EP1656498B1 - Fuel injection valve controlled by a pilot valve - Google Patents

Abstract

The hydraulic control device (20) of the fuel injection valve (10) comprises a pilot valve (70). The pilot valve rod (66) co-operates with both the actuator (18) and the pilot valve seat (68). A discharge chamber (72) is located adjacent to the pilot valve seat (68) and is connected to the low-pressure outlet (76) by means of a throttle passage (74). In order to complete the injection process, the pilot valve rod (66) is inserted into the discharge chamber (72) until it hits the pilot valve seat (68). This leads to an increase in pressure which, in turn, leads to the control body (38) being rapidly lifted from its position on the discharge chamber body (46). The injection valve member (22) is thereby displaced very rapidly into the closing position thereof in order to complete the injection process. The movement of the pilot valve rod (66) can also be mechanically used to support the rapid closing movement of the injection valve member (22).

Description

The present invention relates to a fuel injection valve for intermittent fuel injection into the combustion chamber of an internal combustion engine according to the patent claim 1.

A fuel injection valve is for example in the EP-A-1476652 described. In a hollow cylindrical housing is fixed to the housing a designated in the document as a control body drain body formed with a control passage. In a partially supported on Abflussraumkörper control sleeve on the one hand operatively connected to an injection valve member control piston and on the other hand arranged as a slide valve body control body slidably disposed in a close sliding fit. The control piston defines downwardly a control chamber, which is bounded above by the control body and laterally by the control sleeve. In the control body two axially parallel, a throttle restriction having throttle passages are formed, of which a throttle passage is connected via the throttle restriction with the control passage in Abflussraumkörper and with the control chamber in flow communication. With respect to the throttle restriction, a throttle inlet formed in the control body opens into this control passage on the control chamber side, which is in flow communication with a high-pressure chamber via a cavity formed in the control sleeve, a slot in the control sleeve, and a flow gap formed between the sleeve and the housing, in which high-pressure fuel pressure prevails. Thus, the control chamber is constantly via the throttle inlet directly to the high-pressure chamber in a flow connection.

Another fuel injection valve is in the EP-A-1273791 disclosed. The control chamber of this fuel injection valve is bounded on the one hand by a piston of the injection valve member, on the other hand by a control body designated as a slide valve body and peripherally by a control sleeve. Both the double-acting piston and the control body are guided in a tight sliding fit on the control sleeve. Through the control body passes through a throttle passage, which is permanently connected to a control passage in a designated as a control body discharge space body flow-connected. The discharge space body is partially supported on the control sleeve. From the high-pressure chamber, the throttle inlet leads into the control passage. This is on the side facing away from the control body by means of a pilot valve with a low pressure space connected and disconnected from this again. The connection of the control passage with the low pressure space leads to a pressure drop in the control chamber, whereby the injection valve member moves towards the control body and releases the injectors. After the separation of the control passage from the low-pressure chamber, the latter, together with the injection valve, moves away from the outflow space body as a result of the pressure difference in the control chamber and on that side of the control body which leads to rapid closing of the injection nozzles. Under the force of a spring element, the control body then re-engages tightly against the drainage space body.

Further fuel injection valves are in EP-A-0 426 205 . EP-A-0 603 616 . EP-A-0 824 190 . EP-A-1 273 791 disclosed. They have a controlled by an electromagnetic actuator Pilotvantistift which separates in the closed position provided with a throttle restriction outlet channel of a control chamber of a low-pressure outlet. When the pilot valve pin is lifted from the pilot valve seat, fuel from the exhaust passage flows directly to the low pressure outlet. By opening the pilot valve, an injection process is initiated and closing the pilot valve causes the closing movement of the injection valve member to terminate the injection process.

Based on this prior art, it is an object of the present invention to develop a generic fuel injection valve such that the closing movement of the injection valve member for the completion of an injection process is very fast, while the opening movement can be done relatively slowly at the beginning of an injection process.

A fuel injection valve of this kind is in DE 101 00390 A disclosed. It comprises a nozzle module which has a valve control piston which cooperates with a nozzle needle and a valve control chamber delimited by a spring plate and an end face of the valve control piston which communicates with a high-pressure feed line via an inlet channel and which is actuated via a discharge channel with a piezoelectric actuator unit Valve-shaped valve control module is in operative connection. The valve control module has a arranged in a valve chamber and cooperating with two valve seats valve closing member, wherein the nozzle needle is opened via a caused by the valve control module pressure reduction in the valve control chamber via the flow channel and is closed by a filling of the valve control chamber. In order to achieve a quick closing of the nozzle needle, the injection valve has means for filling the valve control chamber via the inlet channel and the outlet channel.

This object is achieved by means of a fuel injection valve, which has the features of patent claim 1.

Particularly preferred embodiments of the fuel injection valve according to the invention are specified in the dependent claims.

When the pilot valve of a fuel injection valve according to the invention is opened, fuel flows into a relief space, from which it can only continue to flow to a low-pressure outlet through a throttle passage. Minimization of fuel loss through the low pressure outlet during the injection process is achieved. The throttle passage may be formed by a sliding fit for the pilot valve pin, but preferably the pilot valve pin is guided in a tight sliding fit and the relief space is connected to the low pressure outlet via a separately formed throttle passage. The behavior of the fuel injector upon opening, that is, at the beginning of an injection event, may be very similar to that of known fuel injectors in which the exhaust port is provided with a throttle restriction. In order to terminate an injection process, however, in a fuel injection valve according to the invention, the pilot valve pin is moved into the discharge chamber at high speed until it bears against the pilot valve seat. Since the throttle passage prevents rapid escape of the fuel from the discharge space, the said movement of the pilot valve pin and the associated displacement of fuel is followed by a very rapid increase in pressure in the discharge space and in a discharge space adjoining the latter upstream of the pilot valve seat, which results in a very rapid closing movement of the Injector valve member causes. This closing movement can be further supported be used that the movement of the pilot valve pin is mechanically utilized.

