WO2018108316A1

WO2018108316A1 - Piston control assembly, in particular for a fuel injector

Info

Publication number: WO2018108316A1
Application number: PCT/EP2017/001423
Authority: WO
Inventors: Ingmar Berger; Enrico Bärow; Michael Nitsche
Original assignee: L'orange Gmbh
Priority date: 2016-12-16
Filing date: 2017-12-13
Publication date: 2018-06-21
Also published as: DE102016015038B4; DE102016015038A1

Abstract

The invention relates to a piston control assembly (1), in particular for use with a fuel injector (3), having a control housing (5) and a control piston (11) which is accommodated therein and can be controlled hydraulically back and forth in a displacement direction (±A) in the control housing (5). The control piston (11) can assume a first end position and a second end position. A working element (13) is connected to the control piston (11) for displacement with the control piston. The control piston (11) is accommodated in the control housing (5) and surrounded by an annular piston (25), which annular piston (25) can likewise be controlled hydraulically back and forth in the displacement direction (±A) into a first end position and a second end position in correspondence with the end positions of the control piston (11). The piston control assembly (1) is designed such that the annular piston (25) precedes the control piston (11) on hydraulically controlled displacement of the latter into an end position and assumes the end position before the control piston (11) assumes the corresponding end position. The piston control assembly (1) is also designed to displace hydraulic fluid out of the control housing (5) via in each case at least one throttle device (41, 43), active in each end position, of the annular piston (25) when the annular piston (25) assumes each of its end positions and the lagging control piston (11) is still being displaced.

Description

DESCRIPTION Piston control arrangement, in particular for a fuel injector

The present invention relates to a piston control arrangement according to the preamble of claim 1, in particular for a fuel injector. In the prior art, efforts have always been made to dampen the impact of nozzle valve members or nozzle needles in their seat in fuel injectors. While in liquid fuel injectors, a fuel cushion is able to dampen the impact, this is not possible in the desired manner with fuel gas injectors. With conventional controls for the valve member, in particular double acting piston controls, the contact point of the nozzle valve member and seat is subject to a high load due to insufficient damping, which can result in increased wear. Furthermore, pressure waves are induced which can reach large amplitudes. As a result, the component load increases again.

Based on this, the present invention has the object to provide a control device for fuel injectors, which is suitable to the intended

To allow stop attenuation.

This object is achieved by a piston control arrangement having the features of claim 1.

Advantageous developments and embodiments are specified in the further claims.

According to the invention, a piston control arrangement is proposed, in particular for a fuel injector. Such a fuel injector may be intended for use with liquid fuel, eg, diesel fuel, bio-oil, or heavy oil, preferably (alternatively or additionally) for use with fuel gas, for example, off-gas, biogas, natural gas, or similar gaseous fuel. Preferably, a fuel injector formed with the piston control assembly is a dual-fuel fuel injector or a multi-fuel injector means intended for use with liquid fuel and fuel gas, wherein operating pressure levels may be at liquid fuel beyond 2500 bar, with the fuel gas ausudüsenden for example at 350 bar or more. The fuel injector can be provided in the context of the invention for a large engine, for example a motor vehicle such as a ship, a locomotive or a utility or special vehicle, or be provided for example for a stationary device, eg for a combined heat and power plant, an (emergency ) Generator, eg also for industrial applications.

In the context of the present invention, the piston control arrangement is particularly suitable for use with a fuel gas nozzle valve member of a fuel injector, that is to say to effect a stroke control of the same in addition to reliable impact damping.

The piston control assembly includes a control housing with a (control) piston received therein. The control housing may generally in the manner of a hollow cylinder or as

Hollow chamber may be formed on a fuel injector, for example in a fuel injector housing element such as a nozzle body. The control piston can, for example, in

Have substantially cylindrical shape or generally piston shape. In the context of the piston control arrangement, the control piston in the control housing in a displacement direction (in particular in positive and negative displacement direction) hydraulically back and forth (hub) controllable or displaceable, wherein the control piston can assume a first and a second end position. In the first end position, a first control chamber, in the control housing minimum volume, in the second end position, a second control chamber in the control housing (which control chambers are formed in particular in the displacement direction respectively opposite sides of the control piston).

