KR20200120546A - Valve for metering a fluid - Google Patents

Abstract

The present invention relates to a fluid metering valve (1), in particularly, a fuel injection valve for an internal combustion engine, which comprises a housing (6), an actuator (2), and a valve needle (15) operated against a return spring (30) in a longitudinal axis (8) by an amateur (4) of the actuator (2). An outer surface (43) of the amateur (4) is at least partially guided in an inner wall (42) of the housing (6). The valve has at least one partial surface (44) of the outer surface (43) of the amateur (4) approximately placed in a spherical surface (47). Also, the amateur (4) is designed to be guided on the partial surface (44) at least approximately placed in the spherical surface (47) when the amateur (4) is axially aligned with at least the longitudinal axis. Accordingly, the valve can have an improved design and operating principle, in particular, an improved injection behavior.

Description

Fluid metering valve {VALVE FOR METERING A FLUID}

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

DE 10 2016 225 776 A1 discloses a fuel injection valve for a fuel injection system of an internal combustion engine. The disclosed fuel injection valve includes a valve needle having a valve closing body that interacts with a valve seat surface to form a sealing seat, and an armature disposed on the valve needle. Stop elements are arranged on the valve needle, between which the armature can be moved along the armature free path. The guide of the valve needle to the longitudinal axis or to the housing in one embodiment takes place via a stop element away from the sealing seat in the guide area on the inner bore of the inner pole. The armature includes a through bore. In the through bore, the armature is guided on the valve needle. Further, the fuel injection valve comprises a return spring, which moves the valve needle through a stop element to its starting position, in which the sealing seat is closed. In a variant embodiment, the guide of the valve needle is realized via an armature. In this case, the outer surface of the armature extends at least partially to the inner surface of the housing, and instead of the guide area, an annular gap can be implemented between the inner pole and the stop element far from the sealing sheet.

It is an object of the present invention to provide a valve that allows an improved design and principle of operation, in particular an improved injection behavior.

A valve according to the invention having the features of claim 1 has the advantage that an improved design and operating principle become possible. In particular, the injection behavior can be improved.

By means of the measures set forth in the dependent claims, a desirable improvement of the valve set forth in claim 1 is possible.

Valves are preferably used for metering liquids, in particular liquid fuels. As fuel, gasoline or mixtures containing gasoline are particularly suitable. In this case, the fuel is preferably injected directly into the combustion chamber of the internal combustion engine. The liquid can flow through the armature chamber in which the armature is placed, which contributes to the damping of the armature. However, alternative embodiments are possible, for example with suitable pressure fluids in the armature chamber. Thus, by the choice of the respective design, metering of suitable liquids and, in some cases, gases can be made possible.

The valve includes an electromagnetic actuator having an armature disposed on the valve needle. The armature is not fixedly connected to the valve needle, but is supported in a cantilever manner between two stops provided on the valve needle. In this case, the axial clearance (amateur free path) between the armature and the two stops is predetermined. Since the armature is held at rest via the armature free-path spring at rest, which lies closer to the sealing seat, in the subsequent control of the actuator and in the operation of the armature in this case, preferably a complete armature free path is provided as the acceleration distance.

This embodiment with an amateur free path has a number of advantages. By the impact of the armature upon opening, if the magnetic force is the same, the valve needle can be reliably opened even at a higher fluid pressure, in particular fuel pressure, which creates a mechanical boost. In addition, the moved mass can be separated so that the impact force is divided into two impacts, resulting in less sheet wear. In addition, the bouncing tendency of the armature, especially in high dynamic valves, can be achieved by separation of the mass.

The armature is pulled from the inner pole of the actuator when the solenoid coil of the actuator is energized. The guide bore for the guide along the longitudinal axis is preferably formed on the inner pole. Preferably this allows the valve needle to be supported radially on the inner pole. In a preferred embodiment, the guide is made via a guide element connected to the valve needle, which guide element is simultaneously used as a stop element for the armature. The guide of the valve needle through the guide element at the inner pole makes it possible to support the valve needle in the housing, and since the support is not via the armature, the corresponding radial force between the armature and the valve needle or between the armature and the housing is initially Is prevented from This prevents wear of the armature and the valve needle or the radial guide between the armature and the valve housing.