Fig. 1

im Längsschnitt eine erste Ausbildungsform eines erfindungsgemässen Brennstoffeinspritzventils, bei welchem ein Entlastungsraum an einer Haltemutter ausgebildet ist;

Fig. 2

ebenfalls im Längsschnitt einen Ausschnitt des in Fig. 1 gezeigten Brennstoffeinspritzventils vergrössert;

Fig. 3

in gleicher Darstellung wie Fig. 2, einen Ausschnitt aus einer zweiten Ausbildungsform eines erfindungsgemässen Brennstoffeinspritzventils mit einem zwei Drosselverengungen aufweisenden Drosseldurchlass im Pilotventilstift;

Fig. 4

in gleicher Darstellung wie Fig. 2, einen Ausschnitt aus einer dritten Ausbildungsform eines erfindungsgemässen Brennstoffeinspritzventils, bei welchem der Entlastungsraum vollständig in einem Abflussraumkörper angeordnet ist, an welchem auch der Pilotventilstift gelagert ist;

Fig. 5

in gleicher Darstellung wie Fig. 2, einen Ausschnitt aus einer vierten Ausführungsform des erfindungsgemässen Brennstoffeinspritzventils, ähnlich jener gemäss Fig. 3, mit jedoch nur einer einzigen Drosselverengung im Drosseldurchlass;

Fig. 6

in gleicher Darstellung wie Fig. 2, einen Ausschnitt eines nicht erfindungsgemässen Brennstoffeinspritzventils mit einem Schieberventil, wie es beispielsweise in EP-A-1 273 791 oder der PCT-Patentanmeldung PCT/CH/03/0005 offenbart ist;

Fig. 7

in gleicher Darstellung wie Fig. 2, einen Ausschnitt eines nicht erfindungsgemässen Brennstoffein spritzventils mit einem Blattfederventil, ähnlich wie aus der EP-A-1 273 791 bekannt;

Fig. 8

in gleicher Darstellung wie Fig. 2, einen Ausschnitt aus einer fünften Ausführungsform des erfindungsgemässen Brennstoffeinspritzventils, bei welcher ein Steuerkörper pilzartig ausgebildet und im Einspritzventilglied verschiebbar gelagert ist; und

Fig. 9

in gleicher Darstellung wie Fig. 2, einen Ausschnitt aus einer sechsten Ausführungsform des erfindungsgemässen Brennstoffeinspritzventils, bei welcher ein Übertragungsstift die Bewegung des Pilotventilstiftes an einen Steuerkörper überträgt.

The invention will be explained in more detail with reference to embodiments shown in the drawing. It shows purely schematically:

Fig. 1

in longitudinal section a first embodiment of a fuel injection valve according to the invention, in which a relief space is formed on a retaining nut;

Fig. 2

also in longitudinal section a section of the in Fig. 1 shown enlarged fuel injection valve;

Fig. 3

in the same representation as Fig. 2 , A section of a second embodiment of a fuel injection valve according to the invention with a throttle restriction having throttle passage in the pilot valve pin;

Fig. 4

in the same representation as Fig. 2 a section of a third embodiment of a fuel injection valve according to the invention, in which the discharge chamber is arranged completely in a discharge chamber body, on which also the pilot valve pin is mounted;

Fig. 5

in the same representation as Fig. 2 , a section of a fourth embodiment of the inventive fuel injection valve, similar to that according to Fig. 3 but with only a single throttle restriction in the throttle passage;

Fig. 6

in the same representation as Fig. 2 , A section of a non-inventive fuel injection valve with a slide valve, as for example in EP-A-1 273 791 or the PCT patent application PCT / CH / 03/0005 is disclosed;

Fig. 7

in the same representation as Fig. 2 , A section of a non-inventive Kraftstoffein injection valve with a leaf spring valve, similar to that of EP-A-1 273 791 known;

Fig. 8

in the same representation as Fig. 2 , A section of a fifth embodiment of the inventive fuel injection valve, in which a control body is formed like a mushroom and slidably mounted in the injection valve member; and

Fig. 9

in the same representation as Fig. 2 , A section of a sixth embodiment of the inventive fuel injection valve, in which a transmission pin transmits the movement of the pilot valve pin to a control body.

Fig. 1 shows in longitudinal section an inventive fuel injection valve 10 having a substantially cylindrical, a lateral high-pressure inlet 12 having valve housing 14. This has a running in the direction of the longitudinal axis 16, continuous, stepped bore 17, in which an electric controlled actuator 18, a controlled by this control device 20 and a needle-shaped injection valve member 22 are arranged with a closing spring 24. The injection valve member 22 is held by means of the closing spring 24 to an injection valve seat 26 in abutment, which is formed on an injection valve seat body 28. This is substantially rotationally symmetrical to the longitudinal axis 16, is located on the front side of the valve housing 14 and is held by a cap nut 30 sealingly on the valve housing 14. In the end region of the exposed tip of the injection valve body 28 injection valve nozzles 32 are formed in a known manner, through which fuel is injected under very high pressure in a combustion chamber, not shown, of an internal combustion engine, when the injection valve member 22 by means of the actuated by the actuator 18 hydraulic control device 20 in the direction the longitudinal axis 16 is lifted from the injection valve seat 26. The injection valve seat 26 delimits a high-pressure space 34 in which the injection valve member 22 is arranged and which, on the other hand, is delimited by the control device 20 and peripherally by the injection valve seat body 28 and valve housing 14. The high-pressure chamber 34 is connected to the high-pressure inlet 12, through which fuel is supplied under very high pressure of up to 1000 bar or even 1800 bar or more to the high-pressure chamber 34 for injection into the combustion chamber of the internal combustion engine and for controlling the injection valve member 22.

