EP3779172B1 - Valve for metering a fluid - Google Patents

Description

State of the art

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

From the DE 10 2013 222 613 A1 a valve for metering fluid is known.

The known valve has an electromagnet for actuating a valve needle that controls an orifice. The electromagnet is used to actuate an armature that can be moved on a valve needle. Here, the armature has a bore adjacent to the valve needle, which forms a spring mount for a pre-stroke spring.

WO 01/25614 A1 shows another fuel injector with a magnetic coil and a two-part armature acted upon by the magnetic coil in a closing direction by a restoring spring.

Disclosure of Invention

The valve according to the invention with the features of claim 1 has the advantage that an improved design and mode of operation are made possible. Here, in particular, improved guidance between the armature and the valve needle, in particular a damping and calming of the armature, and at the same time an advantageous conduction of the fluid through an armature chamber can take place.

Advantageous further developments of the valve specified in claim 1 are possible as a result of the measures listed in the dependent claims.

In the valve for metering the fluid, the armature that serves as the magnet armature is not firmly connected to the valve needle, but is mounted in a cantilevered manner between stops. Such a stop can be formed on a stop element, which can be realized as a stop sleeve and/or a stop ring. However, the stop element can also be formed in one piece with the valve needle. In the resting state, the armature is adjusted by a spring to a stop that is stationary with respect to the valve needle, so that the armature rests there. When the valve is actuated, the entire free travel of the armature is then available as an acceleration path, with the spring being shortened during acceleration. The armature free travel can be specified via the axial play between the armature and the two stops.

A guide length between the armature and the valve needle can be increased by configuring the spring receptacle with an annular groove that is not adjacent to the valve needle. In this case, the spring seat can advantageously be designed close to the longitudinal axis, i.e. at a small radial distance from the longitudinal axis, in order to enable the fluid to be advantageously introduced from the first region of the armature chamber into the spring seat with a corresponding design of the valve.

In the case of a combination of an armature with straight through-flow bores and a stop with a large outside diameter arranged on the valve needle, it is conceivable that there will be an overlap between the through-flow bore and a stop surface (stop) configured on a corresponding stop element. As a result, part of the damping surface between the armature and the relevant stop element is lost. Furthermore, a free flow cross section is also reduced in the area of the end positions of the armature on the stop elements.

Although the resulting situation has the advantage of a low adhesion effect when the armature is released from the respective stop element during an actuation process, it also means that the damping desired for damping an impact or for calming the armature is reduced. Especially when closing the valve, this can lead to In relation to the desired activation times, too long a period is required for the armature to settle sufficiently. With regard to possibly very short pause times, for example less than 1.2 ms, as may be desired in the case of multiple injection, there are considerable disadvantages in a straight flow bore through the armature that is designed close to the valve needle.

A proposed fluid channel can advantageously allow fluid to be conducted through the armature chamber and at the same time an impairment of a damping behavior can be reduced, which is particularly advantageous for calming the armature when the valve closes. As a result, a specification or setting of the desired damping can also be achieved by the design of the stop surface on the stop element, at least largely unaffected by the passage of the fluid through the armature.

The fluid channel can be configured in an advantageous manner by means of coaxial blind holes that are easy to produce in terms of production technology.

Thus, in an advantageous manner, a combination of an armature free travel spring located in the armature can be implemented with an armature which has a fluid channel running radially outwards. This combination makes it possible for a maximally large damping surface to be realized between a stop element and the armature. In particular, a reduction in the damping area can be avoided by overlapping with the corresponding opening. Since the design of a valve preferably provides for a plurality of fluid channels, which are preferably implemented instead of conventional through-flow bores, the functioning of the valve can be significantly influenced, in particular significantly improved damping. For example, two to ten fluid channels, in particular two to six fluid channels, can be implemented. Such fluid channels can at least partially include the spring receptacle together. This can also improve the flow behavior. In principle, however, is also an embodiment with only one Fluid channel or a combination with at least one proposed fluid channel with at least one conventional through hole is conceivable.

