EP1520097A1

EP1520097A1 - Device for damping the needle lift in fuel injectors

Info

Publication number: EP1520097A1
Application number: EP03732208A
Authority: EP
Inventors: Martin Kropp; Hans-Christoph Magel; Manfred Mack; Christian Grimminger
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2002-06-29
Filing date: 2003-04-09
Publication date: 2005-04-06
Anticipated expiration: 2023-04-09
Also published as: EP1520097B1; DE10229418A1; US20050077378A1; DE50305275D1; WO2004003375A1; US7083113B2; JP2005531716A

Abstract

The invention relates to a fuel injection device for injecting fuel into the combustion chambers (7) of an internal combustion engine. The fuel injection device comprises a high-pressure accumulator chamber (2), a pressure intensifier (5) and a metering valve (6, 56). The pressure intensifier (5) comprises a working chamber (10) and a control chamber (11), which are separated from one another by an axially displaceable piston (12). A pressure change in the control chamber (11) of the pressure intensifier (5) leads to a pressure change in a compression chamber (15), the latter impinging a nozzle chamber (22) by means of a fuel inlet (28). The nozzle chamber (22) surrounds an injector valve member (29), which can for example be configured as a nozzle needle. A nozzle spring chamber (25) that impinges the injector valve member (29) can be filled on the high pressure side by the compression chamber (15) of the pressure intensifier (5) via a line (23) containing an input throttle (24). On the delivery side, the nozzle spring chamber (28) is connected to a chamber (11) of the pressure intensifier (5) via a line (26, 40) containing a delivery throttle (27).

Description

Device for damping the needle stroke on fuel injectors

Technical field

Both pressure-controlled and stroke-controlled injection systems can be used to supply the combustion chambers of self-igniting internal combustion engines with fuel. In addition to pump-nozzle inlets, pump-line-nozzle units, accumulator injection systems are also used as fuel injection systems. Accumulator injection systems (common rail) advantageously allow the injection pressure to be adapted to the load and speed. In order to achieve high specific outputs 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 in storage injection systems used today is currently limited to approximately 1600 bar. Pressure boosters are used on common rail systems to further increase the pressure in storage injection systems.

EP 0 562 046 B1 discloses an actuating and valve arrangement with damping for an electronically controlled injection unit. The actuation and valve arrangement for a hydraulic unit has an electrically excitable electromagnet with 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, the first surface of the armature facing the stator. A valve is provided which is connected to the armature. The valve is capable of delivering hydraulic actuating fluid to the injector from a sump. A damping fluid can be collected or discharged from one of the cavities of the electromagnet arrangement there. By means of an area of a valve protruding into a central bore, the flow connection of the damping fluid can be selectively released or closed in proportion 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 charged via a high pressure source; Furthermore, the fuel injection device according to DE 101 23 910.6 comprises a pressure intensifier, which has a movable pressure intensifier piston, which separates a space that can be connected to the high pressure source from a high pressure space that is connected to the fuel injector. The fuel pressure in the high-pressure chamber can be varied by infecting a rear chamber of the pressure booster with fuel or by emptying this rear chamber of fuel.

The fuel injector comprises a movable closing piston for opening or closing the injection openings facing the combustion chamber. The locking piston protrudes into a closing pressure chamber so that it can be pressurized with fuel. A force acting on the locking piston in the closing direction is thereby achieved. The closing pressure space and a further space are formed by a common work space, with all partial areas of the work space being permanently connected to one another for the exchange of fuel.

With this solution, by actuating the pressure intensifier via the rear space, it can be achieved that the actuation losses in the high-pressure fuel system can be kept small in comparison to actuation via a work space that is temporarily connected to the high-pressure fuel source. Furthermore, the high-pressure chamber is only relieved to the pressure level of the high-pressure storage chamber and not to the leakage pressure level. On the one hand, this improves the hydraulic efficiency, on the other hand, the pressure can be built up more quickly to the system pressure level, so that the time intervals between the injection phases can be shortened.

In pressure-controlled common rail injection systems with pressure intensifiers, the problem arises that the stability of the injection quantities to be injected into the combustion chamber, in particular the representation of very small injection quantities, as required, for example, in the pre-injection, is not guaranteed. This is mainly due to the fact that the nozzle needle opens very quickly in pressure-controlled injection systems. Therefore, very small variations in the control period of the control valve can have a major impact on the injection quantity. Attempts have been made to remedy this problem by using a separate needle-stroke damper piston which delimits 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 this solution increases the design effort and thus the cost of the injection system very greatly. In view of the continuously increasing demands on the emission and noise development of self-igniting internal combustion engines, further measures are necessary on the injection system in order to meet the tightened limit values to be expected in the near future.

Presentation of the invention

With the solution proposed according to the invention, the use of a precision component, as mentioned above, such as, for example, a needle lift damper piston, can be avoided by the function of the needle lift damping being represented by a flow through the nozzle needle spring chamber. With the proposed solution, on the one hand, the manufacturing outlay can be significantly reduced, and on the other hand, by reducing the needle opening speed, the small quantity capability of the fuel injector is considerably improved. A separate precision component in the form of a needle lift damper piston is not required for this. 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 work space.

