EP1520097B1 - Device for damping the needle lift in fuel injectors - Google Patents

Description

Technical area

To supply combustion chambers of self-igniting internal combustion engines with fuel, both pressure-controlled and stroke-controlled injection systems can be used. As fuel injection systems come next pump-injector units, pump-line-nozzle units and storage injection systems are used. Store injection systems (common rail) allow advantageously to adjust the injection pressure to load and speed. In order to achieve high specific performance and to reduce the emissions of the internal combustion engine, the highest possible injection pressure is generally required.

State of the art

For reasons of strength, the achievable pressure level is currently limited to about 1600 bar in storage injection systems used today. To further increase the pressure on accumulator injection systems, common rail systems use pressure intensifiers.

Such a system according to the preamble of claim 1 starts from e.g. WO 01 / 14726A.

EP 0 562 046 B1 discloses a control and valve arrangement with damping for an electronically controlled injection unit. The actuation and valve assembly for a hydraulic unit comprises an electrically energizable electromagnet having a fixed stator and a movable armature. The anchor has a first and a second surface. The first and second surfaces of the armature define first and second cavities, with the first surface of the armature facing the stator. It is provided a valve which is connected to the armature. The valve is capable of delivering a hydraulic actuating fluid to the injector from a sump. A damping fluid may be collected therefrom with respect to one of the cavities of the solenoid assembly. By means of a projecting into a central bore portion of a valve, the flow connection of the damping fluid can be selectively released or closed proportional to its viscosity.

DE 101 23 910.6 relates to a fuel injection device. This is used on an internal combustion engine. The combustion chambers of the internal combustion engine are supplied with fuel via fuel injectors. The fuel injectors are acted upon by a high pressure source; Furthermore, the fuel injection device according to DE 101 23 910.6 comprises a pressure booster, which has a movable pressure booster piston, which separates a connectable to the high-pressure source chamber from a high-pressure chamber connected to the fuel injector. The fuel pressure in the high pressure chamber can be varied by filling a back space of the pressure booster with fuel or by emptying this back space of fuel.

The fuel injector comprises a movable closing piston for opening or closing the injection openings facing the combustion chamber. The closing piston protrudes into a closing pressure chamber so that it can be pressurized with fuel. This achieves a force acting on the closing piston in the closing direction. The closing pressure chamber and another space are formed by a common working space, wherein all portions of the working space are permanently connected to each other for the exchange of fuel.

With this solution can be achieved by controlling the pressure booster on the back space that the drive losses in the high-pressure fuel system compared to a control of a temporarily connected to the high-pressure fuel source working space can be kept low. Furthermore, the high-pressure chamber is relieved only up to the pressure level of the high pressure accumulator and not up to leak pressure level. This improves on the one hand the hydraulic efficiency, on the other hand, a faster pressure build-up can take place up to the system pressure level, so that the lying between the injection phases temporal distances can be shortened.

In pressure-controlled common-rail injection systems with pressure booster the problem arises that the stability of injected into the combustion chamber injection quantities, especially the representation of very small injection quantities, as required for example in the pilot injection, is not guaranteed. This is primarily due to the fact that the nozzle needle opens very quickly in pressure-controlled injection systems. Therefore, very small variations in the driving time of the control valve can greatly affect the injection quantity. Attempts have been made to remedy this problem by using a separate needle stroke damper piston, which defines a damping space and must be guided in a high-pressure tight clearance fit. Although this solution allows a reduction in the needle opening speed, on the other hand, the design effort and thus the cost of the injection system is greatly increased by this solution.

In view of further increasing demands on the emission and noise development of self-igniting internal combustion engines, further measures on the injection system are required in order to meet the more stringent limit values expected in the near future.

Presentation of the invention

With the proposed solution according to the invention, the use of a precision component, as mentioned above, such as a Nadelhubdämpferkolbens be avoided by the function of Nadelhubdämpfung is represented by a flow through the Düsenadelfelfraumraumes. On the one hand, the production-related expense can be significantly reduced with the proposed solution; on the other hand, the small-quantity capability of the fuel injector is considerably improved by a reduction in the needle opening speed. A separate precision component in the form of a Nadelhubdämpferkolbens is not required. Instead, the nozzle spring chamber of the nozzle needle is filled or relieved of pressure via an inlet throttle from the high-pressure side and an outlet throttle on the low-pressure side or at the working space.

By dimensioning the flow cross sections and the throttle section lengths of inlet and outlet throttle, the needle opening speed can be adjusted. The closing speed of the nozzle needle is determined essentially by the cross-sectional area of the outlet throttle. Thus, it is in principle possible to set the opening and closing speed of the nozzle needle independently by way of dimensioning of inlet and outlet throttle and thus to achieve a slow opening of the injection valve member, for example a nozzle needle, and on the other hand, a fast closing of the injection valve member of the fuel injector , A quick closing of the injection valve member of a fuel injector enables an improvement of the emission values of a self-igniting internal combustion engine. A rapid closing of the injection valve member ensures that a well-defined end time of the injection can be maintained, so that after this injection of fuel into the combustion chamber is omitted, which can not be implemented during combustion and is contained as unburned fuel in the exhaust gas and its HC content extremely negatively affected.

In addition, providing fast needle closing provides the ability to keep the quantitative characteristic in the ballistic operating condition of the nozzle, ie during movement between its stroke stops or injection valve member seat, which greatly improves the metering accuracy of fuel.

Due to the proposed concept of a Hubdämpfung without additional moving components, only by the flow, inertia influences play as when using an additional precision component irrelevant, so that tightly consecutive multiple injection processes are performed, since no reset times of mechanical components with respect to the time intervals of the injection phases are taken into account , To ensure that no high Absteuermengen occur, which flow through inlet and outlet throttle and negatively affect the hydraulic efficiency, the injection valve member can fully close the inlet throttle when reaching the maximum stroke in an advantageous manner. Thus, only during the short opening phase of the injection valve member, a leakage current flows through this throttle point.

An advantageous embodiment is given by the fact that the filling of a high-pressure chamber of a pressure booster can be done without additional check valve on the throttle points. This makes it possible to carry out both the Nadelhubdämpfer and the valve for filling the high-pressure chamber with little design effort.