With the control piston is still a working element to its Mitverlagerung (via the control piston) in connection, for example, in one piece / integrally formed therewith or attached thereto. The working element may be, for example, a piston rod member, further including, for example, a valve member (such as a (fuel gas) nozzle valve member of a fuel injector). The working element emerges in particular from the control housing - on a working side of the piston control arrangement - from. In this respect, the piston control arrangement itself forms the functionality of a hydraulically directly controllable, double-acting hydraulic cylinder, that is to say in particular with a control piston which can be pressurized on both sides by hydraulic pressure. Characteristic in the invention, the control piston is surrounded by an annular piston received in the control housing (insofar as the piston control arrangement comprises a double piston arrangement of control piston and ring piston). The annular piston is in this case also in a first and a second end position, corresponding to the end positions of the control piston (ie, with the first and second end position of the control piston), in the displacement direction hydraulically controllable back and forth.

The annular piston is preferably guided on the outer peripheral side or with an outer wall on a wall (inner wall) of the control housing, on the inner peripheral side or with an inner wall on the outer wall of the control piston. In this case, a sliding seal can be effected both between the annular piston and the control housing and between the annular piston and the control piston, i. the pistons are preferably mounted slidably against each other. If necessary, ring sealing elements could also be considered, for example, piston rings.

The piston control arrangement is further configured such that the annular piston leads the control piston in a hydraulically controlled displacement of the control piston (and thus the working element) in a respective end position (in the control housing) and in this case assumes the (respective) end position before the control piston corresponding end position occupies. For this purpose, the annular piston may preferably have a more dynamic response at Steuerdruckbeaufschlagung than the control piston (including working element). To effect this, the annular piston is designed, for example, with respect to its pressure acting surfaces, its inertia, the design of its guide surfaces and, for example, its release behavior from a respective end position suitable for such a rapid action.

Furthermore, in accordance with the invention, the piston control arrangement is also set up, with or from reaching or receiving respective end positions of the annular piston and continuing, lagging displacement of the control piston (in the corresponding end position of the annular piston end position) hydraulic fluid or control fluid (especially exclusively) via at least one in the respective - occupied by the annular piston - acting end position throttle device of the annular piston from the control housing to displace (by means of the still lagging control piston). The here in particular for each of the two end positions (first and second end position) depending on a throttle device providing annular piston can be referred to as throttling piston. A respective throttle device may be formed, for example, by means of at least one throttle bore through the annular piston, a recess such as a groove or a notch on the annular piston, wherein for example in positive or negative displacement direction at least one throttle device at the end or at an end portion.

The thus configured piston control arrangement thus makes it possible to first displace the annular piston into one or the other end position, wherein the latter in particular overflows a respective control fluid opening on the control housing, so that the control fluid port, with the exception of a throttle cross section controlled in overlap or overlap with the control fluid port, at least one, acting in this end position throttle device of the annular piston is blocked. The control piston which subsequently reaches the corresponding end position must then displace the control fluid still to be displaced from the control housing via this at least one annular piston throttle device to the control fluid port. In this case - via the throttling effect of the throttle device - an advantageously reliable deceleration of the control piston is achieved, by means of which an impact damping in the context of a nozzle valve member control of a fuel injector via the piston control arrangement can be realized. In order to ensure that the at least one, the respective end position associated throttle device regularly reliably overlaps the control line mouth, for example, a rotation of the annular piston can be considered.

In particular, by suitable adjustment of the throttle cross sections of the throttle devices, an intended damping profile can also be adjusted in a simple manner, for example also by means of throttle cross sections, which vary in the direction of displacement over the length of the throttle device. Such may, for example, taper from a longitudinal central region of the annular piston to an end portion or change its shape. Preferably, the piston control arrangement is in this case designed such that at least one, preferably all of the throttle devices for a displacement of hydraulic fluid from the control housing can be flowed through transversely to the direction of displacement. In the context of an axial control piston displacement direction, such a throttle device is preferably radially oriented or can be flowed through. It is also provided in a further development of the piston control arrangement that control lines or control line paths are guided to the control housing, in particular to a first and second control chamber as already mentioned above on both sides of the piston or to the control fluid on the control housing to which the pressure has been displaced via the throttle devices Hydraulic fluid is drained. The control lines are also preferably guided transversely to the direction of displacement to the control housing or the control fluid openings, so that a control fluid outflow can take place in a streamlined manner via a respective correspondingly transversely throughflowable throttling device.