The needle opening speed can be set by dimensioning the flow cross-sections and the throttle section lengths of the inlet and outlet throttles. The closing speed of the nozzle needle is essentially determined by the cross-sectional area of the outlet throttle. In principle, this makes it possible to set the opening and closing speed of the nozzle needle independently of one another by dimensioning the inlet and outlet throttle and thus on the one hand a slow opening of the injection valve element, for example a nozzle needle, and on the other hand a quick closing of the injection valve element of the force reach injector. A rapid closing of the injection valve member of a fuel projector enables an improvement in the emission values of a self-igniting internal combustion engine. A quick closing of the injection valve member ensures that a precisely defined end time of the injection can be maintained, so that after this an injection of fuel into the combustion chamber is omitted, which can no longer be implemented during combustion and is contained in the exhaust gas as unburned fuel and its HC content is influenced extremely negatively.

The introduction of a rapid needle closure also offers the possibility of keeping the quantity characteristic flat in the ballistic operating state of the nozzle, ie during the movement between its stroke stops or injection valve member seat, which considerably improves the metering accuracy of fuel. Due to the proposed concept of stroke damping without additional moving components, simply due to the flow guidance, inertia influences, such as when using an additional precision component, are irrelevant, so that successive multiple injection processes are also carried out since there are no reset times for mechanical components with regard to the time intervals of the injection phases are taken into account. In order to ensure that there are no high control quantities that flow through the inlet and outlet throttles and negatively influence the hydraulic efficiency, the injection valve member can advantageously completely close the inlet throttle when the maximum stroke is reached. A leakage current thus flows through this throttle point only during the short opening phase of the injection valve member.

An advantageous embodiment is given in that the filling of a high-pressure chamber of a pressure booster can take place via the throttle points without an additional check valve. This allows both the needle lift damper and the valve to rest the high-pressure chamber to be constructed with little design effort.

In one embodiment variant of the solution proposed according to the invention, the control of the fuel injection device can take place via a 2/2-way valve. This permits a cost-effective overall construction, in which case pressure equalization can be achieved either via a filling throttle or a pressure relief valve.

With the solution proposed according to the invention, a pressure-controlled opening of the injection valve member can be achieved, which takes place at a speed that enables good atomization of the fuel during the injection into the combustion chamber. 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 can be influenced hydraulically, favors the small quantities during pre and post injection of the fuel injector and prevents fuel gases from being blown back into the seat area of the injection valve member, e.g. a nozzle needle.

A nozzle module with needle stroke damping of the fuel injector preferably comprises a flat seat that can be manufactured using simple processing steps. Lim to ensure high strength and to create few high-pressure sealing surfaces, the flat seat is carried out on the spring chamber giτ. The control room throttles can be installed in the spring holder. If face-ground nozzles are used (stroke = zero), the stroke of the injection valve element can be adjusted by means of appropriate thickness levels of the spring holder. A sensor disc and a sensor bolt can both 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 can be spherically ground on the nozzle side or on the sensor pin side in order to realize a dynamic seat adjustment.

drawing

The invention is described in more detail below with reference to the drawing.

It shows:

FIG. 1 shows a first embodiment variant of a needle stroke damping via a nozzle spring chamber that can be filled or relieved of pressure by an inlet / outlet throttle,

FIG. 2 shows a further embodiment variant of a needle stroke damping with a return line in the nozzle spring chamber in a work chamber of a pressure intensifier connected to it,

FIG. 3 shows a variant of a needle stroke damping with pressure relief valve,

FIG. 4 shows a further embodiment variant of a needle stroke damping, as shown in FIG. 3, in which the pressure relief valve according to FIG. 3 is replaced by a throttle point,

FIG. 5 shows the longitudinal section through an injector with needle stroke damping,

FIG. 6.1 the needle stroke damping above the injection valve element on an enlarged scale,

FIG. 6.2 shows the detail denoted by S in FIG. 6.1 on an enlarged scale,

FIG. 7.1 shows a section through an injector body with an injection valve member, which has a sensor bolt arranged between it and a valve piston,

FIG. 7.2 shows the detail V from the illustration according to FIG. 7.1 on an enlarged scale, FIG. 8.1 the graphic representation of a flat seat on the valve pin above one or 8.2 injection valve member,

9 shows the longitudinal section through a fuel projector with a sensor arrangement in the region of a stroke damping device.

design variants

FIG. 1 shows a first embodiment variant of a needle stroke damping by means of a nozzle spring chamber that can be filled or relieved of pressure by inlet / outlet throttles.

The fuel injection device shown in Figure 1 comprises a fuel injector 1, which is acted upon by a high-pressure fuel chamber under high pressure. In addition to the high-pressure storage chamber 2, the fuel injector 1, the fuel injection device according to FIG. 1 includes a metering valve 6, which in the embodiment variant shown in FIG. 1 is designed as a 3/2-way valve. The fuel injector 1 contains an injector body 3, on the combustion chamber end of which 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, which is indicated schematically here.

