DE102007006083A1 - Fuel injector for hydraulically boosted injection system has pressure boost valve for hydraulically assisted closure of nozzle needle that at least partly closes fuel feed channel when injection finishes - Google Patents

Abstract

The fuel injector has a pressure boost valve (300) for hydraulically assisted closure of a nozzle needle (220). The valve is provided in a fuel feed channel (110) on the high pressure side of the fuel injector (1) so that fluid pressure from fuel (2) at high pressure in the feed channel acts on a rear side of the nozzle needle via the valve when injection finishes, whereby the pressure boost valve at least partly closes the fuel feed channel. An independent claim is also included for a hydraulically boosted injection system.

Description

The The invention relates to a fuel injector for a motor vehicle, in particular a fuel injector for a hydraulically reinforced Injection system of a commercial vehicle for injecting fuel into a combustion chamber of an engine. Furthermore, the invention relates to a hydraulically reinforced injection system especially for a commercial vehicle with a fuel injector according to the invention.

For a good Preparation of a fuel-air mixture must be fuel, depending after combustion process, with a pressure of more than 2,000bar by means of a fuel injector into a combustion chamber of an engine injected and with the highest possible accuracy per injection (multiple injection per injection cycle). To make a compromise between low fuel consumption and compliance with emission limits (Exhaust gases and noise of the engine), it is necessary to start the injection process precise to control. Here are essential parameters: The start of injection (Multiple injection per injection stroke), the injection duration, the respective injection end and dynamic behavior of a nozzle needle at the beginning and at the end of the injection. Because very high fuel pressures necessary are high demands on the dynamic behavior of the Fuel injector.

With Fuel injectors equipped Diesel engines are prone to soot emissions, because an amount of fuel at the end of an injection only with little Pressure is introduced and therefore atomization of the fuel droplets insufficient is. To prevent this is a fast closing of a nozzle needle the fuel injector required, on the one hand the amount of fuel at the end of the injection with more pressure to introduce and on the other hand, a "drop" of the fuel injector to prevent. That is, the closing of the nozzle needle of the fuel injector should be supported be to a desired closing characteristic the nozzle needle to reach.

In hydraulically amplified injection systems, in which a pressure control on an engine oil side and a pressure boost on a fuel side is made (see also the prior art in 1 the drawing), conventional methods for a hydraulically assisted closing of the nozzle needle at the end of an injection process are not applicable.

To the conventional one Methods are included z. B. that an energy of a Absteuerung from a switching valve is passed into a pen of the fuel injector, so a fluid pressure on a nozzle needle back to generate, and the nozzle needle hydraulically supported in its closed position to move. As with hydraulically amplified injection systems whose Pressure control on the engine oil side is made, the cycle of a start and end control over the Switching valve in the engine oil it is not possible a Absteuerstoss in to redirect the pen of the fuel injector, because this means would, the engine oil side to connect to the fuel side.

It It is an object of the invention to provide an improved fuel injector to disposal to deliver. In particular, it is an object of the invention to provide a improved fuel injector for a pressure-boosted injection system to disposal to provide its pressure control on a motor oil side and its pressure boost is made on a fuel side. Here is a with a fuel injector according to the invention equipped Internal combustion engine low soot emissions exhibit.

According to the invention is a under high pressure fuel, the in the prior art at a termination of the injection into an inlet of the fuel injector relaxed, deflected into a pen or to a nozzle needle back. This leads to a hydraulically assisted, faster Shut down the nozzle needle at the end of an injection process.

According to the invention is a Fuel injector with a pressure booster valve for hydraulically assisted closing of nozzle needle to disposal provided, wherein the pressure booster valve such on or in a high pressure side fuel supply passage of the fuel injector it is provided that the pressure booster valve at a termination an injection of the fuel injector, a fluid pressure, from under high pressure fuel in the fuel inlet channel, in closing direction the nozzle needle on the nozzle needle allow to act.

The hydraulically assisted, fast closing the nozzle needle leads to a higher middle one Injection pressure of the fuel injector and thus lower soot emissions an internal combustion engine.

Here, a pressure control of the fuel injector is performed on an engine oil side, whereas the pressure increase of the fuel injector on a fuel side (fuel to be injected) is made. According to the invention closes at a Absteuern on the engine oil side, the pressure boosting valve at least partially the fuel inlet channel and passes the fuel under high pressure in the spring chamber or to the nozzle needle back, whereby the nozzle needle, a force is impressed in its closing direction. Ie. it becomes the high-pressure force diverted material located in a nozzle needle side portion of the fuel inlet channel. Preferably, the closing of the fuel inlet channel by the pressure boost valve takes place completely.

