EP3194757B1 - Fuel injection valve for combustion engines - Google Patents

Description

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

A fuel injector of this type is from the document WO 2010/088781 A1 known. A mushroom-shaped intermediate valve member has a shaft guided in a sliding fit in an intermediate element and a head which, with its sealing surface in the closed position of the intermediate valve member, at least partially abuts a surface of an intermediate valve seat formed on the intermediate element in order to separate a high-pressure inlet from a control chamber, the sealing surface of the Head and the surface of the intermediate valve seat are designed such that they produce a throttled fluid connection between the high pressure inlet and the sliding fit in the closed position of the intermediate valve.

Other fuel injectors are for example from the WO 2007/098621 A1 known. Such fuel injection valves enable both the controllability of the opening movement of the injection valve member and a rapid closing process of the injection valve member with a minimal construction effort. The realization of multiple injections with very short time intervals is possible. While the control room and the valve room are only permanently connected to each other via a precise throttle passage, an intermediate valve also separates these two rooms from each other. A connected to the high pressure chamber of the injection valve, in the control chamber leading high pressure inlet of large cross-section, compared to the cross-section of the throttle passage, is controlled by the intermediate valve. Since the cross-section of the outlet from the valve chamber controlled by an electrical actuator arrangement can also be considerably larger than the cross-section of the throttle passage, the opening movement of the injection valve element depends essentially solely on the cross-section of the throttle passage. When the outlet from the valve chamber is closed by means of the actuator arrangement, the intermediate valve opens quickly and releases the passage of large cross-section connected to the high-pressure chamber, which causes the injection process to be ended quickly.

The intermediate valve member of the intermediate valve is mushroom-shaped and has a shaft which is guided in a guide passage of an intermediate part in a narrow sliding fit and a head which, with a sealing surface running around the shaft at a radial distance, in the closed position of the intermediate valve member, on an annular formed on the intermediate part Intermediate valve seat is present.

It has been shown that when the high-pressure approval is completely closed and thus the flat contact between the sealing surface of the head and the surface of the intermediate valve seat, high adhesive forces can act, which can make it difficult to open the intermediate valve again to end the injection process, in particular the temporal precision of the Termination of the injection process may be worsened.

This problem of adhesion is already in the document WO 2010/088781 A1 addressed. To solve the problem, it is proposed to leave a throttled fluid connection between the high-pressure inlet and the sliding fit of the stem on the intermediate part in the closed position of the intermediate valve. For this purpose, the sealing surface of the head and the sealing surface of the intermediate valve seat are designed to be inclined to one another in such a way that, when the intermediate valve is in the closed position, they rest radially on the outside and radially inward, a throttling gap that increases in the axial direction for throttling the high-pressure inlet towards the valve chamber form there. An annular line seal between the valve member and the valve seat of the intermediate valve is thus sought. The extremely precise manufacture of the mushroom-shaped intermediate valve member and the intermediate part interacting with this solution is extremely delicate and very expensive.

Furthermore, embodiments of the fuel injection valve are disclosed in this document, in which the intermediate part and an intermediate element resting thereon on the side facing away from the guide part are designed in the form of a circular disk and are arranged in a section of the housing which is approximately completely cylindrical on the inside. They leave a section of the high-pressure space free between them and the housing. This section is connected on the one hand to the injection valve seat and on the other hand to the high-pressure fuel inlet. The connection to the high-pressure inlet can take place, for example, in that recesses are formed on the housing in the otherwise cylindrical section in the radial direction towards the outside and obliquely to the longitudinal axis. Such recesses weaken the Stability of the housing, for example the nozzle body in this area, which requires a correspondingly thicker design of the housing wall.

The document US 2011/0233309 A1 discloses a fuel injector in which a pressure surface of a pressure member presses against an orifice wall surface to break communication between an inflow port and a pressure control chamber when a connection between an outflow port and a return passage is made by a pressure control valve. The pressure surface of the pressure element is displaced or separated from the opening wall surface to open the inflow mouth of the opening wall surface to the pressure control chamber when the connection between the outflow mouth and the return channel is interrupted by the pressure control valve. The pressure surface of the pressure element or the opening wall surface of the control housing is provided with a lowered inflow section and a lowered drain section, which are separated from each other. A lowering dimension of the lowered inflow section is larger than the lowering dimension of the lowered inflow section.