In particular, an embodiment can thus be implemented in which, with respect to a stop surface on the relevant stop element, there is no longer any overlapping between the relevant opening or the relevant openings of the at least one fluid channel and the stop surface on the stop element. This means that the maximum damping surface is available.

Brief description of the drawings

• Fig. 1 ein Ventil in einer auszugsweisen, schematischen Schnittdarstellung entsprechend einem nicht erfindungsgemäßen Beispiel;
• Fig. 2 ein Ventil in einer auszugsweisen, schematischen Schnittdarstellung entsprechend einem nicht erfindungsgemäßen Beispiel;
• Fig. 3 ein Ventil in einer auszugsweisen, schematischen Schnittdarstellung entsprechend einem nicht erfindungsgemäßen Beispiel und
• Fig. 4 ein Ventil in einer auszugsweisen, schematischen Schnittdarstellung entsprechend einem erfindungsgemäßen Ausführungsbeispiel.

A preferred embodiment of the invention is explained in more detail in the following description with reference to the accompanying drawings, in which corresponding elements are provided with the same reference symbols. Show it:

• 1 a valve in a partial, schematic sectional view according to an example not according to the invention;
• 2 a valve in a partial, schematic sectional view according to an example not according to the invention;
• 3 a valve in a partial, schematic sectional view corresponding to an example not according to the invention and
• 4 a valve in a partial, schematic sectional view according to an embodiment of the invention.

Embodiments of the invention

1 shows a valve 1 for metering a fluid in a partial, schematic sectional view according to a first example not according to the invention. The valve 1 can in particular as Fuel injector 1 be formed. A preferred application is a fuel injection system in which such fuel injectors 1 are designed as high-pressure injectors 1 and are used for direct injection of fuel into associated combustion chambers of the internal combustion engine. Liquid or gaseous fuels can be used as the fuel. Accordingly, the valve 1 is suitable for metering liquid or gaseous fluids.

The valve 1 has a housing (valve housing) 2 in which an inner pole 3 is arranged in a stationary manner. A valve needle 5 arranged within the housing 2 in this exemplary embodiment is guided along a longitudinal axis 4 with respect to the housing 2 .

An armature (magnetic armature) 6 is arranged on the valve needle 5 . A stop element 7 and a further stop element 8 are also arranged on the valve needle 5 . Stop surfaces 7', 8' are formed on stop elements 7, 8. The armature 6 can be moved between the stop elements 7, 8 relative to the valve needle 5 when it is actuated along the longitudinal axis 4, with an armature free path 9 being predetermined. The longitudinal axis 4 can be referred to here as the longitudinal axis 4 of the valve needle 5 or as the longitudinal axis 4 of the armature 5 . The armature 6, the inner pole 3 and a magnet coil (not shown) are components of an electromagnetic actuator 10.

A valve closing body 11 is formed on the valve needle 5 and interacts with a valve seat surface 12 to form a sealing seat. When the armature 6 is actuated, it is accelerated in the direction of the inner pole 3 . If the armature 6 hits the stop 7' of the stop element 7 and thereby actuates the valve needle 5, then fuel can be injected via the opened sealing seat and at least one nozzle opening 13 into a space, in particular a combustion chamber.

The valve 1 has a restoring spring 14, which moves the valve needle 5 via the stop element 7 into its initial position, in which the sealing seat is closed.

The armature 6 is based on a cylindrical basic shape 20 with a through hole 21 , the armature 6 being guided on the through hole 21 on the valve needle 5 . Here, the basic shape 20 of the armature 6 has a length 24 between a first face 22 of the armature 6 facing the inner pole 3 and a second face 23 of the armature 6 facing away from the inner pole 3 . The armature 6 is arranged in an armature space 16 . In this case, the first end face 22 adjoins a first region 17 of the armature space 16 . Furthermore, the second end face 23 adjoins a second area 18 of the armature space 16 . During operation, fuel can be conducted through the armature over at least part of its length 24 through at least one fluid channel 15 .