In an embodiment The invention is the pressure booster valve a 3/2-way valve, which when applying under high pressure standing fuel, a valve member of the pressure booster valve moved into a second valve seat (biased pressure booster valve), if the valve member is not already on this. hereby The room is off the nozzle needle back sealed against the high pressure and the fuel injector works in a conventional Wise. Ie. the high-pressure fuel enters a injection the fuel injector, wherein the fuel injector an injection as before.

at the completion of the injection is deactivated on the engine oil side, resulting in a pressure drop on one side of the valve member of the 3/2 Way valve leads, so that the valve member from the second valve seat in the first Valve seat moves. This has the consequence that now a fluid connection from nozzle needle side Section of the fuel inlet duct is created to a room the adjacent to the nozzle needle back lies. Preferably, this space is the spring space in the spring holder of the fuel injector. This relaxes the nozzle needle side section the fuel inlet channel fuel in this for Nozzle needle back adjacent room and raised thereby a pressure on the nozzle needle back, which adds an extra closing force for the nozzle needle is produced.

hereby results according to the invention over the State of the art a double advantage. By omitting one check valve in the fuel inlet duct downstream of a pressure-generating Piston and the inventive provision the pressure booster valve, results within the fuel inlet channel at the end of a Injection a faster pressure reduction and at the same time a pressure build-up im to the nozzle needle back neighboring room. Ie. the nozzle needle can due to two events more precise or close faster. On the one hand due to the rapid pressure reduction in the fuel inlet duct and on the other hand by a force on the nozzle needle back through the inventive provision the pressure booster valve is caused.

One further inventive advantage is that an energy for pressure assisted closing the nozzle needle does not have to be taken from a high pressure. Ie. it becomes one Reservoir no energy and therefore no pressure deprived, since that still existing high pressure volume anyway in a low pressure range relaxed.

By a choice of the position of the pressure booster valve and / or a Length of the Valve channel and / or a position of the mouth of the valve channel in the Spring chamber or nearby the nozzle needle back let yourself determine when the print support should work and / or how big this is. The nearer the pressure boost valve at an injection nozzle the fuel injector is provided, the faster is a printing support effective. It is also essential whether a mouth the valve channel above or below a displaceable in the spring chamber mounted locking piston opens possibly over a needle piston on the nozzle needle back acts. It should be noted that the pressure support available High pressure volume and thus the stored energy the smaller is, the closer the pressure boost valve at the injection nozzle is arranged.

In an embodiment The invention is the closing piston with a small clearance in the spring chamber, so that it acts as a piston can. ends the valve channel of the pressure booster valve in the spring chamber, so the to the nozzle needle opposite Side of the closing piston, so can the closing piston as a pressure booster piston acting, whereby a force effect of a pressure pulse in the fuel by compared to the nozzle needle back larger area of the closing piston is reinforced. However, it is also possible the estuary of the valve channel on the back to the nozzle needle back facing side of the closing piston z. B. still in the spring chamber or on the needle piston or directly adjacent to the nozzle needle back provide, and there existing, relatively small volume to pressurize with the fuel pressure pulse. Please note that the pressure in this small volume until the beginning of the next injection is dismantled again. Of course, this also applies to the others embodiments the invention.

In embodiments The invention is the pressure booster valve at one longitudinal end the spring chamber provided in the spring holder, wherein the valve channel at this longitudinal end opens in the spring chamber. It is also possible the pressure booster valve according to the invention provide laterally on the spring chamber, in which case also the valve channel preferably opens laterally into the spring chamber. In addition, it is possible the Valve channel at the nozzle needle back, on the needle piston, which may optionally be faceted, or in nearby of the closing piston flow allow. In this case, the pressure boost valve is also preferred adjacent to this estuary intended.

at the pressure intensifier valve according to the invention is a nozzle needle side Section of the fuel inlet channel always in a fluid communication either with the adjacent section of the fuel feed channel or the valve channel. Ie. the nozzle needle side portion of the fuel inlet channel none of the two positions of the valve member is closed.

The Pressure booster valve according to the invention can z. B. as a ball valve with two conical valve seats, as a hemispherical valve with a cone-shaped Valve seat and a flat seat or as a plate valve with two flat seats be educated.

is the pressure booster valve according to the invention designed as a plate valve, so is a plate-shaped valve member within a valve disc (housing) of the pressure booster valve linearly guided and preferably not biased. However, it is possible, the plate-shaped valve member to bias, in which case the valve member biased in one direction is, in which it at least partially closes the fuel inlet and thereby opens the valve channel to the spring chamber.

The disc-shaped Valve member may have a valve member bore which serves for pressure support. Here, the valve member bore is preferably designed such that it allows a pressure build-up in the spring chamber. That is, an outlet throttle geometry the spring chamber allows a lower fluid flow (pressure reduction), as the valve member bore, and so a pressure build-up in the spring chamber possible at a time is where an injection takes place. To a cavitation reduction in the fuel inlet passage, the valve member bore can be so in the valve member be provided that they have a permanent fluid communication between creates the fuel inlet channel and the valve channel.

One Pressure reduction in the spring chamber takes place through an outlet throttle. These is preferred by an annular gap between the guided in the spring holder closing piston and an inner wall of the spring chamber. A space adjoining the rifle butt is then emptied through a drain hole, which preferably does not is designed as a fluid throttle, but designed as such can be. Furthermore, a pressure in the spring chamber by a fluid throttle be reduced in the pen holder. This can additionally or optionally to the annular gap choke between closing piston and spring chamber inner wall be provided.

Further embodiments The invention results from the remaining dependent claims.