Between the outer surface of the armature and the inner wall of the housing, preferably the support of the armature is realized in the housing, which support, on the one hand, enables axial movement of the armature along the longitudinal axis between stops provided on the valve needle, and the other On the one hand, it is possible to tilt the armature, which is preferably implemented according to the principle of a ball bearing.

For example, for the manufacture of valves, a specific tolerance range for the design of relevant stops for armatures is predetermined. This in particular relates to the stop surfaces of the stopping element and the stop surfaces on the inner pole which are seated when the armature starts to operate. In manufacturing, deviations from the longitudinal axis and the ideal vertical alignment of the stop surfaces may occur. In particular, this makes it impossible for the stop surfaces to be oriented parallel to each other. The bearing of the armature, realized according to the principle of a ball bearing on the inner wall of the housing, allows the armature to tilt due to the orientation of the stop surfaces during the injection process in which the valve needle is operated once or several times, in this case increased wear due to eg edge runners. Does not appear.

In a refinement according to claims 2 and 3, it is particularly preferred that the first axial section of the armature is embodied as an intermediate axial section spaced apart from the first and second end faces of the armature. A suitable design of the outer surface of the armature, respectively, between the first or intermediate axial section and the two end surfaces can be implemented. In this case, it can be considered that the gap between the outer surface of the armature and the inner wall of the housing is kept as small or small as possible, in order to achieve a high magnetic flux density, particularly during excitation of the solenoid coil.

The advantage of the improvement example according to claim 4 is that the tilting of the armature is possible over a range or tilt angle of the optimum size. In particular, the embodiment according to claim 5 is suitable. In the refinement example according to claim 6, it is preferred that a uniform transition is made from each further axial section of the armature to the first or intermediate axial section. Due to this, the outer surface of the armature can be designed such that a tangential transition from the cone to the ball radius or from the ball radius to the cone is realized when viewed along the longitudinal axis. The armature is designed according to the convex shape in the area of its outer surface. The outer surface in one axial section as viewed along the longitudinal axis has a radial design in the first section, preferably a conical shape on both sides following the radial design. Thus, if the improvement according to claim 5 or 6 is realized, essential advantages are achieved.

The improvement example according to claim 7 has the advantage that ball bearings are always realized in the intermediate section when the armature is inclined. In this case at least one additional axial section is used not to guide the armature in the inner wall of the housing, but to achieve tilting through the gap which is wedge-shaped in profile. The at least one additional axial section can be designed so as to create an optimally small gap between the outer surface of the armature and the inner wall of the housing. Corresponding advantages are achieved in a preferred refinement according to claim 8.

The improvement example according to claim 9 has the advantage that the magnetic flux density can be optimized when the coil is excited. Due to this, a further improvement in the switching behavior of the valve is achieved. The switching behavior of the valve is improved by means of an improvement example according to claim 10, and a reduction in wear over the lifetime and thus the uniformity of the switching behavior becomes possible.

Preferably the armature can be placed in a liquid filled armature chamber to enable damping of the movement of the armature. The liquid may in particular be a fluid metered by a valve. The fluid to be metered can be guided into the armature chamber, for example through a guide bore in the inner electrode. The armature may comprise, for example, a through bore capable of guiding the fluid into the sliding seat.

Preferred embodiments of the present invention will be described in detail in the following description with reference to the accompanying drawings. In the drawings, corresponding elements are indicated by the same reference numerals.

1 is a schematic cross-sectional view of a valve according to an embodiment of the present invention,
2 is a schematic cross-sectional view showing an armature of the valve shown in FIG. 1,
Fig. 3 is a schematic diagram of the valve shown in Fig. 1, with an armature seated on or hitting a stop element, to illustrate the principle of operation of a possible embodiment of the present invention,
Fig. 4 is a schematic diagram of the valve shown in Fig. 1 with an armature hitting an inner pole, to illustrate the working principle of a possible embodiment of the present invention.