The armature 6 has a spring mount 25 . The fluid channel 15 includes the spring mount 25 here. Thus, the fluid channel 15 leads at least over part of the spring seat 25. The spring seat 25 on the end face 22 of the armature 6 is open. A spring support surface 26 on which a spring 27 partially arranged in the spring seat 25 is supported is formed by the bottom 26 of the spring seat 25 . The spring 27 is also supported on the stop surface 7 ′ of the stop 7 . When the armature 6 is actuated, the spring 27 is shortened compared to its initial length, and it can dip completely into the spring receptacle 25 .

Furthermore, the spring 27 is designed with ground spring ends 43, 44 in this exemplary embodiment. This results in an even better edition. Furthermore, there is reduced wear and a more even introduction of force into the armature 6 on the spring support surface 26 on the one hand and on the stop 7′ of the stop element 7 on the other hand.

In this exemplary embodiment, a guide web 28 is formed on the armature 6 . As a result, the guide length of the armature 6 on the valve needle 5 is equal to the length 24 of the armature 6 between its end faces 22, 23.

In this exemplary embodiment, the valve needle 5 is guided with respect to the longitudinal axis 4 or with respect to the housing 2 via the stop element 7 . In a modified embodiment, the valve needle 5 can also be guided via the armature 6 in addition or as an alternative. The outside 32 of the armature 6 extends at least partially to the inside 33 of the housing 2. In this embodiment, instead of the guide area 30, an annular gap can then be realized between the stop element 7 and the inner pole 3.

In this exemplary embodiment, the fluid channel 15 has an inclined bore 50 . In this case, the fluid channel 15 preferably has precisely one oblique bore 50 . The fluid channel 15 then leads via the inclined bore 50 and at least part 51 of the spring mount 25.

In this exemplary embodiment, there is a direction 19 which is coaxial with respect to the longitudinal axis 4 and which is oriented from the first end face 22 to the second end face 23, in an orientation opposite to an opening direction 52 in which the valve needle 5 is actuated when the valve 1 is opened.

The oblique bore 50 is designed in the armature 6 in such a way that it runs radially outwards along the coaxial direction 19, i.e. away from the longitudinal axis 4, with an angle of inclination in the plane of the drawing between the coaxial direction 19 and an axis 53 of the oblique bore 50 54 results. However, the design of the oblique bore 50 is not limited to the axis 53 lying in the same plane as the longitudinal axis 4 of the valve needle 5, as is the case in the exemplary embodiment shown with the plane defined by the plane of the drawing.

Furthermore, the inclined bore 50 in this embodiment runs from the first end face 22 of the armature 6 to the second end face 23 of the armature 6. Here, a first opening 55 of the fluid channel 15, which adjoins the first area 17, is in the end face 22, while a second opening 56, which adjoins the second region 18, is located in the second end face 23. An advantageous hydraulic connection between the first area 17 and the second area 18 is made possible by the inclined bore 50 running from the first end face 22 to the second end face 23 of the armature 6 . By positioning the first opening 55 on the longitudinal axis 4 close to the axis, the fluid, in particular the fuel, can advantageously flow from the inner bore 31 of the inner pole 3 into the fluid channel 15 . Due to the fact that the second opening 56 of the fluid channel 15 is arranged away from the axis with respect to the longitudinal axis 4, an inner part 57 of the second end face 23, on which the armature 6 interacts with the second stop surface 8', can be sufficiently large in accordance with a predetermined and possibly large second stop surface 8' be specified without the second opening 56 being in this inner part 57 or without the fluid channel 15 intersecting this inner part 57 of the second end face 23 . As a result, a large damping surface can be realized between the second stop surface 8 ′ and the second end face 23 .

Since the inclined bore 50 advantageously intersects with the spring mount 25 over an entire length 58 of the spring mount 25 along the longitudinal axis 4, this results in favorable flow behavior and a first opening 55 of the fluid channel 15 that is even larger than the spring mount 25 Point 60, at which the first opening 55 is at a maximum radial distance from the longitudinal axis 4, is still outside the spring mount 25. A point 61, at which the first opening 55 has a minimum distance from the longitudinal axis 4, however, is still at the edge of the spring mount 25. Furthermore, there are points 62, 63 at the second opening 56, the point 62 being at a maximum distance from the longitudinal axis 4 at the edge of the second opening 56 and the point 63 being at a minimum distance from the longitudinal axis 4 at the edge of the second Opening 56 is located. Viewed radially, point 62 is further away from the longitudinal axis 4 than point 60. Point 63 is also of the second opening 56, viewed radially, further away from the longitudinal axis 4 than the point 61 on the edge of the first opening 55. Furthermore, a centroid 64 of the first opening 55 is radially closer to the longitudinal axis 4 than a centroid 65 of the second opening 56.