The Invention will be described below with reference to exemplary embodiments with reference on the attached Drawing closer explained. In the drawing show:

1 a hydraulic circuit diagram of an injection system according to the prior art;

2 a hydraulic circuit diagram of an injection system according to the invention;

3 a foot assembly of a fuel injector according to the invention with a pressure booster valve according to the invention;

4 a hydraulic circuit diagram of a first embodiment of the fuel injector according to the invention;

5 a hydraulic circuit diagram of a second embodiment of the fuel injector according to the invention;

6 a hydraulic circuit diagram of a third embodiment of the fuel injector according to the invention;

7 a hydraulic circuit diagram of a fourth embodiment of the fuel injector according to the invention;

8th a three-dimensional view of a pressure booster valve according to the invention, in which a valve member is plate-shaped;

9 a centrally cut view of the 8th ;

10 a second embodiment of the plate-shaped valve member;

11 a third embodiment of the plate-shaped valve member; and

12 a foot assembly of a fifth embodiment of the fuel injector according to the invention.

The following versions relate to a hydraulically amplified fuel injector, wherein a translation piston a ruling in a rail high pressure hydraulically ver strengthens and so very high injection pressures can realize the fuel injector. However, the invention is not limited to such a hydraulically amplified fuel injector, but can on all Fuel injectors, such. As common rail injectors or pump-nozzle injectors be applied.

1 shows a hydraulically amplified Ein Injection system according to the prior art, in which a pressure control on an engine oil side 10 and a pressure boost on a fuel side 20 is made. For an initialization of an injection process of an injector 1 of the injection system is a fluid high pressure in the rail 400 via a switching valve 410 with a first volume 421 within a hydraulic amplifier 420 connected. This first volume 421 acts on a piston 422 the hydraulic amplifier 420 that has a second volume 427 and an associated second piston 424 having, wherein the two pistons 422 . 424 preferably rigidly connected to each other. Here, the piston points 422 a larger hydraulically effective surface than the piston 424 on. According to a surface ratio of the two pistons 422 . 424 becomes the pressure in the second volume 427 the hydraulic amplifier 420 elevated. The second volume contains fuel 2 from a fuel supply 500 ,

This in the fuel 2 translated high pressure is via a check valve 160 a fuel inlet channel 110 on the high pressure side of the fuel injector 1 supplied and opens against a spring force from a biasing spring 122 a nozzle needle 220 of the injector 1 and an injection process begins. For a termination of the injection process, the switching valve 410 in the in 1 shown position and the first volume 421 the hydraulic amplifier 420 with a drainage 402 connected. Furthermore, the hydraulic booster has 420 a piston return spring 426 on whose space within the hydraulic booster 420 also with a drainage 428 is in fluid communication. A space of the piston return spring 426 facing room of the piston 424 is also with a drainage 429 in fluid contact. Preference is given to the drainage 428 in the engine oil 3 and the drainage 429 in a reservoir for the fuel 2 ,

By a hydraulically amplified fuel injector, it is possible to work in a line system with low pressure, which is easier manageable, and only in the fuel injector to generate the required pressure itself. By increasing the pressure, atomization of the fuel can be improved, which improves mixture preparation within the combustion chamber and thus reduces the formation of soot. Furthermore, one achieves a more homogeneous combustion process, which can reduce nitrogen oxide emissions. The invention is also applicable to injection systems or injectors whose pressure control and pressure boost on the fuel side 20 is made.

2 now shows a schematic hydraulic circuit diagram of an injection system according to the invention or a fuel injector according to the invention 1 , On the engine oil side 10 preferably no change takes place. However, it is possible in one embodiment of the invention, the piston return spring 426 (in 2 not shown) omit. On the fuel side 20 According to the invention, the check valve 160 omitted and a pressure booster valve 300 in or on the fuel inlet channel 110 intended. Ie. it becomes the check valve 160 through the pressure boost valve 300 replaced.

The pressure boost valve 300 Preferably, a 3/2-way valve is in one position the fuel inlet channel 110 at least partially obstructed, with a nozzle needle side portion 112 of the fuel inlet channel 110 from the remaining fuel inlet channel 110 that in the second volume 427 the hydraulic amplifier 420 opens, at least partially separated. In this partial, but preferably complete blocking of the fuel inlet channel 110 lifts a valve member 310 the pressure booster valve 300 from his second valve seat 302 from, with a valve channel 320 from the nozzle needle side section 112 of the fuel inlet channel 110 to a spring chamber 120 or a nozzle needle back 224 is opened.

Ie. at a Absteuern the switching valve 410 , ie when moving a valve member of the switching valve 410 in the in 2 shown position (reduction of the high pressure in the first volume 421 the hydraulic amplifier 420 ), the second volume relaxes 427 the hydraulic amplifier 420 , where the pressure in the fuel inlet channel 110 upstream of the pressure boost valve 300 begins to decrease. This results in one side of the valve member 310 to a pressure drop, so that the valve member 310 , possibly supported by a spring 314 (please refer 3 ), from the second 302 into the first valve seat 301 moves and the nozzle needle side section 112 of the fuel inlet channel 110 from the remaining fuel inlet channel 110 separates. The in the nozzle needle side section 112 of the fuel inlet channel 110 Existing high pressure escapes through the valve channel 320 in the spring chamber 120 or a space adjacent to the nozzle needle back 224 , increases the pressure there and shapes the nozzle needle 220 a force in its closing direction. The spring chamber 120 or the space adjacent to the nozzle needle back 224 is via an outlet throttle 130 with a fuel reservoir (tank) or a fuel supply, which may be under low or medium pressure, hydraulically connected. Here is the outlet throttle 130 such that the pressure in the spring chamber 120 or at the nozzle needle back 224 is substantially reduced for a subsequent injection or has a certain value for a subsequent main injection.

