EP1656498A1

EP1656498A1 - Fuel injection valve controlled by a pilot valve

Info

Publication number: EP1656498A1
Application number: EP04738118A
Authority: EP
Inventors: Marco Ganser
Original assignee: Ganser Hydromag AG
Current assignee: Ganser Hydromag AG
Priority date: 2003-08-22
Filing date: 2004-07-30
Publication date: 2006-05-17
Anticipated expiration: 2024-07-30
Also published as: WO2005019637A1; EP1656498B1; DE502004008540D1; ATE415554T1

Abstract

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

Description

Pilot valve controlled fuel injector

The present invention relates to a

Fuel injector for intermittent

Fuel injection into the combustion chamber of an internal combustion engine according to the preamble of patent claim 1.

Fuel injection valves of this type are generally known and are disclosed, for example, in EP-A-0 426 205, EP-A-0 603 616, EP-A-0 824 190, EP-A-1 273 791. They have a pilot valve pin which is controlled by means of an electromagnetic actuator and which, in the closed position, separates an outlet duct of a control chamber provided with a throttle restriction from a low-pressure outlet. When the pilot valve pin is lifted from the pilot valve seat, fuel flows from the outlet duct directly to the low-pressure outlet. An injection process is initiated by opening the pilot valve and the closing movement of the injection valve member is caused to end the injection process by closing the pilot valve.

Starting from this prior art, it is an object of the present invention to develop a generic fuel injector in such a way that the closing movement of the injection valve member for the termination of an injection process takes place very quickly, while the opening movement at the start of an injection process can take place relatively slowly. This object is achieved by means of a fuel injector, which has the features of patent claim 1.

When opening the pilot valve. of a fuel injection valve according to the invention, fuel flows into a relief chamber, from which it can only continue to flow through a throttle passage to the low-pressure outlet. A minimization of the fuel valve through the low pressure outlet is achieved during the injection process. The throttle passage can be formed by a slide fit for the pilot valve pin, but preferably the pilot valve pin is guided in a narrow slide fit and is. the relief chamber is connected to the low-pressure outlet via a separately designed throttle passage. The behavior of the fuel injection valve when it is opened, that is to say at the start of an injection process, can be very similar to that of known fuel injection valves in which the outlet channel is provided with a throttle restriction. To end an injection process, however, in a fuel injection valve according to the invention, the pilot valve pin is moved into the relief chamber at high speed until it rests on the pilot valve seat. Since the throttle passage prevents the fuel from being quickly removed from the relief chamber, the movement of the pilot valve pin and the associated displacement of fuel result in a very rapid increase in pressure in the relief chamber and in a discharge chamber adjoining it upstream of the pilot valve seat, which results in a very fast closing movement of the Injector member caused. This can further support this closing movement that the movement of the pilot valve pin is mechanically exploited.

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

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

1 shows a longitudinal section of a first embodiment of a fuel injector according to the invention, in which a relief chamber is formed on a retaining nut;

FIG. 2 likewise shows an enlarged detail of a section of the fuel injector shown in FIG. 1;

3 shows, in the same representation as FIG. 2, a section from a second embodiment of a fuel injector according to the invention with a throttle passage in the pilot valve pin having two throttle constrictions;

4 shows, in the same representation as FIG. 2, a section from a third embodiment of a fuel injector according to the invention, in which the relief chamber is arranged entirely in a drain chamber body on which the pilot valve pin is also mounted;

5 in the same representation as FIG. 2, a section of a fourth embodiment of the fuel injector according to the invention, Similar to that of Figure 3, but with only a single throttle restriction in the throttle passage.

6, in the same representation as FIG. 2, a section of a fifth embodiment of the fuel injection valve according to the invention with a slide valve, as disclosed for example in EP-Al 273 791 or PCT patent application PCT / CH / 03/0005; ^•

7, in the same representation as FIG. 2, a section of a sixth embodiment of the fuel injector according to the invention with a leaf spring valve, similar to that known from EP-A-1 273 791;

8 shows, in the same representation as FIG. 2, a detail from a seventh embodiment of the fuel injection valve according to the invention, in which a control body is mushroom-shaped and is displaceably mounted in the injection valve member; and

Fig. 9 in the same representation as Fig. 2, a section of a. eighth embodiment of the fuel injector according to the invention, in which a transmission pin transmits the movement of the pilot valve pin to a control body.

