical intensification, and decoupling of the involved masses is achieved, as a result of which the resultant stopping force at the valve seat surface is divided into two pulses.

However, certain problems are obtained in connection with the floating bearing of the armature on the valve needle.

In conventional designs, the free-stroke armature spring, which is designed as a cylindrical spring, therefore requires, above all, a relatively large amount of installation space in the radial direction, which must be provided in the form of a groove in the armature. The main reason for this is the necessary large wire size in the range of 0.4 mm. Furthermore, large manufacturing tolerances are obtained, which relate to the spring constant and thus to the spring force. In addition, a small contact surface is obtained between the armature and the stop element, on which the armature free-travel spring is arranged, as a result of design. This reduces the damping and results in a smaller speed change during the closing process at the time of disengagement, which can have an effect on the detection (detection), in particular on the CVO detection (CVO: short-term precise injector control), for example in the context of a regulated valve actuation. Another disadvantage is the high wear over the service life, because the contact surface is small. Furthermore, the design-dependent goal conflict arises, since the fuel which is conducted through the armature chamber is generally conducted through the passage opening of the armature. The spring winding of a conventional armature free-travel spring may cover a large portion of the flow cross section, which leads to a pressure drop. Furthermore, the machining of the armature is complicated and expensive, in particular due to the receptacle for the free-travel spring of the armature, which may involve, for example, the deburring necessary for the bore intersection (Bohrungsverschneidung).

In the proposed configuration, the armature free-travel spring is designed as a disk spring and/or a wave spring. Depending on the configuration of the valve, the above-mentioned disadvantages can thus be avoided. The design of the armature free travel spring can be implemented such that the main parameters, such as the working travel and the contact pressure, are predefined, which is obtained even in the case of cylindrical springs.

Thus, complex and expensive spring grooves in the armature for receiving the cylindrical spring can be dispensed with. Furthermore, the free flow cross section can be increased, so that a smaller pressure drop results. Furthermore, the stop surface between the armature and the stop element or the damping surface between the armature and the proposed spring element can be increased. Depending on the configuration, shorter dwell times and better CVO signal detection can be achieved with multiple injections if necessary. Wear may also be reduced due to the larger contact surface.

According to an advantageous embodiment of the invention, the armature free travel spring has at least one recess on its outer edge.

According to a further advantageous embodiment of the invention, the recess is at least substantially concavely shaped.

According to a further advantageous embodiment of the invention, the armature free travel spring has a plurality of slot-shaped cutouts on its outer edge.

According to a further advantageous embodiment of the invention, the slot-shaped incisions are configured as at least substantially radially extending slot-shaped indentations.

In particular, an improved throughflow of the armature chamber can be achieved by the above-described advantageous embodiment of the invention.

According to one embodiment of the invention, at least one positioning element is provided on the armature free travel spring, which positioning element interacts with the stop element in such a way that the armature free travel spring is limited and/or prevented from rotating relative to the stop element in the circumferential direction about the longitudinal axis. The embodiment also makes it possible to achieve torsion protection.

According to a further development of the invention, the configuration of the armature free travel spring is based on the basic shape of a circular ring.

According to a further development of the invention, the armature free travel spring is of a closed annular design.

According to a further development of the invention, the armature free travel spring has a slot, at which the circular basic shape is open.

According to a further development of the invention, a plurality of armature free travel springs are provided, which are in the form of disk springs and/or wave springs and are arranged in series between the stop element and the armature. The advantageous adaptation to different application situations can be achieved by this embodiment. In particular, the predefined size of the armature free travel can be adapted by the number of armature free travel springs provided.

According to a further development of the invention, a recess is provided on the armature, in which recess at least one armature free travel spring partially sinks when the valve is closed. According to a further preferred embodiment, a recess is provided on the stop element, in which recess at least one free-travel spring is partially immersed when the valve is closed. In the above-described embodiments, in particular: when the valve is open, contact is made directly between the armature and the associated stop element. Even though this is still possible, this direct contact is not necessary in these configurations because the armature free-travel springs are fully compressed together.

