EP1853813B1 - Injection nozzle - Google Patents

Abstract

An injection nozzle for an internal combustion engine, in particular in a motor vehicle, the nozzle including a nozzle body having at least one injection port, a nozzle needle supported to execute a stroke inside the nozzle body to control an injection of fuel through the at least one injection port, a booster piston that is drive-coupled to an actuator and having a booster surface, the nozzle needle or a needle unit including the nozzle needle having a control surface that is hydraulically coupled to the booster surface. A bypass piston is supported to execute a stroke inside the booster piston, the bypass piston having a bypass surface that is hydraulically coupled to the booster surface, the bypass piston resting against a stop that is stationary in relation to the nozzle body, in an initial state in which the nozzle needle closes the at least one injection port, and the bypass piston having a reservoir surface that delimits a reservoir provided inside the booster piston.

Description

State of the art

The present invention relates to an injection nozzle for an internal combustion engine, in particular in a motor vehicle, having the features of the preamble of claim 1.

Such injection nozzle is for example from the DE 103 26 046 A1 and comprises a nozzle body having at least one injection hole. In the nozzle body, a nozzle needle is mounted adjustable in stroke, with which an injection of fuel through the at least one injection hole is controllable. Furthermore, a booster piston is provided, which is drive-coupled with an actuator and having a translator surface. The nozzle needle has a hydraulically coupled to the translator surface control surface.

The known injection nozzle works with a direct needle control. This means that the nozzle needle or a needle assembly comprising the nozzle needle has at least one pressure stage, which is hydraulically coupled to a feed path which supplies the fuel under injection pressure to the at least one injection hole. While opening forces can be introduced into the nozzle needle or needle assembly via the at least one pressure stage, closing forces can be introduced into the nozzle needle or needle assembly via the control surface. When the nozzle needle is closed, the closing forces predominate. To open the nozzle needle of the pressure acting on the control surface pressure is lowered, whereby the closing forces are reduced, so that the opening forces predominate. As a result, the nozzle needle lifts and opens at least one Injection port. The pressure reduction at the control surface is achieved by an actuation of the actuator and thus by a stroke of the booster piston. A hydraulic space bounded by both the translator surface and the control surface is increased by the stroke of the intensifier piston, thereby decreasing the pressure therein. Such direct needle control allows for short injection times as well as dynamic response to the injector.

With modern injection nozzles both small injection quantities and large injection quantities should be possible as accurately as possible and with the shortest possible injection times. For small injection quantities, it is necessary to keep the opening stroke of the nozzle needle small in order to be able to recirculate the nozzle needle correspondingly quickly back into the needle seat with a corresponding closing stroke. For large injection quantities, however, it is necessary to realize a relatively large opening stroke for the nozzle needle as quickly as possible. The realizable with the actuator stroke of the booster piston leads according to the selected area ratio between the translator surface and the control surface to a corresponding needle stroke. A large gear ratio results in the actuation of the actuator to a fast opening movement of the nozzle needle and a large opening stroke, which is advantageous for the realization of large injection quantities with short injection times. A small gear ratio results in the actuation of the actuator to a correspondingly slower opening movement of the nozzle needle and a correspondingly smaller opening stroke. This is advantageous for the realization of precisely dimensioned, small injection quantities with short injection times. Known injection nozzles, with which both small injection quantities and large injection quantities to be realized, thus have a mean transmission ratio as a compromise. However, in order to still be able to realize a large opening stroke with a comparatively small gear ratio, the actuator must be designed to carry out a correspondingly large stroke on the booster piston. This has the consequence that the actuator builds relatively large volume. However, the available installation space is limited in internal combustion engines.

Advantages of the invention

The injector according to the invention with the features of the independent claim has the advantage over that two different depending on the needle stroke Translation ratios are effective. In contrast, the gear ratio is constant in known injectors. For this purpose, a bypass piston is provided. In a small opening stroke of the nozzle needle of the bypass piston remains at its stop, so that the stroke of the booster piston moves only the translator surface. According to the ratio of control surface to translator surface, the nozzle needle follows the stroke of the booster piston. In an expediently predetermined opening stroke of the nozzle needle, the forces acting on the escape surface of the bypass piston are greater than the forces acting on the storage surface of the bypass piston. As a result, then the bypass piston lifts from its stop and thus moves in the same direction as the booster piston. This has the consequence that then both the translator surface and the alternate surface are moved in the same direction at the stroke of the booster piston. The nozzle needle then follows the stroke of the booster piston according to the new gear ratio, which results from the ratio of the control surface to the sum of the translator surface and the deflection surface. This new or second gear ratio is significantly greater than the first gear ratio, so that the nozzle needle then opens faster and can perform a relatively large opening stroke.