For example, particularly preferred embodiments may be such that the control lines open (on or off) annularly (in the circumferential direction of the control housing) into the control housing, for which purpose the control housing has an annular control fluid opening (ring mouth) on a respective control chamber (in the circumferential direction of the control housing) Control housing). In this case, furthermore, preferably the throttle openings or throttle cross-sections of a respective throttle device are distributed over the circumference of the annular piston, so that a rotational position-related alignment of the annular piston to the control housing, thus an anti-rotation, advantageously unnecessary and continue to distribute control fluid advantageously homogeneously distributed over the circumference or fed is. Thus, approximately equal pressure in the circumferential direction of the piston can be produced, thus advantageously avoiding tilting thereof during a displacement.

In particular, with embodiments as discussed above is provided so far that the piston control arrangement is capable of the control piston and the annular piston from the respective end position on the - by means of the control lines - transversely to the displacement direction to the control housing supplied hydraulic fluid also to displace, including preferably suitable pressure shoulder surfaces on the control piston and / or the annular piston are provided. A pressure shoulder surface may be formed, for example, as an end chamfer or stepped surface on the piston. With such configurations providing for cross flow, an axially small-sized arrangement can be achieved by virtue of which a plurality of piston control arrangements can be easily connected via transverse control lines, for example in a ring or star configuration. In the context of the present invention, a fuel injector is proposed which has at least one piston control arrangement as discussed above. In the context of a fuel injector formed with the piston control arrangement, the working element, which is mitverlagert with the control piston, in particular a nozzle valve member, which is hubsteuerbarbar via the piston control arrangement by displacement of the control piston, further preferably a fuel gas nozzle valve member or a fuel gas nozzle needle.

In particular, a fuel injector with the piston control arrangement is preferably designed to effect a stop damping of the nozzle valve member by means of the hydraulic fluid displaced via the respective throttle device acting in the assumed end position or the associated braking effect. Especially with fuel injectors having a plurality of nozzle valve members, for example dual-fuel fuel injectors having a plurality of fuel gas nozzle valve members (which are concentrically disposed about a liquid fuel nozzle needle, for example), the fuel injector may include a plurality of piston control assemblies, each such a nozzle valve member hubsteuern.

In this case, the piston control arrangements can communicate via common control lines, for example by means of ring arrangements of the control lines as discussed above. Such ring arrangements, in which a respective control line opens, for example, each on both sides of a respective control housing, in particular preferably each in a ring mouth, can be formed on the injector in an advantageously simple manner, for example by means of grooves, which are incorporated in end faces of housing elements.

With such a fuel injector, a common hydraulic control of all piston control arrangements can be carried out in a simple manner via a single control valve, to which the control lines communicating with the piston control arrangements are guided. The hydraulic fluid used to control the respective piston control arrangement may be liquid fuel or, for example, a control oil.

Finally, the invention also proposes an internal combustion engine which has at least one fuel injector as discussed above.

Also proposed within the scope of the present invention is an internal combustion engine which has at least one fuel injector as discussed above. Further features and advantages of the invention will become apparent from the following description of embodiments of the invention, with reference to the figures of the drawings, which show details essential to the invention, and from the claims. The individual features may be implemented individually for themselves or for a plurality of different combinations in a variant of the invention.

Preferred embodiments of the invention are explained below with reference to the accompanying drawings. Show it:

1 shows an example and schematically greatly simplified in partial section a piston control arrangement in a fuel injector according to a possible embodiment of the invention.

2 shows by way of example and schematically a view of the piston control arrangement with a first piston position, in which both pistons are in a first end position.

Fig. 3 analogous to FIG. 2, the piston control arrangement with a second piston position.

Fig. 4 analogous to Fig. 2 and 3, the piston control arrangement with a third piston position, in which both pistons are in a second end position.

5 shows an example and schematically a view of the annular piston, wherein the

Have throttle devices per throttle bore rows.

Fig. 6 analogous to FIG. 5, the annular piston, wherein the throttle devices notched

Have throttle cross sections.

Fig. 7 analogous to Fig. 5 and 6, the annular piston with slit-shaped throttle cross sections of

Throttle devices.

8 shows by way of example and schematically a view of a fuel injector with a

Plurality of piston control assemblies. In the following description and the drawings, the same reference numerals correspond to elements of the same or comparable function.

