DE102013003104A1 - Fuel injector for use with diesel fuel in fuel injection device of fuel injection system, has pressure shock absorber that is arranged in leakage flow path to attenuate pressure waves, which run through leakage flow path to actuator chamber - Google Patents

Abstract

The fuel injector (1) has a pilot valve (29) to control the needle stroke of an axially displaceable nozzle needle (7). The pilot valve is controlled from an actuator (33). An actuator chamber (41) is connected to a leakage system (31) through a leakage flow path (49). A pressure shock absorber (65) is arranged in the leakage flow path to attenuate the pressure waves in the leakage system. The pressure waves run through the leakage flow path to the actuator chamber. The leakage flow path leads to a nozzle needle distal end (41a) of an actuator area (41) in the actuator chamber. An independent claim is included for a fuel injection system with a common leakage system.

Description

The present invention relates to a fuel injector according to the preamble of claim 1.

Fuel injectors, in particular conventional pilot-valve-controlled injectors, z. B. magnetaktuierte, which are mostly for use with diesel fuel, for. As well as heavy oil or biofuel, are provided, when used in fuel injection systems regularly run the risk of being affected in the functionality of their actuators by pressure waves, which propagate in the fuel injection system.

Such pressure waves arise in particular when the pilot valve opens, the pressure wave being triggered by the fuel exiting from the high-pressure side of the pilot valve. The pressure wave passes through the injector's own leakage system, and the leakage system of the fuel injection system (engine) is detected by the wave propagation. In this case, a pressure wave via the leakage system of the fuel injection system can also reenter the injector's own leakage system, i. e. with attenuated amplitude. Also, pressure waves of other injectors can pass through the leakage system of the engine in the leakage system of the injector.

Such pressure waves are particularly problematical when it is necessary to keep the shot-to-Schussstreuung low, for example in the sensitive smallest amount of Injektorkennlinie in which a quick and undisturbed opening and closing of the pilot valve and insofar unimpaired functionality of the actuator is required.

To prevent negative pressure wave influences suggests the document JP 2005-69135 A an injection system providing the location of a variable-area opening downstream of a merge point of leakage outlets of a plurality of injectors. In addition, it can be provided according to the same document, in addition to arrange a variable opening in each case downstream of a leakage outlet of a respective injector upstream of the Zusammenführungspunkts.

A disadvantage of the proposed solution, however, is that - in addition to the considerable structural complexity of the system - the pressure waves generated in the injector still pass through the injector own leakage system and can disturb the actuators.

Proceeding from this, the present invention seeks to propose a generic fuel injector, which overcomes the above disadvantages.

This object is achieved by the features of claim 1.

Advantageous developments and embodiments of the invention are specified in the dependent claims.

According to the invention, a fuel injector for a fuel injector is proposed. The injector may preferably be provided for use in a common rail system, the fuel injector being generally intended for use with internal combustion engines in the form of gasoline or diesel engines, in particular large diesel engines and furthermore, in particular, vehicle engines, for example in offroad or marine applications also in stationary applications, for example combined heat and power plants.

The fuel injector comprises a pilot valve for indirectly controlling the nozzle needle stroke of an axially displaceable nozzle needle of the injector, the pilot valve being controlled by an actuator whose actuator chamber is connected via a leakage flow branch, in particular formed by a drilling channel, to a leakage system in the injector (injector-internal leakage system).

The actuator is preferably provided with the injector as Magnetaktuatorik, alternatively, for example, a Piezoaktuatorik. The fuel injector further comprises a leakage outlet, which constitutes a leakage outlet of the injector-internal leakage system (to the outside).

The fuel injector is characterized in that a pressure shock absorber is arranged in the leakage flow branch. Here, the pressure shock absorber is in particular arranged such that to the actuator chamber via the leakage flow branch running waves minimized (attenuated), in particular broken.