In one embodiment of the proposed solution according to the invention, the control of the fuel injection device via a 2/2-way valve can be carried out. This allows a cost-effective overall construction, in which case a pressure equalization can be brought about either via a filling throttle or a pressure reduction valve.

With the proposed solution according to the invention, a pressure-controlled opening of the injection valve member, which takes place at a speed which allows a good atomization of the fuel during the injection into the combustion chamber, can be achieved. Good atomization of the injected fuel favors the formation of a homogeneous fuel / combustion air mixture. A stroke-controlled closing of the injection valve member, which is hydraulically influenced, favors the smallest quantity capability in the pre-injection and post-injection of the fuel injector and prevents back-burning of fuel gases in the seating area of the injection valve member, e.g. a nozzle needle.

A nozzle module with Nadelhubdämpfung the fuel injector preferably comprises a flat seat, which can be manufactured with manufacturing technology simple processing steps. To ensure high strength and to create few high-pressure sealing surfaces, the flat seat on the spring chamber is basically carried out. The control room throttles can be introduced into the spring holder. When plane ground nozzles (stroke = zero) can be adjusted by appropriate thicknesses of the spring holder, the stroke of the injection valve member. Both a sensor disk and a sensor bolt can be used the movement of the injection valve member and the peak injection pressure reached are measured.

In a further advantageous embodiment of the solution according to the invention, the support of the valve pin on the nozzle side or sensorbolzenseitig be ground spherical, in order to realize a dynamic seat adjustment.

drawing

With reference to the drawing, the invention will be described below in more detail.

Figur 1

eine erste Ausführungsvariante einer Nadelhubdämpfung über einen durch Zulauf-/Ablaufdrossel befüllbaren bzw. druckentlastbaren Düsenfederraum,

Figur 2

eine weitere Ausführungsvariante einer Nadelhubdämpfung mit Rückführungsleitung im Düsenfederraum in einen mit diesem verbundenen Arbeitsraum eines Druckübersetzers,

Figur 3

eine Ausführungsvariante einer Nadelhubdämpfung mit Druckabbauventil,

Figur 4

eine weitere Ausführungsvariante einer Nadelhubdämpfung, wie in Figur 3 dargestellt, bei der das Druckabbauventil gemäß Figur 3 durch eine Drosselstelle ersetzt ist,

Figur 5

den Längsschnitt durch einen Injektor mit Nadelhubdämpfung,

Figur 6.1

die Nadelhubdämpfung oberhalb des Einspritzventilgliedes in vergrößertem Maßstab,

Figur 6.2

das mit S bezeichnete Detail in Figur 6.1 in vergrößertem Maßstab,

Figur 7.1

einen Schnitt durch einen Injektorkörper mit einem Einspritzventilglied, welches über einen zwischen diesem und einem Ventilkolben angeordneten Sensorbolzen verfügt,

Figur 7.2

das Detail V aus der Darstellung gemäß Figur 7.1 in vergrößertem Maßstab,

Figur 8.1 bzw. 8.2

die zeichnerische Darstellung eines Flachsitzes am Ventilbolzen oberhalb eines Einspritzventilgliedes,

Figur 9

den Längsschnitt durch einen Kraftstoffinjektor mit einer Sensoranordnung im Bereich einer Hubdämpfungseinrichtung.

It shows:

FIG. 1

a first embodiment of a Nadelhubdämpfung about a fillable by inlet / outlet throttle or pressure relief nozzle spring chamber,

FIG. 2

a further embodiment of a Nadelhubdämpfung with return line in the nozzle spring chamber in a working space associated therewith a pressure booster,

FIG. 3

a variant of a Nadelhubdämpfung with pressure reduction valve,

FIG. 4

a further embodiment of a Nadelhubdämpfung, as shown in Figure 3, in which the pressure reduction valve is replaced according to Figure 3 by a throttle point,

FIG. 5

the longitudinal section through an injector with Nadelhubdämpfung,

Figure 6.1

the needle lift damping above the injection valve member on an enlarged scale,

Figure 6.2

the detail denoted S in FIG. 6.1 on an enlarged scale,

Figure 7.1

3 a section through an injector body with an injection valve member which has a sensor bolt arranged between it and a valve piston,

Figure 7.2

the detail V from the illustration according to FIG. 7.1 on an enlarged scale,

FIGS. 8.1 and 8.2

the graphic representation of a flat seat on the valve pin above an injection valve member,

FIG. 9

the longitudinal section through a fuel injector with a sensor arrangement in the region of a Hubdämpfungseinrichtung.

variants

Figure 1 is a first embodiment of a Nadelhubdämpfung by means of a fillable by inlet / outlet throttles or pressure relieved nozzle spring chamber.

The fuel injection device shown in Figure 1 comprises a fuel injector 1, which is acted upon by a high-pressure storage space 2 with fuel under high pressure. The fuel injection device according to FIG. 1 comprises, in addition to the high-pressure reservoir 2, the fuel injector 1, a metering valve 6 which is designed as a 3/2-way valve in the embodiment shown in FIG. The fuel injector 1 includes an injector body 3, at whose brennraumseitigem end a nozzle body 4 is arranged. The tip 34 with the injection openings 36 of the fuel injector 1 formed there protrudes into a combustion chamber 7 of a self-igniting internal combustion engine indicated schematically here.

The fuel injector shown in Figure 1 comprises a pressure booster 5, which has a working space 10 and a control chamber 11. Via a line 9, which extends from the high-pressure accumulator 2 to the injector body 3 of the fuel injector 1, the working space 10 of the pressure booster 5 is acted upon by high-pressure fuel. Within the pressure booster 5, the working space 10 and the control chamber 11 are separated from each other by a piston 12. The piston 12 comprises a formed in a larger diameter first part piston 13 and a formed compared to the first part piston 13 with a reduced diameter second partial piston 14, whose end face a high-pressure chamber 15 of the pressure booster 5 acts. In the injector body 3, a ring-shaped stop 16 is present, on which a return spring 17 is supported, which acts on a return spring stop 18, which is fastened to the first partial piston 13 with the interposition of a rod-shaped or pin-shaped element. By means of the return spring 17, the piston 12 of the pressure booster 5 can be returned to its initial position.