It is possible in preferred embodiments of the invention, the outlet throttle 130 in a penholder body 102 (please refer 3 ) of a spring holder 100 of the injector 1 to be replaced by another outlet throttle. Such an outlet throttle 132 is then preferred as an annular gap choke 132 between a piston 140 and an inner wall of the pen holder body 102 educated. This is the piston 140 formed spherically at its substantially circular circumference. Ie. the inner wall of the spring holder body 102 and the piston 140 form a fluid throttling annular sealing gap between them, wherein the pressure in the spring chamber 120 can relax in a room adjacent to it. This space is then over a preferably unthrottled drain hole 134 emptied. Such embodiments of the invention are in the 2 and 3 dashed and in the 4 to 7 , as well as the 12 not shown in dashed lines. The reverse is the case with the outlet throttles 130 in the spring holder body 102 are formed. In the present embodiments, the piston 140 as a closing piston 140 for the nozzle needle 220 formed, wherein the space below the closing piston 140 or a space above the nozzle needle 220 through the drain hole 134 can be emptied. The outlet throttle 132 in interaction with the drain hole 134 is preferably designed as above.

At a driving (this position of the valve member of the switching valve 410 is in 2 not shown) of the switching valve 410 , So a fluid connection of the first volume 421 the hydraulic amplifier 420 with the high-pressure rail 400 or another high pressure source (fuel 2 or engine oil 3 ), becomes a pressure in the second volume 427 the hydraulic amplifier 420 and starting in the fuel inlet channel 110 built up. Does the high pressure in the fuel inlet passage 110 to the valve member 310 the pressure booster valve 300 , so the valve member moves 310 in his second valve seat 302 back, thus closes the inlet via the valve channel 320 to the spring room 120 or to the nozzle needle back 224 and gives the nozzle needle side section 112 of the fuel inlet channel 110 free, whereby an injection can begin. A tax deduction then takes place again as described above.

When pressure booster valve according to the invention come medium-actuated valves, in particular medium-actuated 3/2 way valves in question. A preferred embodiment of the pressure booster valve according to the invention 300 is a sphere, hemisphere (see 3 ), Partial ball, mushroom or plate valve (see 8th to 11 ).

3 shows a foot assembly of a fuel injector according to the invention 1 with a pressure boost valve 300 its valve member 310 is designed as a hemisphere. However, it is also possible, the valve member 310 form teilkugel-, ball or mushroom-shaped, wherein in the latter embodiment of the valve member 310 a "stem" of the mushroom in the biasing spring 314 is guided. It should be noted that a fluid passage cross section between the stem and biasing spring 314 is big enough.

The in 3 shown fuel injector 1 points inside an injection nozzle 200 a between a closed and an open position back and forth movable nozzle needle 220 on. On the nozzle needle 220 acts a biasing spring 122 over the closing piston 140 and a needle piston 145 with one by the spring constant of the biasing spring 122 certain closing force. In other embodiments of the invention, it is possible to 140 and needle piston 145 to train in one piece. Further, it is possible to use the biasing spring 122 directly on the nozzle needle back 224 to act. The biasing spring 122 is between the closing piston 140 and an upper longitudinal end of the spring chamber 120 clamped. A pressure shoulder 226 having section of the nozzle needle 220 is of a preferred as an annulus 206 trained pressure room 206 surrounded, in fluid contact with the fuel to run channel 110 stands. The one in the pressure room 206 pressurized fuel 2 exercises one referring to the representation of the 3 upward opening force at the pressure shoulder 226 on the nozzle needle 220 out. The nozzle needle 220 assumes its open position as soon as the pressure in the pressure chamber 206 opening force caused is greater than the sum of the opening of the nozzle needle 220 opposing frictional forces and by the biasing spring 122 downward force on the nozzle needle 220 ,

The spring chamber 120 is preferred as a blind hole in the spring holder body 102 a spring holder 100 formed, wherein the spring holder body 102 is open at one longitudinal end. About this longitudinal end is the spring chamber 120 with a pressure from the high-pressure fuel 2 acted upon. Ie. a fuel pressure in the nozzle needle side section 112 of the fuel inlet channel 110 can via the pressure boost valve 300 at the upper longitudinal end of the spring chamber 120 be introduced into this. For this purpose, the spring holder body 103 with a slice 330 sealed above, with the disc 330 a valve housing 330 or a portion of a valve housing 330 the pressure booster valve 300 is. The disc 330 serves as a repository for the biasing spring 122 the nozzle needle 220 , thus the closing piston 140 with a force from the disc 330 pushes. Inside the disc 330 is the valve channel 320 the fluid connection between the fuel inlet channel 110 and the spring chamber 120 dependent on a valve member position 301 . 302 the pressure booster valve 300 manufactures. Ie. the valve channel 320 is from the valve member 310 lockable, wherein the valve member 310 also the fuel inlet channel 110 can close. In the present embodiment, depending on the valve member position 301 . 302 the corresponding channel 310 . 320 fluid-tight. However, it is possible, especially for the first valve member position 301 only a partially fluid-tight connection by means of the valve member 310 to set up.