The injection valve member 22 delimits, with its end region facing away from the injection valve seat 26, a control chamber 36, on the other hand, from a control body 38 is limited, in which concentric to the longitudinal axis 16 is formed with a throttle restriction 40 'Auslaßdurchlass 40 is formed; see in particular also Fig. 2 , which a section of the fuel injection valve 10 of Fig. 1 with the control device 20 shows enlarged. With its end face 42 facing away from the control chamber 36, the control body 38, with the assistance of a compression spring 44 which is supported on the control body 38 and on the injection valve member 22, seals against a face 46 'of a mushroom-shaped discharge space body 46 facing it. In the discharge space body 46, a discharge space 48 is formed by a longitudinal bore 16 coaxial longitudinal bore, without throttling constriction - which is aligned with the outlet passage 40 and with this flow directly connected.

The substantially circular cylindrical control body 38 is slidably mounted with a radial play of about 0.02 mm to 0.1 mm or 0.2 mm in a control sleeve 50 in the direction of the longitudinal axis 16 and forms a valve member together with the discharge chamber body 46, whose end face 46 'acts as a valve seat, an intermediate valve 52. The control sleeve 50, at whose the injection valve seat 26 facing the end of the closing spring 24 is supported, is held by the force of this closing spring 24 on Abflussraumkörper 46 in sealing engagement. At the control chamber 36 circumferentially limiting control sleeve 50, the injection valve member 22 is guided in close sliding fit with a game of about 2 microns to 10 microns.

The mushroom-shaped discharge space body 46 is sealingly against a by a, in an internal thread on the valve housing 14 einindeten retaining nut 54 with its hat part against a Ablageschulter 56 of the valve housing 14 pressed. Furthermore, the retaining nut 54 and the drainage space body 46 lie flat against one another in a sealing manner. In the stem part of the mushroom-shaped discharge chamber body 46, distributed in the circumferential direction, at least 2 high-pressure channels 58 are formed, on the one hand with a valve housing 14, the stem and the head portion of Abflussraumkörpers 46 and the control sleeve 50 limited annular space 60 in fluid communication and the other on the other the valve seat of the intermediate valve 52 forming end face 46 'open. The annular space 60 is connected to the high-pressure chamber 34 and thus to the high-pressure inlet 12 by a longitudinal groove 62, which extends in the axial direction and is integrally formed on the radially outer side of the control sleeve 50. The high pressure channels 58 may, as in Fig. 1 and Fig. 2 shown to the right of the longitudinal axis 16, by oblique holes in the discharge chamber body 46 or, as in Fig. 2 shown to the left of the longitudinal axis 16, be generated by angular holes.

The mouth openings of the high-pressure channels 58 on the front side 46 'are closed by the control body 38 when it rests against the drainage space body 46. In order to improve the sealing effect of the intermediate valve 52 by increasing the surface pressure, can, as Fig. 2 a recess 64 may be formed on the drainage space body 46, which ensures that the contact surface extends as a relatively narrow band-shaped area along the outer circumference of the control body 38 and around the mouths of the high-pressure channels 58. Of course, corresponding recesses may be formed on the control body 38.

On the retaining nut 54 is concentric with the longitudinal axis 16, a pilot valve pin 66 slidably mounted in close sliding fit of about 2 microns to 10 microns in the direction of the longitudinal axis 16. In his in the FIGS. 1 and 2 The drainage space body 46 forms an annular pilot valve seat 68, which forms a pilot valve 70 together with the pilot valve pin 66 as a valve member around the mouth side opening of the drainage space 48. The pilot valve seat 68 is designed as a flat seat.

An annular relief chamber 72 directly adjoins the pilot valve seat 68 on the low-pressure side, which is formed on the retaining nut 54 serving as a relief space body as a recess running around the pilot valve pin 66. This otherwise closed relief space 72 is permanently connected via a throttle passage 74 to a low-pressure outlet 76 of the valve housing 14. Fuel flowing out through the low-pressure outlet 76 is returned to a fuel storage container in a known manner.

In Fig. 2 is shown in solid lines that the throttle passage 74 as an oblique bore in the pilot valve pin 66 or, as indicated by dashed lines, may be formed on the retaining nut 54. The diameter of the throttle body 74 'of the otherwise larger diameter throttle passage 74 is for example about ten times smaller than the diameter of the pilot valve pin 66 and about five times smaller than the clear diameter of the discharge space 48. However, these ratios may be different. From Another advantage is that the pilot valve pin 66, when lifted from the pilot valve seat 68, very quickly releases a substantially larger flow cross-section than it is defined by the throttle point 74 '.