Drawings

Preferred embodiments of the present invention are further explained in the following description with reference to the drawings, in which corresponding elements are provided with consistent reference numerals. The attached drawings are as follows:

fig. 1 shows, in a partially schematic sectional view, a valve corresponding to a first embodiment of the invention;

fig. 2 shows in a perspective view an armature free-stroke spring of the valve shown in fig. 1, corresponding to the first exemplary embodiment;

fig. 3 shows a partially schematic perspective sectional view of the valve shown in fig. 1, corresponding to the first embodiment;

fig. 4 shows an armature free travel spring of the valve shown in fig. 1 in a perspective view, corresponding to a second exemplary embodiment;

fig. 5 shows a partially schematic perspective view of the valve shown in fig. 1, corresponding to a second embodiment;

fig. 6 shows an armature free travel spring of the valve shown in fig. 1 in a perspective view, corresponding to a third exemplary embodiment;

fig. 7 shows a partially schematic perspective view of the valve shown in fig. 1, corresponding to a third embodiment;

FIG. 8 shows a partial schematic cross-sectional view of the valve shown in FIG. 1 corresponding to a third embodiment;

fig. 9 shows a partially schematic perspective view of the valve shown in fig. 1, corresponding to a fourth embodiment;

fig. 10 shows a partially schematic perspective view of the valve shown in fig. 1, corresponding to a fifth embodiment;

fig. 11 shows an armature free travel spring of the valve shown in fig. 1 in a perspective view, corresponding to a sixth exemplary embodiment;

fig. 12 shows an armature free travel spring of the valve shown in fig. 1 in a perspective view, corresponding to a seventh exemplary embodiment;

fig. 13 shows an armature free travel spring of the valve shown in fig. 1 in a perspective view, corresponding to an eighth exemplary embodiment;

fig. 14 shows an armature free-travel spring of the valve shown in fig. 1 in a perspective view, corresponding to a ninth exemplary embodiment;

FIG. 15 shows a partial schematic cross-sectional view of the valve shown in FIG. 1 corresponding to a modified configuration; and

fig. 16 shows a partial schematic cross-sectional view of the valve shown in fig. 1, corresponding to another modified configuration.

Detailed Description

Fig. 1 shows a partially schematic sectional illustration of a valve 1 of a fuel injection system, corresponding to a first exemplary embodiment, for metering a fluid. The valve 1 can be designed in particular as a fuel injection valve 1. A preferred application is the following fuel injection device: in the fuel injection system, such a fuel injection valve 1 is designed as a high-pressure injection valve 1 and is used to inject fuel directly into an associated combustion chamber of the internal combustion engine. Here, liquid fuels are preferably used as the fuel. However, injection or injection of gaseous fuel is also conceivable.

The valve 1 has an actuator 2 comprising an electromagnetic coil 3 and an armature 4. By energizing the electromagnetic coil 3, a magnetic field is generated by means of the inner pole 5, the armature 4 and the at least partially magnetically conductive housing 6. The inner pole 5 is fixedly connected with the shell 6. The valve 1 has a valve needle 8 which is adjustable along a longitudinal axis 7 within a housing 6 and on which a valve closing body 9 is arranged. The valve closing body 9 cooperates with the valve seat surface 10 to form a sealing seat. Valve closing body 9 may also be formed in one piece with valve needle 8.

Stop

elements

11, 12 are arranged on the valve needle 8 and are fixedly connected to the valve needle 8. The armature 4 is movable along the longitudinal axis 7 between the

stops

11, 12, wherein it is guided on an outer circumferential surface 13 of the valve needle 8. In a modified embodiment, at least one of the

stop elements

11, 12 can also be formed on the valve needle 8. In this exemplary embodiment, valve needle 8 is acted upon by a return spring 16 via a stop element 11, which acts upon valve-closing body 9 by means of valve needle 8 against valve seat surface 10. The valve 1 is thereby kept closed in the rest state.