In order to achieve the intended effect even in the event that several leakage flow branches are each provided for the connection of the actuator chamber to the injector-internal leakage system in the injector, in such modifications of the invention is also provided to design the injector such that in all such flow branches each a pressure shock absorber is arranged according to the invention.

The inventively designed fuel injector is advantageously able to protect the pressure fluctuation-sensitive actuator in the actuator space from potentially harmful effects on the part of the leakage outlet in the injector introduced pressure waves. In addition, the invention However, designed fuel injector also suitable to effectively protect the pressure fluctuation-sensitive actuator in the actuator space before the negative effects of the pressure waves or pressure surges generated in the injector itself and injector inside running (on the part of the high pressure part).

In this case, the pressure shock absorber generally acts in such a way that fluid communication of the actuator chamber with the injector-internal leakage system via the leakage flow branch is made possible at any time for leakage removal (automatic opening of the pressure shock absorber or permanent maintenance of the communication connection of the actuator chamber - injector-internal leakage system).

The pressure shock absorber preferably has a cross-sectional tapering element, a flutter valve, a diaphragm, one or more screen disks, at least one throttle-for example with a cross-sectional width of one tenth of a millimeter-or a throttle device or a combination formed from the aforementioned elements.

Such a pressure shock absorber, as they are preferred for the invention, is advantageously small and can - as was recognized in the invention - both achieve the desired pressure wave attenuation and are easily arranged in Leckageströmungszweig. A pressure shock absorber according to the invention can be integrally and inexpensively, for. B. advantageous as a self-retaining or self-clamping element, for. B. be formed as a spring element, or as a mere throttle bore. The pressure shock absorber according to the invention may preferably be accommodated in a receptacle between the actuator chamber and the injector-internal leakage system in the leakage flow branch, wherein the receptacle z. B. is formed by a simple drill profile.

In preferred embodiments of the fuel injector, the leakage flow branch opens into the actuator chamber at a nozzle needle-distal end of the actuator chamber (top). Such a leakage flow branch can be provided in a simple manner by means of a drilling channel, in particular on the part of the actuator chamber. Here, the pressure shock absorber may continue to be arranged at the mouth-side end of the Aktuatorikraumes, so that a receptacle for the pressure shock absorber also as an unobtrusive bore, in particular on the part of the Aktuatorikraums, can be performed.

In a further preferred embodiment of the fuel injector, in which the pilot valve is controlled via an anchor rod of the actuator of the injector, it is provided that communicating with a (creepage) leadership of the anchor rod at least one further branch (Führungsleckageabfuhrzweig) formed leader in the leakage system in the injector which reduces the ingress of guide leakage into the actuator space via the anchor rod guide (creep gap). This can further optimize the pressure wave reduction and keep the leakage volume flows in the actuator space small.

Also proposed is a fuel injection system having at least one fuel injector as described above, e.g. As a common rail system. Preferably, the fuel injection system has a plurality of such fuel injectors, which are connected in particular via a common leakage system.

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 can be realized individually for themselves or for several in any combination in a variant of the invention.

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

1 exemplary and schematically a fuel injector in section according to a possible embodiment of the invention;

2a to 2d exemplary and schematic views of various pressure shock absorbers, which are usable in the context of the present invention; and

3 by way of example and schematically a simplified view for illustrating a further possible arrangement of a pressure shock absorber in a fuel injector according to another possible embodiment of the invention.

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

1 shows schematically and by way of example a fuel injector 1 for a fuel injection device, in particular for a common rail system. The fuel injector 1 is preferably usable with diesel fuel, alternatively for example with biofuel or heavy oil.

The fuel injector 1 has an injector housing 3 with a nozzle body 5 on, in which a nozzle needle 7 is received axially displaceable. Via a nozzle needle valve 9 , which by means of the nozzle needle 7 and a valve seat 11 in the Nozzle body is formed, a flow path from a high-pressure fuel volume 13 in the nozzle body 5 towards a nozzle arrangement 15 of the injector 1 , which at the nozzle-near end 5a of the nozzle body 5 is provided for the injection of fuel into a combustion chamber of an internal combustion engine, are blocked needle-dependent.