On the basis of this prior art, it is an object of the present invention to develop the known fuel injection valve in such a way that adhesive forces between the intermediate valve member and the intermediate part are minimized with favorable manufacture.

This is solved with an injection valve according to claim 1.

The fuel injection valve according to the invention for the intermittent injection of fuel into the combustion chamber of an internal combustion engine has a housing which has at least one housing body and a nozzle body with an injection valve seat. The housing is preferably designed radially on the outside over its entire length at least approximately in the form of a circular cylinder, optionally with a stepped outer diameter.

There is a high-pressure chamber in the housing, which runs from a high-pressure fuel inlet of the housing to the injection valve seat.

In the housing in the high-pressure chamber, a preferably needle-shaped injection valve member is arranged adjustable in the direction of its longitudinal axis, which cooperates with the injection valve seat. To inject fuel into the combustion chamber, the injection valve member is lifted off the injection valve seat and brought to bear against it again to end the injection.

There is also a compression spring, which is supported at one end on the injection valve member and acts upon it with a closing force directed in the direction toward the injection valve seat. The other end of the compression spring is supported in a stationary manner relative to the housing, preferably on a guide part, which is preferably designed as a guide sleeve.

Furthermore, the guide part, in which a control piston of the injection valve member is guided in a preferably narrow sliding fit, is arranged in the high-pressure chamber.

Furthermore, a preferably plate-shaped intermediate part is present in the housing in the high-pressure space, which, together with the guide part and the control piston, delimits and separates a control space from the high-pressure space.

A control device for controlling the axial movement of the injection valve member by changing the pressure in the control chamber is also present in the fuel injection valve. The control device has an intermediate valve, the mushroom-shaped intermediate valve member of which has a stem which is guided in a guide passage of the intermediate part in a preferably narrow sliding fit and a head. The head faces the control chamber and, with its sealing surface running at a radial distance around the shaft, in the closed position of the intermediate valve member, rests against an annular intermediate valve seat formed on the intermediate part, forming an annular sealing surface. The ring sealing surface lies in a plane running at right angles to the axis of the shaft and thus of the intermediate valve member.

A high-pressure inlet formed on the intermediate part and permanently connected to the high-pressure inlet opens into an annular space which is delimited by the intermediate part, shaft and head and has an at least approximately hollow-cylindrical inner ring space which runs around the shaft.

In the closed position of the intermediate valve member, the intermediate valve separates the high pressure inlet and the annular space from the control chamber and, if the intermediate valve member is not in the closed position, there is a connection between the annulus and the high-pressure inlet with the control room.

Furthermore, the intermediate valve with the stem, which is guided in a preferably narrow sliding fit on the intermediate part, continuously separates the control chamber from a valve chamber, except for a precise size throttle passage, which is preferably formed on the intermediate valve member and which connects the control chamber to the valve chamber permanently.

The fuel injector has an electrically actuated actuator arrangement for connecting the valve chamber to and separating the valve chamber from a low-pressure fuel return.

The annular space further has an annular gap annular space directly adjoining the inner annular space, which, in the closed position of the intermediate valve member, is formed by a gap between the intermediate part and the head of the intermediate valve member, the gap width of the gap annular space measured in the longitudinal direction of the intermediate valve member being smaller than that Inner annular space, preferably at least five times smaller.

Since the high-pressure inlet opens into the inner annulus, it forms - in contrast to the teaching in the document WO 2010/088781 A1 - The split ring space no throttled fluid connection between the high pressure inlet and the sliding fit of the shaft of the intermediate valve member on the intermediate part.

However, the split ring space enables a noticeable reduction in the size of the ring sealing surface and thus the adhesive forces as well as an optimal placement of the ring sealing surface in the radial direction. Depending on that Fuel injection valve, the ring sealing surface can be selected further out in the radial direction or further in. Since the intermediate valve member functions as a double-acting piston, the size of the active control piston surface of the injection valve member can be adjusted in this simple manner, given the available space.