The fuel injector shown in FIG. 1 comprises a pressure intensifier 5, which has a working chamber 10 and a control chamber 11. Via a line 9, which extends from the high-pressure storage chamber 2 to the injector body 3 of the fuel injector 1, the working chamber 10 of the pressure booster 5 is pressurized with fuel under high pressure. Within the pressure intensifier 5, the working space 10 and the control space 11 are separated from one another by a piston 12. The piston 12 comprises a first partial piston 13 with a larger diameter and a second partial piston 14 with a smaller diameter than the first partial piston 13, the end face of which acts on a high-pressure chamber 15 of the pressure intensifier 5. In the injector body 3 there is an annular stop 16, 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. The piston 12 of the pressure booster 5 can be returned to its starting position by means of the return spring 17. The pressure intensifier 5 is assigned the metering valve 6, which is acted upon by the working chamber 10 of the pressure intensifier 5 via a feed line 19 and, in the switching position shown in FIG. 1, connects the feed line 19 to a control line 20, which in turn is in the control chamber 11 of the pressure intensifier 5 below the first partial piston 13 of the piston 12 opens. In addition, a return pressure 8 on the low-pressure side branches off from the metering valve 6, in which, with a corresponding change in the switching position on the metering valve 6, the control chamber 11 can be relieved of pressure in an opposite flow direction via the control line 20.

A fuel inlet 21 extends from the compression chamber 15 of the pressure booster 5 without the interposition of a non-return valve to a nozzle chamber 22 formed in the nozzle body 4. The nozzle chamber 22 encloses an injection valve member 29 that can be designed as a nozzle needle, for example. The fuel flows from the nozzle chamber 22 along an annular gap designated by reference number 33 in Direction towards the nozzle needle tip 34, which, in the stroke position shown in FIG. 1, closes injection openings 36 projecting into a combustion chamber 7 of a self-igniting internal combustion engine. The injection valve member 29 is pressurized on its end face 30 via a nozzle control chamber 25. The nozzle chamber 25 shown in the embodiment variant of the fuel injector according to FIG. 1 can be acted upon independently of the nozzle chamber 22, but also via the compression chamber 15 of the pressure booster 5. For this purpose, an inlet 23 to the nozzle control chamber 25 is provided from the compression space, which contains an inlet throttle point 24. In addition, the nozzle control chamber 25 is connected to the control chamber 11 of the pressure booster 5 via a connecting line 26, which contains an outlet throttle point 27. A closing spring element 28 is received within the nozzle control chamber 25 and 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 designed as an essentially cylindrical body, the end face 32 of which lies opposite the inlet throttle point 24 and closes the inlet throttle point 24 at maximum stroke of the injection valve member 29, so that a leakage current via the throttles 24, 27 occurs only during the short opening phase of the injection valve member 29.

The nozzle control chamber 25, which acts on the injection valve member 29, is flowed through by the compression chamber 15 via the inlet throttle point 24 and via 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 essentially determined 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 point 27. The opening or closing speed of the injection valve member 29 can thereby be specified independently of one another, in particular a slow opening of the inlet achieve spray valve member 29 and a quick closing of the same regardless of the respective setting of the other speed. Rapid closing of the injection valve member 29, which is preferably designed as a nozzle needle, is very important with regard to improving the emission values of a self-igniting internal combustion engine. By quickly closing the injection valve member 29, the quantity characteristics in ballistic needle operation can be kept flat, which increases the accuracy of the measurement. In the ballistic operation of the injection valve member 29, the latter is freely movable between the respective extreme stops.