1 shows a piston control arrangement 1, in particular formed in a fuel injector 3, the fuel injector 3 being a fuel gas injector arranged for fuel gas ejection, in particular formed as part of a dual-fuel fuel injector (a liquid fuel injector part is not shown, however). ,

The piston control assembly 1 comprises a control housing 5, which may for example be formed in a nozzle body 7 of the fuel injector 3, e.g. as a hollow chamber. For the

Provision of the control housing 5, the nozzle body 7 may have a blind hole or a bore, which (s) is capped, for example, by a lidding element 9 such as a washer or a valve housing. In the control housing 5, a (control) piston 1 1 is added, which in a displacement direction A hydraulically back and forth controllable (that is, in positive "+ A" and negative "-A" displacement direction), the control piston 11 is a first and take a second end position (this will be discussed in more detail below in the context of Figures 2 to 4).

The control piston 11 is formed substantially cylindrical or piston-shaped and further connected to a working element 13, which on the control piston 1 1 - in the same hydraulic control - mitverlagert (in the displacement direction ± A). In the context of the injector 3 formed with the piston control arrangement 1, the working element 13 is in particular a (fuel gas) nozzle valve member or a (fuel gas) nozzle needle, which via the piston control arrangement 1, in particular its control piston 1 1 (together with this), (extent Controlled in the seat 15 is the ejection of fuel gas via a downstream nozzle assembly 17 of the fuel injector 3 is prevented controlled from the seat 15, the fuel injector 3 (FIG. in the operating case) fuel gas from a fuel gas nozzle chamber 19 and the nozzle assembly 17 eject. The fuel gas is supplied to the nozzle chamber 19, with a pressure level of, for example, 350 bar, preferably via a high-pressure line 21, which has a Fuel gas inlet 23 of the fuel injector with the nozzle chamber 19 connects. Furthermore, the nozzle valve member 13 emerges on the nozzle side from the control housing 5 (where it is then guided over a section in a guide (of the nozzle body 7)). In the context of the proposed piston control arrangement 1, the control piston 11 is received in the control housing 5 surrounded by an annular piston 25 (ie, the annular piston 25 and the control piston 11 form a double-piston arrangement). Here, the annular piston 25 is displaceable separately from the control piston 1 1, ie in the displacement direction ± A. Like the control piston 1 1, the annular piston 25 is also in a first and second end position, corresponding to the end positions of the control piston 1 1, in the displacement direction ± A hydraulically controllable back and forth.

The annular piston 25 has substantially the height of the control piston 1 1 and nestles

- Sliding and slidable - with its inner peripheral wall to the outer peripheral wall of the control piston 11 at. With its outer peripheral wall, the annular piston 25 nestles

- In turn, sliding and slidingly sliding - on the inner peripheral wall of the control housing 5 at. In the context of this thus substantially fluid-tight arrangement, an inadvertent passage of hydraulic or control fluid between a first, more distant control chamber 27 of the piston control arrangement 1 and a second, nearer control chamber 29 of the piston control arrangement 1 is advantageously avoided. As the hydraulic fluid may serve, for example, a control oil or liquid fuel, which is supplied to the fuel injector 3 from an external source 31 (high) pressurized.

For the hydraulic control of the pistons 1 1, 25 (control piston 1 1, annular piston 25) in the context of the piston control arrangement 1 is a respective control chamber 27, 29 and a first and in the displacement direction ± A opposite second (front) side of the piston first 1, 25 in the control housing 5 hyraulisch druckbeaufschlagbar. For this purpose, the piston control arrangement 1 control lines 33, 35 in particular two control lines, which open into the control housing 5, that is, the first control line 33 opens on the first side of the piston 1 1, 25 or in the first control chamber 27, the second control line 35 on the second side of the piston 1 1, 25 and in the second control chamber 29th

The control lines 33, 35 are each guided to a - common - control valve 37, preferably in the form of a 4/2-way valve, which in the context of the fuel injector 3 as a pilot valve is provided or acts. The control valve 37 is further connected via flow paths with the control fluid source 31 and a leakage outlet 39 or a low-pressure side (eg a tank) in connection. Depending on the position of the control valve 37, one of the control chambers 27 and 29 can be relieved hydraulically (via control fluid control via the control valve 37 to the low pressure side 39, ND) while the other control chamber 29 and 27 is hydraulically loaded (via metering of control fluid via the control valve 37 by the control fluid source 31) and vice versa. In that regard, an alternately loading and unloading of the control chambers 27, 29 allows, in the context of which the control piston 1 1 and the annular piston 25 are both controllable from the first end position to the second end position (from a nozzle distal End- läge in a near-nozzle end position) and vice versa.

