Valves for metering fluids

Abstract

The invention relates to a valve (1) for metering a fluid, in particular a fuel injection valve for an internal combustion engine, comprising a housing (6), an actuator (2) and a valve needle (15), the valve needle being actuatable along a longitudinal axis (8) by an armature (4) of the actuator (2) against a return spring (30), wherein the armature (4) is guided at least partially on an inner wall (42) of the housing (6) with an outer side (43) of the armature (4). The valve is designed such that at least one partial surface (44) of the outer side (43) of the armature (4) lies at least approximately in a spherical surface (47), wherein, at least when the armature (4) is axially oriented on the longitudinal axis (8), the armature (4) is guided on the partial surface (44) which lies at least approximately in the spherical surface (47).

Description

Technical Field

[0001] 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 present invention relates to the field of injectors for fuel injection systems in motor vehicles, in which fuel is preferably injected directly into the combustion chamber of the internal combustion engine. Background Art

[0002] DE 10 2016 225 776 A1 discloses a fuel injection valve for a fuel injection system of an internal combustion engine. The known fuel injection valve includes a valve needle having a valve closing body and an armature arranged on the valve needle, the valve closing body cooperating with a valve seat surface to form a sealing seat. Stop elements are arranged on the valve needle, between which the armature can move according to the armature's free path. In one embodiment, the valve needle is guided relative to the longitudinal axis or relative to the housing by a stop element in a guide area on the inner bore of the inner pole, further away from the sealing seat. The armature has a through-hole. The armature is guided on the valve needle at the through-hole. The fuel injection valve also includes a return spring that adjusts the valve needle to its initial position, in which the sealing seat is closed, via the stop element. In a modified embodiment, the valve needle is guided by the armature. Here, the outer side of the armature at least partially reaches the inner side of the housing, wherein, instead of the guide area, an annular gap can be formed between the stop element further away from the sealing seat and the inner pole. Summary of the Invention

[0003] The present invention provides a valve for metering a fluid, in particular a fuel injection valve for an internal combustion engine, comprising a housing, an actuator, and a valve needle. The valve needle can be actuated along a longitudinal axis by an armature of the actuator against a return spring. The armature is guided at least partially with its outer side on an inner wall of the housing, at least one partial surface of the outer side of the armature lies at least approximately in a spherical surface, and at least when the armature is axially oriented about the longitudinal axis, the armature is guided on the partial surface that lies at least approximately in the spherical surface. The valve according to the present invention has the advantage that an improved design and operating mode can be achieved. In particular, the injection performance can be improved.

[0004] Advantageous embodiments of the valve proposed by the invention can be achieved by the measures listed in the preferred embodiment.

[0005] The valve is preferably used for metering fluids, particularly liquid fuels. Gasoline or mixtures containing gasoline are particularly suitable as fuels. The fuel is preferably injected directly into the combustion chamber of the internal combustion engine. The liquid fluid can flow through the armature chamber in which the armature is located, thereby contributing to the armature's vibration damping. However, an alternative configuration is also conceivable, in which, for example, a suitable pressurized fluid is present in the armature chamber. Thus, by selecting the appropriate configuration, suitable liquids and, if necessary, gases can be metered.

[0006] The valve comprises an electromagnetic actuator with an armature arranged on a valve needle. The armature is not fixedly connected to the valve needle, but is instead mounted in a floating manner between two stops provided on the valve needle. An axial gap, referred to as the armature free path, is predetermined between the armature and the two stops. Due to the armature free path, the armature can be held in a stationary state against the stop closer to the sealing seat. Thus, when the actuator is subsequently actuated and the armature is actuated, the entire armature free path is preferably available as an acceleration stroke.

[0007] This design with a free armature path offers several advantages. Due to the pulse generated by the armature during opening, the valve needle can be reliably opened even at higher fluid pressures, particularly fuel pressures, provided the magnetic forces are equal. This constitutes a mechanical boost. Furthermore, the moving mass can be decoupled, so that the stop force is divided into two pulses, resulting in less valve seat wear. Furthermore, the mass decoupling makes it possible to reduce the armature's tendency to collide, particularly in highly dynamic valves.

[0008] When the actuator's solenoid coil is energized, the armature is attracted to the actuator's inner pole. A guide hole for guidance along the longitudinal axis is preferably formed on the inner pole. This advantageously allows the valve needle to be radially supported on the inner pole. In a preferred embodiment, this guidance is achieved via a guide element connected to the valve needle, which also serves as a stop for the armature. This guidance of the valve needle on the inner pole by the guide element allows the valve needle to be supported in the housing, rather than by the armature. This avoids corresponding radial forces between the armature and valve needle, or between the armature and the housing. This prevents wear on the radial guide between the armature and valve needle, or between the armature and the valve housing.