The pressure intensifier 5, the metering valve 6 is assigned, which is acted upon by the working chamber 10 of the pressure booster 5 via a supply line 19 and in the switching position shown in Figure 1, the supply line (19) with a control line 20 which in turn in the control chamber 11 of the pressure booster. 5 below the first part piston 13 of the piston 12 opens. In addition, from the metering valve 6 branches off a low-pressure side return 8, in which, with a corresponding change in the switching position on the metering valve 6, the control chamber 11 is relieved of pressure via the control line 20 in an opposite flow direction.

From the compression chamber 15 of the pressure booster 5 extends a fuel inlet 21 without interposition of a check valve to a nozzle body 4 formed in the nozzle chamber 22. The nozzle chamber 22 encloses a nozzle needle, for example ausbildbares injection valve member 29. From the nozzle chamber 22, the fuel flows along an annular gap designated 33 in FIG Direction to the nozzle needle tip 34, which closes in the stroke position shown in Figure 1 in a combustion chamber 7 of a self-igniting internal combustion engine injection port 36 protrudes. The injection valve member 29 is acted upon at its end face 30 via a Düsensteuer- or nozzle spring chamber 25 with pressure. The nozzle chamber 25 shown in the embodiment of the fuel injector according to Figure 1 is independent of the nozzle chamber 22, but also acted upon via the compression chamber 15 of the pressure booster 5. For this purpose, an inlet 23 to the nozzle control chamber 25 is provided by the compression space, which contains an inlet throttle point 24. In addition, the nozzle control chamber 25 is connected via a connecting line 26, which contains a discharge throttle point 27, with the control chamber 11 of the pressure booster 5. Within the nozzle control chamber 25, a closing spring element 28 is received, which acts on the end face 30 of the injection valve member 29 with the interposition of a stroke limiter 31. The stroke limiter 31 is formed as a substantially cylindrical body, the end face 32 of the inlet throttle 24 is opposite and closes the inlet throttle point 24 at maximum stroke of the injection valve member 29, so that only during the short opening phase of the injection valve member 29, a leakage current through the throttles 24, 27 occurs.

The injection valve member 29 acting on the nozzle control chamber 25 is flowed through the inlet throttle point 24 from the compression chamber 15 and the outlet throttle point 27 in the connecting line 26 to the control chamber 11 of the pressure booster 5. The needle opening speed is determined essentially by the ratio of the cross sections of the inlet throttle point 24 and the outlet throttle point 27. The closing speed per se is determined by the cross-sectional area of the outlet throttle body 27. The opening or closing speed of the injection valve member 29 can be characterized independently pretend, in particular, can be a slow opening of the injection valve member 29 as well as quickly closing it regardless of the setting of the other speed. A quick closing of the injection valve member 29, which is preferably designed as a nozzle needle, is very important with regard to an improvement of the emission values of a self-igniting internal combustion engine. By a rapid closing of the injection valve member 29, in particular, the quantitative characteristics can be kept flat in ballistic needle operation, which increases the Zumeßgenauigkeit. In the ballistic operation of the injection valve member 29, this is freely movable between the respective extreme strokes.

In the illustration according to FIG. 1, the metering valve 6 designed as a 3/2-way valve is not actuated and no injection takes place. The pending in the high-pressure accumulator chamber 2 pressure is in the working space 10 of the pressure booster 5, further via the supply line 19 on Zumeßventil 6, via this and the control line 20 in the control chamber 11 of the pressure booster 5, further from this via the connecting line 26 in the nozzle spring chamber 25. Further the pressure level in the high-pressure reservoir 2 (common rail) via the inlet throttle point 24 in the compression chamber 15, since in this switching state, the inlet 23 is flowed through from the nozzle chamber 25 in the direction of compression chamber 15 for its filling. In the illustrated in Figure 1 basic state all pressure chambers on the pressure booster 5, ie the spaces 10, 11 and 15, acted upon by rail pressure, whereby the pressure booster 5 is pressure balanced. The pressure booster 5 is not activated and there is no pressure gain instead, since the piston 12, a first part piston 13 and a second part piston 14 comprising, is placed in this state via the return spring 15 in its initial position. Due to the pressure in the nozzle spring chamber 25, which corresponds to the pressure prevailing in the high-pressure reservoir 2 pressure, a hydraulic closing force is applied to the end face 30 of the injection valve member 29. This closes the injection valve member 29 against the force acting on the injection valve member 29 in the nozzle chamber 22 via the pressure shoulder 35 opening force. Due to the closing force exerted by the closing spring element 28 on the injection valve member 29, the injection valve member 29 remains against the pressure shoulder 35 acting on the opening force in its closed position. The metering of the fuel, ie an injection process, is carried out by a pressure relief of the control chamber 11 of the pressure booster 5. For this, the metering valve 6 is controlled and the control chamber 11 of the pressure booster 5 of the system pressure supply, ie from the high-pressure reservoir 2, separated and connected to the low-pressure side return 8 , As a result, the pressure in the working chamber 10 of the pressure booster 5 decreases, whereby the piston 12 is activated and a pressure build-up in the compression chamber 15 of the pressure booster 5 takes place. With increasing pressure in the compression chamber 15 rises above the fuel inlet 21 and the pressure in the nozzle chamber 22 within the nozzle body 4 at. As a result, the pressure force acting on the pressure shoulder 35 of the injection valve member 29 within the nozzle chamber 22 and the injection valve member increases 29 starts to open. At the same fuel flows from the compression chamber 15 in the nozzle spring chamber 25 and from there via the outlet throttle 27 in the connecting line 26 in the working space 10. By the design of the throttle cross sections of the inlet throttle 24 and the outlet throttle 27 can be within the nozzle spring chamber 25 set a control pressure level, which determines the opening speed of the injection valve member 29. In the fully open state, the injection valve member 29 closes the connection from the compression chamber 15 to the nozzle spring chamber 25, since the end face 32 of the stroke limiter 31 rests against the ceiling of the nozzle spring chamber 25 and thus closes the connection 23 to the compression chamber 15. As a result, no loss amount can escape via the inlet throttle 24 during the injection process. The opening speed of the injection valve member 29 can therefore be adjusted and specified via the ratio of the throttle points 23 and 24. As long as the control chamber 11 of the pressure booster 5 remains depressurized, ie the metering valve 6 connects the low-pressure side return 8 to the control line 20, the pressure booster 5 is activated and compresses the fuel within the compression chamber 15. About the fuel inlet 21 of the compressed fuel flows into the nozzle chamber 25th , from there via the annular gap 33 to the nozzle needle tip 34, where it is injected via the injection openings 36 into the combustion chamber 7 of the self-igniting internal combustion engine.