The nozzle needle 7 is by means of a nozzle spring 17 loaded in the closing direction, wherein the nozzle spring 17 against a ring collar 19 the nozzle needle 5 acts. The nozzle spring 17 is here at the other end to a needle guide sleeve 21 supported, which together with an intermediate plate 23 of the injector housing 3 and the upper end 7a the nozzle needle 7 a control room 25 for controlling the needle stroke at the injector 1 Are defined.

Starting from and in communication with the control room 25 leads a throttle bore 27 (Outlet throttle, simplified dashed lines drawn) towards a pilot valve 29 of the fuel injector 1 , via which throttle bore 27 the control room 25 with open pilot valve 29 with an injector-internal leakage system 31 (Absteuerleckagesystem 31 ) communicates.

In the control room 25 also opens an inlet throttle (not shown), via which the control room 25 with high pressure fuel from a high pressure line in the injector 1 (also not shown) can be charged. The high pressure line is further provided for high pressure fuel in the fuel volume 13 contribute.

The fuel injector 1 also has an actuator system 33 on which the pilot valve 29 controlled. The actuators 33 which is presently formed as Magnetaktuatorik (alternatively, for example, as Piezoaktuatorik) comprises a closing spring 35 loaded anchor 37 (closer to the nozzle), which comes with a (nozzle-distant) magnetic packet 39 the actuatorics 33 for the control of the pilot valve position cooperates. The actuators 33 , ie magnetic package 39 , Closing spring 35 and anchor 37 , is in an actuator room 41 at the injector 1 taken (together with a fixing arrangement 43 for the actuators 33 ).

The actuator room 41 is by means of a valve plate or a valve housing 45 of the injector housing 3 and one against the valve housing 45 crowded single pressure accumulator 47 of the fuel injector 1 formed or defined (via each corresponding recess in the valve housing 45 or the single-pressure accumulator 47 ), which single pressure accumulator 47 The nozzles continue to remove an end portion of the housing 3 Are defined. For the training of the actuator room 41 Alternatively, a mere lidding element instead of the single-pressure accumulator 47 be provided.

According to the invention the actuator space 41 via a leakage flow branch 49 to the leakage system 31 in the injector 1 connected, ie to the injector-internal Absteuerleckagesystem 31 , The leakage flow branch 49 is preferably formed as a drilling channel and provided to prevent leakage (solid arrows in 1 ) from the actuator room 41 towards the leakage system 31 To be able to dissipate, so that it is avoided that leakage or fuel in the actuator chamber 41 stands and ages in it, so for example to a sticking or a malfunction of the actuator 33 leads.

The actuator room 41 is present, see eg B. 1 , at the nozzle-distant end 41a at the leakage flow branch formed as a drilling channel 49 communicatively connected (via one with the actuator room 41 communicating opening 49a at the end 41a ), wherein the Bohrkanal starting from the actuator space 41 can be easily manufactured.

From the actuator room 41 (at the nozzle-near end 41b ) out extends an anchor rod 51 which with the anchor 37 is axially displaceable. The anchor rod 51 is in an anchor rod guide 53 led, which like the pilot valve 29 in the valve housing 45 of the injector housing 3 is included. A jet-close end 51a the anchor rod 39 acts to form the pilot valve 29 with a valve seat 29a the pilot valve 29 together. The pilot valve 29 is present as a pressure balanced pilot valve 29 provided, alternatively, the pilot valve 29 in the context of the present invention, however, also a non-pressure compensated pilot valve 29 be.

Along the anchor rod guide 53 extends a leakage creepage (pilot leakage), about which leakage from the pilot valve 29 in the actuator room 41 may occur anchor side. In order to minimize the leakage flow along the creepage gap and thus the influencing of the actuator 33 in the actuator room 41 by an associated flow through the actuator chamber 41 can be further reduced (ie, from the nozzle closer to the nozzle side remote) may be provided in preferred embodiments of the invention - as in 1 Simplified illustrates - that the injector 1 a guide leakage removal branch 55 having, which the anchor rod guide 53 with the injector leakage system 31 combines. This allows the leakage flow along the creeping gap 53 are divided into a primary current and a secondary current, only only the smaller secondary current in the actuator chamber 41 can occur.