In a preferred embodiment of the invention, the valve member 310 the pressure booster valve 300 formed hemispherical, wherein the valve member 310 by means of a biasing spring 314 , which is preferably designed as a helical compression spring is biased. The biasing spring 314 clamps the valve member 310 in the first valve seat 301 in front. Here is the first valve seat 301 preferably designed as a conical seat. The biasing spring 314 protrudes with a longitudinal section preferably in the valve channel 320 into it, whereby by means of a fixed connection between the biasing spring 314 and the valve member 310 the valve member 310 is guided. A second valve seat 302 is preferred as a flat seat on the disc 330 formed together with a circular ring portion on a flat side of the hemispherical valve member 310 cooperates (second valve member position 302 ).

According to the invention opens the valve channel 320 the in 3 shown embodiment centrally in a longitudinal end of the spring chamber 120 one. Is the valve member 310 in the first valve member position 301 , so is the first valve seat 301 , the z. B. at a lower portion 600 a foot assembly of the fuel injector 1 may be provided on, so is the nozzle needle side section 112 of the fuel inlet channel 110 in fluid communication with the spring chamber 120 , Ie. the valve member moves 310 in the first valve seat 301 so becomes the section in the nozzle needle side 112 of the fuel inlet channel 110 located fluid pressure the spring chamber 120 impressed. This results in a closing direction of the nozzle needle 220 directed force on the closing piston 140 , whereby a hydraulically assisted closing of the nozzle needle 220 is realized. Is the valve member 310 on his second valve seat 302 ie the valve channel 320 through the valve member 310 closed, so is the fuel inlet channel 110 free, whereby an injection can be initiated.

The spring chamber 120 is about the outlet throttle 130 emptied, the throttle effect is set so that the pressure after the imprinting of the high pressure in the spring chamber 120 dismantled before the next injection. It is also possible, thereby a certain pressure level in the spring chamber 120 for a z. B. set a pilot injection following main injection by a specific throttle cross-section.

For an injection, the fuel channel 110 subjected to high pressure, wherein the valve member 310 from its first valve member position 301 in its second valve member position 302 (in 3 not shown) moves. This will be the penholder 100 sealed against the high pressure and the high pressure is spreading in the inlet channel 110 to the injection nozzle 200 out; an injection begins. For a completion of the injection is deactivated and a pressure drop propagates through the fuel inlet channel 110 downstream, ie with respect to 3 from top to bottom, out, causing it to be on top of the valve member 310 comes to a pressure drop, which the valve member 310 in its first valve member position 301 emotional. As a result, the fuel inlet channel 110 closed, and located in the nozzle needle side section 112 of the fuel inlet channel 110 high-pressure fuel 2 relaxes in the spring chamber 120 , whereby through the throttled outflow (outlet throttle 130 ) of the spring chamber 120 the pressure in the spring chamber 120 increases. This will be the closing piston 140 subjected to fluid pressure, which is due to its mechanical connection with the nozzle needle 220 accelerates into her nozzle needle seat 222 emotional.

The outlet throttle 130 can be at any position on the spring chamber 120 be provided. It is not absolutely necessary in 3 shown position of the outlet throttle 130 but it is possible, the outlet throttle 130 at any longitudinal position of the spring chamber 120 provided. It is also possible, the outlet throttle 130 in the area of the closing piston 140 , especially in relation to the 3 below the closing piston 140 form (flow restrictor 132 , see above). Here, the closing piston 140 together with the spring holder body 102 be formed as an annular gap throttle, whereby the outlet throttle 130 can be chosen larger in diameter, to the same closing force on the nozzle needle 220 cause.

According to the invention, the pressure booster valve 300 or the valve channel 320 the pressure booster valve 300 at different positions within the fuel injector 1 be provided. By choosing the position of the pressure booster valve 300 or the valve channel 320 (Volume and length) can be set when the pressure support for the nozzle needle 220 should work. The closer z. B. the pressure booster valve 300 at the injection nozzle 200 is provided, the faster the pressure support becomes effective. The larger a volume of the valve channel 320 is, the lower the pressure support. Overall is to be seen that in the spring chamber 120 the closer the pressure boost valve is to smaller, relaxing, high-pressure volume 300 at the injection nozzle 200 is provided.

The 4 to 7 now each show in a schematic representation of a hydraulic circuit diagram of a fuel injector according to the invention 1 , wherein the pressure booster valve 300 in different positions in the fuel injector 1 is provided. Here again is the pressure boost valve 300 preferably a 3/2 way valve whose valve member 310 preferably as a plate, ball, part ball or mushroom-shaped valve member 310 is trained.

4 shows one for 3 analogue position, where the valve channel 320 on of the nozzle needle 220 farthest end of the spring chamber 120 in this opens.

5 shows a pressure boost valve 300 , its valve channel 320 in an upper side region of the spring chamber 120 empties. Here is compared to 4 the nozzle needle side section 112 of the fuel inlet channel 110 shorter. Furthermore, it is possible to use the valve channel 320 below, so z. B. in a lower or in a central region of the spring chamber 120 to flow into these.