1 shows in longitudinal section a fuel injection valve 10 according to the invention with an essentially cylindrical valve housing 14, which has a lateral high-pressure inlet 12. This has a continuous, stepped bore 17 running in the direction of the longitudinal axis 16, in which an electrical Actuated actuator 18, a control device 20 actuated by the latter and a needle-shaped injection valve member 22 with a closing spring 24 are arranged. The injection valve member 22 is held by means of the closing spring 24 on an injection valve seat 26, which is formed on an injection valve seat body 28. This is essentially rotationally symmetrical with respect to the longitudinal axis 16, rests on the end face of the valve housing 14 and is held in a sealing manner on the valve housing 14 by means of a union nut 30. In the end region of the exposed tip of the injection valve body 28, injection valve nozzles 32 are formed in a known manner, through which fuel is injected under very high pressure into a combustion chamber (not shown) of an internal combustion engine when the injection valve member 22 is directed in the direction by means of the hydraulic control device 20 controlled by the actuator 18 the longitudinal axis 16 is lifted off the injection valve seat 26. The injection valve seat 26 delimits a high-pressure space 34, in which the injection valve member 22 is arranged and which on the other hand is delimited by the control device 20 and on the circumferential side by the injection valve seat body 28 and valve housing 14. The _. High-pressure chamber 34 is connected to high-pressure inlet 12, through which fuel is fed to high-pressure chamber 34 for injection into the combustion chamber of the internal combustion engine and for controlling injection valve member 22 under very high pressure of up to 1000 bar or even 1800 bar or more.

The injection valve member 22 delimits a control chamber 36 with its end area facing away from the injection valve seat 26, which on the other hand is bounded by a control body 38 is limited in which an outlet passage 40 equipped with a throttle constriction 40 ′ is formed concentrically to the longitudinal axis 16; see in particular also FIG. 2, which shows a detail of the fuel injector 10 from FIG. 1 with the control device 20 enlarged. With its end face 42 facing away from the control chamber 36, the control body 38, with the support of a compression spring 44, which is supported on the one hand on the control body 38 and on the other hand on the injection valve member 22, bears sealingly on an end face 46 'of a mushroom-shaped drain chamber body 46 facing it. A relief chamber 48 is formed in the drain chamber body 46 through a longitudinal bore that is coaxial with the longitudinal axis 16 - without throttling constriction - which is aligned with the outlet passage 40 and is directly flow-connected to it.

The essentially circular cylindrical control body 38 is mounted with radial play of about 0.02 mm to 0.1 mm or 0.2 mm in a control sleeve 50 in the direction of the longitudinal axis 16 and forms as a valve member together with the drain chamber body 46, the end face 46 'acts as a valve seat, an intermediate valve 52. The control sleeve 50, at whose end facing the injection valve seat 26, the closing spring 24 is supported, is from the. Force of this closing spring 24 on, drain chamber body 46 held in sealing contact. On the control sleeve 50 which delimits the control chamber 36 on the circumference, the injection valve member 22 is guided in a close sliding fit with a play of approximately 2 μm to 10 μm.