The completion of the injection takes place by renewed switching of the metering valve 6, which may be formed both as a solenoid valve, and a piezoelectric actuator containing. As Zumeßventile 6 come next directly controlled valves or servo valves in question. By re-switching the Zumeßventiles 6, the control chamber 11 of the pressure booster 5 and the nozzle spring chamber 25 is separated from the low-pressure side return 8 and acted upon by the pressure prevailing in the high-pressure reservoir 2 pressure level again. In the control chamber 11 and the nozzle spring chamber 25 thereby again this pressure level, ie the pressure level in the high-pressure accumulator 2, on. The pressure in the compression chamber 15 and in the control chamber 22, which act on the injection valve member 29, now falls to the pressure prevailing in the high-pressure reservoir 2 pressure level. Rail pressure is applied in the nozzle spring chamber 25, as a result of which the injection valve member 29 is now hydraulically balanced and is closed by the closing spring 28 acting on its end face 30. Thus, the injection is terminated by retracting the injection valve 29 in its combustion chamber-side needle seat. The closing speed of the injection valve 29, ie the speed at which the injection valve member 29 moves into its combustion chamber side seat can be influenced by the dimensioning of the outlet throttle 27 in the connecting line 26 to the working space 10 of the pressure booster 5. When the injection valve member 29 is closed, the connection from the compression chamber 15 into the nozzle spring chamber 25 via the inlet 23 and the intake throttle point accommodated therein 24 open. After pressure equalization within the fuel injection device, the piston 12 of the pressure booster 5 is returned by the return spring 17 in its initial position, the compression chamber 15 is filled via the line 23, which is now flowed through in the opposite direction, via the inlet throttle point 24 again with fuel.

By inventively proposed solution a Nadelhubdämpfer is realized by a flow through the nozzle spring chamber 25. On the one hand, the opening speed of the injection valve member 29 can be reduced and thus improve the small quantity capability of the fuel injector 1, without an additional precision component in the form of a damping piston is needed. The opening speed of the injection valve member 29 is determined by way of the cross-sectional relationships of the inlet throttle point 24 and the outlet throttle point 27, while the closing speed of the same is determined by the design of the cross-sectional area of the outlet throttle point 27. Thus, the opening and closing speed of the injection valve member 29 can be adjusted independently of each other, which in particular a slow needle opening, i. favoring the smallest quantity capability, and fast closing, i. the further subsequent flow of the fuel into the combustion chamber at the end of the combustion phase prevents. Since the proposed Nadelhubdämpfer has no moving parts that must be reduced after activation in their initial state, can be realized with the proposed solution according to the invention also closely behind each other multiple injections unrestricted.

To stabilize switching sequences, further measures for damping pressure pulsations, which can form between the injector body 3 and the high-pressure reservoir 2 in the conduit 9, can be taken. For this purpose, in the line 9 between the high-pressure accumulator chamber 2 and the working space 10 of the pressure booster 5, a throttle point on the high-pressure accumulator side connection can be arranged. Alternatively, a check-throttle valve could be used.

A faster filling of the compression chamber 15 of the pressure booster 5 can be achieved by an additional provided check valve. The proposed Nadelhubdämpfung can be realized in an advantageous manner even in difficult, ie limited space, since no additional components are required. The proposed Nadelhubdämpfung can also be used on a fuel injector 1, which includes a Vario-register injector, that is, a plurality of injection cross-sections 36, for example, formed as concentric hole circles, at the combustion chamber end of the nozzle body 4. Furthermore, a coaxial nozzle needle may be used in addition to a vario-register nozzle which may comprise two independently opening or closing interdigitated nozzle needles.

Figure 2 shows a further embodiment of a Nadelhubdämpfung with return line from the nozzle spring chamber in a working space associated therewith a pressure booster.

The embodiment of a Nadelhubdämpfers shown in Figure 2 without additional precision components in the form of damping piston differs from the embodiment shown in Figure 1 embodiment of the invention essentially in that the nozzle chamber 25 of the injection valve member 29 in this embodiment via a connecting line 40 between the nozzle spring chamber 25 and the Working space 10 of the pressure booster 5 is connectable. In the connecting line 40 to the working space 10 of the pressure booster 5, the outlet throttle body 27 is integrated. While in the embodiment of the Nadelhubdämpfers shown in Figure 1, the control volume from the nozzle spring chamber 25 via the outlet throttle 27 is disconnected via connecting line 26 into the control chamber 11 of the pressure booster 5 and from there via the control line 20 in the opposite direction of flow in the low-pressure side return 8 is at the embodiment of the Nadelhubdämpfers shown in Figure 2, the control amount from the nozzle spring chamber 25 via the outlet throttle 27 in the working space 10 of the pressure booster 5 is controlled. With this solution, the energy losses can be reduced by the control amount and thus improve the hydraulic efficiency of the proposed fuel injector 1, since the taxed from the nozzle chamber 25 control amount is not completely relaxed, but only to the pressure prevailing in the working chamber 10 pressure level is relaxed.

In the embodiment variant of a nozzle needle damping illustrated in FIG. 2, the metering valve 6 is likewise designed as a 3/2-way valve, be it as a solenoid valve or as a piezoelectric actuator. In addition, the metering valve 6 can be formed analogously to the illustration in Figure 1 as a direct-controlled valve or as a servo valve.