The injector according to the invention can thus control the nozzle needle for carrying out small needle strokes in the region of the first transmission ratio, so as to realize precise and small injection quantities with short injection times. In addition, the injection nozzle according to the invention by the second ratio, the nozzle needle so control that in comparatively short times large needle strokes and thus large injection quantities can be realized. Furthermore, the large second gear ratio leads to the fact that the actuator only has to realize a relatively small stroke and accordingly can be built comparatively small.

According to a preferred embodiment, the storage space can be subdivided into a first storage subspace and into a second storage subspace. Furthermore, a throttle piston is provided, which is drive-coupled to the bypass piston at least for the transmission of compressive forces, which is mounted in a manner adjustable in stroke in the booster piston and which contains a throttle path hydraulically coupling the two storage subspaces. In addition, the storage area is in a first storage subspace limiting, for example, formed directly on the bypass piston first memory sub-area and in a second Dividing memory space, formed on the throttle piston second memory sub-area divided. By this construction, the lifting movement of the bypass piston can be damped relative to the booster piston, which is accompanied by a damping of the opening movement of the nozzle needle during the larger, second transmission ratio. The damped needle movement reduces vibration excitation of the system consisting of actuator, booster piston, bypass piston and nozzle needle. The injection process is thus more stable and has a reproducible accuracy. Furthermore, a sudden "popping" of the nozzle needle, so an uncontrolled high speed increase in the transition from the first gear ratio to the second gear ratio is avoided. In this way, the larger needle strokes can still be controlled relatively accurately.

Further important features and advantages of the injection nozzles according to the invention will become apparent from the subclaims, from the drawings and from the associated description of the figures with reference to the drawings.

drawings

Fig. 1

eine stark vereinfachte, prinzipielle Darstellung einer Einspritzdüse nach der Erfindung im Längsschnitt,

Fig. 2

eine Ansicht wie in Fig. 1 auf ein Detail der erfindungsgemäßen Einspritzdüse, jedoch bei einer anderen Ausführungsform,

Fig. 3 bis 7

Ansichten wie in Fig. 2, jedoch bei weiteren verschiedenen Ausführungsformen.

Embodiments of the injection nozzle according to the invention are illustrated in the drawings and are explained in more detail below, wherein like reference numerals refer to the same or similar or functionally identical components. Show, in each case schematically,

Fig. 1

a greatly simplified, schematic representation of an injection nozzle according to the invention in longitudinal section,

Fig. 2

a view like in Fig. 1 to a detail of the injection nozzle according to the invention, but in another embodiment,

Fig. 3 to 7

Views like in Fig. 2 but in other different embodiments.

Description of the embodiments

Corresponding Fig. 1 an injection nozzle 1 according to the invention comprises a nozzle body 2, which has at least one injection hole 3. The injection nozzle 1 is provided for an internal combustion engine, which can be arranged in particular in a motor vehicle, and serves for injecting fuel into an injection space 4 into which the injection nozzle 1 protrudes in the mounted state at least in the region of the at least one injection hole 3.

The injection nozzle 1 contains a nozzle needle 5, which may be part of a needle assembly 6 and with the aid of which an injection of fuel through the at least one injection hole 3 can be controlled. For this purpose, the nozzle needle 5 cooperates with its needle tip 7 with a needle seat 8. If the nozzle needle 5 is seated in its needle seat 8, the at least one injection hole 3 is blocked, that is to say that at least one injection hole 3 is separated from a supply path 9, supplied via the injection-pressure fuel, and supplied to the at least one injection hole 3.

In the present case, the feed path 9 is guided through the interior of the nozzle body 2, so that the components arranged in the nozzle body 2 virtually "float" in the feed path 9 in the fuel. In principle, however, another guidance of the feed path 9 is possible.

The nozzle needle 5 or the needle assembly 6 is mounted in the nozzle body 2 in an adjustable stroke. This storage is realized here by a first bearing sleeve 10, in which the needle assembly 6 and the nozzle needle 5 is inserted at a distal end of the needle tip 7. The first bearing sleeve 10 is attached to an intermediate plate 11, which forms a part of the nozzle body 2. The intermediate plate 11 separates the injection nozzle 1 into a needle area containing the nozzle needle 5 and a translator area containing a booster piston 12 and an actuator 13. By means of at least one connecting channel 14, the feed path 9 is passed through the intermediate plate 11.