6 shows one opposite 5 again shorter nozzle needle side section 120 of the fuel inlet channel 110 , where the valve channel 320 below the closing piston 140 in the spring chamber 120 or a fluid channel between the spring chamber 120 and nozzle needle back 124 empties. In such an embodiment, the closing piston 140 preferably not with a tight play in the spring chamber 120 but there is an unthrottled fluid connection from the mouth zone of the valve channel 320 in the remaining spring chamber 120 ,

Further, it is possible to see 7 , the mouth of the valve channel 320 directly adjacent to the nozzle needle back 324 provided. Here again is the closing piston 140 analogous to the closing piston 140 the embodiment according to 6 designed.

Is, according to embodiments of the invention 4 and 5 , the closing piston 140 with a tight game in the pen holder 100 led, so this can be used as a pressure booster piston 140 acting, whereby a force effect of the high-pressure pulse from the fuel 2 through the surface of the closing piston 140 is reinforced. Such a pressure boost is in embodiments of the 6 and 7 not possible, because here the high-pressure pulse directly on the nozzle needle back 224 is directed.

The 8th and 9 show a first embodiment of a plate valve 300 trained inventive pressure booster valve 300 , Here is the valve member 310 plat tenförmig formed and in a valve housing 330 translationally back and forth or movably mounted up and down. Preference is given to the valve housing 330 a disk 330 in the fuel injector 1 ,

According to the invention, the plate-shaped valve member closes 310 in the first valve member position 301 the fuel inlet channel 110 at least in part, and allows fluid communication between the nozzle needle side portion 112 of the fuel inlet channel 110 and the spring chamber 120 then the valve channel 320 with the nozzle needle side section 112 of the fuel inlet channel 110 is in fluid communication.

Is the plate-shaped valve member 310 in its second valve member position 302 so is the valve channel 320 closed and the fuel inlet channel 110 open. This can be the fuel 2 the plate-shaped valve member 310 flow around, ie the fuel 2 can through a recess 316 on the plate-shaped valve member 310 over into a depression 334 in the valve housing 330 enter and from there into the nozzle needle side section 112 of the fuel inlet channel 110 flow. Ie. in the area of the valve housing 330 is the mouth of the nozzle needle side section 112 of the fuel inlet channel 110 by means of the depression 334 extended so that the fuel at the recesses 316 past the depression 334 and thus in the nozzle needle side section 112 of the fuel inlet channel 110 can occur. In a preferred embodiment of the invention, the plate-shaped valve member preferably has two such recesses 316 on.

According to the invention, in an embodiment of the pressure booster valve 300 as a plate valve, the two valve seats 301 . 302 designed as flat seats or as a ring flange seats.

To tilt the plate-shaped valve member 310 To prevent, the valve member has 310 at least one further recess 312 on whose limit in the valve member 310 is part-circular. This part-circular recess closes with a recess 332 in the valve housing 330 to a full circle hollow cylinder, in which in the mounted state of the fuel injector 1 a guide pin is located. As a result, the plate-shaped valve member 310 slide along the guide pin, with the valve member 310 can only translate move. Ie. twisting in the valve member level and tilting are no longer possible.

The plate-shaped valve member 310 is preferably in a cylinder recess 340 of the valve häuses 330 added. Here is the cylinder recess 340 as a blind hole in the valve body 330 intended.

The recesses 312 . 316 in the plate-shaped valve member 310 are preferably each in an edge region of the plate-shaped valve member 310 provided as a sector recess, so that the plate-shaped valve member 310 gets a cross-like training, wherein the respective meeting of each other bars of this cross are executed rounded.

The 10 shows a second embodiment of the plate-shaped valve member 310 , wherein inside the valve member 310 a valve member bore 318 is provided, which completely through the valve member 310 passes through and a fluid connection between an upper and a lower side (with respect to 10 ) of the valve member 310 through the valve member 310 through it. Otherwise, the valve member 310 analogous to a valve member 310 according to the 8th and 9 built up.

In the in 10 drawn position of the valve member 310 (Valve member 310 lies at the first valve seat 301 an) finds - as described above - a fluid communication between the nozzle needle side portion 112 of the fuel inlet channel 110 and the valve channel 320 instead of; the other section of the fuel inlet passage 110 is fluid-sealed. Is the valve member 310 but at the second valve seat 302 on, so exists through the valve member bore 318 a preferably throttled fluid connection between the fuel inlet channel 110 and the valve channel 320 , Ie. while the fuel inlet duct 110 with its nozzle needle side section 112 is in fluid communication, simultaneously flows fuel 2 in the spring chamber 120 ,

It is now preferred that the outlet throttle 130 . 132 of the spring chamber 120 throttles more than the valve member bore 318 , This can be done in the spring chamber 120 already during an injection of the injector 1 a pressure in the spring chamber 120 be constructed, resulting in a pressure support according to the invention for the nozzle needle, in particular between a pre-injection and main injection results. Furthermore, this results in an even faster closing of the nozzle needle 220 ,

The 11 shows a third embodiment of the plate-shaped valve member 310 , wherein in all valve member positions (on the valve seat 301 or at the valve seat 302 or the positions therebetween) again throttled fluid communication between the fuel inlet passage 110 and the valve channel 320 exist. Ie. in contrast to an embodiment of the 10 exists in the embodiment according to 11 a fluid communication between the upper portion of the fuel supply passage 110 and the valve channel 320 even if the valve member 310 at the first valve seat 301 is applied.