The mushroom-shaped drain chamber body 46 is sealed against one with its hat part by means of a retaining nut 54 which is threaded into an internal thread on the valve housing 14 Contact shoulder 56 of the valve housing 14 pressed. Furthermore, the retaining nut 54 and the drain chamber body 46 lie against one another in a sealing manner. Distributed in the circumferential direction, at least 2 high-pressure channels 58 are formed in the trunk part of the mushroom-shaped drain chamber body 46, which are in flow connection on the one hand with an annular space 60 delimited by the valve housing 14, the trunk and the head part of the drain chamber body 46 and the control sleeve 50 and which are on the other of the end face 46 'forming the valve seat of the intermediate valve 52. The annular space 60 is connected to the high-pressure space 34 and thus to the high-pressure inlet 12 by a longitudinal groove 62 which extends in the axial direction and is formed on the radially outer side of the control sleeve 50. The high-pressure channels 58 can, as shown in FIGS. 1 and 2 on the right of the longitudinal axis 16, be produced by oblique bores in the drain space body 46 or, as shown in FIG. 2 on the left of the longitudinal axis 16, by angled bores. The orifices of the high-pressure channels 58 on the end face 46 ′ are closed by the control body 38 when the latter lies against the drain chamber body 46. In order to improve the sealing effect of the intermediate valve 52 by increasing the surface pressure, as shown in FIG. 2, a recess 64 can be formed on the drain chamber body 46, which ensures that the contact surface as a relatively narrow, band-shaped area along the outer circumference of the control body 38 and around the mouths of the high pressure channels 58 runs around. Corresponding recesses can of course be formed on the control body 38. A pilot valve pin 66 is mounted on the retaining nut 54 concentrically to the longitudinal axis 16 and can be displaced in the direction of the longitudinal axis 16 in a close sliding fit of approximately 2 μm to 10 μm. In its closed position shown in FIGS. 1 and 2, the pilot valve pin 66 lies against the drain chamber body 46 and thereby closes the relief chamber 48. Around the mouth opening of the relief chamber 48 on this side, the drain chamber body 46 forms an annular pilot valve seat 68 which, together with the pilot valve pin 66 as a valve member forms a pilot valve 70. The pilot valve seat 68 is designed as a flat seat.

An annular relief chamber 72 is directly connected to the pilot valve seat 68 on the low pressure side and is formed on the retaining nut 54 serving as the relief chamber body as a recess extending around the pilot valve pin 66. This otherwise closed relief chamber 72 is continuously flow-connected via a throttle passage 74 with a low-pressure outlet 76 of the valve housing 14. Fuel flowing out through the low-pressure outlet 76 is fed back to a fuel storage container in a known manner.

2 shows in solid lines that the throttle passage 74 can be designed as an oblique bore in the pilot valve pin 66 or, as indicated by dashed lines, on the holding nut 54. The diameter of the throttle point 74 'of the otherwise having a larger diameter ^• throttle passage 74th is, for example, about ten times smaller than the diameter of the pilot valve pin 66 and about five times smaller than the inside diameter of the drainage space 48. However, these ratios can be different. From Another advantage is that the pilot valve pin 66, when it is lifted from the pilot valve seat 68, very quickly releases a substantially larger flow cross-section than is defined by the throttle point 74 '.

The pilot valve pin 66 is held in contact with the pilot valve seat 68 by means of the actuator 18. Here, an actuator shaft 78 rests with its spherically shaped end on the front side of the pilot valve pin 66 facing away from the pilot valve seat 68. The actuator 18 is preferably a piezoelectric or magnetostrictive actuator. Such actuators 18 allow only a relatively small stroke of the actuator shaft 78 and thus of the pilot valve pin 66, for example 0.03 mm. However, they have the advantage that they move the pilot valve pin 66 with great speed and great force.

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

The game between the control body 38 and the control sleeve 50 ensures that through this game and the outlet passage 40, the control chamber 36 is filled with fuel very quickly as soon as - to end an injection process by closing the pilot valve 70, the control body 38 from its system on Drain chamber body 46 is moved away.

With "H" is the maximum stroke of the

Injection valve member 22 specified, which it execute between, on the one hand, the contact with the injection valve seat 26 and, on the other hand, the contact with the control body 38 can. However, the possible stroke of the control body 38 is preferably less; a stroke limiting shoulder 84 on the control sleeve 50 limits the maximum possible distance between the outlet space body 46 and the control body 38 to, for example, approximately 0.05-0.2 mm or 0.02-0.2 mm.

On the side facing away from the control sleeve 50

Closing spring 24 on an intermediate plate 86, which in turn is located on a shoulder of the

Injection valve member 22 supporting support disc 86 'abuts. The intermediate disk 86 can be exchanged in order to coordinate the behavior of the fuel injection valve 10 by selecting the desired thickness.

By means of guide ribs 88 projecting in a star-like manner on the injection valve member 22, this is displaceably mounted on the injection valve body 28, the inflow of fuel to the injection valve seat 26 being ensured.