Furthermore, the piston control assembly 1 is arranged in accordance with the invention so that the annular piston 25 leads the control piston 1 1, i. in a hydraulically controlled displacement of the control piston 11 (in particular together with the nozzle valve member 13) in a respective end position, wherein the annular piston 25 takes the respective end position in time before the control piston 1 1. To accomplish this, the annular piston 25 is configured so that its response to a controlled hydraulic pressure loading or switching between the control chambers 27, 29 with the result of releasing from the respective end position and the displacement in the other end position is faster than that of the control piston 11. Thus, the annular piston 25 is at a corresponding Steuerdruckbeaufschlagung ever time before the lagging control piston 1 1 (including nozzle valve member 13) in the respective end position. For this purpose, the annular piston 25 in addition to a smaller mass inertia relative to that of the control piston 1 1 (including associated nozzle valve member 13), for. also relatively large-sized pressure acting surfaces on (front side), e.g. still only slightly friction-bearing contact surfaces on the

Peripheral walls (individual aspects will be discussed in more detail below with reference to FIGS. 2 to 7).

According to the invention, the piston control arrangement 1 is further set up, in particular for achieving the intended impact damping of the nozzle valve member 13, with or from reaching or taking a respective end position of the annular piston 25 and still persistent, lagging displacement of the control piston 11, hydraulic fluid via at least one in the respective - end position acting throttle device 41 or 43 of the annular piston 25 to be displaced from the control housing 5 (by means of the trailing control piston 11, in each case in one of the guided to the control housing 5 control lines 33, 35; over the mouth 45 and 47). In the present case, the annular piston 25 per eingestbare end position a throttle device 41 and 43, which acts in the corresponding end position.

In this embodiment, the leading annular piston 25 passes over upon reaching a respective end position, first an orifice 45 and 47 of the corresponding control line 33 and 35 in the control housing 5, whereupon control fluid from the corresponding control chamber 27 and 29 via the control piston 11 only over that Throttle device 41 and 43 of the annular piston 25 can be displaced, which acts in this assumed end position (and insofar as the communication with the control line 33 and 35 is maintained (by overlapping

Positioning with the mouth 45 or 47)).

Due to the hereby adjusting Abbremseffekts, 41 and 43 also advantageously easy variable with adjustment of the throttle cross-sections of a respective throttle device, the adoption of the corresponding end position of the control piston 1 1 is delayed, so that a stop bouncing the mitverlagerten nozzle valve member 13 effectively avoided, thus the intended impact attenuation is achieved. Advantageously, this also results in a double effect to the effect that a damping for the adoption of both end positions is realized. In addition, due to the rapid response of the annular piston 25, a virtually delay-free release of the control piston 1 1 and the extent of the nozzle valve member 13 from the respective end position can be effected.

The orifices 45 and 47 of the control lines 33 and 35 are each formed on opposite end portions of the control housing 5, woneben also the throttle devices 41 and 43 of the annular piston 25 are formed at respective opposite end portions thereof. It can thus be effected that the control fluid is also displaced (ie over the entire travel of the control piston 11) until it reaches the respective end position of the control piston 11 (adjacent to a respective control housing front side) via the throttling device 41 or 43 acting in the respective end position. As can be seen, it is further provided according to FIG. 1 that the throttling device 41 or 43 acting in the respective end position can be flowed through for displacement of hydraulic fluid from the control housing 5 transversely to the displacement direction ± A. In this way, the respective throttle device 41, 43 are made extremely inexpensive and robust on the annular piston 25, in particular by simply formable throttle openings or cross-sections across the Wall. With this configuration, however, there is also the advantage that the overall height of the control housing 5 together with the control lines 33, 35 can be made very small, which criterion is always considerable, especially in space-constrained Injektorumgebungen. As illustrated, for example, in FIG. 1, it is provided with such embodiments that the control line paths 33, 35, via which the hydraulic fluid displaced via the throttle device 41, 43 acting in the respective end position can be discharged, are also oriented transversely to the direction of displacement , ie in such a way that the displaced hydraulic fluid can be discharged in a streamlined manner. In a further development of the invention is also also provided that the control piston 1 1 and the annular piston 25 from the respective end position over the transverse to the displacement direction ± A to the control housing 5 supplied hydraulic fluid or the associated control pressure are displaced (from the respective end position and releasably displaceable towards the other end position), ie via the radially or transversely opening control lines 33, 35. For this purpose, both the annular piston 25 and the control piston 1 1 suitably provided pressure shoulder surfaces 49 (for control pressure introduction) on.