About the injector-internal leakage system 31 is Absteuerleckage part of the control room 25 over the outlet throttle 27 to a leakage outlet 57 of the injector 1 discharged as soon as the pilot valve 29 (at applied injection pressure) opens. The leakage system 31 of the injector 1 has at least one, preferably a plurality of leakage lines 59 on which ever downstream of the pilot valve 29 can be flowed, for example, via a common branch point 61 ,

It can be provided that the leakage lines 59 via a ring channel 63 upstream of the leakage outlet 57 to be reunited. The one for the leakage discharge from the actuator chamber 41 provided leakage flow branch 49 in this case flows upstream of the leakage outlet 57 into the injector-internal leakage system 31 , for example in the ring channel 63 ,

According to the invention, in the leakage flow branch 49 a pressure shock absorber 65 arranged, see eg. 1 or 3 , The pressure shock absorber 65 is provided to access the actuator room 41 over the leakage flow branch 49 incoming pressure waves (dashed arrows in 1 ), in particular also those pressure waves which occur in the injector-internal leakage system 31 spread. Such pressure waves arise in particular when the pilot valve 29 opens when the high pressure is applied.

The pressure shock absorber 65 is preferred as a flutter valve, in particular small-scale flutter valve 65 , trained, z. B. 1 , The flutter valve 65 , which can act as a check valve, is suitable only because of pressure differences (on the two valve sides) in the forward direction (leakage downstream of the actuator chamber 41 over the leakage flow branch 49 ) to automatically close again (eg flap function).

The flutter valve 65 can, for example, as Einpressteil in the leakage flow branch 49 be arranged, for example, integrated in a sleeve.

In further preferred embodiments of the injector 1 is the pressure shock absorber 65 by means of a cross-shaped material section, see 2a , or an aperture, see 2 B , or at least one, in particular also a cascading of sieve inserts, see 2c , or z. B. a mere throttle bore, z. B. 3 , Such pressure shock absorbers 65 which also in combination in the leakage flow branch 49 can be arranged, also advantageously build small, are inexpensive to produce and allow - due to the concomitant cross-sectional constriction in the leakage flow branch 49 - The reduction of a pressure wave pulse, thus achieving the intended attenuation.

Particularly favorable and easily executable embodiments of suitable pressure shock absorbers 65 arise when one or more spring elements 67 on a pressure shock absorber 65 are formed, for. B. 2d , which, for example, in a receiving bore 69 for the pressure shock absorber 65 in the leakage flow branch 49 supported and this can be fixed against slipping, for example, against the nozzle-distal end 41b of the actuator room 41 ,

The pressure shock absorber provided according to the invention 65 allows in particular due to its arrangement in the leakage flow branch 49 that too over the outlet 57 in the injector 1 incoming waves no adverse dysfunction of the actuator 33 can effect. The pressure shock absorber is preferred 65 arranged in the context of the invention, sz B. 1 that in particular those towards the actuatorics 33 current pressure waves by means of the pressure shock absorber 65 be attenuated in their effect, the wave fronts otherwise against a (movable) effective surface of the actuator 33 , z. B. that of the anchor 37 (Anchor plate) would flow, ie perpendicular or nearly vertical.

3 shows another possible embodiment of an injector 1 in which the injector 1 for example, a Piezoaktuatorik 33 , recorded in an actuator room 41 , having. The actuator room 41 is - in contrast to the embodiment according to 1 - at a nozzle-near end 41a via a - only short - leakage flow branch 49 to the injector-internal leakage system 31 connected, which, however, as before suitable, the pressure shock absorber 65 take in the intended manner, for example in the form of a throttle bore or a flutter valve 65 , Again, the intended effect of the pressure wave effect reduction in the injector 1 running waves are advantageously achieved.