The pilot valve pin 66 is held in abutment with the pilot valve seat 68 by means of the actuator 18. In this case, an actuator shaft 78 lies with its ball-shaped end on the pilot valve seat 68 facing away from the end face of the pilot valve pin 66 at this. Preferably, the actuator 18 is a piezoelectric or magnetostrictive actuator. Such actuators 18 allow only a relatively small stroke of the Aktuatorschafts 78 and thus the pilot valve pin 66, for example, 0.03 mm. However, they have the advantage that they move the pilot valve pin 66 with great speed and great force.

The actuator 18 is arranged in an actuator housing 80, which projects into the valve housing 14 and is fastened thereto by means of a fastening screw 82.

The clearance between the control body 38 and the control sleeve 50 ensures that through this clearance and the outlet passage 40 the control chamber 36 is filled with fuel very quickly as soon as - to terminate an injection process by closing the pilot valve 70 - the control body 38 is out of its installation is moved away from the drainage space body 46.

With "H" is in FIG. 1 the maximum stroke of the injection valve member 22 is indicated, which it perform between the one hand of the system at the injection valve seat 26 and on the other hand, the concerns of the control body 38 can. However, the possible stroke of the control body 38 is preferably lower; a Hubbegrenzungsschulter 84 on the control sleeve 50 limits the maximum possible distance between Abflussraumkörper 46 and control body 38 to, for example, about 0.05 - 0.2 mm or 0.02 - 0.2 mm.

On the side facing away from the control sleeve 50, the closing spring 24 bears against an intermediate disk 86, which in turn bears against a support disk 86 'which is supported on a shoulder of the injection valve member 22. The intermediate disc 86 is replaceable in order to tune the behavior of the Brennstöffeinspritzventils 10 by selecting the desired thickness.

By means of the injection valve member 22 formed, star-like projecting guide ribs 88 this is slidably mounted on the injection valve body 28, wherein the inflow of the fuel to the injection valve seat 26 is ensured.

In the FIGS. 3 to 6 are used for the training according to FIGS. 1 and 2 corresponding parts use the same reference numerals as in FIG. 1 and FIG. 2 , In the following, only the differences between the embodiment shown in the relevant figure and those according to the FIGS. 1 and 2 explained.

When in the Fig. 3 shown embodiment, only a single high-pressure channel 58 is provided which is formed as an angular bore and coaxial with the longitudinal axis 16 from the discharge chamber body 46 opens. On the other hand, the high-pressure passage 58 opens, as in the in the Fig. 2 and 3 shown embodiment, in the annular space 60, which is connected to the high-pressure chamber 34. The recess 64 in the drainage space body 46 is annular formed so that radially inside a running around the mouth of the high-pressure passage 58 sealing surface and radially outside an annular sealing surface for cooperation with the control body 38 remains.

Subsequent to the throttle restriction 40 'formed coaxially with the longitudinal axis 16 on the control body 38, the outlet passage 40 extends obliquely with respect to the longitudinal axis 16 so that it opens into the annular space formed by the recess 64. Correspondingly, the discharge space 48 is formed by a bore oblique with respect to the longitudinal axis 16 through the discharge space body 46, the discharge space 48 opening into the recess 64 on the one hand and the mouth of the discharge space 48 being arranged on the side of the pilot valve 70 centric to the longitudinal axis 16.

The pilot valve pin 76 is in turn in the retaining nut 54, in which the discharge chamber 72 is excluded, mounted in close sliding fit. The throttle passage 74 is formed on the pilot valve pin 66 by a blind hole from the actuator side, which - instead of a single throttle 94 '- by means of a radial first throttle bore 90 with the relief space 72 and a radial second throttle bore 90' with the low pressure outlet 76 in Flow connection is. The diameter of these two throttle bores 90, 90 ', in comparison to the single throttle restriction 74' in the throttle passage 74 according to FIG. 1 and 2 , are slightly larger and therefore somewhat inaccurate, in order to achieve a corresponding throttle effect. The cooperating with the pilot valve pin 66 end face of Aktuatorschafts 78 is flat to To seal the blind hole in the pilot valve pin 68.

Also in the in the Fig. 3 shown embodiment, it is recommended to use an electrically driven piezoelectric or magnetostrictive actuator 18; such actuators 18 have about 3 to 8 times faster performance than known electromagnets. However, it is also conceivable to use electromagnets as actuator 18 for fuel injection valves 10 according to the present invention. In this case, it is recommended that the drainage chamber 48 by means of a Drosselzulasses 92 - as well as in Fig. 8 shown - to connect to the high-pressure chamber 34. Such a throttle admission 92 accelerates the closing movement of the injection valve member 22 to terminate the injection process.

When in the Fig. 4 shown embodiment, the control body 38 is similar to that according to Fig. 2 however, the throttle restriction 40 'of the outlet passage 40 is located in the end region facing the outflow chamber 48.

The otherwise circular-cylindrical outlet passage 40 has in its control-chamber-side end region a conical shape, in which the counter-shaped end portion of the injection valve member 22 engages when the injection valve member 22 is in the maximum open position. This leads to a very good sealing of the outlet passage 40 and contributes at the end of the injection process a very rapid lifting of the control body 38 from the injection valve body 28 and thus a very fast closing movement of the injection valve member 22 at.

Next are in Fig. 4 , left or right of the longitudinal axis 16, two other possible embodiments for the high-pressure passage 58 shown. These are formed by bores in the discharge space body 46, which extend obliquely to the longitudinal axis 16 and communicate with the annular space 60, and by bores, which are in flow communication with the former and parallel or oblique to the longitudinal axis 16, but in that region on the front side 46 'open, which acts as a valve seat of the intermediate valve 52.