In the injector body 3 of the fuel injector 1 according to Figure 2, the pressure booster 5 is added, analogous to the embodiment, which is shown in Figure 1. The pressure booster 5 also contains here a piston 12, which may have a first part piston 13 in an enlarged diameter and a second part piston 14 in a reduced diameter. The booster piston 12 of the pressure booster 5 can be made of the mentioned sub-piston 13 and 14, both as a one-piece component as well as a multi-part component. The lower end face of the second sub-piston 14 acts analogously to the illustration in Figure 1, the compression chamber 15, from which a fuel feed 21 in the Nozzle spring chamber 25 leads. From the compression chamber 15 also branches off an inlet 23 to the nozzle spring chamber 25, which contains an inlet throttle point 24.

Also, according to the embodiment shown in Figure 2 with a reduced power loss by controlling the control amount from the nozzle spring chamber 25 in the working space 10 of the pressure booster 5 can be determined by designating the cross sections of the inlet throttle body 24 and the outlet throttle 27 of the connecting line 40, the opening speed of the injection valve member 29. By a suitable dimensioning of the cross section of the outlet throttle body 27 in the connecting line 40 from the nozzle spring chamber 25 to the working space 10 of the pressure booster 5, the closing speed of the injection valve member 29, which is preferably designed as a nozzle needle, determine, so that in this embodiment, the opening or the closing speed of the injection valve member 29 are independently definable.

Apart from the differences of the embodiment variant according to FIG. 2 in comparison with the embodiment variant shown in FIG. 1, the structure and function of the fuel injection device according to FIG. 2 correspond to the design and function of the embodiment variant of the inventive solution of a needle stroke damper shown in FIG.

FIG. 3 shows a variant embodiment of a needle lift damping on a fuel injection device with a pressure reduction valve.

According to this embodiment of the solution according to the invention in the line 9 to the working chamber 10 of the pressure booster 5 an inlet throttle 50 is received, via which are damped in the line 9 adjusting pressure pulsations and an unacceptably high indoor load of the high pressure accumulator 2 by pressure oscillations, which the life of the high-pressure accumulator 2, is prevented. The pressure booster 5 is formed in the injector body 3 of the fuel injector 1 and includes the working chamber 10 and the control chamber 11. The pressure booster piston within the pressure booster 5 comprises a first part piston 13 which abuts with its lower end face on a disk-shaped stop 18, which on a second part piston 14, which acts on the compression space 15 with its lower end face, is formed. The stop 18 at the upper end of the second partial piston 14 is acted upon by a return spring 17. In contrast to the illustrated in Figure 1 and Figure 2 variants of an integrated in an injector body 3 pressure booster 5, the return spring 17 is not included in the embodiment of Figure 3 in the working space 10, but in the control chamber 11 of the pressure booster 5. On the Compression space 15 at the lower end of the pressure booster 5 are supplied via the fuel inlet 21 of the nozzle chamber 22 in the nozzle body 4 and via the inlet 23 with inlet throttle point 24 of the nozzle spring chamber 25 of the injection valve member 29 with fuel. The nozzle spring chamber 25 is connected via the connecting line 26 with discharge throttle point 27 with the control chamber 11 of the pressure booster 5 in combination.

The injection valve member 29, pressurized via the nozzle spring chamber 25 and over the pressure in the nozzle chamber 22, opens or closes in an analogous manner to the embodiment in Figure 1 by a pressure relief or pressurization of the control chamber 11 by actuation of the metering valve 6 and 56th

In contrast to the embodiment variant of a needle lift damping on a fuel injection device illustrated in FIG. 1, on the one hand the metering valve 6 is designed as a 2/2-way valve 56, which is connected to a low-pressure return 8. Further, a pressure reduction valve 51 is interposed in the control line 20 between the working space 10 of the pressure booster 5 and the metering valve 56 designed as a 2/2-way valve. The pressure relief valve comprises a pressure reduction channel 52, which extends from a first piston part 53 in a second piston part 57 of the pressure reduction valve 51. The control section 20 zuweisende first piston part 53 of the pressure reduction valve 51 is enclosed by a valve chamber 54, in which the control line 20 from the working space 10 of the pressure booster 5 opens. The second piston part 57 of the pressure reduction valve 51 is acted upon by a valve spring 55, which is received in a cavity of the pressure reduction valve 51 which is connected via a connecting line (no reference numeral) with the constructed as a 2/2-way valve metering valve 56.

While the opening speed of the injection valve member 29 in the nozzle body 4 of the fuel injector 1 by the ratio of the throttle cross-sections of the inlet throttle body 24 and the outlet throttle body 27 can be specified, the control line 20 to the control chamber 11 of the pressure booster 5, a rapid pressure reduction in the control chamber 11 by the integration of a pressure reduction valve 51 the pressure intensifier 5 and thus a fast needle closing are ensured towards the end of the injection phase. The construction and operation of the illustrated in Figure 3 variant of a Nadelhubdämpfung corresponds substantially to the structure and function of the embodiment shown in Figure 1 a Nadelhubdämpfung to a fuel injection device. In contrast to the embodiment variant shown in FIG. 1, a feed throttle 50 is accommodated in the line 9 of the fuel injection device according to the embodiment in FIG. 3, and a pressure reduction valve in the control line 20 between the working space 10 and the metering valve 56, wherein the metering valve 6 in the embodiment variant shown in FIG in contrast to the embodiment in Figure 1 as a 2/2-way valve can be trained. The design of the metering valve 6 as a 2/2-way valve allows a cost-effective overall construction.

FIG. 4 shows a further embodiment variant of a needle lift damping, similar to the embodiment variant shown in FIG. 3, but with the pressure reduction valve according to FIG. 3 being replaced by a throttle.