In the illustration according to FIG. 1, the metering valve 6 designed as a 3/2-way valve is not activated and there is no injection. The pressure present in the high-pressure storage chamber 2 is present in the working chamber 10 of the pressure intensifier 5, further via the feed line 19 at the metering valve 6, via this and the control line 20 in the control chamber 11 of the pressure intensifier 5, furthermore via the connecting line 26 in the nozzle spring chamber 25 the pressure level prevailing in the high-pressure storage chamber 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 the compression chamber 15 for filling it. In the basic state shown in FIG. 1, all pressure spaces on the pressure intensifier 5, ie spaces 10, 11 and 15, are subjected to rail pressure, as a result of which the pressure intensifier 5 is pressure-balanced. The pressure intensifier 5 is not activated and there is no pressure boosting since the piston 12, comprising a first partial piston 13 and a second partial piston 14, is in its state 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 storage chamber 2, 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 opening force acting on the injection valve member 29 in the nozzle chamber 22 via the pressure shoulder 35. Due to the closing force exerted by the closing spring element 28 on the injection valve member 29, the injection valve member 29 remains in its closed position against the opening force acting on the pressure shoulder 35. The metering of the fuel, ie an injection process, is carried out by relieving the pressure in the control chamber 11 of the pressure intensifier 5. For this purpose, the metering valve 6 is activated and the control chamber 11 of the pressure intensifier 5 is separated from the system pressure supply, ie from the high-pressure storage chamber 2, and connected to the low-pressure return 8 , As a result, the pressure in the working chamber 10 of the pressure booster 5 drops, as a result of which the piston 12 is activated and pressure builds up in the compression chamber 15 of the pressure booster 5. With increasing pressure in the compression chamber 15, the pressure in the nozzle chamber 22 within the nozzle body 4 also rises via the fuel inlet 21. This increases 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 29 begins to open. At the same time, fuel flows from the compression space 15 into the nozzle spring space 25 and from there via the outlet throttle point 27 into the connecting line 26 into the work space 10. By designing the throttle cross sections of the inlet throttle point 24 and the outlet throttle point 27, a control pressure level can be set within the nozzle spring space 25, 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 space 15 to the nozzle spring space 25, since the end face 32 of the stroke limiter 31 bears against the ceiling of the nozzle spring space 25 and thus closes the connection 23 to the compression space 15. As a result, no loss can escape through the inlet throttle 24 during the injection process. The opening speed of the injection valve member 29 can accordingly be set and predefined via the ratio of the throttling points 23 and 24. As long as the control chamber 11 of the pressure intensifier 5 remains depressurized, ie the metering valve 6 connects the low pressure side return 8 to the control line 20, the pressure intensifier 5 remains activated and compresses the fuel within the compression space 15. The compressed fuel flows into the nozzle space 25 via the fuel inlet 21 , 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 injection is terminated by switching the metering valve 6 again, which can be designed both as a solenoid valve and also containing a piezo actuator. Directly controlled valves or servo valves can also be used as metering valves 6. By switching the metering valve 6 again, the control chamber 11 of the pressure booster 5 and the nozzle spring chamber 25 are separated from the low-pressure return 8 and the pressure level prevailing in the high-pressure storage chamber 2 is again applied. In the control chamber 11 and in the nozzle spring chamber 25, this pressure level builds up again, ie the pressure level in the high-pressure storage chamber 2. The pressure in the compression chamber 15 and in the control chamber 22, which act on the injection valve member 29, now drops to the pressure level prevailing in the high-pressure storage chamber 2. Rail pressure is present 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 moving the injection valve 29 into its needle seat on the combustion chamber side. The closing speed of the injection valve 29, ie the speed at which the injection valve member 29 moves into its seat on the combustion chamber side, can be influenced via the dimensioning of the outlet throttle point 27 in the connecting line 26 to the working chamber 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 is via the inlet 23 and the inlet throttle accommodated therein. position 24 open. After the pressure equalization within the fuel injection device, the piston 12 of the pressure booster 5 is returned to its starting position by the return spring 17, the compression space 15 being refilled with fuel via the line 23, which is now flowed through in the opposite direction, via the inlet throttle point 24.

The solution proposed according to the invention realizes a needle lift damper through 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 the small-volume capability of the fuel injector 1 can be improved without the need for an additional precision component in the form of a damping piston. The opening speed of the injection valve member 29 is determined via the cross-sectional relationships of the inlet throttle point 24 or the outlet throttle point 27, while the closing speed thereof is determined by the design of the cross-sectional area of the outlet throttle point 27. The opening and closing speeds of the injection valve member 29 can thus be set independently of one another, which in particular means a slow needle opening, i.e. favoring the small-quantity capability, and fast closing, i.e. prevents the fuel from continuing to flow into the combustion chamber towards the end of the combustion phase. Since the proposed needle lifting damper does not have any moving parts that have to be returned to their initial state after activation, the solution proposed according to the invention can also be used to perform multiple injections in close succession without restriction.

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

Faster filling of the compression space 15 of the pressure booster 5 can be achieved by an additional check valve to be provided. The proposed needle stroke damping can be realized in an advantageous manner even with difficult, ie limited installation space, since no additional components are required. The proposed needle stroke damping can also be used on a fuel injector 1 which contains a vario register injection nozzle, ie a plurality of injection cross sections 36, for example designed as concentric bolt circles, at the end of the nozzle body 4 on the combustion chamber side. In addition to a vario register nozzle, a coaxial nozzle needle can be inserted. are set, which can include two nozzle needles that open and close independently of one another.

FIG. 2 shows a further embodiment variant of a needle stroke damping with a return line from the nozzle spring chamber into a work chamber of a pressure intensifier connected to it.

The embodiment variant of a needle-stroke damper shown in FIG. 2 without additional precision components in the form of damping pistons differs from the embodiment variant of the solution according to the invention shown in FIG. 1 essentially in that the nozzle chamber 25 of the injection valve member 29 in this embodiment variant has a connecting line 40 between the nozzle spring chamber 25 and the Working space 10 of the pressure intensifier 5 can be connected. The outlet throttle point 27 is integrated in the connecting line 40 to the working space 10 of the pressure booster 5. While in the embodiment variant of the needle-stroke damper shown in FIG. 1, the control volume is discharged from the nozzle spring chamber 25 via the outlet throttle point 27 via the 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 into the return 8 on the low-pressure side, at In the embodiment variant of the needle-stroke damper shown in FIG. 2, the control quantity is diverted from the nozzle spring chamber 25 via the outlet throttle point 27 into the working chamber 10 of the pressure intensifier 5. With this solution, the energy losses due to the control quantity can be reduced and thus the hydraulic efficiency of the proposed fuel injector 1 can be improved, since the control quantity controlled from the nozzle chamber 25 is not completely relaxed, but is only relaxed to the pressure level prevailing in the working chamber 10.