The needle needle 5 and the needle assembly 6 is biased by a closing pressure spring 15 in the closing direction of the nozzle needle 5. Here, the closing compression spring 15 is supported here on the one hand on a step 16 of the nozzle needle 5 and the needle assembly 6 and on the other hand on the first bearing sleeve 10th

The needle needle 5 or its needle assembly 6 has a control surface 17, specifically on a side remote from the at least one spray hole 3. The control surface 17 delimits a control chamber 18 axially, which is also axially limited relative to the control surface 17 of the intermediate plate 11. The control chamber 18 is also enclosed radially by the first bearing sleeve 10. The control chamber 18 may be hydraulically coupled to the feed path 9 via a control space path 19. This control space path 19 can be formed, for example, as here in the region of the bearing between the nozzle needle 5 or needle assembly 6 and the first bearing sleeve 10, e.g. as a clearance or as at least one longitudinal groove which may be formed in the first bearing sleeve 10 and / or in the nozzle needle 5 or in the needle assembly 6. It is also possible to realize the control chamber path 19 by a transverse bore through the first bearing sleeve 10, which connects the control chamber 18 with the supply path 9 hydraulically. The control space path 19 is throttled.

As already mentioned above, the injection nozzle 1 contains the booster piston 12, which is drive-coupled to the actuator 13. The booster piston 12 is mounted adjustable in height in the nozzle body 2. For this purpose, the booster piston 12 is inserted into a second bearing sleeve 20 which is fixedly connected to the intermediate plate 12. The drive coupling between the booster piston 12 and the actuator 13 causes a stroke adjustment of the actuator 13 inevitably produces an identical stroke adjustment of the booster piston 12. The actuator 13 is expediently designed as a piezoelectric actuator, which in the energized state in the stroke direction has a larger dimension than in a de-energized state.

The booster piston 12 has a booster surface 21 which axially delimits a coupler space 22. The translator surface 21 is configured annular. Axially opposite the translator surface 21, the coupler space 22 is axially bounded by the intermediate plate 11. Furthermore, the coupler space 22 is bounded radially by the second bearing sleeve 20. The coupler space 22 is hydraulically coupled by a control path 23 with the control chamber 18. The control path 23 is realized here in the form of at least one bore, which penetrates the intermediate plate 11.

The coupler space 22 can be hydraulically coupled to the feed path 9 via a coupler space path 24. The coupler space path 24 can be formed radially between the booster piston 12 and the second bearing sleeve 20, for example as a radial play or as at least one longitudinal groove in the second bearing sleeve 20 and / or in the It is also possible in principle to configure the coupler space path 24 by a transverse bore which penetrates the second bearing sleeve 20 and connects the coupler space 22 with the feed path 9. The coupler space path 24 is throttled.

According to the invention, the injection nozzle 1 is also equipped with an evasive piston 25, which is mounted in a stroke-adjustable manner in the booster piston 12. For this purpose, the booster piston 12 is designed as a hollow piston open on one side. The bypass piston 25 protrudes into the coupler space 22 and has there an evasion surface 26, which likewise limits the coupler space 22 accordingly. On the side facing away from the escape surface 26, the bypass piston 25 also has a storage surface 27, which defines a storage space 28 which is formed in the booster piston 12.

The booster piston 12 can optionally have at least one throttle 29, which hydraulically couples the storage space 28 to the feed path 9. Alternatively or additionally, the bypass piston 25 may include a throttle 30 which hydraulically couples the reservoir 28 to the coupler chamber 22. Such a throttle 30 may also be formed radially between bypass piston 25 and booster piston 12, e.g. in the form of a corresponding radial clearance and / or in the form of at least one longitudinal groove in the booster piston 12 and / or in the bypass piston 25.

The bypass piston 25 is axially biased by a return spring 31 against a stop 32. The restoring spring 31 is supported on the one hand on the booster piston 12 and on the other hand on the bypass piston 25, namely on the storage surface 27. The stop 32 is arranged stationary with respect to the nozzle body 2. In the present case, the stop 32 is formed on the intermediate plate 11. The contact between the escape piston 25 and stop 32 is advantageously carried out so that the escape surface 26 is as large as possible. In the present case, the contacting is quasi punctiform, which is achieved by a convex shaping of the bypass piston 25 in the region of its escape surface 26.

The booster piston 12 is biased with an opening compression spring 33 in its opening direction. The opening compression spring 33 is supported on the one hand on the second bearing sleeve 20 and on the other hand on a collar 34 of the booster piston 12 from. The volume of the storage space 28 is expediently greater than the common volume of the coupler space 22 and the control space 18.

Although in the embodiment shown here, coupler space 22 and control space 18 form separate spaces which are interconnected by the control path 23, another embodiment is possible in which control space 18 and coupler space 22 coincide in a common space.