The gap ring space, measured in the closed position of the intermediate valve member and in the longitudinal direction of the shaft and thus of the intermediate valve member, preferably has an at least approximately constant gap width.

The mouth of the high-pressure inlet is preferably located completely in the region of the inner annular space. This enables the production of the high pressure approval by means of a bore running in the radial direction. In addition, this prevents the mouth from being partially in the area of the split ring space, which means that the ring sealing surface is formed at a shorter distance from the shaft, i.e. radially far inside, allows.

The ring surface, measured in the radial direction, preferably has a width between 0.1 mm and 1 mm. The width is preferably between 0.2 mm and 0.5 mm. With a flat ring sealing surface, this ensures a good seal on the one hand and minimal adhesion on the other.

In the closed position of the intermediate valve member, the gap ring space, measured in the longitudinal direction of the shaft, preferably has a gap width of 0.04 mm to 0.4 mm. On the one hand, the split ring space is designed to be space-saving and, on the other hand, it is large enough to optimally act upon the transient processes Ensure surface of the head between the stem and the sealing surface with fuel. The gap width in the area of the entire gap ring space is preferably at least approximately constant.

The split ring space, measured in the radial direction, preferably has a width of at least 0.2 mm. This enables simple manufacture of the sealing surface on the head on the one hand and the sealing surface of the intermediate valve seat on the other.

Preferably, an annular sealing bead is formed on the head on the side facing the intermediate part, the free end face of which forms the sealing surface. The end face of the intermediate part facing the control chamber is preferably flat. Together with the part that interacts with the sealing surface of the head, it forms the auxiliary valve seat.

The sealing bead preferably has an at least approximately square or rectangular cross section. The head preferably has, on its side facing the intermediate part, a circular ring surface running radially around the outside of the sealing bead, which lies at least approximately in the same plane as the ring surface between the shaft and the sealing bead.

The sealing bead preferably has a cross section corresponding at least approximately to a right-angled trapezoid, the right angles being radially on the inside. The shorter of the two sides of the trapezoid running parallel to one another thus lies in the sealing surface of the intermediate valve member and the obliquely extending side extends obliquely from this radially outside in the direction away from the intermediate part. The head preferably has a cross-section seen, a straight extension of the radially outer oblique side of the trapezoid up to its radial outer edge. This also enables simple manufacture of the intermediate valve member.

A radially inner undercut and, on the intermediate part, a radially outer undercut can be formed on the head, on the side facing the intermediate part, these undercuts limiting the annular sealing surface when the intermediate valve member is in contact with the intermediate part. The reverse construction would also be possible, namely that a radially outer undercut is formed on the head and a radially inner undercut on the intermediate part, these undercuts limiting the annular surface.

Preferably, on the intermediate part, on the side facing the head, an annular sealing projection, preferably at least approximately square or rectangular in cross section, is formed, the free end side facing the head forming the valve seat. In this case, the sealing surface on the head can lie in the same plane as the surface between the shaft and the annular sealing surface.

The valve chamber is preferably permanently connected to the high-pressure chamber via a further throttle passage. This further throttle passage can be formed in the intermediate part, for example, starting from the high-pressure inlet. If the valve chamber is separated from the low-pressure fuel return by means of the actuator arrangement, a higher pressure is built up more quickly through this further throttle passage in the valve chamber, which leads to a faster opening of the intermediate valve member and thus to a faster termination of the injection process.

A preferably plate-shaped intermediate element preferably bears against the intermediate part, on its side facing away from the guide part. On this, an eccentric to the shaft and the guide passage in the intermediate element, an outlet passage is formed which, together with the intermediate part and the intermediate valve member, delimits the valve space and which can be closed and released on the side of the intermediate element facing away from the intermediate part by means of a plunger of the actuator arrangement. The valve chamber can thus be formed in a simple manner with the desired volume. Furthermore, the end face of the intermediate element facing the actuator arrangement can be flat, on which the tappet comes to rest to separate the valve chamber from the low-pressure fuel return.

The guide part is preferably formed by a guide sleeve which is circular in cross section and on which the compression spring is supported. The compression spring presses the guide sleeve to the preferably plate-shaped intermediate part in a sealing manner.