In this embodiment, the drainage space body 46 is no longer mushroom-shaped but pill-shaped and pressed by means of the retaining nut 54 in sealing contact with the contact shoulder 56 of the valve housing 14. Further, the relief space 72 is disposed in the interior of the drain chamber body 46, on which also the pilot valve pin 66 is guided in close sliding fit. In this case, the drainage space body 46 also serves as a relief space body. The sealing of the high-pressure chamber 34 with respect to the low-pressure outlet 76 thus takes place by the sealing abutment of the discharge space body 46 on the abutment shoulder 56. In addition to the valve seats, only these two interacting surfaces have to be designed with high precision, in contrast to the embodiments according to FIGS Figures 1 - 3 where also the abutting end faces of the discharge chamber body 46 and the retaining nut 54 are to be formed as sealing surfaces.

When in the Fig. 4 training form shown is the pilot valve seat 68 and, thereafter, the relief chamber 72 by a conical extension - seen from the control body 38 forth - the drainage chamber 48 forming hole formed. Corresponding to the same the cooperating with the pilot valve seat 68 part of the pilot valve pin 66 is formed conically. The relief space 72 in turn extends as an annular space around the pilot valve pin 66 around and the throttle passage 74 is formed as with respect to the longitudinal axis 16 oblique bore in the pilot valve pin 66, but now - in contrast to the embodiment according to the FIGS. 1 and 2 - Throttle throat 74 'is located in the low pressure outlet 76 facing end portion of the throttle passage 44. Hydraulically, therefore, the volume of the throttle passage 74 upstream of the throttle restriction 74 'is part of the relief space 72.

In this case, the retaining nut 54 is formed to tighten with a hexagon socket, which at the same time surrounds the pilot valve pin 66 at a distance to form the flow connection between the throttle passage 74 and the low-pressure outlet 76.

Fig. 5 shows one of the Fig. 3 very similar form of training, the drainage space body 46 is no longer mushroom but pills shaped. As in the form of training according to Fig. 3 The annular space 60 extends around the overhead end region of the control sleeve 50. The high-pressure channel 58 is formed by two bores running obliquely with respect to one another and with respect to the longitudinal axis 16. The one opens to the annular space 60 and the other in the middle of the end face 46 'of the discharge space body 46. Next is - in contrast to the embodiment according to Fig. 3 - The throttle restriction 40 'of the outlet passage 40 at the recess 64, which is integrally formed on the control body 38.

At the in Fig. 6 shown non-inventive fuel injection valve 10 is the Outflow chamber 46 formed pills and centrally has the run-off in the axial direction of the drain chamber 48 but no high-pressure channel 58 on. With the drain space body 46, the pilot valve pin 66 cooperates, which as in Fig. 1 and Fig. 2 is shown formed.

The control body 38 is guided in the manner of a slide valve body in the control sleeve 50 in close sliding fit of about 2 microns to 10 microns. The annular space 60 which is recessed radially on the inside of the control sleeve 50 extends around its end region facing the discharge space body 46 and is connected to the high-pressure space 34 via a radial passage and the longitudinal groove 62. Concentric with the longitudinal axis 16 extends through the control body 38 through the outlet passage 40 with its throttle restriction 40 'at the control chamber 36 end facing. Parallel thereto, but offset radially with respect to the longitudinal axis 16, extends through the control body 38 through a connecting channel 94, which is closed when abflussraumkörper 46 Abflussraumkörper control body 38. If the control body 38 does not abut on the discharge space body 46, the connection channel 94 connects the control space 36 to the high-pressure space 34. Functionally, the connection channel 94 has the same function as in the embodiments shown above, the radial clearance between the control body 38 and the control sleeve 50th Next are on the control body 38, formed on the end face 42, inner and outer recesses 64, which serve to form the surface with which the control body 38 sealingly against the discharge chamber body 46, small in order to achieve a high surface pressure. Further, by a more or less large radially outer recess 64 the dynamic behavior of the control body 38 relative to lift-off from the installation on the discharge room body 46 can be varied.

Fig. 7 shows a non-inventive fuel injection valve 10, wherein the control body 38 is replaced by a leaf spring 96. The leaf spring 96 is similar to that of EP-A-1 273 791 formed known leaf spring. From a disc of spring steel, a C- or U-shaped slot is excluded, which separates a radially inner leaf spring tongue 98 of a retaining ring 100. The leaf spring 96 is held clamped with its retaining ring 100 between the control sleeve 50 and the drain chamber body 46. For radial alignment of the retaining ring 100 and the control sleeve 50 are jointly encompassed by a centering ring 102. Of course, centering pins could also be used instead of the centering ring 102 or the centering ring 102 could be formed on the control sleeve 50. Next, the throttle restriction 40 'is formed on the leaf spring tongue 98, kozentrisch to the longitudinal axis 16 as a through hole. The leaf spring tongue 98 closes when it concerns the discharge chamber body 46 both from the high-pressure passage 58 formed therein and from the discharge space 48 extending centrally with respect to the longitudinal axis 16. When lifted from the Entüllungsraumkörper 46 leaf spring tongue 98 of the high-pressure chamber 34 and, with a larger flow cross-section than the throttle restriction 40 ', the discharge chamber 48 with the control chamber 36 fluidly connected. On the leaf spring 96, a throttle admission 92 may be excluded, which connects the high-pressure chamber 34 with the discharge chamber 48. The effect of this throttle admission 92 is the same as that of the throttle passage 92 of the embodiments according to Fig. 3 and 8th , namely In particular, when using an electromagnetic actuator 18 to support the rapid closing of the injection valve member for the completion of the injection process.