To actuate the valve 1, the solenoid 3 is energized, as a result of which the armature 4 is accelerated in the opening direction 17 along the longitudinal axis 7 against the force of the armature free travel spring 18. In this case, the return spring 16 initially holds the valve needle 8 in its initial position shown in fig. 1. When the armature 4 is at least indirectly stopped at the stop element 11, i.e. after the armature free travel 19 has been traveled, both the magnetic force and the impact force are transmitted to the valve needle 8, which results in the valve needle 8 opening. The valve needle 8 is then accelerated further together with the armature 4. After the stop of the armature 4 on the inner pole, the valve needle 8 continues to move in the opening direction 17 due to its inertia, wherein a reversal of movement occurs due to the force of the restoring spring 16. Subsequently, the valve needle 8 strikes the armature 4 or the stop 11 again strikes the armature 4 when it moves in a closing direction 20, which is oriented opposite to the opening direction 17, which ideally rests on the inner pole 5 up to this point in time.

The armature 4 has one or preferably several through-

openings

20, 21, which extend from an end face 22 of the armature 4 to an end face 23 of the armature 4. Through the axial through-opening 24 formed in the inner pole 5, during operation, liquid fluid, in particular fuel, is conducted to the armature chamber 25 and then further through said armature chamber to the sealing seat formed between the valve closing body 9 and the valve seat surface 10. The valve needle 8 is guided in the housing 6 in a suitable manner at least indirectly along the longitudinal axis 7. In this embodiment, the valve needle 8 is guided in the through-opening 24 by the stop element 11. The stop element 11 has

recesses

26, 27 in order to enable a fluid flow. The through

openings

20, 21 enable a flow through of the armature 4, wherein fluid can also be conducted through the annular gap 28 between the armature 4 and the housing 6.

In this exemplary embodiment, the armature free-travel spring 18 is designed as a disk spring 18. In this case, the armature free travel spring 18 is arranged between the end face 22 of the armature 4 and the stop face 30 of the stop element 11. In this case, the armature free travel spring 18 can be designed in such a way that the working range of the disk spring 18 in the closed state of the valve 1 is in a taper of 0.05 to 0.08 mm. When the electromagnetic coil 3 is energized, the armature free-travel spring 18 is deformed until it lies at least substantially flat between the end face 22 of the armature 4 and the stop face 30 of the stop element 11 in the opened state of the valve 1.

Fig. 2 shows an armature free-travel spring 18 of the valve 1 shown in fig. 1 corresponding to the first exemplary embodiment in a perspective view. Since the outer diameter 31 of the armature free travel spring 18 projects into the

passage openings

20, 21 of the armature 4, the fuel flow is influenced if the outer edge 32 is of circumferential shape. In order to provide less or as little resistance as possible to the fuel flowing through,

notches

33, 34, 35, 36 are formed at outer edge 32 in the basic shape 37 of armature free travel spring 18. This allows adaptation to the respective application based on the circular basic shape 37. This relates in particular to the number, shape and size of the indentations 33 to 36. For example, the number of openings 33 to 36 can be selected to be the same as the number of through-

openings

20, 21 of the armature 4. The shape of the recesses 33 to 36 can be selected such that covering with the through-

openings

20, 21 is at least largely avoided.

In order to avoid twisting of the armature free travel spring 18 about the longitudinal axis 7 relative to the armature 4 to such an extent that the through-

openings

20, 21 are again completely or partially covered, the circumferential twisting of the armature free travel spring 18 relative to the stop element 11 is limited. For this purpose,

positioning elements

40, 41 are provided on the armature free travel spring 18. The

positioning elements

40, 41 can be designed in particular as latching

lugs

40, 41. The number of

positioning elements

40, 41 can be, for example, the same as the number of

recesses

26, 27 on the stop element 11. However, more or

fewer positioning elements

40, 41 may be provided. The

detent elements

40, 41 can project into the

recesses

26, 27 of the stop element 11 to such an extent that a rotation prevention is achieved. In particular, a configuration with one to four

positioning elements

40, 41 is advantageous if four

recesses

26, 27 are provided, which are arranged with respect to six through-

openings

20, 21 in the armature 4.

Fig. 3 shows a partially schematic perspective sectional view of the valve 1 shown in fig. 1, corresponding to the first exemplary embodiment. It is illustrated here how the positioning element 40, which is designed as a latching lug 40, engages into the groove 26 of the stop element 11.