The control piston 11 can, at its nozzle-distal end, e.g. a pressure shoulder surface 49 in the form of a ring inclined surface or bevel (or, for example, a step surface, which is further formed, for example, to a (central) stop 51), which on the one hand allows to get on the control housing 5 in the first, nozzle-distant end position in Appendix Consequently, take a defined position, while still leaving a gap over which the pressure can be introduced to the pressure shoulder 49 for a shift.

At the same time "adhesive gaps", which would be detrimental to a quick release, largely avoided.As well as the annular piston 25 such an inclined surface 49 on

have corresponding end, e.g. formed as a chamfer, alternatively, e.g. as a stage. This also serves to define the end position and as a pressure shoulder 49 for a shift.

Furthermore, the length of the control piston 1 1 can be seen so dimensioned that in the other end position, in which the nozzle valve member 13 rests in the seat 15, thus defining the nozzle near end position of the control piston 1 1, close to the nozzle a clearance between the control piston 1 1 and the control housing end wall remains , which in this case formed step surface in turn acts as a pressure shoulder 49 for the hydraulic controllability. The annular piston 25 can in this case again have a chamfer (or step surface) at the other end to define the end position and provide a further pressure shoulder 49.

In the preferred embodiment of the piston control arrangement 1 shown in FIG. 1, the mouths 45, 47 of the control lines 33, 35 on the control housing 5 are each designed as a ring mouth (in the circumferential direction of the control housing 5), and the throttle device 41 acting in the respective end position also woes , 43 in the circumferential direction of the control housing 5 and the annular piston 25 arranged or oriented throttle openings, that is distributed over the circumference of the annular piston 25. This has the advantage associated with the control fluid homogeneously distributed over the circumference of the respective control chamber 27, 29th Furthermore, to be able to displace the control fluid also homogeneously into the respective control chamber 27, 29, thus to achieve an optimal control behavior for the control of the piston 1 1, 25. Now, with reference to the figures 2 with 4, which illustrate a Umsteuerungsvorgang of control piston 11 and annular piston 25 with the piston control assembly 1 of FIG. 1, further discussed additional aspects in the context of the invention.

Fig. 2 illustrates a position of the control piston 11 and the annular piston 25, in which both pistons 11, 25 are controlled in the first or nozzle-distal end position. For this purpose, the nozzle-near control chamber 29 is acted upon by control pressure or hydraulic pressure (indicated by the arrows), that is, via the control valve 37 and the control fluid source 31, while the nozzle-remote control chamber 27 is relieved via the control valve 37 toward the low pressure side 39 (also indicated by arrows ). In this position, the nozzle valve member 13 - controlled by the control piston 11 - from the seat 15, both pistons 1 1, 25 are further in contact with the nozzle-distal end wall of the control housing 5, i. with a serving as a stop 51, projecting end portion.

In order to control the nozzle valve member 13 back into the seat 15, thus closing the fuel gas nozzle valve, the control valve 37 is now reversed first. As a result, the nozzle-remote or first control chamber 27 is switched in communication with the control fluid source 31, thus now the nozzle-distant control chamber 27 charged. At the same time, the nozzle closer or second control chamber 29 experiences a discharge, along with the outflow of control fluid through the control valve 37 to the low pressure side 39. Due to the adjusting, now reverse pressure gradient across the piston 1 1, 25 first dissolves the faster responsive annular piston 25 from its first end position and moves toward the nozzle near control chamber 29 until it reaches its second end position, thus in abutment with the nozzle near the control housing end wall. This position is shown in Fig. 3. About the guided to the nozzle-near control chamber 29 control line 35, the fluid displaced by the annular piston 25 is discharged from the control housing 5.

When the second or near-nozzle end position is taken, the annular piston 25, with the exception of its throttling device 43 acting in this end position, obstructs the mouth 47 of the control line 35 guided to the nozzle-near control chamber 29, so that subsequently to be displaced

Control fluid can only be displaced from the control housing 5 via the throttle openings of the throttle device 43 acting in this, near-end end position.