In FIGS. 3 to 6, the same reference numerals are used for the embodiment according to FIGS. 1 and 2 as in FIGS. 1 and 2. Only the differences between the embodiment shown in the figure and that according to the figures are shown below 1 and 2 explained.

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

Following the throttle constriction 40 ′ formed coaxially to the longitudinal axis 16 on the control body 38, the outlet passage 40 runs obliquely with respect to the longitudinal axis 16, so that it opens into the annular space formed by the recess 64. Correspondingly, the drainage space 48 is also formed through a bore which is oblique with respect to the longitudinal axis 16 through the discharge space body 46, the drainage space 48 opening into the recess 64 on the one hand and the mouth of the drainage space 48 being arranged centrally on the side of the pilot valve 70 to the longitudinal axis 16.

The pilot valve pin 76 is in turn mounted in the holding nut 54, on which the discharge space 72 is excluded, in a close sliding fit. The throttle passage 74 is formed on the pilot valve pin 66 by a blind hole made from the actuator side, which - instead of a single throttle point 9 '- by means of a radial first throttle bore 90 with the relief chamber 72 and a radial second throttle bore 90' with the low pressure outlet 76 in Flow connection is established. The diameter of these two throttle bores 90, 90 'can, compared to the single throttle constriction 74' in the throttle passage 74 according to FIGS. 1 and 2, be chosen somewhat larger and thus somewhat less precise in order to achieve a corresponding throttling effect .mu.m. The cooperating with the pilot valve pin 66 end face of the Aktuatorschafts ^"78 is formed flat to to seal the blind hole in the pilot valve pin 68.

In the embodiment shown in FIG. 3, too, it is advisable to use an electrically controlled piezoelectric or magnetostrictive actuator 18; such actuators 18 behave approximately 3 to 8 times faster than known electromagnets. However, it is also conceivable to use electromagnets as the actuator 18 for fuel injection valves 10 according to the present invention. In this case, it is advisable to connect the discharge space 48 to the high-pressure space 34 by means of a throttle admission 92 - as also shown in FIG. 8. Such a throttle admission 92 accelerates the closing movement of the injection valve member 22 to end the injection process.

In the embodiment shown in FIG. 4, the control body 38 is designed similarly to that according to FIG. 2, but the throttle restriction 40 ′ of the outlet passage 40 is located in the end region facing the drainage space 48.

The otherwise circular-cylindrical outlet passage 40 has a conical shape in its end area on the control chamber, in which the opposite end area of the injection valve member 22 engages when the injection valve member 22 is in the maximum open position. This leads to a very good sealing of the outlet passage 40 and, upon completion of the injection process, contributes to a very rapid lifting of the control body 38 from the injection valve body 28 and thus a very fast closing movement of the injection valve member 22. 4, left and right of the longitudinal axis 16, two further possible embodiments for the high-pressure duct 58 are shown. These are formed by bores in the drain chamber body 46, which run obliquely to the longitudinal axis 16 and communicate with the annular space 60, and by bores which are in flow communication with the former and run parallel or obliquely to the longitudinal axis 16, but in that area on the end face 46 'open, which acts as a valve seat of the intermediate valve 52.

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

In the embodiment shown in FIG. 4, the pilot valve seat 68 and, subsequently, the relief chamber 72 are formed by a conical enlargement - seen from the control body 38 - of the bore forming the drain chamber 48. Is accordingly opposite that part of the pilot valve pin 66 which cooperates with the pilot valve seat 68 is conical. The relief space 72 in turn runs as an annular space around the pilot valve pin 66 and the throttle passage 74 is designed as an oblique bore in the pilot valve pin 66 with respect to the longitudinal axis 16, but now - in contrast to the embodiment according to FIGS. 1 and 2 - the throttle restriction 74 'is in the End region of the throttle passage 44 facing the low-pressure outlet 76. From a hydraulic point of view, the volume of the throttle passage 74 upstream of the throttle restriction 74 ′ is therefore part of the relief space 72.