• In dem in Fig. 1 gezeigten Ausgangszustand befindet sich die Düsennadel 5 im Nadelsitz 8. Dementsprechend ist das wenigstens eine Spritzloch 3 gesperrt. Die Steuerfläche 17 weist ihren größten Abstand von der Zwischenplatte 11 auf. Der Steuerraum 18 besitzt somit sein größtes Volumen. Der Aktor 13 ist bestromt und besitzt dadurch seine größte Ausdehnung. Dementsprechend ist der Übersetzerkolben 12 maximal in Richtung Zwischenplatte 11 verstellt. Der Kopplerraum 22 besitzt somit sein kleinstes Volumen. Desweiteren liegt der Ausweichkolben 25 am Anschlag 32 an. Im Speicherraum 28, im Kopplerraum 22 und im Steuerraum 18 herrscht derselbe Druck wie im Zuführpfad 9, also der Einspritzdruck.

The injection nozzle 1 according to the invention operates as follows:

• In the in Fig. 1 shown initial state, the nozzle needle 5 is in the needle seat 8. Accordingly, the at least one injection hole 3 is locked. The control surface 17 has its greatest distance from the intermediate plate 11. The control chamber 18 thus has its largest volume. The actuator 13 is energized and thus has its greatest extent. Accordingly, the booster piston 12 is maximally adjusted in the direction of intermediate plate 11. The coupler space 22 thus has its smallest volume. Furthermore, the bypass piston 25 abuts against the stop 32. In the storage space 28, in the coupler space 22 and in the control chamber 18, the same pressure prevails as in the feed path 9, that is, the injection pressure.

In order to carry out an injection of fuel through the at least one spray hole 3 into the injection space 4, the actuator 13 is de-energized, that is, the energization of the actuator 13 is interrupted. The actuator 13 is thus operated inversely. This means that the actuator 13 must be energized to close the at least one injection hole 3.

When the actuator 13 flows away, the actuator 13 contracts and performs an actuator stroke 35 indicated by an arrow. This stroke adjustment follows the booster piston 12 inevitably, causing it to move away from the intermediate plate 12. In this case, on the one hand, the volume of the coupler space 22 is increased, which is accompanied by a corresponding pressure drop in the coupler space 22. On the other hand, the volume of the storage space 28 is also increased since the escape piston 25 remains biased against its stop 32. With the increase of the storage space volume, a corresponding pressure drop in the storage space 28 is accompanied.

About the hydraulic coupling between the control chamber 18 and coupler space 22, the resulting pressure drop in the coupler chamber 22 directly propagates into the control chamber 18. Since the storage space 28 - as explained above - at least in the initial state has a larger volume than the total volume of the coupler chamber 22 and the control chamber 18, the pressure in the storage chamber 28 decreases slower than in the coupler chamber 22 and the control chamber 18. Accordingly, the effective on the storage surface 27 Pressure forces greater than the pressure acting on the alternate surface 26 pressure forces. As a result, the bypass piston 25 initially remains biased against its stop 32.

With decreasing pressure in the control chamber 18, the forces acting in the closing direction on the nozzle needle 5 also decrease. From a predetermined control pressure, the opening forces acting on the nozzle needle 5 or on the needle dressing 6 are then greater than the effective closing forces. Accordingly, the nozzle needle 5 lifts off from the needle seat 8. As a result, the at least one spray hole 3 communicates with the feed path 9. The injection process begins.

To initiate effective in the opening direction pressure forces in the nozzle needle 5 and in the needle assembly 6, the nozzle needle 5 and the needle assembly 6 is equipped with at least one pressure stage 36 and 37, which is permanently coupled hydraulically to the feed path 9 /.

During this first phase of the opening movement there is a first transmission ratio between the stroke movement of the booster piston 12 and the lifting movement of the nozzle needle 5. This first ratio is at least initially defined by the ratio of the control surface 17 to the translator surface 21. This first transmission ratio is comparatively small, so that a small stroke of the booster piston 12 also causes a comparatively small stroke of the nozzle needle 5, which may already be greater than the stroke of the booster piston 12. If only a small injection quantity to be realized can now within this first phase, during which the first ratio is present , the actuator 13 are energized again to stop the initiated opening movement and reverse. While the opening movement of the booster piston 12 is intensively supported by the opening compression spring 33, the closing pressure spring 15 assists the closing movement of the nozzle needle 5.

However, if a larger injection quantity to be realized, the outflow of the actuator 13 is maintained longer, so that the booster piston 12 can move further away from the intermediate plate 11. Accordingly, the nozzle needle 5 can continue to stand out from its needle seat 8. With the lifting of the nozzle needle 5 from the needle seat 8 can in a space 38, from which the at least one spray hole 3 goes off and is limited by retracted into the needle seat 8 nozzle needle 5 formed by a needle tip 7 seat surface 39, an increasing pressure build up. In this way, the forces acting in the opening direction on the needle dressing 6 increase, which additionally accelerates the opening movement of the nozzle needle 5. This has the consequence that the volume of the control chamber 18 decreases faster than the volume of the coupler chamber 22 increases. As a result, there is a pressure increase in the control chamber 18 and in the coupler chamber 22. This increase in pressure causes the deflection piston 25 from a, in particular predetermined, opening stroke of the nozzle needle 5, the forces acting on the escape surface 26 forces are greater than acting on the memory surface 27 forces, namely the restoring force of the return spring 31 and the pressure force in the storage space 28th As a result, the second phase of the opening movement is initiated.