1 shows a fluid metering valve 1 according to an embodiment in a schematic cross-sectional view. The valve 1 can in particular be designed as a fuel injection valve 1. A preferred application example is a fuel injection system in which the fuel injection valve 1 is designed as a high pressure injection valve 1 and is used to inject fuel directly into the corresponding combustion chamber of an internal combustion engine. The design of the valve 1 for a liquid, in particular a liquid fuel such as gasoline or diesel, or a liquid mixture with at least one fuel is particularly suitable.

The valve 1 has an electromagnetic actuator 2 comprising a solenoid coil 3, an armature 4 and an inner electrode 5. When the solenoid coil 3 is energized, the magnetic circuit is closed through the housing (valve housing; 6), the armature 4 and the inner electrode 5, so that the armature 4 operates in the open direction 7 and the housing 6 ) Along the longitudinal axis (8). The housing 6 comprises a housing portion 9, a valve seat body 11 connected to the housing portion 9, and a supply portion 12.

The armature 4 is disposed on the valve needle 15, and cantilever support of the armature 4 on the valve needle 15 is realized. For this purpose, stops realized by means of stop surfaces 16 and 17 are provided, which are fixedly arranged on the valve needle 15. Stop surfaces 16, 17 are provided on stop elements 18, 19, which are respectively connected to the valve needle 15 by means of a welding seam or by pressing against the valve needle 15, respectively. do. The stops 16 and 17 are arranged with the valve needle 15 so that the armature free path 20 (Fig. 3) is predefined along the longitudinal axis 8 between the stops 16 and 17 with respect to the armature 4 Placed on top.

In the starting state, the armature 4 contacts the stop 17. When the armature 4 is activated, the armature 4 first passes through the armature free path 20 until the armature 4 hits the stop 16. Then, the armature 4 is moved in the opening direction 7 together with the valve needle 15. Due to this, a larger opening shock is provided to open the valve 1. When the valve 1 is opened, the valve closing body 21 connected to the valve needle 15 is lifted from the valve seat surface formed on the valve seat body 11, so that between the valve closing body 21 and the valve seat surface The formed sealing sheet is opened. The fluid, in particular fuel, can then be injected from the inner space 24 of the valve housing 6 into the chamber, in particular the combustion chamber of the internal combustion engine, through the furnace holes formed in the valve seat body 11.

When the valve 1 is opened, the armature 4 hits the stop surface 28 formed on the inner electrode 5. The stop surface 28 limits the movement of the armature 4 relative to the valve housing 6. In this case, the valve needle 15 can be moved further in the opening direction and then returned until the stop element 18 reaches the armature 4. To close the valve 1, the solenoid coil 3 is de-energized, so the valve needle 15 is moved back to the starting position shown in FIG. 1 by the return spring 30. The return spring 30 may also be referred to as a closed spring 30 or a compression spring 30. In addition, the return spring 30 is designed to receive a predetermined prestress at the starting position of the valve needle 15, and apply a closing force corresponding to the closed sealing seat at the starting position in the non-energized solenoid coil 3, and Installed. In the closed state, the starting position of the armature 4 shown in FIG. 1 where the armature 4 contacts on the stop surface of the stop 17 is ensured by the armature free path spring 31.

Thus, the valve needle 15 can be actuated against the force of the return spring 30 by the actuator 2 to open the valve 1. Upon opening and subsequent closing of the valve 1, the guide of the valve needle 15 is made. The guide of the valve needle 15 is on the one hand in the guide bore 33 of the inner pole 5 by means of a stop element 18 which is also used here as a guide element and on the other hand in the area of the valve seat body 11. Done.

FIG. 2 shows the armature 4 of the valve 1 shown in FIG. 1 in a schematic cross-sectional view. The armature 4 comprises a first section 34 which in this embodiment is an intermediate section 34. An additional (second) section 36 is provided between the first section 34 and the first end face 35 of the armature 4. In addition, an additional (third) section 38 is provided between the middle section 34 of the armature 4 and the second end face 37. The middle of the intermediate section 34 is arranged at a distance 39 with respect to the second end face 37 when viewed along the longitudinal axis 8. In this case, the distance 39 is selected so that the intermediate section 34 of the armature 4 lies as intermediate as possible to the magnetic region 40 (Fig. 1) of the housing 6 (valve housing), and the magnetic region 40 In) the magnetic flux extends at the transition between the armature 4 and the housing 6. The arrangement of the intermediate section 34 over the distance 39 to the magnetic region 40 of the housing 6 is in particular the housing 6 in which the outer surface 43 of the armature 4 is guided in the intermediate section 34 It relates to the magnetic wall region 41 on the inner wall 42 of the.