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

FIG. 5 shows an embodiment very similar to that of FIG. 3, the drain chamber body 46 no longer being mushroom-shaped but pill-shaped. As in the embodiment according to FIG. 3, the annular space 60 extends around the upper end region of the control sleeve 50. The high-pressure duct 58 is formed by two bores running obliquely to one another and to the longitudinal axis 16. One opens into the annular space 60 and the other into the center of the end face 46 'of the discharge space body 46. Furthermore, in contrast to the embodiment shown in FIG. 3, the throttle restriction 40' of the outlet passage 40 is located at the recess 64, which is integrally formed on the control body 38 is.

In the embodiment of the fuel injector 10 according to the invention shown in FIG Drain chamber body 46 is pill-shaped and does not have a high pressure channel 58 in the center of the drain chamber 48 running in the axial direction. The pilot valve pin 66, which is designed as shown in FIGS. 1 and 2, interacts with the drain chamber body 46.

The control body 38 is in the form of a spool valve body ^'in the control sleeve 50 microns in a close sliding fit of approximately 2 out microns to 10th The annular space 60, which is recessed radially on the inside of the control sleeve 50 and which is connected to the high-pressure space 34 via a radial passage and the longitudinal groove 62, runs around its end region facing the drain space body 46. The outlet passage 40 runs through the control body 38 concentrically to the longitudinal axis 16. Throttle restriction 40 'at the end facing the control chamber 36. Parallel to this, but radially offset with respect to the longitudinal axis 16, a connecting channel 94 runs through the control body 38 and is closed when the control body 38 abuts the drain chamber body 46. If the control body 38 is not in contact with the drain chamber body 46, the connecting channel 94 connects the control chamber 36 to the high-pressure chamber 34. In terms of function, the connecting channel 94 has the same function as the radial play between the control body 38 and the control sleeve 50 in the embodiments shown above formed on the control body 38, on its end face 42, inner and outer recesses 64, which serve to make the surface with which the control body 38 lies sealingly against the discharge chamber body 46, in order to achieve a high surface pressure. Furthermore, through a more or less large radially outer recess 64 the dynamic behavior of the control body 38 with respect to lifting off from contact with the discharge space body 46 can be varied.

FIG. 7 shows an embodiment of the fuel injection valve 10 according to the invention, in which the control body 38 is replaced by a leaf spring 96. The leaf spring 96 is similar to that of the leaf spring known from EP-A-1 273 791. A C or U-shaped slot is cut out of a spring steel disk and separates a radially inner leaf spring tongue 98 from a retaining ring 100. The leaf spring 96 is held with its retaining ring 100 between the control sleeve 50 and the drain chamber body 46. For radial alignment, the retaining ring 100 and the control sleeve 50 are jointly encompassed by a centering ring 102. Instead of the centering ring 102, centering pins could of course also be used, or the centering ring 102 could be integrally formed on the control sleeve 50. Furthermore, the throttle constriction 40 ′ is formed on the leaf spring tongue 98, concentrically to the longitudinal axis 16, as a through hole. The leaf spring tongue 98, when it bears against the drain chamber body 46, closes off both the high-pressure channel 58 formed therein and the drain chamber 48 running centrally to the longitudinal axis 16. When the leaf spring tongue 98 is lifted off the discharge chamber body 46, the high-pressure chamber 34 and, with a larger flow cross section than the throttle constriction 40 ′, the discharge chamber 48 are flow-connected to the control chamber 36. A throttle inlet 92, which connects the high-pressure chamber 34 to the outlet chamber 48, can be excluded on the leaf spring 96. The effect of this throttle approval 92 is the same as that of the throttle passage 92 of the embodiment according to FIGS. 3 and 8, namely especially when using an electromagnetic

Actuator 18 the quick closing of the

To assist injection valve member for the completion of the injection process.

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

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

To trigger an injection process, the actuator 18 pulls the actuator shaft 78 upward in the axial direction, that is to say in the direction away from the pilot valve seat 68. Since there is high pressure in the discharge space 48, the pilot valve pin .66 is lifted off the pilot valve seat 68 in accordance with the movement of the actuator shaft 78. This leads to a very rapid pressure increase in the relief space 72 and a correspondingly rapid pressure reduction in the discharge space 48 and in the outlet passage 40 downstream of the throttle restriction 40 '. The fuel flows from the relief chamber 72 through the throttle passage 74 to the low-pressure outlet 76 in a damped manner. The throttled constriction 40 ′ dampens the fuel from the control chamber 36. This leads to a pressure reduction in the control chamber 36, as a result of which the injection valve member 22 is known is lifted off the injection valve seat 26.