During this second phase of the opening movement, the bypass piston 25 lifts off from the stop 32 and in particular enters the storage space 28. This results in a new value for the transmission ratio between the stroke of the booster piston 12 and the stroke of the nozzle needle 5. The new, second transmission ratio is defined by the ratio of the control surface 17 to the total area of translator surface 21 and alternate surface 26. The stroke of the booster piston 12 together with the stroke of the Ausweichkolbens 25 thus produce a relatively large stroke adjustment of the nozzle needle 5. As a result, results for the nozzle needle 5 a particularly high opening speed, wherein in addition a comparatively large opening stroke can be realized. In this case, due to the large second opening ratio at the same time the required stroke of the actuator 13 remain relatively small, so that the actuator 13 and thus the injector 1 can build comparatively small.

In the injection nozzle 1 according to the invention are thus control surface 17, translator 21, alternate surface 26, memory surface 27, the maximum possible Aktorhub and the maximum possible Düsennadelhub coordinated so that when Hubverstellung of the actuator 13 to open the nozzle needle 5, the described two-phase or two-stage stroke adjustment for the nozzle needle 5 sets. During the first phase or first stage, the bypass piston 25 bears against its stop 32. The gear ratio is relatively small. In contrast, the bypass piston 25 moves away from its stop 32 during the second phase or second stage. The associated gear ratio is relatively large.

According to the FIGS. 2 to 4 It may be appropriate to dampen the opening movement of the nozzle needle 5 during the second phase, for example, to avoid an undesirable vibration behavior of the oscillatory system of nozzle needle 5, booster piston 12 and actuator 13. This is achieved by damping the lifting movement of the bypass piston 25. In the embodiments shown here, the storage space 28 is subdivided into a first storage subspace 40 and into a second storage subspace 41 for this purpose. Furthermore, a throttle piston 42 is provided, which is drive-coupled with the bypass piston 25 at least for the transmission of compressive forces. The throttle piston 42 is also mounted in a stroke-adjustable manner in the booster piston 12 and contains a throttle path 43 which hydraulically couples the two storage subspaces 40 and 41 throttled.

In the embodiment according to Fig. 2 the throttling path 43 expediently has a throttle 44 which is arranged between a longitudinal bore 45 which opens into the second storage subspace 41 and a transverse bore 46 which opens into the first storage subspace 40. In the embodiments of the FIGS. 2 and 3 the throttle piston 42 is fixedly connected to the bypass piston 25.

Furthermore, in the embodiments of the Fig. 2 to 4 the storage area 27 is divided into a first storage partial area 47 and a second storage partial area 48. The first memory sub-area 47 is at least in the variants of FIGS. 2 and 3 formed directly on the bypass piston 25 and limits the first storage part space 40. In contrast, the second memory sub-area 28 is formed on the throttle piston 42 and limits the second memory sub-area 41st

In the variant according to Fig. 2 the retraction of the bypass piston 25 is throttled into the storage space 28, that this fuel from the second storage subspace 41 must be displaced by the throttle path 43 in the first storage part 40 space.

The embodiment according to Fig. 3 differs from the one according to Fig. 2 in that the throttle path 43 has its path end radially on the throttle piston 42. The throttle 44 forms this path end here. Furthermore, the throttle piston 42 includes a bypass path 49, which is realized here by a connecting bore 50 between the longitudinal bore 45 and the transverse bore 46. The bypass path 49 thus bypasses the throttle path 43 and is here also equipped with a non-return valve 51, which blocks when retracting the throttle piston 42 into the second storage subspace 41.

In the embodiment according to Fig. 3 In addition, the throttle path 43 is controlled in dependence on the Drosselkolbenhubs. When retracting the bypass piston 25 into the storage space 28, the fuel volume is first displaced from the second storage subspace 41 through the throttle path 43 into the first storage subspace 40. The check valve 51 locks in this movement, the connecting hole 50. From a certain retraction stroke passes over a control edge 52 of the booster piston 12 said path end, so here the throttle 44, whereby the throttle path 43 is locked.