LIST OF REFERENCE NUMBERS

1

injector

3

injector

5

nozzle body

5a

Close to the nozzle 5

7

nozzle needle

7a

nozzle-far end 7

9

nozzle valve

11

valve seat

13

High volume printing

15

nozzle assembly

17

nozzle spring

19

collar

21

Needle guide sleeve

23

intermediate plate

25

control room

27

outlet throttle

29

pilot valve

29a

valve seat 29

31

Absteuerleckagesystem

33

actuators

35

closing spring

37

anchor

39

magnet set

41

Aktuatorikraum

41a

Nozzle remote end 41

41b

Close to the nozzle 41

43

fixing arrangement

45

valve housing

47

Single accumulator

49

Leakage flow branch

49a

opening 41a

51

anchor rod

51a

Close to the nozzle 51

53

Anchor rod guide

55

Reference leakage branch

57

leakage outlet

59

leakage line

61

branching point

63

annular channel

65

shock absorbers

67

spring element

69

location hole

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• JP 2005-69135 A [0005]

Claims (10)

Fuel injector ( 1 ) for a fuel injection device with a pilot valve ( 29 ) for the indirect control of the nozzle needle stroke of an axially displaceable nozzle needle ( 7 ) of the injector ( 1 ), the pilot valve ( 29 ) of an actuator system ( 33 ) whose actuator space ( 41 ) via a leakage flow branch ( 49 ) to a leakage system ( 31 ) in the injector ( 1 ), characterized in that in the leakage flow branch ( 49 ) a pressure shock absorber ( 65 ) is arranged. Fuel injector ( 1 ) according to claim 1, characterized in that the pressure shock absorber ( 65 ) is adapted to dampen pressure waves which in the leakage system ( 31 ) in the injector ( 1 ) to the actuator room ( 41 ) via the leakage flow branch ( 49 ). Fuel injector ( 1 ) according to one of the preceding claims, characterized in that the leakage flow branch ( 49 ) at a nozzle needle distal end ( 41a ) of the actuator room ( 41 ) into the actuator room ( 41 ) opens. Fuel injector ( 1 ) according to one of the preceding claims, characterized in that the pressure shock absorber ( 65 ) at the nozzle needle distal end ( 41a ) of the actuator room ( 41 ) is arranged. Fuel injector ( 1 ) according to one of the preceding claims, characterized in that the pressure shock absorber ( 65 ) has a cross-sectional tapered element, a flutter valve, a diaphragm, one or more screen discs, at least one throttle or a throttle device or a combination formed from the aforementioned elements. Fuel injector ( 1 ) according to one of the preceding claims, characterized in that the pressure shock absorber ( 65 ) in a recording ( 69 ) between the actuator space ( 41 ) and the injector internal leakage system ( 31 ) in the leakage flow branch ( 49 ) is recorded. Fuel injector ( 1 ) according to one of the preceding claims, characterized in that the pilot valve ( 29 ) via an anchor rod ( 51 ) of the actuators ( 33 ) of the injector ( 1 ), communicating with a leadership ( 53 ) of the anchor rod ( 51 ) at least one branch ( 55 ) into the leakage system ( 31 ) in the injector ( 1 ), which prevents the penetration of leakage into the actuator space (FIG. 41 ) via the anchor rod guide ( 53 ) reduced. Fuel injector ( 1 ) according to one of the preceding claims, characterized in that the actuators ( 33 ) an active element ( 37 ), which one to the leakage discharge direction from the actuator chamber ( 41 ) via the leakage discharge branch ( 49 ) has transverse active surface. Fuel injection system, characterized by at least one fuel injector ( 1 ) according to any one of the preceding claims. Fuel injection system according to claim 9, characterized in that a plurality of fuel injectors ( 1 ) are connected according to one of claims 1 to 8 via a common leakage system.

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