To end the injection process, the pilot valve pin 66 is moved very quickly downward into contact with the pilot valve pin 66 by means of the actuator 18, and the pilot valve 70 is thereby closed. Since the pilot valve seat 68 dips very quickly into the relief space 72, there is an increase in pressure Generated, which propagates through the drain chamber 48 and leads to the lifting of the control body 38, or the leaf spring tongue 98, from the drain chamber body 46, since a rapid pressure equalization in the control chamber 36 can not take place because of the throttle restriction 40 '. By lifting the control body 38, the entire end face 42 of the control body 38 is immediately subjected to fuel under high pressure, since the high-pressure channel 58 or the high-pressure channels 58 are opened. This leads to a very rapid movement of the control body 38 away from the discharge chamber body 46 and to a rapid pressure increase in the control chamber 36, which causes a rapid closing movement of the injection valve member 22 to end the injection process. With the aid of the force of the compression spring 44 or the spring force of the leaf spring tongue 98, the control body 38 or the leaf spring tongue 98 rests against the injection valve seat body 28. So that this movement is not slowed down too much, fuel can flow through the throttle restriction 40 ′ and relatively quickly through the radial gap between the control body 38 and the control sleeve 50 or through the connecting channel 94, and in the embodiment according to FIG. 7 through the gap between the leaf spring tongue 98 and retaining ring 100, flow into the control room 36. After which the initial state set out at the beginning of the functional description is reached again.

Although the fuel injection valve 10 according to the invention has a pilot valve 70, the losses in fuel caused thereby are small, since during the period in which the pilot valve 70 is open, in the embodiment according to FIGS. 1, 2, 4, 5 and 6 there is no hydraulic Connection between the drainage space 48 and the high pressure chamber 34. In the embodiments according to FIGS. 3, 7 and 8, a throttle passage 92 is present; however, because of the very small cross section, the throttle passage 92 prevents a large amount of fuel from being drained off quickly.

The faster the pilot valve pin 66 is moved to close the pilot valve 70, the faster the pressure increases and thus the injector closes very quickly. This rapid and large increase in pressure has an effect on the actuator 18. Piezoelectric and magnetostrictive actuators are therefore particularly suitable for fuel injection valves 10 according to the invention because they can exert very large forces, so that the pressure increase mentioned practically does not delay the movement of the pilot valve pin 66. Although the aforementioned actuators 18 have a faster switching behavior than electromagnets, they can also be used. The desired pressure increase can thus be achieved by designing the diameter and the stroke of the pilot valve pin 66.

The embodiment shown in FIG. 9 has, in addition to the advantages shown in connection with the embodiments according to FIGS. 1 to 8, an increased ability for multiple injections in very short time intervals. The same reference numerals are used for parts having the same effect in the description of FIG. 9 as in connection with FIGS. 1 to 8.

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

On the end face of the holding nut 54, the pill-shaped drain chamber body 46 lies sealingly. It has a central axial passage, which forms the discharge space 48. In the same way as. Explained in connection with FIGS. 1 to 3 and 5 to 8, the end face of the discharge space body 46 facing the retaining nut 54 forms the planar pilot valve seat 68 which interacts with the pilot valve pin 66. The pilot valve pin 66 and the pilot valve seat 68 form the pilot valve controlled by an actuator 18 70, which separates the discharge space 48 from the discharge space 72 in the closed state.

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

Furthermore, the high-pressure channel 58 is formed on the drain chamber body 46, which has a radial blind hole and one from the end face 46 'of the drain chamber body 46 in Axial direction in the blind hole leading through hole is formed. The high-pressure channel 58 opens at the end face 46 'at a distance from _^ bflussraum 48 so that the control body 38, when in contact with the end face 46', closes the mouth of the high-pressure channel 58th The drain chamber body 46, with its end face 46 ′ and the control body 38, in turn forms an intermediate valve 52.