Figur 1

im Längsschnitt ein erfindungsgemässes Einspritzventil;

Figur 2

gegenüber Figur 1 vergrössert, den dort mit einem mit II bezeichneten Rechteck gekennzeichneten Teil des Einspritzventils;

Figur 3

gegenüber Figur 2 vergrössert, den dort mit III bezeichneten Rechteck eingerahmten Teil des Brennstoffeinspritzventils mit der Steuereinrichtung;

Figur 4

gegenüber Figur 1 vergrössert, den dort mit dem Rechteck II zeichneten Teil des Brennstoffeinspritzventils in einer rechtwinklig zur dortigen Schnittebene verlaufenden Längsschnitt;

Figur 5

in perspektivischer Darstellung ein pilzförmiges Zwischenventilglied;

Figur 6

in perspektivischer Darstellung ein Zwischenteil für das pilzförmig ausgebildete Zwischenventilglied gemäss Figur 5;

Figur 7

ebenfalls in perspektivischer Darstellung ein Zwischenelement, welches dazu bestimmt ist, am Zwischenteil dichtend anzuliegen;

Figur 8

in gleicher Darstellung wie Figur 3 eine zweite Ausführungsform der Steuervorrichtung;

Figur 9

in gleicher Darstellung wie die Figuren 3 und 8 eine dritte Ausführungsform der Steuervorrichtung; und

Figur 10

in gleicher Darstellung wie die Figuren 3, 8 und 9 einen Ausschnitt aus einer vierten Ausführungsform der Steuervorrichtung.

The invention is described in more detail with reference to the embodiments shown in the figures. It shows purely schematically:

Figure 1

in longitudinal section an injection valve according to the invention;

Figure 2

across from Figure 1 enlarged, the part of the injection valve marked there with a rectangle designated II ;

Figure 3

across from Figure 2 enlarged, the part of the fuel injector framed there by III with the control device;

Figure 4

across from Figure 1 enlarged, the part of the fuel injector drawn there with the rectangle II in a longitudinal section running at right angles to the sectional plane there;

Figure 5

in a perspective view a mushroom-shaped intermediate valve member;

Figure 6

a perspective view of an intermediate part for the mushroom-shaped intermediate valve member according to Figure 5 ;

Figure 7

also in perspective an intermediate element, which is intended to lie sealingly on the intermediate part;

Figure 8

in the same representation as Figure 3 a second embodiment of the control device;

Figure 9

in the same representation as that Figures 3 and 8th a third embodiment of the control device; and

Figure 10

in the same representation as that Figures 3 , 8th and 9 a section of a fourth embodiment of the control device.

In the description of the figures, the same reference numerals are always used for corresponding parts.

That in the Figure 1 The fuel injection valve 10 shown is intended for the intermittent injection of fuel into the combustion chamber of an internal combustion engine. The fuel is under very high pressure, for example up to 2,000 bar or more.

The fuel injector has a housing 12 with a housing body 14, a nozzle body 16, on which an injection valve seat 18 is formed, and an actuator receiving body 20, which is arranged between the housing body 14 and the nozzle body 16. A union nut 22, which is supported on the nozzle body 16, receives the actuator receiving body 20 and is wound onto the housing body 14. The housing body 14 and the actuator receiving body 20, as well as this and the nozzle body 16 abut one another on the end face, are pressed against one another in a sealing manner by means of the union nut 22 and are aligned with one another in the direction of the housing axis L.

The outer shape of the housing 12 is at least approximately circular cylindrical in a known manner.

On the end face of the housing body 14 facing away from the nozzle body 16, a high-pressure fuel inlet 24 is arranged, from which a high-pressure chamber 26 runs inside the housing 12 up to the injection valve seat 18. The high-pressure fuel inlet 24 is formed by a valve carrier 28, which carries a check valve 30 and a basket-like perforated filter 32 for retaining any foreign particles in the fuel. The disk-shaped valve member of the check valve 30, which cooperates with a valve seat formed on the valve support 28, has a bypass bore.