When in the Fig. 8 shown drainage chamber body 46, the retaining nut 54 with the relief space 72 and the pilot valve pin 66 with the first and second throttle bore 90, 90 ', and the actuator 18 with its actuator shaft 78 are formed the same as in the embodiment according to the Fig. 3 , However, the control body 38 is now mushroom-shaped and its trunk is slidably guided in a blind hole-like recess of the injection valve member 22 in the direction of the longitudinal axis 16. The compression spring 44 is supported on the one hand at the bottom of this blind hole and on the other hand on the trunk of the control body 38. The control sleeve 50 limits the control chamber 36, engages around the hat of the control body 38 with a radial distance and lies with its end face sealingly against the end face 46 'of the discharge space body 46. At the hat of the mushroom-shaped control body 38, the throttle restriction 40 'is formed. It communicates with the annular recess 64 on the discharge chamber body 46 and thus communicates with the discharge space 48 in fluid communication. For completeness, it should be added that between the stem of the mushroom-shaped control body 38 and the injection valve member 22, a radial clearance is present to achieve a rapid pressure equalization between the control chamber 36 and the space in which the compression spring 44 is arranged.

All in the Figures 1 - 8 shown fuel injectors 10 operate after the same Principle. In the operating state shown in all the figures, the injection valve formed by the injection valve member 22 and injection valve seat 26, the intermediate valve 52 formed by the control body 38 and the leaf spring 96 and the discharge chamber body 46, respectively, and the pilot valve 70 formed by the pilot valve pin 66 and the mushroom valve seat 68 are in the closed position. In the control chamber 36, outlet passage 40 and discharge chamber 48, the fuel is under high pressure.

To initiate an injection process, the actuator 18 pulls the actuator shaft 78 in the axial direction upwards, that is, in the direction away from the pilot valve seat 68. Since there is high pressure in the discharge space 48, the pilot valve pin .66 is lifted off the pilot valve seat 68 in accordance with the movement of the actuator shaft 78. This leads to a very rapid increase in pressure in the relief space 72 and a correspondingly rapid pressure reduction in the discharge space 48 and in the outlet passage 40 downstream of the throttle restriction 40 '. From the discharge space 72, the fuel flows through the throttle passage 74 attenuated to the low-pressure outlet 76. The throttle restriction 40 'attenuates the flow of fuel out of the control chamber 36. This leads to a pressure reduction in the control chamber 36, whereby the injection valve member 22 in a known manner is lifted from the injection valve seat 26.

To end the injection process, the pilot valve pin 66 is moved very quickly by means of the actuator 18 down into abutment with the pilot valve pin 66, thereby closing the pilot valve 70. Since the pilot valve seat 68 very quickly dives deeper into the relief space 72, an increase in pressure generated, which propagates through the drainage chamber 48 and leads to the lifting of the control body 38, or the leaf spring tongue 98, from the drain chamber body 46, since a rapid pressure equalization in the control chamber 36 due to the throttle restriction 40 'can not be done. By lifting off the control body 38 immediately the entire end face 42 of the control body 38 is acted upon by fuel under high pressure, since the high pressure passage 58 and the high pressure passages 58 are released. This leads to a very rapid movement of the control body 38 away from the drain body 46 and to a rapid pressure increase in the control chamber 36, causing a quick closing movement of the injection valve member 22 to terminate the injection process. With the help of the force of the compression spring 44 or the spring force of the leaf spring tongue 98, the control body 38 or the leaf spring tongue 98 again engages the injection valve seat body 28. So that this movement is not retarded too much, fuel through the throttle restriction 40 'and relatively quickly through the radial gap between the control body 38 and the control sleeve 50 and through the connecting channel 94, and in the embodiment according to Fig. 7 through the gap between the leaf spring tongue 98 and retaining ring 100, flow into the control chamber 36. After which the initial state described at the beginning of the functional description is reached again.

Although the fuel injection valve 10 according to the invention comprises a pilot valve 70, the fuel losses caused thereby are small since, during the period in which the pilot valve 70 is open, in the embodiment according to FIGS Fig, 1 . 2 . 4 . 5 and 6 no hydraulic connection between the drainage chamber 48 and the high-pressure chamber 34 is made. In the embodiments according to the Fig. 3 . 7 and 8th a throttle passage 92 is present; however, because of the very small cross-section, the throttle passage 92 prevents rapid outflow of a larger amount of fuel.

The faster the pilot valve pin 66 is moved to close the pilot valve 70, the faster a pressure increase and thus a very rapid closing of the injector. This rapid and large pressure increase has a retroactive effect on the actuator 18. Piezoelectric and magnetostrictive actuators are therefore particularly suitable for fuel injectors 10 according to the invention because they can apply very large forces, so that said pressure increase practically does not delay the movement of the pilot valve pin 66. Although the aforementioned actuators 18 have a faster switching behavior than electromagnets, such can be used. By designing the diameter and the stroke of the pilot valve pin 66 thus the desired pressure increase can be achieved.

In the Fig. 9 shown embodiment has, in addition to those in the context of the embodiments according to Fig. 1 to 8 shown benefits, increased ability for multiple injections in very short time intervals. For equivalent parts are in the description too Fig. 9 the same reference numerals as used in connection with the Fig. 1 to 8 ,

In the retaining nut 54, the pilot valve pin 66 is guided in close sliding fit. The discharge space 72 is formed by a recess on the retaining nut 54 and it is through the throttle body 74 'and the throttle passage 74 in the retaining nut 54 permanently connected to the low-pressure chamber, in the same manner as in the Fig. 2 indicated by dashed lines.