Also shown in Figure 4 embodiment of a Nadelhubdämpfung via a nozzle control chamber 25 associated inlet throttle points 24 and outlet throttles 27 includes a metering valve 6, which is designed as a 2/2-way valve 56. In contrast to the embodiment variant of a needle lift damping illustrated in FIG. 3, the supply line 9, containing an inlet throttle point 50, ends from the high-pressure reservoir 2 on the one hand into the working space 10 of the pressure booster 5, wherein according to this embodiment a line branch 60, containing an outlet throttle point 61, also in the control chamber 11 of FIG Pressure Translator 5 opens. According to this embodiment, the control of volume control from the nozzle spring chamber 25 via the connecting line 26 into the working space 10 of the pressure booster 5, wherein in the connecting line 26, the outlet throttle body 27 is integrated. However, according to the embodiment shown in Figure 4, the control chamber 11 of the pressure booster 5 via the control line 20, which is flowed through in the opposite direction, pressure relieved. About the branch 60 and the throttle 61, the pressure build-up in the control chamber 11 takes place after the end of injection.

The variant shown in Figure 4 using a designed as a 2/2-way valve metering valve 56 allows a Düsennadeldämpfung by a flow through the nozzle spring chamber 25 via the compression chamber 15 of the pressure booster 5 extending inlet throttle point 24 in the inlet 23, as well as on in In this embodiment can be analogous to the embodiments shown in Figures 1 to 3, the opening speed of the injection valve member 29 by the design of the throttle cross-sections of the inlet throttle 24 and the outlet throttle point 27 reach while the closing speed of preferably designed as a nozzle needle Injection valve member 29 is determined by the dimensioning of the cross-sectional area of the outlet throttle body 27 in the connecting line 26. Also in this embodiment, an independent adjustment of the opening speed of the closing speed of the injection valve member 29 is analogous to the embodiments shown in Figure 1 to 3 possible.

Also, the embodiments of a Nadelhubdämpfung shown in Figures 3 and 4 can advantageously in conjunction with a Vario-register nozzle, with several be used independently releasable or closable injection cross sections; In addition, an application of the Nadelhubdämpfung shown in Figure 3 or 4 is also possible on a coaxial nozzle needle, which may comprise mutually guided, independently pressure-actuated nozzle needle parts.

FIG. 5 shows a longitudinal section through a fuel injector with needle lift damping.

Figure 5 shows the longitudinal section through the fuel injector 1, in the upper region of the metering valve 6 - is formed here - designed as a solenoid valve - is arranged. On the side of the injector body 3, a high-pressure inlet 70 is formed, via which the high-pressure fuel in the injector body 3, i. the working space of a pressure booster 5, is supplied. In the screw-in socket designated by reference numeral 70 may be added to a fuel-filtering rod filter element in an advantageous manner.

The pressure intensifier 5 integrated in the injector body 3 comprises a first partial piston 13 and the second partial piston 14, wherein the first partial piston 13 is acted upon by the return spring 17, which is supported on the injector body 3. The end face of the second part piston 14 acts on a compression space 15, which is arranged symmetrically to the symmetry line of the injector body 3. From this, the inlet 23 extends with integrated throttle 24. The inlet 23 to the nozzle control chamber 25 follows via a throttle plate 72. Below the throttle plate 72, a damping plate 77 is arranged, which limits the Düsensteuerraum25. In the nozzle control chamber / damping chamber 25 is the valve spring 74 and the valve pin 73, on which a flat seat ring edge 76 is formed (see Figure 6.2). The Flachsitzringkante 76 and the Hubbegrenzer 31 of the throttle plate 72 form the stroke limiter of the injection valve member 29 and the valve closing function to the inlet throttle 24. The injection valve member 29 is partially shown in longitudinal section in FIG. Analogous to the schematically illustrated in Figures 1 to 4 variants of a stroke damping the injection valve member 29 is enclosed according to the longitudinal section through the fuel injector 1 of a nozzle chamber 22 in which the circumference of the injection valve member 29, a conically configured pressure shoulder 35 is formed. The damping disk 77 or a further disk element are centered relative to one another via centering pins 75 in their installed position relative to the injector body 3. The nozzle body 4, the further disk element, the damping disk 77 and the throttle disk 72 are enclosed by a sleeve-shaped nozzle retaining nut 71 and are screwed to an external thread in the lower region of the injector body 3 of the fuel injector 1.

The area denoted by D in FIG. 5 is shown on an enlarged scale in the illustrations according to FIGS. 6.1 and 6.2.

The illustration according to FIG. 6.1 shows the needle stroke damping above the injection valve member in an enlarged scale.

Above the end face 86 of the injection valve member 29, a sensor pin 85 is shown, which is a part of the stroke limiter 31 according to the embodiments in Figures 1 to 5 and is used for Wegedetektion means of a sensor. The sensor pin 85 is surrounded by a disk-shaped element 84, which defines a cavity in the lower region. In the cavity of the disc 84 opens a leak oil hole.

The sensor pin 85 and disc-shaped member 84 are optional components and are not essential to the function of injector member stroke damping. As part of a function extension for stroke measurement, they can be integrated into the fuel injector as required.
According to the illustration of the injection valve member 29 in the nozzle body 4 of the fuel injector 1, this is enclosed by the nozzle chamber 22, which is supplied via an opening 89 with fuel under high pressure, wherein the opening 89, ie a nozzle chamber inlet, the discharge point of the in FIG 3 and 4 represents fuel supply line 21 from the compression space 15. From the nozzle chamber 22, the fuel flows along an annular gap 33 in the direction of the nozzle needle tip 34 of the injection valve member 29 (see FIG. At the lower end in the region of the nozzle needle tip 34, a combustion chamber-side seat 91 is formed on the injection valve member 29 as shown in FIG. Between the nozzle chamber 22 and the nozzle needle tip 34, the injection valve member 29 may be provided with a number of symmetrically distributed on the periphery of the injection valve member 29 arranged free surfaces along which the fuel flows within the annular gap 33, which surrounds the injection valve member 29 in an annular manner in the direction of the nozzle needle tip 34 , In the region of the nozzle chamber 22, the injection valve member 29 is provided on its outer peripheral surface analogous to the schematic diagrams shown in FIGS. 1 to 4 with a conically shaped pressure shoulder 35.

FIG. 6.2 shows the area designated S in FIG. 6.1 on an enlarged scale.