Fig. 4 shows an armature free travel spring 18 of the valve 1 shown in fig. 1 in a perspective view, which corresponds to a second exemplary embodiment. In this exemplary embodiment, a plurality of slot-shaped cutouts 42 to 45 are formed on the basic shape 37, which cutouts are configured to extend at least substantially radially. To simplify the illustration, only the slit-shaped incisions 42 to 45 are indicated here. A plurality of small recesses 42 to 45 are formed by the slit-shaped cutouts 42 to 45 in order to achieve a sufficiently large flow area. As shown in fig. 5, the free flow surface is thus kept at least approximately as large as the

passage opening

20, 21, 20A, 20B, regardless of the angular position of the armature free travel spring 18.

Fig. 6 to 8 show a valve 1 and an armature free-travel spring 18 corresponding to a third exemplary embodiment. In this case, the armature free travel spring 18 is designed to correspond to the circular basic shape 37, wherein no recesses are provided. As illustrated in fig. 7 and 8, in this exemplary embodiment, the free flow area in the

passage openings

20, 21, 20A, 20B to the armature 4 is realized by a correspondingly small outer diameter 31 of the basic shape 37. If the outer diameter 31 is selected to be smaller than the inner bore circle of the through-

bore

20, 21, 20A, 20B, the through-

bore

20, 21, 20A, 20B is no longer covered. Thus, with this configuration it is possible to achieve: the through-

holes

20, 21, 20A, 20B are not covered at all or at least not substantially covered.

In the exemplary embodiment illustrated in fig. 1 to 8, the armature free-travel spring 18 is designed as a disk spring 18, while the following configuration is realized in the exemplary embodiment illustrated in fig. 9 to 14: in this configuration, the armature free-travel spring 18 is realized as a disk spring and/or as a wave spring 18, having at least one partial configuration as a wave spring.

Fig. 9 shows a partially schematic perspective view of the valve 1 shown in fig. 1 according to a fourth exemplary embodiment. The free-stroke spring 18 is designed as a wave spring 18.

Fig. 10 shows a partially schematic perspective view of the valve 1 shown in fig. 1 according to a fifth exemplary embodiment. In this exemplary embodiment, two armature free-travel springs 18, 18 'are provided, which are each in the form of a wave spring 18, 18'. In this case, the armature free-travel spring 18 is supported on the stop element 11 by means of an armature free-travel spring 18'. The armature free travel spring 18' is supported on the armature 4 by means of the armature free travel spring 18.

Fig. 11 to 14 show different configurations of the armature free-travel spring 18 of the valve 1 corresponding to the sixth to ninth exemplary embodiments, respectively. Here, the configuration shown in fig. 11 has a larger number of waveforms than the configuration shown in fig. 13. The form of the armature free-travel spring 18 shown in fig. 12 as a wave spring 18 has a slot 50, on which the basic shape 37 is open. The outer edge 32, although interrupted by the slit 50, has no tilting (circling) as viewed along the longitudinal axis 7. In the configuration illustrated in fig. 14, the basic shape 37 also has a slit 50. However, the outer edge 32 has an abrupt change 51, as seen along the longitudinal axis 7. Thereby, the winding of the wave spring 18 is obtained to some extent.

The illustrations shown in the figures should, of course, be understood schematically. In particular, the conicity of the cup spring variant and the wave height of the wave spring variant are not shown in a dimensionally correct manner, wherein these conicity and wave height can be shown in a particularly greatly enlarged manner for better recognition.

In particular, in the configuration illustrated in fig. 2, the recesses 33 to 36 can be concavely, i.e. concavely mirrored, formed in the basic shape 37. Other configurations are contemplated. In the embodiment of the armature free travel spring 18 as a wave spring 18, such a recess can be dispensed with. Furthermore, if a plurality of armature free-travel springs 18, 18 'are provided, it is also possible to combine differently configured armature free-travel springs 18, 18'. In this case, more than two armature free-travel springs 18, 18' can also be provided.

Fig. 15 shows a partially schematic sectional view of the valve 1 shown in fig. 1, corresponding to a modified configuration. In this case, a recess 60 is provided in the armature 4, which recess enables a partial depression of the free travel spring 18 on the end face 22 of the armature 4 in the closed state of the valve 1. The recess 60 can be designed such that the armature 4 directly stops against the stop element 11 when the valve 1 is open. At the stop, the mechanical contact occurs directly, rather than solely by means of the armature free travel spring 18. This has the following advantages: the armature free travel spring 18 does not have to be completely compressed at the stop, since the opening pulse is transmitted directly from the armature 4 to the stop element 11. In this case, however, the recess 60 can be designed, depending on the application, in such a way that the armature free travel spring 18 is at least substantially completely compressed or largely flattened at the stop.