In the embodiment variant of a nozzle needle damping shown in FIG. 2, the metering valve 6 is also designed as a 3/2-way valve, be it as a solenoid valve or as a piezo actuator. In addition, the metering valve 6 can be designed analogously to the illustration in FIG. 1 as a directly actuated valve or as a servo valve.

The pressure intensifier 5 is accommodated in the injector body 3 of the fuel injector 1 according to FIG. 2, analogous to the embodiment variant shown in FIG. 1. Here, too, the pressure intensifier 5 contains a piston 12, which can have a first partial piston 13 with an enlarged diameter and a second partial piston 14 with a reduced diameter. The booster piston 12 of the pressure booster 5 can be made from the mentioned partial pistons 13 and 14 both as a one-piece component and as a multi-part component. Analogously to the illustration in FIG. 1, the lower end face of the second partial piston 14 acts on the compression space 15, from which a fuel inlet 21 flows into the Dusenfederraum 25 leads. An inlet 23 branches off from the compression chamber 15 to the nozzle spring chamber 25, which contains an inlet throttle point 24.

According to the embodiment variant shown in FIG. 2, with a reduced power loss by controlling the control quantity from the nozzle spring chamber 25 into the working chamber 10 of the pressure booster 5, the opening speed of the injection valve member 29 can be designed by designing the cross sections of the inlet throttle point 24 and the outlet throttle point 27 of the connecting line 40 determine. The closing speed of the injection valve member 29, which is preferably designed as a nozzle needle, can be determined by a suitable dimensioning of the cross-section of the outlet throttle point 27 in the connecting line 40 from the nozzle spring chamber 25 to the working chamber 10 of the pressure booster 5, so that the opening or the closing speed of the injection valve member 29 can be predetermined independently of one another.

Except for the differences shown in the embodiment variant according to FIG. 2 in comparison to the embodiment variant shown in FIG. 1, the structure and function of the fuel injection device according to FIG. 2 correspond to the structure and function of the embodiment variant shown in FIG. 1 and described above of the inventive solution of a needle-stroke damper.

Figure 3 shows an embodiment of a needle stroke damping on a fuel injection device with a pressure relief valve.

According to this embodiment variant of the solution according to the invention, an inlet throttle point 50 is received in line 9 to the working space 10 of the pressure booster 5, via which the pressure pulsations occurring in line 9 are damped and an impermissibly high interior load on the high-pressure storage space 2 due to pressure vibrations, which increases the service life of the high-pressure storage space 2 can impair, is prevented. The pressure intensifier 5 is formed in the injector body 3 of the fuel injector 1 and comprises the working chamber 10 and the control chamber 11. The pressure intensifier piston within the pressure intensifier 5 comprises a first partial piston 13, which bears with its lower end face against a disk-shaped stop 18, which rests against a second partial 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 embodiment variants shown in FIG. 1 and FIG. 2 of a pressure intensifier 5 integrated in an injector body 3, the return spring 17 in the embodiment variant according to FIG. 3 is not accommodated in the working space 10 but in the control chamber 11 of the pressure intensifier 5. On the Compression chamber 15 at the lower end of the pressure booster 5 is supplied with fuel 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. The nozzle spring chamber 25 is connected to the control chamber 11 of the pressure booster 5 via the connecting line 26 with the outlet throttle point 27.

The injection valve member 29, pressurized via the nozzle spring chamber 25 and via the pressure present in the nozzle chamber 22, opens or closes in an analogous manner to the embodiment variant in FIG. 1 by depressurizing or pressurizing the control chamber 11 by actuating the metering valve 6 or 56.

In contrast to the embodiment variant of a needle stroke damping on a fuel injection device shown 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 return 8 on the low pressure side. Furthermore, 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 relief duct 52 which extends from a first piston part 53 into a second piston part 57 of the pressure relief valve 51. The first piston part 53 of the pressure reduction valve 51 facing the control line 20 is enclosed by a valve chamber 54, in which the control line 20 opens from the working chamber 10 of the pressure booster 5. The second piston part 57 of the pressure relief valve 51 is acted upon by a valve spring 55 which is received in a cavity of the pressure relief valve 51, which is connected via a connecting line (without reference numerals) to the metering valve 56 constructed as a 2/2-way valve.

While the opening speed of the injection valve member 29 in the nozzle body 4 of the fuel injector 1 can be predetermined by the ratio of the throttle cross sections of the inlet throttle point 24 or the outlet throttle point 27, the control line 20 to the control chamber 11 of the pressure booster 5 can be rapidly reduced by integrating a pressure relief valve 51 of the pressure intensifier 5 and thus a quick needle closing towards the end of the injection phase can be guaranteed. The structure and mode of operation of the embodiment of a needle stroke damping shown in FIG. 3 essentially corresponds to the structure and function of the embodiment variant of a needle stroke damping shown in FIG. 1 on a fuel injection device. In contrast to the embodiment variant shown in FIG. 1, an inlet throttle point 50 is accommodated in line 9 of the fuel injection device according to the embodiment variant in FIG. 3, and a pressure relief valve in control line 20 between working chamber 10 and metering valve 56, with metering valve 6 in the embodiment variant shown in FIG in contrast to the embodiment variant in FIG. 1 as 2/2 Way valve can be formed. The design of the metering valve 6 as a 2/2-way valve allows an inexpensive overall construction.