With displacement of the annular piston 25 continues to experience the control piston 1 1, the full hydraulic pressure from the nozzle remote control chamber 27 and is also, the annular piston 25 so far lagging, towards the nozzle-near control chamber 29 relocated, that is in the

Displacement direction ± A. Due to the fact that now but the displacement of the control fluid is only possible via the throttle device 43 of the nozzle-proximal end portion of the annular piston 25, the control piston 1 1 is decelerated, thus the nozzle valve member 13 is controlled back gently into the seat 15. In such a position of the nozzle valve member 13, i. in accordance with the piston position in Fig. 4, then the control piston 1 1 in its second or

Close to the nozzle end position.

For a subsequent reversal (not shown), in which the nozzle valve member 13 is again controlled from the seat 15, the control valve 37 can then be switched again, whereupon the pressure difference between the control chambers 27, 29 and via the piston 1 1, 25 reverses again, so that the annular piston 25 - in turn, the control piston 1 1 leading - initially shifted toward the first, remote nozzle control chamber 27 and occupies its nozzle-remote end position. In this case, the control piston 11 again trails the annular piston 25 and, after taking the nozzle-distal end position of the annular piston 25, can displace control fluid from the control chamber 27 only from the control housing 5 via the throttling device 41 (of the end portion remote from the nozzle) of the annular piston 25 acting in this end position , Thus, the control piston 11 is braked wear-reducing in an advantageous manner even when taking this nozzle remote end position. 7 shows in partial section exemplary embodiments of the throttle devices 41, 43 of the annular piston 25. In the annular piston 25 shown in Fig. 5, the throttle device 41, 43 at a respective end portion - distributed over the circumference - throttle bores, that is two each in the displacement direction ± A adjacent rows 53, 55 of throttle bores (radial bores). In this case, the effective throttle cross-section is reduced by passing over or closing (passing) of each inner throttle row 55 by the control piston 1 1, so that sets a reduced throttle cross-section with increased braking effect shortly before each In-stop-Ganges.

In the annular piston 25 shown in FIG. 6, a respective throttle device 41, 43 is formed by notches distributed over the circumference in the end face of the annular piston 25. In this case, over the entire travel of the control piston 11 so far a constant effective throttle cross section is provided because the control piston 11 over its entire travel in the direction of displacement, the throttle cross sections of the throttle devices 41, 43, which are available for the displacement of the control fluid, not overrun. 7 illustrates by way of example an annular piston 25, in which the throttle devices 41, 43-again distributed over the circumference-are formed by means of gaps or grooves oriented in the direction of displacement ± A (in the present case axially), which extend from the respective end faces into the annular piston 25 are worked. Here as well, with increasing closing of the gap by the control piston 11, an increasing braking effect or delay, hence damping, can be achieved.

8 shows, by way of example and schematically, a fuel injector 3, in particular again for the ejection of fuel gas, which has a plurality of piston control arrangements 1, each of which controls a working element 13 in the form of a nozzle valve member.

In the embodiment of the fuel injector 3 shown in FIG. 8, which provides, for example, three fuel gas nozzle valve members 13, the respective control chambers 29 close to the nozzle and the control chambers 27 of the piston control assemblies 1 remote from the nozzle are each provided with a common control line 33 and 35, in this case each a common control line, communicating with each other.

The respective control line 33, 35 for connecting the nozzle-near control chambers 29 and the nozzle-remote control chambers 27 is further guided to the control valve 37, so that the entirety of the piston control arrangements 1, thus the fuel gas nozzle valve members 13, advantageously via a single control valve 37 is controllable, that is hydraulically controlled.

As FIG. 8 also shows, it can also be provided to connect the nozzle chambers 19 of the fuel gas nozzle valve members 13 in a communicating manner via a common supply line 57. Fuel gas from a fuel gas supply source can be distributed in a simple manner via a single inlet 23 to the entirety of the nozzle chambers 19. Overall, such a solution provides an advantageously simple and robust fuel injector 3 with the intended impact attenuation functionality.

In addition to an embodiment according to FIG. 8, which provides the connection of the control chambers 27, 29 via a control line ring arrangement, it is also possible (although not shown) to provide a star-shaped control line arrangement for connecting the control chambers 27 and 29, respectively.