[0009] The armature is advantageously supported in the housing between the outer side of the armature and the inner wall of the housing, which, on the one hand, enables an axial movement of the armature between stops arranged on the valve needle along the longitudinal axis and, on the other hand, enables a tilting of the armature, which is preferably achieved according to the principle of a ball bearing.

[0010] For example, for the manufacture of the valve, a certain tolerance range can be predefined for the configuration of the stop surface in which the armature participates. This relates in particular to the stop surface of the stop element on which the armature rests at the start of actuation, or precisely on which it rests, and on the inner pole. Due to manufacturing factors, deviations from the ideally perpendicular orientation of these stop surfaces on the longitudinal axis can occur. In particular, the stop surfaces cannot be oriented parallel to each other. The support of the armature on the inner wall of the housing, which is implemented according to the principle of a ball bearing, can cause the armature to tilt due to the orientation of the stop surface during injection with one or more actuations of the valve needle, without causing increased wear, for example due to edge loads.

[0011] According to a preferred embodiment, a portion of the outer side of the armature that lies at least approximately within the spherical surface, as viewed along the longitudinal axis, is arranged in a first axial section of the armature, which is located between a first end side of the armature and a second end side of the armature. Furthermore, the first axial section of the armature is spaced apart from the first end side and / or the first axial section of the armature is spaced apart from the second end side. In these embodiments of the invention, it is particularly advantageous if the first axial section of the armature is implemented as an intermediate axial section that is spaced apart from both the first end side and the second end side of the armature. A correspondingly suitable configuration of the outer side of the armature can be achieved between this first axial section or intermediate axial section and the two end sides. In particular, it is conceivable that the gap between the outer side of the armature and the inner wall of the housing be kept as small or as minimal as possible to achieve a high magnetic flux density when the electromagnetic coil is excited.

[0012] According to a preferred embodiment, a further axial section is provided between the first axial section and the first end face of the armature, in which the armature tapers on its outer side toward the first end face, and / or a further axial section is provided between the first axial section and the second end face of the armature, in which the armature tapers on its outer side toward the second end face. This embodiment according to the invention has the advantage that the armature can be tilted within a preferably large range or at a preferably large tilt angle. A conical design of the armature outer side in one of the further axial sections is particularly suitable. Furthermore, one of the further axial sections extends from the first axial section to the first end face or from the first axial section to the second end face. According to this embodiment according to the invention, it is advantageous that each further axial section of the armature transitions uniformly into the first axial section or the intermediate axial section. The armature outer side can thus be configured such that, viewed along the longitudinal axis, a tangential transition occurs from a cone to a spherical radius or vice versa. The armature is accordingly convex in its outer region. In an axial section viewed along the longitudinal axis, the armature outer side has a spherical radius in a first section, to which a cone preferably adjoins on both sides. Therefore, significant advantages result if the armature outer side is conical in one of the further axial sections and / or if one of the further axial sections extends from the first axial section to the first end side or from the first axial section to the second end side.

[0013] According to a preferred embodiment, an inner pole is provided, which is arranged fixedly within the housing. During actuation, the armature abuts against the inner pole with its first end face, and one of the further axial sections or the further axial section is designed such that the armature can tilt and thus abut flatly against a stop surface of the inner pole, thereby compensating for certain manufacturing tolerances. This embodiment according to the invention has the advantage that even if the armature tilts, a ball bearing is always achieved in the center section. The at least one further axial section does not guide the armature against the inner wall of the housing, but rather achieves the tilting by means of a gap that is wedge-shaped in profile. The at least one further axial section can be designed such that a preferably small gap still exists between the outer side of the armature and the inner wall of the housing. Furthermore, a stop element is provided, which is preferably arranged in a fixed position on the valve needle, against which the armature abuts with its second end face during actuation, and one of the further axial sections or the further axial section is designed such that the armature can be tilted and thus abut flatly against a stop surface of the stop element in order to compensate for certain manufacturing tolerances. This embodiment also yields the corresponding advantages described above.

[0014] According to a preferred embodiment, the housing comprises a magnetic housing part, the housing inner wall extending over a magnetic wall region of the magnetic housing part, as viewed along the longitudinal axis, and a first axial section of the armature is arranged between a first end side and a second end side such that, as viewed along the longitudinal axis, the first axial section is positioned at least approximately centrally relative to the magnetic wall region. This embodiment of the invention has the advantage that the magnetic flux density can be optimized when the coil is excited. This results in a further improvement in the switching behavior of the valve. Furthermore, when the armature is oriented along the longitudinal axis, a radial compensating play is predetermined between the armature and the valve needle, and / or the armature is always guided over a subsurface that lies at least approximately within a spherical surface. This embodiment of the invention also improves the switching behavior of the valve, reducing wear over the service life and thus enabling a uniform switching behavior.