In this exemplary embodiment, the oblique bore 50 is also designed in such a way that the bottom 26 of the spring receptacle 25 is cut into by the oblique bore 50 . The spring receptacle 25 can thus be used in an advantageous manner for conducting the fuel through and can be integrated into the fluid channel 15 over its entire length 58 .

2 shows a valve 1 in a partial, schematic sectional view corresponding to a second example not according to the invention. In this exemplary embodiment, the second opening 56 or a partial surface 56 ′ on the second end face 23 of the armature 6 , in which the second opening 56 lies, is oriented perpendicular to the axis 53 of the oblique bore 50 . The partial surface 56' of the armature 6 can be designed with a circumferential groove 85 or individual countersunk holes. In particular, the partial surface 56 ′ on the second end face 23 of the armature 6 can first be configured, and then the oblique bore 50 can be drilled starting from the second end face 23 . This allows a drill bit to hit the partial surface 56' of the anchor 6 at right angles 1 described first embodiment, which is used in particular to improve drilling. In this way, breakage of a drill can also be avoided, since drilling does not take place at an angle to a surface.

With regard to several oblique bores to be realized on the armature 6, which are designed in accordance with the oblique bore 50, it is particularly advantageous if the partial surface 56' is configured by a groove running around the longitudinal axis 4, from which the individual oblique bores 50 then spread out circumferentially .

3 shows a valve 1 in a partial, schematic sectional view corresponding to a third example not according to the invention. In this exemplary embodiment, a chamfer 66 is configured on the armature 6, which cuts into the second end face 23 at its outer diameter 42. The chamfer 66 then lies between the second end face 23 and the outside 32 of the armature 6. The chamfer 66 is preferably designed at right angles to the axis 53 of the oblique bore 50. FIG. This configuration has the advantage that a production optimization is achieved, as is based on the 2 is described. Furthermore, the inner part 57 of the second end face 23, on which the armature 6 interacts with the stop surface 8', can be designed to be as large as possible. This results in particularly great design freedom. A very large hydraulic damping can therefore be achieved in the respective application.

4 shows a valve 1 in a partial, schematic sectional view according to an embodiment of the invention. In this exemplary embodiment, the fluid channel 15 has a first coaxial blind hole 71 and a second coaxial blind hole 72 . The first coaxial blind hole 71 runs from the first end face 22 in the coaxial direction 19. The second coaxial blind hole 72 runs from the second end face 23 in the opposite direction to the coaxial direction 19. Within the armature 6, the two blind holes 71, 72 intersect with one another. Viewed along the longitudinal axis 4 , an intersection area 73 can be arranged close to the base 26 of the spring receptacle 25 . This results in favorable flow conditions.

When the fluid is passed through the armature 6, the blind holes 71, 72 and at least part 51 of the spring receptacle 25 can then be used. In this way, the spring receptacle 25 can also be advantageously at least partially integrated into the fluid channel 15 in this exemplary embodiment. In the area of intersection 73 the fluid is guided radially outwards along the longitudinal axis 4 viewed in the coaxial direction 19 . This also results in an advantageous introduction of the fluid from the inner bore 31 of the inner pole 3 into the fluid channel 15 and at the same time an advantageous damping on the second stop element 8.

It is therefore particularly advantageous that a point 60 of a first opening 55 of the fluid channel 15 that is radially at most far outside of the longitudinal axis 4 is closer to the longitudinal axis 4 than a point 62 of a second opening 56 of the fluid channel 15 that is radially at most far outside of the longitudinal axis 4. It is also advantageous if a centroid 64 of a first opening 55 of the fluid channel 15 is closer to the longitudinal axis 4 than a centroid 65 of a second opening 56 of the fluid channel 15.