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

The embodiment variant of a needle stroke damping shown in FIG. 4 via inlet throttle points 24 or outlet throttle points 27 assigned via a nozzle control chamber 25 also includes a metering valve 6 which is designed as a 2/2-way valve 56. In contrast to the embodiment variant of a needle stroke damping shown in FIG Pressure intensifier 5 opens. In accordance with this embodiment variant, control volumes are controlled from the nozzle spring chamber 25 via the connecting line 26 into the working chamber 10 of the pressure booster 5, the outlet throttle point 27 being integrated in the connecting line 26. However, according to the embodiment variant shown in FIG. 4, the control chamber 11 of the pressure booster 5 is relieved of pressure via the control line 20 which is flowed through in the opposite direction. Via branch 60 and throttle 61, pressure builds up in control chamber 11 after the end of injection.

The embodiment shown in FIG. 4, using a metering valve 56 designed as a 2/2-way valve, permits nozzle needle damping by flowing through the nozzle spring chamber 25 via the inlet throttle point 24 in the inlet 23, which extends from the compression chamber 15 of the pressure booster 5, as well as via the outlet throttle point 27 received in the connecting line 26. In this embodiment variant, analogously to the embodiment variants shown in FIGS. 1 to 3, the opening speed of the injection valve member 29 can be achieved by designing the throttle cross sections of the inlet throttle 24 or the outlet throttle point 27, while the closing speed is preferably as Nozzle needle trained injection valve member 29 is determined by the dimensioning of the cross-sectional area of the outlet throttle point 27 in the connecting line 26. Also in this embodiment variant, independent of the embodiment variants shown in FIGS. 1 to 3, the opening speed can be set independently of the closing speed of the injection valve member 29.

The embodiment variants of a needle stroke damping shown in FIGS. 3 and 4 can also be advantageously used in conjunction with a vario register nozzle, with multiple injection cross sections that can be released or closed independently of one another are used; In addition, use of the needle stroke damping shown in FIGS. 3 and 4 is also possible on a coaxial nozzle needle, which may include nozzle needle parts which are guided into one another and can be actuated independently of one another.

5 shows a longitudinal section through a force material injector with needle stroke damping.

FIG. 5 shows the longitudinal section through the fuel injector 1, in the upper region of which the metering valve 6 - here designed as a solenoid valve - is arranged. A high pressure inlet 70 is formed on the side of the injector body 3, via which the fuel under high pressure in the injector body 3, i.e. the working space of a pressure intensifier 5 is supplied. A rod filter element that filters the fuel can be accommodated in an advantageous manner in the screw-in connector designated by reference numeral 70.

The pressure intensifier 5 integrated in the injector body 3 comprises a first partial piston 13 and the second partial piston 14, the first partial piston 13 being acted upon by the return spring 17, which is supported on the injector body 3. The end face of the second partial piston 14 acts on a compression space 15, which is arranged symmetrically to the line of symmetry of the injector body 3. From this extends the inlet 23 with an integrated throttle point 24. The inlet 23 to the nozzle control chamber 25 follows a throttle disc 72. A damping disc 77 is arranged within the throttle disc 72, which delimits the nozzle control chamber 25. The valve spring 74 and the valve pin 73, on which a flat seat ring edge 76 is formed, are located in the nozzle control chamber / damping chamber 25 (cf. FIG. 6.2). The flat seat ring edge 76 and the stroke limiter 31 of the throttle disk 72 form the stroke limitation of the injection valve member 29 and the valve closing function for the inlet throttle 24. The injection valve member 29 is partially shown in longitudinal section according to FIG. Analogous to the embodiment variants of stroke damping shown schematically in FIGS. 1 to 4, the injection valve member 29 is, according to the longitudinal section through the fuel injector 1, enclosed by a nozzle chamber 22 in which a conically configured pressure shoulder 35 is formed on the circumference of the injection valve member 29. 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 clamping 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 representations according to FIGS. 6.1 and 6.2.

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

Above the end face 86 of the injection valve member 29, a sensor bolt 85 is shown, which represents part of the stroke limiter 31 according to the embodiment variants in FIGS. 1 to 5 and is used for path detection by means of a sensor. The sensor pin 85 is enclosed by a disk-shaped element 84 which delimits a cavity in the lower region. A leak oil hole opens into the cavity of the disk 84.

The sensor pin 85 and the disk-shaped element 84 are optional components and are not absolutely necessary for the function of the injection valve member stroke damping. As part of a functional expansion for stroke measurement, they can be integrated into the fuel injector if required.

According to the representation of the injection valve member 29 in the nozzle body 4 of the fuel injector 1, the latter is enclosed by the nozzle chamber 22, which is supplied with fuel under high pressure via an opening 89, the opening 89, i.e. a nozzle chamber inlet which represents the mouth of the fuel inlet line 21 from the compression chamber 15 shown in FIGS. 1, 2, 3 and 4. The fuel flows from the nozzle chamber 22 along an annular gap 33 in the direction of the nozzle needle tip 34 of the injection valve member 29 (cf. FIG. 7.1). At the lower end in the area of the nozzle needle tip 34, a combustion chamber-side seat 91 is formed on the injection valve member 29 as shown in FIG. 9. Between the nozzle chamber 22 and the nozzle needle tip 34, the injection valve member 29 can be provided with a number of free surfaces distributed symmetrically around the circumference of the injection valve member 29, along which the fuel flows in the direction of the nozzle needle tip 34 within the annular gap 33, which surrounds the injection valve member 29 in a ring , In the area of the nozzle chamber 22, the injection valve member 29 is provided with a conical pressure shoulder 35 on its outer circumferential surface analogous to the schematic representations here according to FIGS. 1 to 4.