The 12 shows a preferred embodiment of the injector according to the invention 1 , Here is a pressure boost valve 300 with plate-shaped valve member 310 provided, which according to one embodiment of the 10 is trained. However, it is possible to use the other plate-shaped valve members described above 310 ( 8th . 9 and 11 ), ie with or without valve member bore 318 , Furthermore, it is possible to pressure booster valves 300 according to the embodiments of 2 to 7 on the in 12 illustrated injector 1 apply.

A pressure reduction in the spring chamber 120 takes place via an annular gap choke 132 instead, between the closing piston 140 and an inner wall of the spring holder 102 is formed, wherein in the below (with reference to 12 ) the closing piston 140 lying room builds up a pressure, which through a drain hole 134 is degradable again. This drain hole is preferred 134 not designed as a fluid throttle. However, it is possible to build up pressure in this spring chamber 120 Admit adjacent room, then drain hole 134 is designed as a fluid throttle. Alternatively or additionally, the in 3 illustrated outlet throttle 130 be provided. Advantageously, a circumference of the closing piston 140 crowned to tilt the closing piston 140 in the spring chamber 120 to avoid.

By the in 12 illustrated drain hole 134 may also be a leakage of the nozzle needle 220 be promoted again in the direction of fuel reservoir.

1

injector, Fuel injector, in particular for a pressure-boosted injection system

2

Fuel, z. B. diesel fuel, gasoline

3

Oil, engine oil

10

Motor oil side

20

Fuel side

100

penholder

102

Penholder body

110

Fuel supply channel High pressure side

112

nozzle needle side portion of the fuel inlet channel 110

120

spring chamber

122

biasing spring

130

outlet throttle (Optional)

132

Outflow throttle, between closing piston 140 and spring chamber 120 designed as an annular gap choke (optional)

134

drain hole (Optional), may be formed as a fluid throttle

140

Closing piston, piston with a preferably spherical circumference to form the outlet throttle 132

145

Needle piston (can with closing piston 145 be formed in one piece)

150

check valve

160

check valve (only state of the art)

190

Disc, shim

200

injection

206

Pressure chamber, annulus

210

nozzle body

220

nozzle needle

222

Nozzle needle seat

224

Nozzle needle back

226

pressure shoulder

300

Pressure boost valve, 3/2 way valve; preferably plate, ball, part ball or mushroom valve

301

first Valve seat, first valve member position

302

second Valve seat, second valve member position

310

Valve member, preferably plate, mushroom or (part) spherical

312

Recess in the plate-shaped valve member 310 for guide pencil

314

Preloading spring for valve member 310 but preferably not for a plate-shaped valve member 310

316

Recess in the plate-shaped valve member 310 for flow of the fuel 2

318

Valve member bore, preferably in the plate-shaped valve member 310 and preferably designed as a throttle bore

320

Valve channel to the spring chamber 120 or to an area above the nozzle needle 220

330

Valve housing or (valve) disc for plate-shaped valve member 310 , with valve channel 320 and second valve seat 302

332

recess for guide pencil

334

deepening

340

cylinder recess

400

Rail (High pressure)

402

drainage (Low pressure)

410

switching valve

420

hydraulic amplifier

421

first volume of the hydraulic booster 420

422

piston with big ones surface

424

piston with a small surface

426

Piston return spring

427

second volume of hydraulic booster 420

428

drainage (Low pressure)

429

drainage (Low pressure)

500

Fuel supply (Low or medium pressure)

600

lower portion of a foot assembly of the fuel injector 1

Claims (27)