When extending the bypass piston 25 from the storage space 28 opens the check valve 51, whereby the bypass path 49 is opened and the throttle path 43 can be bypassed. The extension movement of the bypass piston 25 is therefore unthrottled and is also supported by the return spring 31. This has the consequence that the initial state is relatively quickly adjustable and that the nozzle needle 5 is relatively quickly zurückverstellbar in their seat 8. The closing process for ending the injection process can thus be controlled relatively quickly and precisely.

The embodiment according to Fig. 4 Also has a throttled path 43 controlled by the throttle piston stroke and a bypass path 49 with a check valve 51. The embodiment according to FIG Fig. 4 differs from those according to the FIGS. 2 and 3 in that the throttling piston 42 and the deflecting piston 25 are separate components which lie only loosely against one another. The return spring 31 drives the throttle piston 42 and via this the bypass piston 25 at. The bypass path 49 here has an axial mouth end 53, which is closed at an axial contact between the escape piston 25 and throttle piston 42. When retracting the bypass piston 25 in the storage chamber 28, this is supported on the throttle piston 42 and drives it to retract into the second storage subspace 41. Because the bypass path 49 is closed, the throttle path 43 is active and the retraction of the bypass piston 25 is throttled. To extend the bypass piston 25 can lift off the throttle piston 42, whereby the bypass path 49 is opened. The bypass piston 25 can thereby extend relatively quickly and relatively undamped and occupy its starting position with abutment against the stop 32. The throttle piston 42 follows, driven by the return spring 31. In the bypass path 49, a further throttle 54 may be arranged.

In the embodiment according to Fig. 4 the non-return valve 51 is formed by the interaction of escape piston 25 and throttle piston 42. In the embodiment according to Fig. 4 the first storage subarea 47 is itself designed on the bypass piston 25. Depending on the tightness of a supported on the bypass piston 25 head 55 of the throttle piston 42, this first memory sub-area 47 may also be formed on this head 55.

According to the Fig. 5 to 7 If necessary, the injection nozzle 1 can also be equipped with an escape path 56 in the region of the bypass piston 25. This escape path 56 is formed in the embodiments shown here by an escape passage 57 which penetrates the bypass piston 25 from the storage surface 27 to the escape surface 26 and is arranged in particular coaxially in this. Alternatively, the escape path 56 and the escape passage 57 may also have any other shape and arrangement. For example, the escape path 56 may be formed by a deflection channel 57 arranged obliquely in the bypass piston 25. When lifted off from the stop 32 Ausweichkolben 25 of the escape path 56 and the escape passage 57 leads to a hydraulic coupling between memory surface 27 and escape surface 26 and thus between memory space 28 and coupler space 22. In addition, the escape path 56 is designed so that it is adjacent to the stop 32 Evasive piston 25 is locked. The blocking effect of the escape path 56 in the initial state of the bypass piston 25, ie in abutment against the abutment 32 bypass piston 25 is achieved in the preferred embodiments shown here, characterized in that the bypass piston 25 has an annular sealing zone 58 on its alternate surface 26. This sealing zone 58 encloses an opening 59 of the escape channel 57, which is associated with the escape surface 26 and lies in this. In the initial state, the bypass piston 25 abuts against the stop 32 with its sealing zone 58. The sealing zone 58 thereby separates the escape path 56 from the coupler space 22 tightly. Deviating from the central arrangement of Dodge channel 57 in the Fig. 5 to 7 may in another embodiment Ausweichkolben 25 and / or intermediate plate 11 be configured such that the sealing surface 58 is on any other diameter, for example, on the outer diameter of the bypass piston 25.

Corresponding Fig. 6 the escape path 56 may be throttled. For example, the throttle path 56 contains a throttle 60 for this purpose. In the present case, the throttle 60 is arranged in the escape passage 57.

Corresponding Fig. 7 For example, the escape path 56 may optionally be configured such that it is blocked at a predetermined or a predetermined deviation stroke of the bypass piston 25, in which the bypass piston 25 moves into the storage space 28. This is achieved here, for example, by means of a storage space check valve 61, which blocks the escape path 56, here the escape channel 57 when the predetermined deviation stroke is reached. For this purpose, the storage space valve 61 comprises, for example, a valve member 62, which cooperates with a circular valve seat 63. The valve seat 63 is formed on the bypass piston 25, specifically on the storage area 27 thereof. The valve seat 63 encloses an opening 64 of the bypass channel 57, which is assigned to the storage area 27, ie lies in the latter. Upon reaching the predetermined Ausweichhubs the valve member 62 moves into its valve seat 63 and blocks said opening 64 of the escape passage 57 tightly. The valve member 62 is here exemplarily equipped with a flat end face; the valve seat 63 is shaped to be complementary. Alternatively, the valve member 62 may also have any other suitable shape, such as a conical shape or a spherical shape; the valve seat 63 is then formed in each case complementary.