[0015] The armature can advantageously be arranged in an armature chamber filled with a liquid fluid to achieve damping of the armature movement. The liquid fluid can, in particular, be a fluid metered by a valve. The metered fluid can, for example, be guided into the armature chamber via a guide hole in the inner pole. The armature can, for example, have through-holes through which the fluid can then be guided further to the sealing seat. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In the following description, preferred embodiments of the present invention are described in detail with reference to the accompanying drawings, in which corresponding elements are provided with corresponding reference numerals. The accompanying drawings show:

[0017] Figure 1 A partially schematic cross-sectional view of a valve according to an embodiment of the present invention;

[0018] Figure 2 exist Figure 1 A schematic cross-sectional view of the armature of the valve shown in FIG;

[0019] Figure 3 exist Figure 1 , wherein the armature is stationary or abuts against the stop element or is stationary on the stop element, for explaining the working mode of a possible configuration of the present invention; and

[0020] Figure 4 exist Figure 1 The schematic partial view of the valve shown in FIG, in which the armature abuts against the inner pole, serves to illustrate the mode of operation of a possible embodiment of the invention. DETAILED DESCRIPTION

[0021] Figure 1A schematic, partially cutaway view of a valve 1 for metering a fluid according to one embodiment is shown. The valve 1 can be designed, in particular, as a fuel injection valve 1. A preferred application is a fuel injection system in which 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 an internal combustion engine. The design of the valve 1 is particularly suitable for liquid fluids, in particular liquid fuels such as gasoline or diesel, or for liquid mixtures with at least one fuel.

[0022] The valve 1 has an electromagnetic actuator 2, which includes a solenoid coil 3, an armature 4, and an inner pole 5. When the solenoid coil 3 is energized, a magnetic circuit is closed via a housing (valve housing) 6, the armature 4, and the inner pole 5, thereby actuating the armature 4 in an opening direction 7 along a longitudinal axis 8 of the housing 6. The housing 6 includes a housing part 9, a valve seat body 11 connected to the housing part 9, and an inlet nozzle 12.

[0023] The armature 4 is arranged on the valve needle 15, wherein a floating support of the armature 4 on the valve needle 15 is realized. For this purpose, a stop is provided by stop surfaces 16, 17, which are arranged in a fixed position on the valve needle 15. The stop surfaces 16, 17 are arranged on stop elements 18, 19, which are each connected to the valve needle 15, for example by welding or by pressing onto the valve needle 15. The stops 16, 17 are arranged on the valve needle 15 in such a way that a free armature path 20 ( Figure 3 ).

[0024] In the initial state, the armature 4 rests against the stop 17. When the armature 4 is actuated, it first moves through the armature free path 20 until it comes into contact with the stop 16. The armature 4 then moves the valve needle 15 in the opening direction 7. This provides a larger opening pulse to open the valve 1. When the valve 1 opens, the valve closing element 21 connected to the valve needle 15 lifts off the valve seat surface formed on the valve seat element 11, thereby opening the sealing seat formed between the valve closing element 21 and the valve seat surface. A fluid, in particular fuel, can then be injected from the interior 24 of the valve housing 6 through the nozzle opening formed in the valve seat element 11 into a chamber, in particular a combustion chamber of an internal combustion engine.

[0025] When the valve 1 is open, the armature 4 stops on the stop surface 28, which is configured on the inner pole 5. The stop surface 28 limits the movement of the armature 4 relative to the valve housing 6. Here, the valve needle 15 can also move further in the opening direction and then vibrate back until the valve needle rests on the armature 4 with its stop element 18 again. In order to close the valve 1, the electromagnetic coil 3 is de-energized, so that the valve needle 15 is adjusted to the position again by the return spring 30. Figure 1The return spring 30 can also be called a closing spring 30 or a compression spring 30. In addition, the return spring 30 is designed and installed in such a way that it is under a predetermined preload in the initial position of the valve needle 15, so that when the electromagnetic coil 3 is de-energized, the closed valve seat is loaded with a corresponding closing force in the initial position. In the closed state, the armature free path spring 31 ensures that the valve seat is in a closed position. Figure 1 , the armature 4 is shown in its initial position, in which the armature 4 rests against the stop surface of the stop 17 .