The check valve 30 allows fuel supplied via a high-pressure feed line to flow into the high-pressure space 26 practically without obstacles in the known manner, but prevents fuel from flowing out of the high-pressure space 26 into the high-pressure feed line with the exception of the bypass.

The structure and the mode of operation of the unit designed as a cartridge with the valve support 28, the check valve 30 and the perforated filter 32 are in the earlier application PCT / EP2014 / 000447 disclosed in detail. The high-pressure fuel inlet 24 and the valve support 28 with check valve 30 and perforated filter 32 can also be designed, as is described in the document WO 2013/117311 A1 is disclosed. A possible embodiment of the high-pressure fuel inlet 24 and the check valve 30, as well as a rod filter instead of the perforated filter 32 is shown in FIG WO 2009/033304 A1 known.

The disclosure of the above-mentioned application and publications is considered to be incorporated into the present disclosure by reference.

Adjoining the valve support 28, the high-pressure chamber 26 has a discrete storage chamber 34 formed on the housing body 14, which on the other hand is connected to the injection valve seat 18 via a flow channel 36 of the high-pressure chamber 26.

The dimensioning and the functioning of the discrete storage chamber 34 together with the check valve 30 with bypass is in the document WO 2007/009279 A1 disclosed in detail; this disclosure is incorporated by reference into the present disclosure.

In a recess of the actuator receiving body 20, an electrically actuated actuator arrangement 38 is accommodated in the known manner, which, with its plunger 40 which is spring-loaded in one direction and movable in the other direction by means of an electromagnet of the actuator arrangement 38, is intended to close a low-pressure outlet 42, around a valve space 44, from a low-pressure fuel return 46 (see Figures 2 and 3rd ) and to release the low pressure outlet 42 to connect the valve space 44 and the low pressure fuel return 46 to each other. The longitudinal axis, designated 48, of the plunger 40 and thus the actuator arrangement 38 runs parallel and eccentrically to the longitudinal axis L.

Parallel to the discrete storage chamber 34 arranged eccentrically with respect to the longitudinal axis L of the housing 12 and thus of the fuel injection valve 10, a channel 52 runs from an electrical connection 50 through the housing body 14 to the actuator arrangement 38, in which channel the electrical control line for controlling the actuator arrangement 38 is received.

How this from the regarding the Figure 1 enlarged Figure 2 emerges, the conical injection valve seat 18 is integrally formed on the nozzle body 16 and is directly connected via the flow channel 36 to the storage chamber 34 and thus to the high-pressure fuel inlet 24.

As seen in the flow direction of the fuel, downstream of the injection valve seat 18, injection openings 54 are formed in a hemispherical free end region of the nozzle body 16 in a known manner, through which orifices are lifted from the injection valve seat 18 Injection valve member 56, the fuel under very high pressure is injected into the combustion chamber of the internal combustion engine.

The injection valve member 56 is needle-shaped and interacts with the injection valve seat 18. The injection valve member 56 is movably guided in a guide bore 57 in the nozzle body, which is concentric with the longitudinal axis L and belongs to the high-pressure chamber 26, in the direction of the longitudinal axis L, the recesses on the injection valve member 56, which run in the longitudinal direction and are open to the outside in the radial direction, causing the low-loss flow of fuel to the injection valve seat 18 and to the injection openings 54 is made possible.

How special from the Figure 2 As can be seen, upstream of this guide bore 57, the interior 58 of the nozzle body 16 belonging to the high-pressure space 26 is designed to widen in a double manner towards the actuator receiving body 20, the portion of the interior 58 extending approximately longitudinally in the center of the nozzle body 16 up to the end face of the interior 58 facing the actuator receiving body 20 being an internally circular-cylindrical portion 60 of the nozzle body 16 with a constant cross section and thus the housing 12 defined.

Between this section 60 and the guide bore 57, a support ring is formed on the injection valve member 56, on which a compression spring 62 is supported at one end. At its other end, the compression spring 62 is supported on the end face on a guide sleeve 64 'forming a guide part 64. The compression spring 62 acts on the injection valve member 56 with a closing force acting in the direction of the injection valve seat 18.