On the end face 46 'of the drain space body 46, there is an intermediate body 50' in a sealing manner, in the central passage of which the control body 38 is arranged to be displaceable in the direction of the longitudinal axis 16. An annular gap is present between the control body 48 and the intermediate body 50 '. The intermediate body 50 'is cup-shaped, the bottom facing the drain chamber body 46, and a pressure spring 44 being located inside the control body 38, which holds the control body 38 in contact with the bottom of the transmission pin 104 when the pilot valve 70 is open. The outlet passage 40 runs through the bottom of the control body 38 and is designed without a throttle restriction 40 ′ and communicates with the drainage space 48 when the control body 38 bears against the end face 46 ′. If the control body 38 rests on the end face 46 ', it closes the mouth of the high-pressure duct 58.

When the pilot valve 70 is closed, as shown in FIG. 9, the bottom of the control body 38 is at a distance from the end face 46 ′, which is given by the difference in length between the transmission pin 104 and the thickness of the drain chamber body 46. The stroke of the pilot valve pin. 66 is at least as large> • but preferably larger than this distance. The compression spring 44 is supported with its end facing away from the bottom of the control body 38 on an end face of a control chamber body 50 ″, which with its end face lies sealingly against the intermediate body 50 ′. The control chamber body 50 ″ delimits the control chamber 36 on the circumference, which is also delimited by the injection valve member 22, which is guided on the control chamber body 50 ″ in a tight sliding fit. The injection valve member 22 is desaxed with respect to the common longitudinal axis 16. However, the control chamber 36 is continuously in flow connection with the interior of the cup-shaped control body 38 and the drain chamber 48.

In a generally known manner, the control chamber body 50 ″ and the holding nut 54 are braced against one another so that the holding nut 54 bears tightly against the discharge chamber body 46, the latter on the other hand on the intermediate body 50 ′, and this in turn on the control chamber body 50 ″. The intermediate body 50 'and control chamber body 50' "can, like the control sleeve 50 in the other exemplary embodiments, be formed in one piece together. It is also conceivable to form the control chamber body 50" together with the injection valve seat body 28 or the valve housing 14 in one piece.

An annular groove 106 open to the end face 46 'can be formed in the drain chamber body 46, into which the high pressure channel 58 opens and which is closed by the latter when the control body 38 bears against the end face 46'.

It is also conceivable to make the control body 38 shorter, as seen in the direction of the longitudinal axis 16, so that the

Shell portion of the cup protrudes only slightly above the bottom of the control body 38 to the end portion of the Record compression spring 44. In a particularly space-saving design in the axial direction, the control body 38 is designed as a disk with an outlet passage 40 and the compression spring 44 designed as a helical spring is replaced by a plate spring or wave spring.

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

In the example shown in FIG. 9, an annular gap is present between the transmission pin 104 and the drain space body 46. However, it is also conceivable to mount the transmission pin 104 in a sliding fit on the drain chamber body 46 and to make grindings on the transmission pin 104 in order to ensure the flow connection between the drain chamber 48 and the relief chamber 72 when the pilot valve 70 is open.

Finally, it should be mentioned that the pilot valve pin 66 can have a shoulder which interacts with the holding nut 54 in order to limit the stroke of the pilot valve pin 66 in the opening direction of the pilot valve 70.

The fuel injection valve 10 shown in FIG. 9 functions as follows. In the starting position shown, the pilot valve 70 is closed. The control body 38 is raised from the end face 46 ′ of the drain chamber body 46, as a result of which the drain chamber 48 and the control chamber 46 are connected to the high pressure inlet 12 via the high pressure channel 58. The injection valve member 22 is in contact with the injection valve seat 26 in the closed position; see also FIG. 1. To initiate an injection process, the actuator 18 pulls back the actuator shaft 78, as a result of which the pilot valve pin 66 moves away from the pilot valve seat 68 and the drain chamber 48 and thus the control chamber 36 are connected to the discharge chamber 72. The extremely rapid movement of the pilot valve pin 66 is followed by the transmission pin 104 and the control body 38, which has the consequence that the intermediate valve 52 closes very quickly and prevents the fuel from flowing through the high-pressure channel 58. The pressure drop in the control chamber 36 and thus a lifting of the injection valve member 22 from the injection valve seat 26 take place very quickly.