[0026] Thus, the valve needle 15 can be actuated by the actuator 2 against the force of the return spring 30 in order to open the valve 1. When the valve 1 is opened and subsequently closed, the valve needle 15 is guided. The valve needle 15 is guided, on the one hand, in the guide bore 33 of the inner pole 5 and, on the other hand, in the region of the valve seat body 11 by means of the stop element 18, which also serves as a guide element here.

[0027] Figure 2 Out of Figure 1 Schematic sectional view of the armature 4 of the valve 1 shown in . The armature 4 has a first section 34, which in this embodiment is a middle section 34. A further (second) section 36 is arranged between the first section 34 and the first end side 35 of the armature 4. In addition, a further (third) section 38 is arranged between the middle section 34 and the second end side 37 of the armature 4. Viewed along the longitudinal axis 8, the center of the middle section 34 is arranged at a distance 39 from the second end side 37. The distance 39 is selected in this case so that the middle section 34 of the armature 4 is located as centrally as possible in the magnetic region 40 ( Figure 1 ), at which magnetic region the magnetic flux runs in the transition between the armature 4 and the housing 6. The arrangement of the intermediate section 34 at a distance 39 relative to the magnetic region 40 of the housing 6 therefore relates in particular to a magnetic wall region 41 on the inner wall 42 of the housing 6, on which the armature 4 is guided with its outer side 43 in the intermediate section 34.

[0028] The outer side 43 is divided into three annular partial surfaces 44, 45, and 46, corresponding to the sections 34, 36, and 38. The partial surface 44 lies within a spherical surface 47. The partial surface 45 in the further section 36 is designed as a conical partial surface 45 that tapers in the opening direction 7. The partial surface 46 in the further section 38 is designed as a conical partial surface 46 that tapers opposite the opening direction 7. When the armature 4 is oriented along the longitudinal axis 8, wedge angles 48 and 49 of the conical partial surfaces 45 and 46 relative to the longitudinal axis 8 or to the inner wall 42 of the housing 6 are generated in the contour. The wedge angles 48 and 49 are predetermined to be as small as possible, so that the gap between the outer side 43 of the armature 4 and the inner wall 42 of the housing 6 is preferably small. However, the wedge angles 48 and 49 are predetermined to be large enough to achieve the desired tilting of the armature 4 relative to the longitudinal axis 8. For example, a value not greater than 2° can be predefined for the wedge angles 48 , 49 (and possibly also equal values).

[0029] Figure 3 Shown in Figure 1 The schematic partial view of the valve 1 shown in FIG, in which the armature 4 is at rest or abuts against the stop element 19 or is at rest on the stop element 19, serves to illustrate the mode of operation of a possible embodiment of the present invention. The valve needle 15 and the longitudinal axis 8 are shown in an ideal orientation relative to the inner wall 42 of the valve housing 6. For the sake of clarity, the stop element 19 is not shown in an ideal orientation. When the end face 37 of the armature 4 rests flatly against the stop surface 17 of the stop element 19, the inclined position of the stop element 19, which should be understood here as schematic (not to scale), causes the armature 4 to tilt relative to the longitudinal axis 8 in the rest position. The partial surface 44 of the intermediate section 34 is selected to be large enough along the longitudinal axis 8 so that even with such an armature tilt, guidance relative to the inner wall 42 is achieved on the partial surface 44 located in the spherical surface 47. During actuation, the ball bearing allows an advantageous rotation or tilting back due to hydraulic centering by means of a liquid fluid which is present in the armature chamber 50 in which the armature 4 is arranged.

[0030] When the armature 4 is actuated, the valve needle 15 is carried along with the stop element 18 through the armature free path 20. It then abuts against the inner pole 5, which is also shown schematically (and not to scale) at an angle.

[0031] Figure 4 Shown in Figure 1 The schematic partial view of the valve 1 shown in FIG, wherein the armature 4 abuts against the inner pole 5, serves to illustrate the working mode of a possible embodiment of the invention. Here, when the armature 4 rests flatly with its first end side 35 against the abutment surface 28 of the inner pole 5, the armature 4 tilts again. For the sake of clarity, this tilt is not shown here in FIG. Figure 3The situation shown in is exactly the opposite. Here, the wedge angles 48, 49 are selected so large that even in the maximum tilted position (tilted) caused by tolerances, one of the conical part surfaces 45, 46 prevents the armature 4 from being clamped or from contacting the inner wall 42. In this case, the diameter 51 of the spherical surface 47 can be predetermined to be at least approximately equal to the guide diameter 52 of the inner wall 42 of the housing 6.