It is clear that the individual features of the embodiments corresponding to the Fig. 5 to 7 Quasi arbitrarily combinable with the features of the embodiments of Fig. 1 to 4 ,

In transient operating conditions, in particular in connection with an increasing fuel pressure in the supply path 9, it is in principle possible that the pressure in the coupler chamber 22 increases so far that the bypass piston 25 lifts off the stop 32, although the actuator 13 is not yet driven to perform an opening stroke , This is, for example, the relative compressibility of the comparatively large Memory space 28 trapped hydraulic volume due. If the injection nozzle 1 is actuated to carry out an injection process in the off-stroke piston 25 lifted off from the stop 32, the second gear ratio is present at the opening stroke of the booster piston 12 from the beginning, in which the booster piston 12 is withdrawn from the actuator 13 at high speed, but with little force. As a result, on the one hand, the precision of the injection process with regard to the injected fuel quantity can be considerably impaired. At the same time, the bypass piston 25 could move in the opposite direction due to the changing pressure conditions, whereby the required pressure drop in the coupler chamber 22 does not occur or only delayed. In extreme cases, the nozzle needle 5 remains closed.

Here creates in the embodiments of the Fig. 5 to 7 provided alternative path 56 remedy. For as soon as the rising pressure at corresponding transient operating conditions in the coupler chamber 22, the bypass piston 25 lifts off from the stop 32, via the escape path 56, a pressure equalization between storage space 28 and coupler 22. The return spring 31 can then the escape piston 25 back to the starting position in which he abuts the stop 32, move back. This ensures that during an opening operation of the actuator 13, the bypass piston 25 initially bears against the stop 32, so that at the beginning of the opening operation, the first gear ratio is present, in which the booster piston 12 is withdrawn slowly, but with great force from the actuator 13.

The throttle 60 and the throttling of the alternate path 56 serves to ensure that the pressure compensation between the coupler chamber 22 and storage space 28 throttled at the desired switching from the first ratio to the second ratio, that the bypass piston 25 can stand properly from the stop 32 and for the duration the injection process remains lifted.

In this case, the storage space check valve 61 for the second phase or second stage of the needle opening can ensure that the pressure compensation between the coupler space 22 and the storage space 28 is terminated when the escape stroke of the escape piston 25 is reached. This also makes it possible to avoid premature return of the bypass piston 25 against its stop 32.

LIST OF REFERENCE NUMBERS

1

injection

2

nozzle body

3

spiracle

4

Injection room

5

nozzle needle

6

needle unit

7

pinpoint

8th

needle seat

9

feeding path

10

first bearing sleeve

11

intermediate plate

12

Booster piston

13

actuator

14

connecting channel

15

Closing pressure spring

16

Stage at 5, 6

17

control surface

18

control room

19

Control Room Path

20

second bearing sleeve

21

Booster surface

22

coupler

23

control path

24

Kopplerraumpfad

25

bypass piston

26

escape surface

27

storage area

28

storage space

29

throttle

30

throttle

31

Return spring

32

attack

33

Opening spring

34

Federation

35

actuator stroke

36

pressure stage

37

pressure stage

38

room

39

seat

40

first storage compartment

41

second storage compartment

42

throttle piston

43

throttle path

44

throttle

45

longitudinal bore

46

cross hole

47

first storage part surface

48

second memory subarea

49

bypass path

50

connecting bore

51

Check stop valve

52

control edge

53

Mouth of 49

54

throttle

55

Head of 42

56

escape path

57

alternate channel

58

sealing zone

59

Opening of 57

60

throttle

61

Memory space check valve

62

valve member

63

valve seat

64

Opening of 57

Claims (10)

1. Injection nozzle for an internal combustion engine, in particular in a motor vehicle,

   - having a nozzle body (2) which has at least one spray hole (3),

   - having a nozzle needle (5) which is mounted with an adjustable stroke in the nozzle body (2) and by way of which an injection of fuel through the at least one spray hole (3) can be controlled,

   - having a transmitter plunger (12) which is drive-coupled to an actuator (13) and has a transmitter face (21),

   - the nozzle needle (5) or a needle system (6) which comprises the nozzle needle (5) having a control face (17) which is coupled hydraulically to the transmitter face (21),
   characterized

   - in that a diverting plunger (25) is mounted with an adjustable stroke in the transmitter plunger (12),

   - in that the diverting plunger (25) has a diverting face (26) which is coupled hydraulically to the transmitter face (21),

   - in that the diverting plunger (25) bears against a stop (32) which is stationary relative to the nozzle body (2), in an initial state, in which the nozzle needle (5) shuts off the at least one spray hole (3), and

   - in that the diverting plunger (25) has an accumulator face (27) which delimits an accumulator space (28) which is formed in the transmitter plunger (12).
2. Injection nozzle according to Claim 1, characterized