To end the injection process, the pilot valve pin 66 is made known by means of the actuator 18

Way brought into contact with the pilot valve seat 68. The transmission pin 104 is moved in the direction against the control body 38, which inevitably lifts off from the end face 46 '. The intermediate valve 52 opens and a connection is established between the control chamber 36 and the high pressure channel 58

High pressure inlet 12. Next, this pressure rise to the movement of the pilot valve pin 66 in ^•

Discharge space 72 is supported. The injection valve member 22 is thus brought very quickly into contact with the injection valve seat 26, as a result of which the injection process is ended.

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

Claims

claims

1. Fuel injection valve for intermittent fuel injection into the combustion chamber of an internal combustion engine, with a hydraulic control device (20) having a pilot valve (70) for controlling the movement of an injection valve member (22) interacting with an injection valve seat (26), the pilot valve (70) having a on the one hand with an electrically controlled actuator (18) and on the other hand with a pilot valve pin (66) interacting with a pilot valve seat (68), which in the firing position separates a control chamber (36) of the control device (20) from a low pressure outlet (76), characterized in that the pilot valve seat (68), on the side facing the low pressure outlet (76), is connected by a closed relief chamber (72) which is permanently connected to the low pressure outlet (76) by means of a throttle passage (74) and into which the pilot valve pin (66) protrudes.

2. Fuel injection valve according to claim 1, characterized in that the pilot valve pin (66) is guided in a sliding fit, preferably in a narrow sliding fit.

3. Fuel injection valve according to claim 2, characterized in that the pilot valve pin (66) in a limiting body (46, 54) for the relief chamber (72) is slidably guided.

, Fuel injection valve according to one of claims 1 or 3, characterized in that the throttle passage (74) is arranged in the pilot valve pin (66).

5. Fuel injection valve according to one of claims 1 to 3, characterized in that the throttle passage (74) in the limiting body (46, 54) is arranged.

6. The fuel injector as claimed in claim 3 or 5, characterized in that the pilot valve seat (68) is arranged on an outlet chamber body (46) which has a drain chamber (48) which is connected to the control chamber (36) and leads to the pilot valve seat (68), on which the limiting body (54) lies sealingly.

7. Fuel injection valve according to claim 3 or 5, characterized in that the pilot valve seat (68) is formed on the limiting body (54).

8. Fuel injection valve according to one of claims 1 to 7, characterized in that in the limiting body (54) or Ab lussraumkörper (46) at least one with the high-pressure inlet (12) connected high-pressure channel (58) is arranged, which, like the outflow chamber (48) an end face which cooperates with a control body (38, 98) which closes the high pressure channel (58) when in contact with the end face.

9. Fuel injection valve according to claim 8, characterized in that the control body (38) is formed by a leaf spring tongue (98) of a leaf spring (96) is.

10. Fuel injection valve according to one of claims 1 to 9, characterized by a throttle admission (92) which connects a discharge space (48) arranged between the control chamber (36) and the pilot valve (70) with the high pressure inlet (12).

11. Fuel injection valve according to one of claims 1 to 10, characterized by a cylindrical control body (38) which is displaceably guided with radial play and which delimits the control chamber (36) and has a throttle restriction (40 ') through which the control chamber (36) also the pilot valve (70) is connected, and wherein the radial play forms a flow connection between the high pressure inlet (12) and the control chamber (36).

12. Fuel injection valve according to one of claims 1 to 9, characterized by a cylindrical control body (38) which is displaceably guided in a close sliding fit and which delimits the control chamber (36) and has a throttle restriction (40 ') by which the control chamber (36) is connected to the pilot valve (70), and wherein the control body (38) has a connecting channel (94) to form a flow connection between the high-pressure inlet (12) and the control chamber (36).

13. Fuel injection valve according to claim 8, characterized in that a transmission pin (104) is arranged in the discharge space (48), which on the one hand interacts with the pilot valve pin (66) and on the other hand with the control body (38) in order to close the pilot valve (70 ) of the front side (46 ').