On the front side of the retaining nut 54 of the pill-shaped drainage chamber body 46 is sealingly. It has an axial passage centrally, which forms the discharge space 48. In the same way as in connection with the Fig. 1 to 3 and 5 to 8 The pilot valve pin 66 and the pilot valve seat 68 form the pilot valve 70 controlled by an actuator 18, which in the closed state separates the discharge chamber 48 from the discharge chamber 72 ,

The discharge space 48 is formed by a central bore which widens in the direction of the control body 38 in a funnel shape. This discharge space 48 is penetrated by a transfer pin 104 whose diameter is smaller than the diameter of the cylindrical portion of the discharge space 48 and whose length is greater than the measured in the direction of the longitudinal axis 16 thickness of Abflussraumkörpers 46. When the pilot valve 70 is closed thus the transfer pin 104 via the drainage space body 46 on the side facing away from the retaining nut 54 and the control body 38 side facing.

Furthermore, the high-pressure channel 58 is formed on the drainage space body 46, which is formed by a radial blind bore and one of the end face 46 'of the drainage space body 46 in FIG axial direction in the blind hole leading through hole is formed. The high-pressure passage 58 opens at the end face 46 'at a distance from the discharge space 48, so that the control body 38, when resting against the end face 46', closes the mouth of the high-pressure passage 58. The discharge space body 46 forms with its end face 46 'and the control body 38, in turn, an intermediate valve 52nd

On the end face 46 'of the discharge chamber body 46 is sealingly an intermediate body 50' in the central passage of the control body 38 in the direction of the longitudinal axis 16 is slidably disposed. Between the control body 48 and the intermediate body 50 ', an annular gap is present. The intermediate body 50 'is cup-shaped, wherein the bottom of the discharge chamber body 46 faces, and in the interior of the control body 38 is a compression spring 44 which holds the control body 38 - with open pilot valve 70 - with the bottom of the transfer pin 104 in abutment. Through the bottom of the control body 38 passes through the outlet passage 40, which is formed without throttle restriction 40 'and communicates with at the end face 46' fitting control body 38 with the discharge chamber 48. If the control body 38 is located on the front side 46 ', it closes the mouth of the high-pressure channel 58.

With the pilot valve 70 closed, as in the Fig. 9 As shown, the bottom of the control body 38 is at a distance from the end face 46 'which is given by the difference in length between the transmission pin 104 and the thickness of the discharge space body 46. The stroke of the pilot valve pin. 66 is at least as large, but preferably greater than this distance.

The compression spring 44 is supported with its end facing away from the bottom of the control body 38 at an end face of a control chamber body 50 '' from which sealingly bears with its end face on the intermediate body 50 '. The control chamber body 50 '' circumferentially bounded the control chamber 36, which is also bounded by the injection valve member 22, which is guided on the control chamber body 50 '' in close sliding fit. The injection valve member 22 is desaxsiert with respect to the common longitudinal axis 16. However, the control space 36 is continuously throttled in flow communication with the interior of the cup-shaped control body 38 and the drainage space 48.

In a well-known manner, the control chamber body 50 "and the retaining nut 54 are clamped against each other so that the retaining nut 54 on Abflussraumkörper 46, this on the other hand on the intermediate body 50 ', and this in turn on the other hand control chamber body 50' 'sealingly. The intermediate body 50 'and control chamber body 50 "may be integrally formed in one piece, similar to the control sleeve 50. It is also conceivable to form the control chamber body 50" in one piece together with the injection valve seat body 28 or the valve housing 14.

In Abflussraumkörper 46 may be an open towards the end 46 'annular groove 106 may be formed, in which the high pressure channel 58 opens and which is closed at the front side 46' abutting control body 38 of this.

It is also conceivable, the control body 38, viewed in the direction of the longitudinal axis 16, shorter form, so that the shell portion of the cup protrudes only slightly above the bottom of the control body 38 to the end of the Comprise compression spring 44. In a particularly space-saving in the axial direction training form of the control body 38 is formed as a disc with an outlet passage 40 and the spring formed as a compression spring 44 replaced by a plate spring or wave spring.

A coaxial arrangement of the injection valve member 22 with the longitudinal axis 16 is conceivable, wherein the compression spring 44 is supported for example on the end face of the control chamber body 50 '' or on a supporting shoulder formed thereon.

I'm in the Fig. 9 As shown, an annular gap exists between the transfer pin 104 and the drain chamber body 46. However, it is also conceivable to mount the transfer pin 104 in a sliding fit on the discharge space body 46 and to make grinding on the transfer pin 104 in order to ensure the flow connection between the discharge space 48 and the discharge space 72 with the pilot valve 70 open.

Finally, it should be mentioned that the pilot valve pin 66 may have a shoulder cooperating with the retaining nut 54 to limit the stroke of the pilot valve pin 66 in the opening direction of the pilot valve 70.