   - in that the transmitter face (21) delimits a coupler space (22),

   - in that the control face (10) delimits a control space (18), and

   - in that the coupler space (22) and the control space (18) are configured either as separate spaces which are connected hydraulically to one another by a control path (23) or as a common space.
3. Injection nozzle according to Claim 2, characterized in that a volume of the accumulator space (28) is greater than a volume of the coupler space (22) together with the control space (18).
4. Injection nozzle according to one of Claims 1 to 3, characterized

   - in that the diverting face (26) delimits a coupler space (22) which is also delimited by the transmitter face (21), and/or

   - in that the control face (17), the transmitter face (21), the diverting face (26), the accumulator face (27), the maximum possible actuator stroke and the maximum possible nozzle needle stroke are adapted to one another in such a way that a two-stage stroke adjustment is set for the nozzle needle (5) in the case of a stroke adjustment of the actuator (13) for opening the nozzle needle (5), the diverting plunger (25) bearing against the stop (32) during a first stage and being removed from the stop (32) during a second stage.
5. Injection nozzle according to one of Claims 1 to 4, characterized

   - in that the accumulator space (28) is divided into a first accumulator part space (40) and into a second accumulator part space (41),

   - in that a restrictor plunger (42) is provided which is drive-coupled, at least for the transmission of pressure forces, to the diverting plunger (25) which is mounted with an adjustable stroke in the transmitter plunger (12) and comprises a restrictor path (43) which couples the two accumulator part spaces (40, 41) hydraulically, and

   - in that the accumulator face (27) is divided into a first accumulator part face (47) which delimits the first accumulator part space (40) and into a second accumulator part face (48) which delimits the second accumulator part space (41) and is formed on the restrictor plunger (42).
6. Injection nozzle according to Claim 5, characterized

   - in that the restrictor path (43) has a restrictor (44), and

   - in that the restrictor plunger (42) comprises a bypass path (49) which bypasses the restrictor (44) and has a non-return shut-off valve (51) which closes when the restrictor plunger (42) moves into the second accumulator part space (41).
7. Injection nozzle according to Claim 6, characterized

   - in that the diverting plunger (25) and the restrictor plunger (42) form separate components,

   - in that, when it moves into the first accumulator part space (40), the diverting plunger (25) is supported on the restrictor plunger (43) and drives the latter to move into the second accumulator part space (41),

   - in that, when the restrictor plunger (42) is pushed into the second accumulator part space (41), the diverting plunger (25) shuts off an opening end (53) of the bypass path (49), and

   - in that, when it is moved out of the first accumulator part space (40), the diverting plunger (25) raises up from the restrictor plunger (42) and opens the opening end (53) of the bypass path (49).
8. Injection nozzle according to one of Claims 5 to 7, characterized

   - in that the restrictor path (43) is controlled as a function of the restrictor plunger stroke, and/or

   - in that the restrictor path (43) has a path end which is arranged radially on the restrictor plunger (42), the restrictor plunger (42), in order to shut off the restrictor path (43), moving into the second accumulator part space (41) until a control edge (52) which is formed on the transmitter plunger (12) moves over the path end.
9. Injection nozzle according to one of Claims 1 to 8, characterized in that a diverting path (56) is provided which, when the diverting plunger (25) is raised up from the stop (32), couples the accumulator face (27) hydraulically to the diverting face (26) and is shut off when the diverting plunger (25) bears against the stop (32).
10. Injection nozzle according to Claim 9, characterized

    - in that the diverting path (56) is formed by a diverting channel (57) which penetrates the diverting plunger (25) from the accumulator face (27) as far as the diverting face (26), and/or

    - in that the diverting plunger (25) has an annular sealing zone (58) on its diverting face (26), by way of which annular sealing zone (58) the diverting plunger (25) bears against the stop (32) in the initial state and which annular sealing zone (58) encloses an opening (59) of the diverting channel (57), which opening (59) is assigned to the diverting face (26), and/or

    - in that the diverting path (56) and/or the diverting channel (57) is restricted or comprises a restrictor (60), and/or

    - in that the diverting path (56) and/or the diverting channel (57) is shut off at or from a predefined diverting stroke of the diverting plunger (25), which diverting stroke is directed into the accumulator space (28), and/or

    - in that an accumulator space shut-off valve (61) is provided which shuts off the diverting path (56) and/or the diverting channel (57) when the diverting stroke is reached, and/or

    - in that a valve element (62) of the accumulator space shut-off valve (61) interacts with a circular valve seat (63) which is formed on the accumulator face (27) and encloses an opening (64) of the diverting channel (57), which opening (64) is assigned to the accumulator face (27).

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