Figure 6.2 shows the area labeled S in 6.1 on an enlarged scale.

6.2 shows that the valve spring 74 surrounds both the stroke limiter 31 and part of the valve pin 73. In the upper area of the valve pin 73, ie on its end face opposite the end face of the stroke limiter 31, a pointed depression 80 is provided as well as a flat seat ring edge 76. In contrast, the end face is of the stroke limiter 31 is formed as a flat surface. According to the illustration in FIG. 6.2, the flat seat ring edge 76 comprises a first bevel 81, which is formed at a first bevel angle, so that the flat seat 76, seen in the radial direction, slopes slightly outward with respect to the peripheral surface of the valve pin 73. As can further be seen from the illustration according to FIG. 6.2, the lower side of the valve pin 73 - with a spherical design - lies opposite the end face of the sensor pin 85.

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

In contrast to the illustration according to FIG. 6.1, the valve pin 73 in the embodiment variant according to FIG. 7.1 is designed with a greater axial length, the stroke limiter 31 being not formed on the throttle disk 72 according to this embodiment variant. The valve bolt 73 lies with its end face opposite the inlet 23 directly against the damping disk 77. This and the throttle disk 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, for example in the form of a nozzle needle, comprises a pressure shoulder 35. Open areas 90 are also 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 bolt 85, the end face of which is opposite a spherical end face of the valve bolt 73, is enclosed by a disk-shaped element 84, which comprises a cavity on which a leakage oil line branches off. The injection valve member 29 bears with its end face 86 against a corresponding lower end face of the sensor bolt 85.

Figure 7.2 shows the reproduction of the section designated V in Figure 7.1 on an enlarged scale.

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

At the upper end of the valve pin 73, a seat geometry, designated by reference numeral 79, is formed. This seat geometry 79 as shown in Figure 6.2 is by characterized a sharp depression 80. The pointed depression 80 merges at a radial distance into a first bevel 81, so that the seat geometry 79 is formed both by the pointed depression 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 FIGS. 1 to 4.

Figure 8.1 shows a second embodiment of the seat geometry. The valve pin 73 as shown in FIG. 8.1 is enclosed by the damping disk 77 and acted on by the valve spring 74. Below the valve pin 73 is the sensor pin 85, which in turn is enclosed by a disk element 84, which comprises a cavity. A leak oil hole opens into the cavity of the disk element 84. LInside the sensor pin 85 extends the injection valve member 29, which rests with its upper end face 86 on the lower plane surface 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 the nozzle chamber 22 of the nozzle body 4 at an outlet 89.

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 is enclosed by the damping disk 77. The valve spring 74 is supported on the one hand on a lower, ring-shaped extension of the valve pin 73 and on the other hand on an annular adjusting disk 88 arranged below the throttle disk 72.

The difference from the embodiment variant 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 flat 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 vibrations between the compression space 15 and the nozzle control space 25, which results in 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 throttles are not integrated in the damping disk 77, but can be designed as interchangeable disks. As a result, these can be easily exchanged as part of the coordination or manufacturing process. Figure 9 shows the longitudinal section through a fuel injector with a stroke sensor arrangement in the upper region of the injection valve member.

9 shows that a sensor disk element 84 is accommodated 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 in the form of 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, which is surrounded by a fuel inlet 21 (not shown in FIG. 8) which is connected to the compression chamber 15 of the pressure intensifier 5 , pressurized with fuel under high pressure. The fuel under high pressure flows from the nozzle chamber 22 along the annular gap 33 along the free flow area 90 formed on the circumference of the injection valve member 29 to the nozzle needle tip 34. In the illustration according to FIG. 8, the tip of the injection valve member 29, i.e. the nozzle needle tip 34, in its combustion chamber-side seat 91.

The arrangement of a sensor disk element 84, which interacts with a stroke sensor 96, allows the movement of the injection valve member 29 in the vertical direction within the nozzle body 4 to be measured and the needle speed reached, the beginning and end of movement of the injection valve member 25 to be measured. Through the application of this measuring system, a closed control loop for the final adjustment and for a possibly necessary map adjustment of a fuel injection system can be represented, with which a fault diagnosis of the fuel injection system as well as a storage of operating data can be made, which can be read out in the context of the constantly recurring maintenance intervals of the self-igniting internal combustion engine.