That in the Fig. 9 shown fuel injector 10 operates as follows. In the starting position shown, the pilot valve 70 is closed. The control body 38 is lifted off the front side 46 'of the discharge space body 46, whereby the discharge space 48 and the control space 46 are connected to the high-pressure inlet 12 via the high-pressure passage 58. The injection valve member 22 is in contact with the injection valve seat 26 in the closed position; see also Fig. 1 , To initiate an injection event, the actuator 18 retracts the actuator shaft 78, thereby moving the pilot valve pin 66 away from the pilot valve seat 68 and connecting the drain chamber 48 and thus the control chamber 36 to the discharge chamber 72. The extremely fast movement of the pilot valve pin 66 follows the transmission pin 104 and the control body 38, with the result that the intermediate valve 52 is closed very quickly and a subsequent flow of fuel through the high-pressure passage 58 is prevented. The pressure drop in the control chamber 36 and thus a lifting of the injection valve member 22 from the injection valve seat 26 are made very quickly.

For the completion of the injection process, the pilot valve pin 66 is brought into contact with the pilot valve seat 68 by means of the actuator 18 in a known manner. In this case, the transmission pin 104 is moved in the direction against the control body 38 which inevitably lifts off the end face 46 '. In this case, the intermediate valve 52 opens and is formed by the high-pressure passage 58, a connection between the control chamber 36 and the high-pressure inlet 12. Further, this pressure increase is supported by the movement of the pilot valve pin 66 into the discharge chamber 72 inside. The injection valve member 22 is thus very quickly brought into abutment with the injection valve seat 26 whereby the injection process is completed.

Since the control body 38 moves with the transmission pin 104 and thus with the pilot valve pin 66, the high-pressure passage 58 is closed or opened very quickly by the control body 38, which results in several Injections in short to very short time intervals is of great advantage.

Claims (13)

1. Fuel injection valve for intermittent fuel injection into the combustion space of an internal combustion engine, with a valve housing (14) having a bore (17) running in the direction of its longitudinal axis (16), and with an injection valve seat (26) which delimits a high-pressure space (34) which is connected to a high-pressure inlet (12) of the valve housing (14) and is delimited, on the other hand, by a hydraulic control device (20), arranged in the bore (17) and controlled by an actuator, and circumferentially by the valve housing (14), and also with a needle-shaped injection valve member (22) arranged in the high-pressure space (34) and cooperating with the injection valve seat (26), the control device (20) having a control sleeve (50) which circumferentially separates a control space (36) sealingly from the high-pressure space (34) and in which the injection valve member (22) is guided in a close sliding fit with its end region facing away from the injection valve seat (26), so as to delimit the control space (36), the control sleeve (50) being held in sealing bearing contact against an outflow space body (46), a control body (38) which delimits the control space (36) being mounted in the control sleeve (50) so as to be displaceable in the axial direction with radial play, the radial play forming a flow connection between the high-pressure inlet (12) and the control space (36), and the control body (38) forming as a valve member, together with the outflow space body (46), the end face (46') of which serves as a valve seat, an intermediate valve (52) of the control device (20), in order to close releasably at least one high-pressure duct (58) running through the outflow space body (46).
2. Fuel injection valve according to Claim 1, characterized in that the outflow space body (46) has formed in it an outflow space (48) connected to the control space (36) and leading to a pilot valve seat (68) of a pilot valve (70).
3. Fuel injection valve according to Claim 2, characterized in that the control space (36) is flow-connected to the outflow space (48) via a throttle contraction (40') in the control body (38).
4. Fuel injection valve according to Claim 3, characterized in that the control body (38) has an outlet passage (40) which is equipped with the throttle contraction (40').
5. Fuel injection valve according to Claim 4, characterized in that the throttle contraction (40') of the outlet passage (40) is formed either in an end region located on the outflow space body side or in an end region located on the control space side, of the control body (38).
6. Fuel injection valve according to Claim 4 or 5, characterized in that the outlet passage (40) and the outflow space (48) are designed cylindrically, and their cylinder axes are oriented either both coaxially or both obliquely with respect to the longitudinal axis (16).
7. Fuel injection valve according to one of Claims 2 to 6, characterized by a throttle admission (92) which connects the outflow space (48) to the high-pressure inlet (12).
8. Fuel injection valve according to one of Claims 2 to 7, characterized in that a recess (64) is formed on the outflow space (48) of the outflow space body (46) on the control body side or on the outlet passage (40) of the control body (38) on the outflow space body side.
9. Fuel injection valve according to one of Claims 2 to 8, characterized in that, with the intermediate valve (52) open, the radial play of the control body (38) in the control sleeve (50) forms the flow connection between the high-pressure inlet (12) and the control space (36).
10. Fuel injection valve according to one of Claims 2 to 9, characterized in that the control sleeve (50) has a stroke limitation shoulder (84) for the control body (38).
11. Fuel injection valve according to one of Claims 2 to 10, characterized in that a compression spring (44) holds the control body (38) in bearing contact against the outflow space body (46) in a manner in which said control body is capable of being lifted off.
12. Fuel injection valve according to one of Claims 2 to 11, characterized in that the pilot valve (70) has a pilot valve pin (66) which cooperates, on the one hand, with an electrically activated actuator (18) and, on the other hand, with the pilot valve seat (68) and which, in the closing position, separates the control space (36) of the control device (20) from a low-pressure outlet (76), and in that the pilot valve seat (68) has adjoining it, on its side facing the low-pressure outlet (76), a closed relief space (72) which is permanently connected to the low-pressure outlet (76) by means of a throttle passage (74) and into which the pilot valve pin (66) projects.
13. Fuel injection valve according to Claim 12, characterized in that the pilot valve pin (66) is guided in the delimiting body (54) in a sliding fit, preferably in a close sliding fit.

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