A step 61 can be formed in the radial direction by the recess 60. When the armature 4 approaches the stop element 11, a fluid volume 62 is enclosed between the step 61 and the valve needle 8 and between the armature 4 and the stop element 11. Here, the fluid must escape via the step 61 as illustrated by the flow arrow 63 and the annular gap 64 between the armature 4 and the valve needle 8 as illustrated by the flow arrow 65. The fluid volume 62 thus enclosed to some extent contributes to the hydraulic damping.

Fig. 16 shows a partial schematic cross-sectional view of the valve shown in fig. 1, corresponding to another modified configuration. In this case, a recess 66 is provided in the stop element 11 on the stop surface 30, which recess enables a partial depression of the armature free-travel spring 18 in the closed state of the valve 1. A step 61' corresponding to step 61 is realized at this recess. The functional manner corresponds to the configuration described with reference to fig. 15.

In principle, combinations of the configurations according to fig. 15 and 16 are also possible. Furthermore, one or more armature free-travel springs 18 may be provided in a suitable configuration.

The invention is not limited to the illustrated embodiments.

Claims

1. A valve (1) for metering a fluid, in particular a fuel injection valve for an internal combustion engine, having an armature (4) of an electromagnetic actuator (2) and having a valve needle (8) which can be actuated by the armature (4) and which serves for actuating a valve closing body (9) which, in cooperation with a valve seat surface (10), forms a sealing seat, wherein the armature (4) is guided movably on the valve needle (8), wherein at least one stop element (11) which is arranged in a positionally fixed manner on the valve needle (8) is provided which, in connection with the actuation of the valve needle (8), delimits a relative movement between the armature (4) and the valve needle (8), wherein an armature free travel spring (18) is provided which is supported at least indirectly on the stop element (11) on one side and on the armature (4) on the other side, characterized in that the armature free travel spring (18) is configured as a disk spring and/or a wave spring (18).

2. Valve according to claim 1, characterized in that the armature free travel spring (18) has at least one notch (33 to 36) on its outer edge (32).

3. Valve according to claim 2, characterized in that the indentations (33 to 36) are at least substantially concavely shaped.

4. A valve according to any one of claims 1 to 3, characterised in that the armature free-stroke spring (18) has a plurality of slit-shaped cutouts (42 to 45) on its outer edge (32).

5. Valve according to claim 4, characterized in that the slit-shaped incisions (42 to 45) are configured as at least substantially radially extending slit-shaped indentations (42 to 45).

6. A valve according to any one of claims 1 to 5, characterised in that at least one positioning element (40, 41) is provided on the armature free travel spring (18), which positioning element interacts with the stop element (11) in such a way that the armature free travel spring (18) is limited and/or prevented from rotating relative to the stop element (18) in the circumferential direction about the longitudinal axis (7).

7. Valve according to any one of claims 1 to 6, characterized in that the configuration of the armature free-stroke spring (18) is based on a circular basic shape (37).

8. Valve according to claim 7, characterized in that the armature free travel spring (18) is of annular closed configuration.

9. Valve according to claim 7, characterized in that the armature free travel spring (18) has a slot (50) at which the circular basic shape (37) is open.

10. Valve according to one of claims 1 to 9, characterized in that a plurality of armature free-stroke springs (18, 18') are provided, which are configured as disk springs and/or wave springs (18, 18'), and in that the free-stroke springs (18, 18') are arranged in series between the stop element (11) and the armature (4).

11. A valve according to any one of claims 1 to 10, characterised in that a recess (60) is provided in the armature (4), in which recess at least one armature free travel spring (18, 18') partially sinks when the valve is closed.

12. Valve according to any one of claims 1 to 11, characterized in that a notch (66) is provided on the stop element (11), in which notch at least one free-stroke spring (18, 18') partially sinks when the valve is closed.