LIST OF REFERENCE NUMBERS

I piston control arrangement

3 fuel injector

5 control housing

7 nozzle body

9 lidding element

I I control piston

13 working element (fuel gas nozzle valve member)

15 nozzle valve member seat

17 nozzle arrangement

19 fuel gas nozzle chamber

21 high-pressure line (fuel gas)

23 fuel gas inlet

25 ring pistons

27 first control chamber (nozzle distant)

29 second control chamber (closer to the nozzle)

31 Source

33 control line (first control chamber)

35 control line (second control chamber)

37 control valve

39 leakage outlet

41 throttle device

43 throttle device

45 estuary

47 muzzle

49 pressure shoulder surface

51 stop

53 series

55 series

57 supply line

A direction of displacement

Claims

1. piston control assembly (1), in particular for use with a fuel injector (3), with a control housing (5) and a control piston (1 1) received therein, which in the control housing (5) in a displacement direction (± A) hydraulically out and can be controlled, wherein the control piston (1 1) can assume a first and a second end position, wherein with the control piston (11) for Mitlegagerung a working element (13) is in communication,

characterized in that

- The control piston (11) surrounded by an annular piston (25) in the control housing (5)

is recorded, which annular piston (25) also in a first and second end position, corresponding to the end positions of the control piston (11), in the displacement direction (± A) hydraulically back and forth controllable;

- Wherein the piston control arrangement (1) is arranged so that the annular piston (25) leads the control piston (11) in a hydraulically controlled displacement of the same in a respective end position and in this case occupies the respective end position before the

Control piston (11) occupies the corresponding end position, wherein

the piston control arrangement (1) is furthermore set up, taking in respective end positions of the annular piston (25) and still continuing lagging displacement of the control piston (11) hydraulic fluid via at least one throttle device (41, 43) of the annular piston (25) acting in the respective end position. to displace from the control housing (5).

Second piston control arrangement (1) according to claim 1,

characterized in that

at least one throttle device (41, 43) for a displacement of hydraulic fluid from the control housing (5) transversely to the displacement direction (± A) is flowed through, in particular all.

3. Piston control arrangement (1) according to one of the preceding claims,

characterized in that

to the control housing (1) control lines (33, 35) are guided, to which via the throttle devices (41, 43) displaced hydraulic fluid can be discharged, in particular transversely to the displacement direction (± A) and / or with respect to the respective throttle device (41, 43) in the flow direction can be discharged.

4. Piston control arrangement (1) according to one of the preceding claims,

characterized in that

the piston control arrangement (1) is configured such that the control piston (1 1) and the annular piston (25) can be displaced from the respective end position via hydraulic fluid supplied transversely to the displacement direction (± A) to the control housing (5), in particular via suitable pressure shoulder surfaces ( 49) on the control piston (11) and the annular piston (25).

5. Piston control arrangement (1) according to one of the preceding claims,

characterized in that

in each case in the displacement direction (± A) mutually opposite end portions of the annular piston (25) at least one throttle device (41, 43) is formed which acts in a respective end position of the annular piston (25).

6. Piston control arrangement (1) according to one of the preceding claims,

characterized in that

a respective control line (33, 35) opens annularly or with a ring mouth on the control housing (5); and or

Throttle openings of at least one of the throttle devices (41, 43) distributed over the circumference of the annular piston (25) are formed.

7. Piston control arrangement (1) according to one of the preceding claims,

characterized in that

at least one of the throttle devices (41, 43) has a throttle cross section which varies over the length of the throttle device (41, 43) in the displacement direction (± A).

8. fuel injector (3),

characterized in that

the fuel injector (3) has at least one piston control arrangement (1) according to one of the preceding claims.

9. fuel injector (3) according to claim 8,

characterized in that

the working element (13) is a nozzle valve member, which can be lift-controlled via the piston control arrangement (1) by means of displacement of the control piston (11).

10. Fuel injector (3) according to claim 9,

characterized in that

the fuel injector (3) is arranged, upon displacement of the control piston (1 1) in a respective end position by means of the displacement of hydraulic fluid via one of the throttle devices (41, 43) to effect a stop damping of the nozzle valve member (13).

11. Fuel injector (3) according to one of claims 8 to 10,

characterized in that

the fuel injector (3) has a plurality of piston control arrangements (1) each of which controls a working element (13) in the form of a nozzle valve member, the piston control arrangements (1) communicating via common control lines (33, 35).

12. Fuel injector (3) according to claim 1 1,

characterized in that

the fuel injector (3) has a control valve (37), in particular a single control valve (37), via which the plurality of piston control arrangements (1) can be hydraulically actuated.

13. Internal combustion engine,

marked by

at least one fuel injector (3) according to one of claims 8 to 12.