On the other hand, the compression spring 62 holds the guide part 64 or the guide sleeve 64 'with its end face facing away from the compression spring 62 in sealing contact with a disc-shaped intermediate part 66.

In the guide sleeve 64 ', a control piston 68 integrally formed on the injection valve member 56 is guided so as to be displaceable in the direction of the longitudinal axis L in a narrow sliding fit of approximately 3 μm to 5 μm. The control piston 68, the guide sleeve 64 ′ and the intermediate part 66 delimit a control chamber 70 from the high-pressure chamber 26.

The intermediate part 66 is part of a control device 72, which also with reference to FIG Figure 3 is described.

Like this especially Figure 3 shows, a circular cylindrical guide passage 74 runs through the intermediate part 66 from the flat end face facing the control chamber 70 to the likewise flat end face facing away from the control chamber 70. In this there is a shaft 76 of a mushroom-shaped design with a close sliding fit of approximately 3 μm to 10 μm Intermediate valve member 78 out. A head 80 of the intermediate valve element 78, which is formed integrally with the shaft 76, is located in the control chamber 70 and, with its side facing the intermediate part 66, interacts with the intermediate part 66, the flat end face of which forms an annular intermediate valve seat 82.

The intermediate valve member 78, together with the intermediate valve seat 82 formed on the intermediate part 66, forms an intermediate valve.

A stop shoulder 84 is formed on the guide sleeve 64 'at a distance from the intermediate part 66, which limits the opening stroke of the intermediate valve member 78. In order to allow the fuel to flow from the fuel admission 86 into the control chamber 70 with as little loss as possible, there is a sufficiently large gap radially outside between the head 80 and the guide sleeve 64 'and the head 80 has four on its side facing the stop shoulder 84, wedge-like flow grooves 88, see also Figure 5 which allow the fuel to flow from the gap to the control piston 68 with little loss, even when the intermediate valve member 78 is in the open position and the head 80 lies against the stop shoulder 84.

Adjacent to the control chamber 70, a throttle passage 90 is formed on the intermediate valve member 78, which on the other hand opens into a blind hole 92 which is recessed on the intermediate valve member 78 and is concentric with the longitudinal axis L.

In the exemplary embodiment, fuel admission 86 is according to FIGS Figures 1 to 3 formed by two diametrically opposed bores which pass through the intermediate part 66 in the radial direction and open into the guide passage 74. The intermediate part 66 is also in the Figure 6 shown. The fuel inlet 86 is permanently connected to the high-pressure fuel inlet 24 and has a much larger flow cross section than the throttle passage 90.

On the front side facing away from the control chamber 70, the intermediate part 66 has a U-shaped recess 94, seen in plan view, which on the one hand opens into the guide passage 74 and on the other hand via a further throttle passage 96 recessed on the intermediate part 66 is permanently connected to the high-pressure chamber 26 and thus to the high-pressure fuel inlet 24.

On the side of the intermediate part 66 facing away from the guide sleeve 64 ', an intermediate element 98 which is likewise disc-shaped and which also in FIG Figure 7 is shown. In the area of the guide passage 74, a flow gap 100 is always present between the intermediate element 98 and the end of the shaft 76 of the intermediate valve member 78, even if the latter is in the closed position.

A step-like tapering outlet bore 102 runs through the intermediate element 98 concentrically to the longitudinal axis 48, which on the one hand opens into the flow gap 100 and the depression 94 and on the other hand forms the low-pressure outlet 42.

For the sake of completeness, it should be mentioned that the flow cross section of this outlet bore 102 is substantially larger everywhere than the sum of the cross section of the throttle passage 90 and the further throttle passage 96.

The intermediate element 98 is also arranged in the section 60 of the nozzle body 16 and, with its flat end face facing away from the intermediate part 66, it lies sealingly against the corresponding end face of the actuator receiving body 20.

For correct positioning of the intermediate element 98 relative to the actuator receiving body 20 and thus to the actuator arrangement 38, both the intermediate element 98 and the actuator receiving body 20 have aligned, mutually facing, blind hole-like positioning bores 106, in which a common positioning pin 104 is inserted.