The outer surface 43 is divided into three annular partial surfaces 44, 45, 46 according to the sections 34, 36, 38. The partial surface 44 lies within the spherical surface 47. The partial face 45 in the further section 36 is formed as a conical conical face 45 which tapers in the opening direction 7. The partial surface 46 in the further section 38 is formed as a conical conical surface 46 which tapers against the opening direction 7. If the armature 4 is aligned with the longitudinal axis 8, the wedge angle of the conical partial faces 45, 46 relative to the longitudinal axis 8 or the inner wall 42 of the housing 6, as viewed in profile ( 48, 49) are formed. Since the wedge angles 48 and 49 are predetermined as small as possible, the gap between the outer surface 43 of the armature 4 and the inner wall 42 of the housing 6 is optimally small. However, in this case, the wedge angles 48 and 49 are predetermined to be a size capable of a predetermined inclination of the armature 4 with respect to the longitudinal axis 8. For example, for the wedge angles 48 and 49, a value not greater than 2° (and, in some cases, the same value), respectively, may be predetermined.

FIG. 3 shows a schematic view of the valve 1 shown in FIG. 1 with the armature 4 seated or bumped against the stop element 19 to illustrate the principle of operation of a possible embodiment of the invention. In this case, the valve needle 15 and the longitudinal axis 8 are shown in ideal alignment with the inner wall 42 of the valve housing 6. For purposes of clarity, the stop element 19 is ideally shown in an unaligned state. If the end face 37 of the armature 4 is in planar contact with the stop face 17 of the stop element 19, the approximate (non-scale) tilt position here of the stop element 19 is the length at the rest position. It causes an inclination of the armature 4 with respect to the directional axis 8. The partial surface 44 of the intermediate section 34 is guided along the longitudinal axis 8 to the inner wall 42 on the partial surface 44 lying in the spherical surface 47 even in the case of said tilting of the armature. It is chosen by size. Such ball bearings enable a desirable re-rotation or re-tilting of the armature 4 in operation due to hydraulic centering by the liquid in the armature chamber 50 in which the armature 4 is disposed.

Upon actuation of the armature 4, after the armature free path 20 has been passed, the valve needle 15 is moved together with the stop element 18. Then, a bump is made against the inner pole 5 shown here schematically (unscaled) tilted.

4 shows a schematic view of the valve 1 shown in FIG. 1 with the armature 4 striking the inner electrode 5 to illustrate the principle of operation of a possible embodiment of the invention. In this case, when the first end surface 35 of the armature 4 contacts the stop surface 28 of the inner electrode 5 in a plane, the inclination of the armature 4 appears again. For purposes of clarity, the inclination here is the opposite of the situation shown in FIG. 3. In this case, the wedge angles 48 and 49 are sized to prevent contact of the inner wall 42 with the feel of the armature 4 or one of the conical partial surfaces 45 and 46 even at an inclined position (inclination) due to the maximum tolerance. Is selected as The diameter 51 of the spherical surface 47 may in this case be predetermined at least substantially equal to the guide diameter 52 of the inner wall 42 of the housing 6.

A radial compensation clearance 53 is pre-determined between the armature 4 and the valve needle 15, and the clearance is when the armature 4 is aligned with the longitudinal axis 8 as shown in FIG. 1, For example, it can be realized by an annular gap 54. The radially compensating play 53 or the annular gap 54 is preferably implemented in this case so that it takes place within the area provided on the outer surface 43 even when the guide of the armature 4 is inclined.

Thus, it can be ensured that the guide of the armature 4 is always made on its outer surface 43 even during operation. In particular, it can be ensured that the guide of the armature 4 is made on the partial surface 44 of its outer surface 43 always lying within the spherical surface 47 in a predetermined range of inclination during operation. This ensures that, at all times during operation, a desirable tilting of the armature 4 and, in some cases, a desirable ball bearing enabling its hydraulic centering.