From Figure 6.2 shows that the valve spring 74 surrounds both the stroke limiter 31 and a part of the valve pin 73. In the upper region of the valve pin 73, that is, on whose end face of the stroke limiter 31 opposite end face a pointed countersink 80 is provided and a flat seat ring edge 76. In contrast, the front side the stroke limiter 31 designed as a plane surface. As shown in FIG. 6.2, the flat seat ring edge 76 comprises a first bevel 81 which is formed in a first bevel angle, so that the flat seat 76 drops slightly outward in relation to the peripheral surface of the valve pin 73 in the radial direction. As can be further seen from the illustration according to FIG. 6.2, the lower side of the valve pin 73-crowned-lies opposite the end face of the sensor pin 85.

FIG. 7.1 shows a sensor bolt received between a valve pin and an injection valve.

In contrast to the representation according to FIG. 6.1, the valve pin 73 in the embodiment variant according to FIG. 7.1 is formed in a larger axial length, wherein the stroke restrictor 31 is not formed on the throttle plate 72 according to this embodiment variant. The valve pin 73 is located with its inlet 23 opposite end directly to the damping plate 77 at. These and the throttle plate 72 are traversed by a high-pressure inlet 23, which opens at the nozzle chamber inlet 89 into the nozzle chamber 22 within the nozzle body 4. In the area of the nozzle chamber 22, the injection valve member 29, which is in the form of a nozzle needle, for example, includes a pressure shoulder 35. Further, open spaces 90 are accommodated on the injection valve member 29, along which the fuel flows into an annular gap 33 and from there to the nozzle needle tip 34. The sensor pin 85, the end face of which lies opposite a crowned end face of the valve pin 73, is surrounded by a disc-shaped element 84, which comprises a cavity, at which a leak oil line branches off. The injection valve member 29 abuts with its end face 86 against a corresponding lower end face of the sensor pin 85.

FIG. 7.2 shows the reproduction of the detail marked V in FIG. 7.1 in an enlarged scale.

The valve pin 73 is enclosed by a valve spring 74. The valve spring 74 is supported with its lower turn on an annular shoulder on the valve pin 73. With its approach to the valve pin 73 opposite end of the valve spring 74 abuts against a shim 88, which is arranged below the throttle plate 72. The valve pin 73 together with this surrounding valve spring 74 is enclosed by a damping disk 77, which is only partially shown here. The valve pin 73 and the underside of the throttle disk / damping disk 72, 77 form a flat seat 76.

At the upper end of the valve pin 73, a, designated by reference numeral 79 seat geometry is formed. This seat geometry 79 as shown in Figure 6.2 is through a pointed depression 80 characterizes. The pointed countersink 80 merges into a first bevel 81 at a radial distance, so that the seat geometry 79 is formed both by the pointed countersink 80 and by the bevel 81 adjoining it. Below the damping disk 77 is another disk element, which forms the guide for the sensor pin 85 below the valve pin 73, both of which represent the stroke limiter 31 shown schematically in Figures 1 to 4.

Figure 8.1 shows a second embodiment of the seat geometry. The valve pin 73 as shown in Figure 8.1 is enclosed by the damping disk 77 and acted upon by the valve spring 74. Below the valve pin 73 is the sensor pin 85, which in turn is enclosed by a disc element 84, which comprises a cavity. In the cavity of the disc member 84 opens a leak oil hole. Below the sensor pin 85 extends the injection valve member 29, which rests with its upper end face 86 on the lower end face of the sensor pin 85. The damping disk 77, the disk element 84 and the nozzle body 4 of the fuel injector 1 are traversed by a high-pressure inlet 23, which opens into a nozzle opening 89 in the nozzle chamber 22 of the nozzle body 4.

The illustration according to FIG. 8.2 shows that the valve pin 73, surrounded by a valve spring 74, is received between the throttle disk 72 and the sensor disk 84 and enclosed by the damping disk 77. The valve spring 74 is supported, on the one hand, on a lower annular projection of the valve pin 73 and, on the other hand, on an annular shim 88 arranged below the throttle plate 72.

The difference from the embodiment according to FIGS. 6.1 and 6.2 is that, according to the embodiment variant shown in FIGS. 8 and 8.1, the flat seat 76 is formed on the plane surface of the throttle disk 72. The advantage is that the volume of the inlet bore 23 is kept very small. This reduces the pressure oscillations between the compression chamber 15 and the nozzle control chamber 25, which results in a better quantity stability of the multiple injections. The seat geometry is designed analogously to the variant according to FIG. 6.1.

In contrast to the embodiment variant shown in FIGS. 7.1 and 7.2, the fact that the throttles are not integrated in the damping disk 77 can be shaped as interchangeable disks. As part of the voting or the manufacturing process, these can therefore be easily replaced.

FIG. 9 shows the longitudinal section through a fuel injector with a stroke sensor arrangement in the upper region of the injection valve member.

From the illustration according to FIG. 9, it can be seen that a sensor disk element 84 has been received above the upper end face of the nozzle body 4 of the fuel injector 1. This encloses a stroke sensor 96.

The injection valve member 29, preferably designed as a nozzle needle, passes through a chamfer 94 in the upper region of the nozzle body 4 and is enclosed by the nozzle chamber 22, of a not shown in Figure 8 fuel inlet 21, which is in communication with the compression chamber 15 of the pressure booster 5, with subjected to high pressure fuel. From the nozzle chamber 22, the fuel under high pressure flows along the annular gap 33 along the flow relief surface 90 of the nozzle needle tip 34 formed on the circumference of the injection valve member 29. In the illustration of Figure 8, the tip of the injection valve member 29, i. the nozzle needle tip 34, placed in the combustion chamber side seat 91.

By arranging a sensor disk element 84, which cooperates with a stroke sensor 96, the movement of the injection valve member 29 can be detected in the vertical direction within the nozzle body 4 and measure the reached needle speed, movement start and end of the injection valve member 25. By applying this measuring system, a closed loop for final adjustment and any necessary mapping of a fuel injection system can be represented, with which a fault diagnosis of the fuel injection system and a storage occurred operating data is possible, which can be read in the context of constantly recurring maintenance intervals of the self-igniting internal combustion engine.