The embodiments shown in the above representations of an injection valve member stroke damping represent embodiment variants in which the nozzle module, that is to say the nozzle body 4 with the ring-shaped configured elements 72, 77, 78 and 84 above it, can be implemented in order to quickly close according to the proposed invention to achieve the injection valve member 29, and to measure its opening speed by designing the inlet throttle point 24 and the outlet throttle point 27 in such a way that the ability to produce small quantities is improved without the need for an additionally required precision component. LIST OF REFERENCE NUMBERS

Fuel injector high-pressure accumulator injector nozzle body pressure intensifier metering valve combustion chamber low-pressure side return feed line working space control chamber piston first part piston second part piston compression chamber abutment return spring restoring spring stop feed metering valve control line control chamber fuel inlet nozzle chamber nozzle chamber inlet Dusenfederraum inlet orifice nozzle control chamber connecting pipe nozzle spring chamber-control chamber pressure intensifier flow restrictor closing spring element injection valve member (nozzle needle) end face travel stop face annular gap nozzle needle tip pressure shoulder Einspritzöffhungen Connection line nozzle spring chamber - work area pressure intensifier mouth point Connection line in the work space pressure intensifier

Inlet throttle

Pressure reduction valve

Pressure relief channel first piston part

valve chamber

valve spring

Metering valve (version as 2/2-way valve) second piston part

junction

Branch throttling point

High pressure inlet injector nozzle clamping nut throttle plate valve pin valve spring centering pin flat seat damping plate

Seat geometry pointed lower first bevel angle flat surface seat spring chamber floor sensor disc sensor pin end face injection valve element / sensor pin

Adjustment disk for nozzle chamber inlet, free surfaces, nozzle needle seat on the combustion chamber side 94 Chamfer

95 crowned edition

96 stroke sensor

Claims

claims

1. Fuel injection device for injecting fuel into the combustion chambers (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) having a work chamber (10) and a control chamber (11), which are separated from each other by a piston (12, 13, 14) and a pressure change in the control chamber (11) of the pressure booster (5) causes a pressure change in a compression chamber (15) via a fuel inlet (21) A nozzle chamber (22) is applied, which surrounds an injection valve member (29), characterized in that a nozzle control chamber (25) acting on the injection valve member (29) is connected both from the high pressure side via a line (23) from the compression region (15, 21, 22, 33) can be filled and connected on the outlet side via a line (26, 40) containing an outlet throttling point (27) to a space (11) of the pressure booster (5) in i st, and can also be connected to the pressure booster (5) via a connecting line (40) with a discharge throttle point (27).

2. Fuel injection device according to claim 1, characterized in that the opening speed of the injection valve member (29) by the ratio of

Cross sections of the inlet throttle point (24) to the outlet throttle point (27) is determined.

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 outlet throttle point (27).

4. Fuel injection device according to spoke 1, characterized in that the injection valve member (29) comprises a stop surface (32) which closes the inlet-side throttle point (24) when the maximum stroke of the injection valve member (29) is reached.

5. Fuel injection device according to spoke 1, characterized in that the nozzle spring chamber (25) via a connecting line (26) with outlet throttle point (27) in the control chamber (11) of the pressure intensifier (5) can be depressurized.

6. Fuel injection device according to spoke 1, characterized in that the nozzle spring chamber (5) via a connecting line (40) with outlet throttle point (27) in the working chamber (10) of the pressure booster (5) can be connected.

7. Fuel injection device according to spoke 1, characterized in that the working space (10) of the pressure intensifier (5) via a feed line (9) from the high-pressure storage space (2) can be filled.

8. Fuel injection device according to spoke 7, characterized in that the line (9) comprises a pressure pulsation between the fuel injector (1) and high-pressure storage space (2) opposing throttle element (50).

9. Fuel injection device according to spoke 1, characterized in that for activating the pressure intensifier (5) whose control chamber (11 via a control line (20) releasing or closing metering valve (6, 56) is provided.

10. Fuel injection device according spoke 9, characterized in that the metering valve (6) is designed as a 3/2-way valve, which has a low-pressure side outlet (8).

11. Fuel injection device according spoke 9, characterized in that the metering valve (56) is designed as a 2/2-way valve, which has a low-pressure side outlet (8).

12. A fuel injection device according to claim 1, characterized in that a stroke limiter (31) arranged above the injection valve member (29) comprises a valve piston (73), a spring element (28, 74) acting on the valve piston (73) in the closing direction of the injection valve member (29) ) is included.

13. Fuel injection device according to spoke 12, characterized in that a flat seat (76) is formed between the valve pin (73) and the stroke limiter (31).

14. Fuel injection device according to claim 13, characterized in that the flat seat (76) is formed a first bevel (81) and a depression (80).

15. Fuel injection device according to spoke 13, characterized in that the flat seat (76) comprises a bevel (81).

16. Fuel injection device according spoke 12, characterized in that the flat seat (76) is formed on the spring chamber of the nozzle spring chamber (25).

17. The 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 end face of the valve bolt (73).

18. The fuel injection device according to claim 12, characterized in that the throttle elements (24, 27) are formed in interchangeable disc elements (72).

19. Fuel injection device according to claim 12, characterized in that the valve pin (73) on its sensor pin (85) facing end face is made in a spherical contour (95).

20. A fuel injection device according to claim 12, characterized in that the valve pin (72) and the sensor pin (85) is assigned a stroke sensor arrangement (96) which serves to detect the path of the injection valve member (29) within the fuel injector (1).