In order to fix the position of the intermediate part 66 to the intermediate element 98, two mutually facing, blind-hole-like further positioning bores 106 'are provided on these components, in which positioning pins 104 are also inserted, these positioning bores 106' being eccentric to the longitudinal axis L in one common plane, which is perpendicular to the Figure 3 shown cutting plane, which is why the positioning pin 104 is shown in dashed lines in this figure.

Figure 4 shows the longitudinal section in this plane, the two positioning pins 104 now being shown in solid lines. Further positioning pins 104 ′, which are inserted in corresponding positioning bores in the nozzle body 16 and in the actuator receiving body 20, define the position of these two bodies relative to one another.

The intermediate part 66 together with the stem 76 and head 80 of the intermediate valve member 78 delimit an approximately hollow cylindrical inner annular space 108 which extends around the stem 76 and in which the high-pressure inlet 86 permanently opens.

As far as described so far, the fuel injection valve 10 is of the same design in all embodiments of the control device 72. In this case, the intermediate valve 83 has the task of separating the high-pressure inlet 86 and the inner annular space 108 from the control chamber 70 in the closed position of the intermediate valve member 78 and, in the case of the intermediate part 66 trained intermediate valve seat 82 lifted head 80 to release the connection between the inner annular space 108 and high pressure inlet 86 with the control chamber 70.

How this in particular from the Figures 3 and 5 emerges, the shaft 76 of the intermediate valve member 78 has a circumferential annular groove 110 which is open in the radial direction and which adjoins the head 80 directly. Seen in the direction of the longitudinal axis L, the annular groove 110 has a dimension such that the mouth of the high-pressure inlet 86 is always completely in the region of the annular groove 110, even when the intermediate valve member 78 is in the open position and thereby abuts the stop shoulder 84.

In the exemplary embodiment shown, the annular groove 110 has a trapezoidal cross section, the oblique side facing away from the head 80 and serving to deflect the fuel flowing through the two bores of the high-pressure inlet 86 with little loss when the intermediate valve member 78 is open.

On the side facing the shaft 76 and thus the intermediate part 66, an annular sealing bead 112 protruding from the rest of this side of the head 80 is formed on the head 80, the free end face 114 of which forms the sealing surface 116 of the intermediate valve member 78. Opposite this sealing surface 116, the head 80 has, on the side facing the intermediate part 66, an undercut 118 radially inside and radially outside, the surfaces of these undercuts 118, in the exemplary embodiment shown, being in a plane which is perpendicular to the longitudinal axis L. . It goes without saying the sealing surface 116 likewise lies in a plane which runs at right angles to the longitudinal axis L, and the flat end face of the intermediate part 66 which forms the intermediate valve seat 82 also lies in a plane which runs perpendicular to the longitudinal axis L.

The guide passage 74 extends in the shape of a circular cylinder with the same cross section through the entire intermediate part 66. Since the sealing bead 112 is offset from the outside in the radial direction with respect to the guide passage 74 by approximately 0.2 mm to 1.0 mm, in the closed position of the intermediate valve member 78, a split ring space 118 remains, which is radial, between the head 80 and the intermediate part 66 is delimited on the outside by the sealing bead 112 and forms an annular space 120 radially on the inside with the inner annular space 108, which is delimited by the intermediate valve member 78 and by the intermediate part 66.

The width of the ring sealing surface 122, measured in the radial direction, is between 0.1 mm and 1.0 mm in the exemplary embodiment shown. Furthermore, in the exemplary embodiment shown, the gap ring space 118 has a width of approximately 0.5 mm measured in the radial direction.

From the Figures 3 and 5 it can be seen that the sealing bead 112 can also be provided further out in the radial direction. This enables the intermediate valve 83 to be optimally adapted to the desired injection properties. If the active area of the intermediate valve member 78, which is designed as a double-acting piston, is enlarged, the intermediate valve 83 opens faster to end an injection process than if this active area is selected to be smaller.

Furthermore, the adhesion between the intermediate part 66 and the intermediate valve member 78 is minimized by minimizing the annular sealing surface 112, which is formed by the sealing surface 116 and the intermediate valve seat 82.

The further throttle passage 96 also supports the movement of the intermediate valve member 78, but it can also be dispensed with depending on the specific requirements.