Fuel injector for a hydraulically amplified injection system, with a pressure boost valve ( 300 ) for a hydraulically assisted closing of a nozzle needle ( 220 ) of the fuel injector ( 1 ), wherein the pressure booster valve ( 300 ) on a high-pressure side fuel supply channel ( 110 ) of the fuel injector ( 1 ) is provided that upon termination of an injection of the fuel injector ( 1 ), through the pressure boost valve ( 300 ) a fluid pressure from high pressure fuel ( 2 ) in the fuel inlet channel ( 110 ), on a nozzle needle back ( 224 ), wherein the pressure boost valve ( 300 ) the fuel inlet channel ( 110 ) at least partially closes. A fuel injector according to claim 1, wherein a pressure control of the fuel injector ( 1 ) on a motor oil side ( 10 ) and a pressure boost of the fuel injector ( 1 ) on a fuel side ( 20 ) is made. A fuel injector according to claim 1 or 2, wherein the fuel supply passage ( 110 ) during an injection of fuel ( 2 ) through the pressure boost valve ( 300 ) is released. A fuel injector according to any one of claims 1 to 3, wherein the completion of injection of the fuel injector ( 1 ) by a Absteuern on the engine oil side ( 10 ) is carried out, wherein the pressure booster valve ( 300 ) the fuel inlet channel ( 110 ) at least partially closes. Fuel injector according to one of claims 1 to 4, wherein the pressure boost valve ( 300 ) is a 3/2-way valve which, during an injection of fuel ( 2 ) a valve channel ( 320 ) relative to the fuel inlet channel ( 110 ) fluid-tight, and at the completion of an injection fluid communication between the valve channel ( 320 ) and a nozzle needle side section ( 112 ) of the fuel inlet channel ( 110 ). Fuel injector according to one of claims 1 to 5, wherein the valve channel ( 320 ) of the pressure booster valve ( 300 ) in a spring chamber ( 120 ) of a spring holder ( 100 ) of the fuel injector ( 1 ), in which a biasing spring ( 122 ) directly on the nozzle needle backside ( 224 ) acts. Fuel injector according to one of claims 1 to 6, wherein the valve channel ( 320 ) at a longitudinal end of the spring chamber ( 120 ) in the spring chamber ( 120 ), or the valve channel ( 320 ) laterally in the spring chamber ( 120 ) opens. Fuel injector according to one of claims 1 to 7, wherein the valve channel ( 320 ) near one in the spring chamber ( 120 ) arranged closing piston ( 140 ) in the spring chamber ( 120 ) opens. Fuel injector according to one of claims 1 to 8, wherein the valve channel ( 320 ) between the closing piston ( 140 ) and the nozzle needle back ( 224 ) in the spring chamber ( 120 ) opens. Fuel injector according to one of claims 1 to 9, wherein the valve channel ( 320 ) near the nozzle needle backside ( 224 ) on the nozzle needle ( 220 ) opens. Fuel injector according to one of claims 1 to 10, wherein the pressure boost valve ( 300 ) is a ball, cone or plate valve. Fuel injector according to one of claims 1 to 11, wherein a valve member ( 310 ) of the pressure booster valve ( 300 ) is biased and biased in a direction in which the valve body ( 310 ) the fuel inlet channel ( 110 ) at least partially closes. A fuel injector according to claim 12, wherein a spherical sealing portion of said valve member ( 310 ) with a conical seat in the fuel inlet channel ( 110 ) can cooperate sealingly and in such a sealing state the fuel inlet channel ( 110 ) at least partially closes. Fuel injector according to claim 12 or 13, wherein a planar sealing portion of the valve member ( 310 ) with a flat sealing portion on the valve channel ( 320 ) can cooperate sealingly and in such a sealing state the valve channel ( 320 ) closes. Fuel injector according to one of claims 1 to 11, wherein a valve member ( 310 ) of the pressure booster valve ( 300 ) plate-shaped and preferably is not biased. A fuel injector according to claim 15, wherein a planar sealing portion of the valve member ( 310 ) with a flat sealing portion on the fuel inlet channel ( 110 ) can cooperate sealingly and in such a sealing state the fuel inlet channel ( 110 ) at least partially closes. Fuel injector according to claim 15 or 16, wherein a planar sealing portion of the valve member ( 310 ) with a flat sealing portion on the valve channel ( 320 ) can cooperate sealingly and in such a sealing state the valve channel ( 320 ) closes. Fuel injector according to one of claims 1 to 17, wherein the pressure boost valve ( 300 ) a valve housing ( 330 ) in which the valve member ( 310 ) is translationally reciprocable. Fuel injector according to one of claims 1 to 18, wherein the valve member ( 310 ) a recess ( 312 ), by means of which the valve member ( 310 ) by a projection or a guide pin in the valve housing ( 330 ) is feasible. Fuel injector according to one of claims 1 to 19, wherein the valve housing ( 330 ) in a sealing portion for the valve member ( 310 ) a recess ( 334 ) such that thereby the nozzle needle side portion ( 112 ) of the fuel inlet channel ( 110 ) in dependence of a position of the valve member ( 310 ) always in fluid communication either with the fuel feed channel ( 110 ) or the valve channel ( 320 ) stands. Fuel injector according to one of claims 1 to 20, wherein the valve member ( 310 ) a valve member bore ( 318 ), which in the valve member ( 310 ) is arranged such that at a through the valve member ( 310 ) released fuel feed channel ( 110 ) a fluid connection between the fuel inlet channel ( 110 ) and the valve channel ( 320 ) exists. Fuel injector according to claim 21, wherein the valve member bore ( 318 ) in each position of the valve member ( 310 ) a fluid connection between the fuel inlet channel ( 110 ) and the valve channel ( 320 ). Fuel injector according to claim 21 or 22, wherein the valve member bore ( 318 ) is designed as a fluid throttle. Fuel injector according to one of claims 1 to 23, wherein a guide gap of the closing piston ( 140 ) in the spring chamber ( 120 ) is designed as a fluid throttle, and a spring chamber ( 120 ) with respect to the closing piston ( 140 ) adjacent space via a drain hole ( 134 ) is emptied. A fuel injector according to claim 24, wherein the drain hole ( 134 ) is designed as a fluid throttle. Fuel injector according to one of claims 1 to 25, wherein the spring chamber ( 120 ) via an outlet throttle ( 130 ) in a penholder ( 102 ) is emptied. Hydraulically reinforced injection system, in particular for a Utility vehicle, with a hydraulically amplified fuel injector one of the claims 1 to 20.