Thus, in particular edge runners can be prevented, which reduces wear between armature 4 and housing 6 and increases switching force. In this case, high opening and closing speeds and uniform switching behavior are possible, in particular by hydraulic centering of the armature 4 with respect to the longitudinal axis 8 which also affects radial centering.

The invention is not limited to the illustrated embodiments.

1: valve
2: actuator
4: amateur
6: housing
8: longitudinal axis
15: valve needle
17: stop surface
19: stop element
30: return spring
34: first axial section
43: external surface
44: partial face
47: spherical

Claims (10)

A fluid metering valve 1, in particular a fuel injection valve for an internal combustion engine, by means of a housing 6, an actuator 2, and an armature 4 of the actuator 2 along the longitudinal axis 8 along a return spring 30 ), wherein the outer surface (43) of the armature (4) is at least partially guided on the inner wall (42) of the housing (6),
At least one partial surface 44 of the outer surface 43 of the armature 4 lies at least approximately in the spherical surface 47, and at least when the longitudinal axis and the armature 4 are axially aligned, Valve, characterized in that the guide of the armature (4) is made on the partial surface (44) lying at least approximately in the spherical surface (47). The method of claim 1,
The partial surface 44 of the outer surface 43 of the armature 4 lying at least approximately in the spherical surface 47 is in the direction of the first axis of the armature 4 when viewed along the longitudinal axis 8 Arranged in section 34, the first axial section 34 being arranged between the first end face 35 of the armature 4 and the second end face 37 of the armature 4 Valve characterized by. The method of claim 2,
The first axial section 34 of the armature 4 is spaced apart from the first end face 35 and/or the first axial section 34 of the armature 4 is at the second end Valve, characterized in that spaced apart from the side surface (37). The method according to claim 2 or 3,
An additional axial section 36 is provided between the first axial section 34 and the first end face 35 of the armature 4, in which the armature ( 4) tapered in the direction of the first end surface 35 and/or between the first axial section 34 and the second end surface 37 of the armature 4 Wherein an additional axial section 38 is provided, in which the outer surface 43 of the armature 4 tapers in the direction of the second end surface 37 Valve. The method of claim 4,
Valve, characterized in that the outer surface (43) of the armature (4) is designed conical in at least one of the further axial sections (36, 38). The method according to claim 4 or 5,
At least one of the further axial sections (36, 38) is from the first axial section (34) to the first end face (35) or from the first axial section (34) to the second end face Valve, characterized in that extending to (37). The method according to any one of claims 4 to 6,
An inner electrode 5 fixedly arranged in the housing 6 is provided, the armature 4 having its first end face 35 hitting the inner electrode 5 when in operation, and the additional axial section 36 , 38) or the additional axial sections (36, 38) are inclined to compensate for certain manufacturing technical tolerances, and thus a flat bump on the stop surface (28) of the inner pole (5). Valve, characterized in that it is designed to enable. The method according to any one of claims 4 to 7,
The valve needle (15) is provided with a preferably fixedly arranged stop element (19), the armature (4) with its second end face (37) striking the stop element (19) in operation, the The additional axial section (36, 38) or the additional axial sections (36, 38) is the tilting of the armature 4 and hence the stopping surface of the stopping element 19 to compensate for certain manufacturing technical tolerances. (17) A valve, characterized in that it is designed to be able to hit the plane. The method according to any one of claims 2 to 8,
The housing 6 comprises a magnetic housing part 9, and the inner wall 42 of the housing 6 is a magnetic wall area of the magnetic housing part 9 when viewed along the longitudinal axis 8 Extending over (41), and the first axial section (34) of the armature (4) is disposed between the first end surface (35) and the second end surface (37) so as to be in the first axial direction Valve, characterized in that the section (34) is arranged at least approximately intermediate to the magnetic wall region (41) when viewed along the longitudinal axis (8). The method according to any one of claims 1 to 9,
When the armature 4 is aligned with the longitudinal axis 8, a radial compensation clearance 53 is pre-determined between the armature 4 and the valve needle 5 and/or the spherical surface 47 Valve, characterized in that the guide of the armature (4) is always made on a partial surface (44) which lies at least approximately in the interior.

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