[0032] As in Figure 1 As shown in FIG, when the armature 4 is oriented on the longitudinal axis 8, a radial compensating gap 53 is predetermined between the armature 4 and the valve needle 15, which can be realized, for example, by an annular gap 54. The radial compensating gap 53 or annular gap 54 is preferably realized in such a way that the armature 4 is guided in the provided area on the outer side 43 even when tilted.

[0033] It can thus be ensured that the armature 4 is always guided on its outer side 43 during operation. In particular, it can be ensured that the armature 4 is always guided on the partial surface 44 of the armature outer side 43, which is located in the spherical surface 47, in the region of a predetermined inclination during operation. This ensures a favorable ball bearing during operation, which allows for favorable inclination of the armature 4 and, if necessary, hydraulic centering of the armature.

[0034] In this way, in particular, edge loads can be avoided, which reduces wear between the armature 4 and the housing 6 and allows the switching force to be increased. In particular, high opening and closing speeds and uniform switching behavior can be achieved by the possible hydraulic centering of the armature 4 relative to the longitudinal axis 8, which also takes effect during radial centering.

[0035] The present invention is not limited to the described embodiments.

Claims

1. A valve (1) for metering a fluid, comprising a housing (6), an actuator (2) and a valve needle (15), which can be actuated along a longitudinal axis (8) by an armature (4) of the actuator (2) against a return spring (30), wherein: The armature (4) is guided at least partially with an outer side (43) of the armature (4) on an inner wall (42) of the housing (6), It is characterized by: At least one partial surface (44) of the outer side (43) of the armature (4) is at least approximately located in a spherical surface (47), wherein, at least when the armature (4) is axially oriented on the longitudinal axis (8), the armature (4) is guided on the partial surface (44), which is at least approximately located in the spherical surface (47), wherein, viewed along the longitudinal axis (8), the partial surface (44) of the outer side (43) of the armature (4) which is at least approximately located in the spherical surface (47) is arranged in a first axial section (34) of the armature (4), which is located between a first end side (35) of the armature (4) and a second end side (37) of the armature (4), wherein A further axial section (36) is provided between the first axial section (34) and the first end side (35) of the armature (4), in which the armature (4) tapers gradually on its outer side (43) in the direction of the first end side (35), and / or a further axial section (38) is provided between the first axial section (34) and the second end side (37) of the armature (4), in which the armature (4) tapers gradually on its outer side (43) in the direction of the second end side (37), wherein the outer side (43) of the armature (4) is conically configured in at least one of the further axial sections (36, 38).

2. The valve according to claim 1, It is characterized by: A first axial section (34) of the armature (4) is spaced apart from the first end side (35) and / or a first axial section (34) of the armature (4) is spaced apart from the second end side (37).

3. The valve according to claim 1 or 2, It is characterized by: At least one of the further axial sections (36, 38) extends from the first axial section (34) to the first end side (35) or from the first axial section (34) to the second end side (37).

4. The valve according to claim 1 or 2, It is characterized by: An inner pole (5) is provided which is arranged in a fixed position in the housing (6), and upon actuation, the armature (4) abuts against the inner pole with its first end side (35), and one of the further axial sections (36, 38) or the further axial section (36, 38) is designed in such a way that the armature (4) can be tilted and thus abut flatly against a stop surface (28) of the inner pole (5) in order to compensate for certain manufacturing tolerances.

5. The valve according to claim 1 or 2, It is characterized by: A stop element (19) is provided on the valve needle (15), on which the armature (4) abuts with its second end side (37) during actuation, and one of the further axial sections (36, 38) or the further axial section (36, 38) is configured such that the armature (4) can be tilted and thus abut flatly on the stop surface (17) of the stop element (19) in order to compensate for certain manufacturing tolerances.

6. The valve according to claim 1 or 2, It is characterized by: The housing (6) has a magnetic housing part (9), the inner wall (42) of the housing (6) extending over a magnetic wall region (41) of the magnetic housing part (9) as viewed along the longitudinal axis (8), and the first axial section (34) of the armature (4) is arranged between the first end side (35) and the second end side (37) such that the first axial section (34) is positioned at least approximately centrally relative to the magnetic wall region (41) as viewed along the longitudinal axis (8).

7. The valve according to claim 1 or 2, It is characterized by: When the armature (4) is oriented on the longitudinal axis (8), a radial compensating play (53) is predetermined between the armature (4) and the valve needle (15), and / or the armature (4) is always guided on the partial surface (44) which lies at least approximately in the spherical surface (47).

8. The valve according to claim 1, It is characterized by: The valve (1) is designed as a fuel injection valve for an internal combustion engine.

9. The valve according to claim 5, It is characterized by: The stop element (19) is arranged on the valve needle (15) in a fixed position.

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