The embodiments of injection valve member damping shown in the above representations represent embodiments in which the nozzle module, ie the nozzle body 4 with the overlying annularly configured elements 72, 77, 78 and 84, respectively, can be designed to close rapidly according to the proposed invention reach the injection valve member 29, and its opening speed so by the design of inlet throttle 24 and outlet throttle body 27 to dimension that the Kleinstmengenfähigkeit is improved without an additionally required precision component is to be used.

LIST OF REFERENCE NUMBERS

1

fuel injector

2

High-pressure accumulator

3

injector

4

nozzle body

5

Pressure intensifier

6

metering valve

7

combustion chamber

8th

low-pressure side return

9

supply

10

working space

11

control room

12

piston

13

first part piston

14

second partial piston

15

compression chamber

16

abutment

17

Return spring

18

Return spring stop

19

Inlet metering valve

20

Control line control room

21

Fuel inlet nozzle chamber

22

nozzle chamber

23

Inlet nozzle spring chamber

24

Inlet restrictor

25

Nozzle control chamber

26

Connecting pipe nozzle spring chamber control chamber pressure intensifier

27

Flow restrictor

28

Closing spring element

29

Injection valve member (nozzle needle)

30

front

31

stroke limiter

32

face

33

annular gap

34

Nozzle needle tip

35

pressure shoulder

36

Injection ports

40

Connecting pipe nozzle spring chamber working space pressure intensifier

41

Discharge point Connecting pipe in the working space Pressure intensifier

50

Supply line choke point

51

Pressure reduction valve

52

Depressurizing passage

53

first piston part

54

valve chamber

55

valve spring

56

Metering valve (version as 2/2-way valve)

57

second piston part

60

junction

61

Branch throttle restriction

70

High pressure inlet injector

71

Nozzle clamping nut

72

throttle disc

73

valve bolt

74

valve spring

75

Centering

76

flat seat

77

damping plate

79

seat geometry

80

tip sinking

81

first polished angle

82

Plane surface seat

83

Spring compartment floor

84

sensor disk

85

sensor bolt

86

Face of injection valve member / sensor bolt

87

88

Focusing

89

Nozzle chamber inlet

90

areas

91

combustion chamber side nozzle needle seat

92

93

94

chamfer

95

crowned edition

96

stroke sensor

Claims (20)

1. Fuel injection device for injection of fuel into the combustion spaces (7) of an internal combustion engine, with a high-pressure source (2), a pressure intensifier (5) and a metering valve (6, 56), the pressure intensifier (5) comprising a working space (10) and a control space (11) which are separated from one another by a piston (12, 13, 14), and a pressure change in the control space (11) of the pressure intensifier (5) bringing about a pressure change in a compression space (15) which acts via a fuel inflow (21) upon a nozzle space (22) surrounding an injection-valve member (29), characterized in that a nozzle control space (25) acting upon the injection-valve member (29) can be filled on the high-pressure side from the compression region (15, 21, 22, 33) via a line (23) containing an inflow throttle point (24) and is connected on the outflow side to the pressure intensifier via a line (26, 40) containing an outflow throttle point (27).
2. Fuel injection device according to Claim 1, characterized in that the opening speed of the injection-valve member (29) is determined by the ratio of the cross sections at the inflow throttle point (24) to the outflow throttle point (27).
3. Fuel injection device according to Claim 1, characterized in that the closing speed of the injection-valve member (29) is determined by the cross-sectional area of the outflow throttle point (27).
4. Fuel injection device according to Claim 1, characterized in that the injection-valve member (29) comprises a stop face (32) which closes the inflow-side throttle point (24) when the maximum stroke of the injection-valve member (29) is reached.
5. Fuel injection device according to Claim 1, characterized in that the nozzle control space (25) can be relieved of pressure into the control space (11) of the pressure intensifier (5) via the line (26) having the outflow throttle point (27).
6. Fuel injection device according to Claim 1, characterized in that the nozzle control space (25) can be connected into the working space (10) of the pressure intensifier (5) via the line (40) having the outflow throttle point (27).
7. Fuel injection device according to Claim 1, characterized in that the working space (10) of the pressure intensifier (5) can be filled from the high-pressure accumulator space (2) via a supply line (9).
8. Fuel injection device according to Claim 7, characterized in that the line (9) comprises a throttle element (50) counteracting pressure pulsations between the fuel injector (1) and high-pressure accumulator space (2).
9. Fuel injection device according to Claim 1, characterized in that, to activate the pressure intensifier (5), the control space (11) of the latter is provided via a metering valve (6, 56) opening or closing a control line (20).
10. Fuel injection device according to Claim 9, characterized in that the metering valve (6) is designed as a 3/2-way valve which has an outflow (8) located on the low-pressure side.
11. Fuel injection device according to Claim 9, characterized in that the metering valve (56) is designed as a 2/2-way valve which has an outflow (8) located on the low-pressure side.
12. Fuel injection device according to Claim 1, characterized in that a stroke limiter (31) arranged above the injection-valve member (29) comprises a valve bolt (73), a spring element (28, 74) which acts in a closing direction of the injection-valve member (29) being received on the valve bolt (73).
13. Fuel injection device according to Claim 12, characterized in that a flat seat (76) is formed between the valve bolt (73) and the stroke limiter (31).
14. Fuel injection device according to Claim 13, characterized in that the flat seat (76) is designed to comprise a first ground-down portion (81) and a countersink (80).
15. Fuel injection device according to Claim 13, characterized in that the flat seat (76) comprises a ground-down portion (81).
16. Fuel injection device according to Claim 12, characterized in that the flat seat (76) is formed in the spring space of the nozzle control space (25).
17. Fuel injection device according to Claim 12, characterized in that the flat seat (76) is formed on the throttle disc (72) which lies opposite the upper face of the valve bolt (73).
18. Fuel injection device according to Claim 12, characterized in that the throttle elements (24, 27) are formed in exchangeable disc elements (72).
19. Fuel injection device according to Claim 12, characterized in that the valve bolt (73) has a crowned contour (95) on its end face facing the sensor bolt (85).
20. Fuel injection device according to Claim 12, characterized in that the valve bolt (73) and the sensor bolt (85) are assigned a stroke sensor arrangement (96) which serves for detecting the travel of the injection-valve member (29) within the fuel injector (1).

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