In the exemplary embodiments presented, which are based in particular on the Figures 2 to 4 are described, it can be realized in an advantageous manner that the fluid duct 15 exits at an exit surface 80 of the armature 6 towards the second region 18 of the armature space 16, with an axis of the fluid duct 15 along which the fluid duct 15 at the exit surface 80 of the armature 6 exits, is oriented perpendicularly to the exit surface 80 . This makes it possible, among other things, to form the fluid channel 15 from this side with a bore that can be introduced into the armature perpendicularly to the exit surface 80, which improves manufacturability. The exit surface 80 can lie in an annular surface 82 that is circumferential with respect to the longitudinal axis 4, with the annular surface 82 being configured as a partial surface 82 of a cone shell 83 that is rotationally symmetrical with respect to the longitudinal axis 4, or as a partial surface 82 of a circular disk 84 oriented perpendicularly to the longitudinal axis 4. This is possible, for example, by designing a circumferential groove 85 or a chamfer 66 .

Claims (5)

1. Valve (1) for metering a fluid, in particular fuel injection valve for internal combustion engines, having an electromagnetic actuator (10) which has an armature (6) which is arranged in an armature chamber (16), and having a valve needle (5) which can be actuated by the actuator (10) by means of the armature (6), wherein the armature (6) is guided on the valve needle (5), wherein, on the valve needle (5), there are arranged a first stop element (7), which interacts with a first face side (22) of the armature (6) during operation, and a second stop element (8), which interacts with a second face side (23) of the armature (6) during operation, said stop elements limiting a movement of the armature (6) relative to the valve needle (5), and wherein the armature (6) has a spring receptacle (25) which is open towards the first face side (22) of the armature (6) and into which there is inserted a spring (27) which is supported against the stop element (7),

   wherein the armature (6) has at least one fluid channel (15) which, during operation, allows fluid to pass between a first region (17), adjoining the first face side (22) of the armature (6), of the armature chamber (16) and a second region (18), adjoining the second face side (23) of the armature (6), of the armature chamber (16),

   wherein the fluid channel (15) at least partially incorporates the spring receptacle (25), and

   wherein the fluid channel (15) at least sectionally extends radially outwardly along a direction (19) which is oriented from the first face side (22) to the second face side (23) and which is coaxial with respect to a longitudinal axis (4),

   characterized

   in that the fluid channel (15) has a first coaxial blind bore (71), which extends in the coaxial direction (19) from the first face side (22) of the armature (6), and a second coaxial blind bore (72), which extends counter to the coaxial direction (19) from the second face side (23) of the armature (6), said blind bores intersecting one another within the armature (6), and in that the second blind bore (72) is situated radially further to the outside than the first blind bore (71) with respect to the longitudinal axis (4).
2. Valve according to Claim 1,
   characterized
   in that a point (61) of a first opening (55) of the fluid channel (15) that is situated radially furthest to the inside with respect to the longitudinal axis (4) is situated closer to the longitudinal axis (4) than a point (63) of a second opening (56) of the fluid channel (15) that is situated radially furthest to the inside with respect to the longitudinal axis (4).
3. Valve according to Claim 1 or 2,
   characterized
   in that the fluid channel (15) emerges at an exit surface (80) of the armature (6) towards the second region (18) of the armature chamber (16), and in that an axis (81) of the fluid channel (15), along which the fluid channel (15) emerges at the exit surface (80) of the armature (6), is oriented perpendicularly to the exit surface (80) .
4. Valve according to Claim 3,
   characterized
   in that the exit surface (80) is situated in an annular surface (82) which is peripheral with respect to the longitudinal axis (4), and in that the annular surface (82) is in the form of a part-surface (82) of a circular disc (84) which is oriented perpendicularly to the longitudinal axis (4).
5. Valve according to one of the preceding claims,
   characterized
   in that the spring receptacle (25) is formed by an annular groove which does not adjoin the valve needle (5), whereby a guide web (28) is formed on the armature (6).

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