If the intermediate valve 83 is closed and the plunger 40 is lifted off the low-pressure outlet 42 for an injection, the opening movement of the injection valve member 56 is determined practically exclusively by the throttle passage 90.

For the sake of completeness, it should be mentioned that the valve chamber 44 is formed by the blind bore 92, the flow gap 100, the depression 94 and the outlet bore 102.

At the in the Figure 8 The embodiment shown is only the cross section of the sealing bead 112, which in the Figure 3 is approximately rectangular, now trapezoidal, the right angle being radially inward and the oblique side being radially outward. The oblique side has a straight extension, seen in cross section, up to the radial outer edge 124 on the head 80.

This variant is particularly useful when the sealing bead 112 is located far outside of the head 80 in the radial direction. In this embodiment, too, the width of the ring sealing surface 122, and thus the free one Front 114 of the sealing bead 112, 0.1 mm to 1 mm, preferably 0.2 mm - 0.5 mm.

At the in the Figure 9 In the embodiment shown, the stem 76 of the intermediate valve member 78 has a circular cylindrical shape with a constant diameter up to the head 80, the transition from the stem 76 to the head 80, of course, being rounded off to avoid high stresses. A cylindrical ring recess 126 is on the intermediate part 66, from the front side facing the head 80 except which ring lift 126 extends to the opposite end of the mouth of the high-pressure inlet 86. The end of the ring recess 126 on this side is rounded.

In relation to this cylindrical annular recess 126, the intermediate valve seat 82 is offset in the radial direction towards the outside in accordance with the embodiments according to FIGS Figures 3 and 8th . In contrast, however, in the embodiment according to Figure 9 the annular sealing bead 112 is formed on the intermediate part 66. It has an approximately rectangular cross-sectional shape and its end face 114 ′ facing the head 80 forms the annular intermediate valve seat 82.

Like in the Figure 9 As shown, the sealing bead 112 can be formed by undercuts on the intermediate part 66 with respect to this radially inside and radially outside.

The side of the head 80 facing the intermediate part 66 can be designed as a flat annular surface, of which an annular section forms the sealing surface 116, which cooperates with the intermediate valve seat 82.

The gap ring space 118 of the annular space 120, which also has the inner annular space 108, is formed by the radially inner undercut.

At the in Figure 10 In the embodiment shown, an undercut 128 is formed on the head 80, with respect to the flat side radially on the inside that otherwise faces the intermediate part 66.

As in the embodiment according to the Figures 3 and 8th , the guide passage 74 runs through the intermediate part 66 with a constant cross section. The end face facing the head 80 has a further undercut 130, but is located radially on the outside with respect to the undercut 128. The ring sealing surface 120 is thus delimited radially on the inside by the undercut 128 and radially on the outside by the further undercut 130. Seen in the radial direction, the distance between the two undercuts 128 and 130 is between 0.1 mm to 1 mm, preferably 0.2 mm to 0.5 mm.

Here too, the annular space 120 is formed by the split ring space 118 and the inner annular space 108 formed by the annular groove 110 on the shaft 76; see also Figure 3 .

In this embodiment too, it is possible to design the shaft 76 as cylindrical over its entire length and to provide an annular recess 126 on the intermediate part 66.

Like this in particular Figures 2 to 4 8 and 9 can be removed, the intermediate part 66 and the intermediate element 98 are arranged in the inner circular-cylindrical section 60, which is formed on the nozzle body 16 in the exemplary embodiment shown. These are like this too Figures 6 and 7 is removable, disc-shaped and are shaped radially on the outside in the form of a ring, with the exception of a recess 132 in the shape of a sector of a circle when viewed in plan view.

In the assembled state, the intermediate part 66 and the intermediate element 98 are inserted into the section 60, the recesses 132 on the intermediate part 66 and the intermediate element 98 being flush with one another and the flat sides of the intermediate part 66 and the intermediate element 98 formed by the circular sector-shaped recesses 132 together with the inner wall of the housing 12 in section 60 delimit a section of the high-pressure space 26 and the flow channel 36. This section enables the low-loss flow of fuel from the high-pressure fuel inlet 24 to the injection valve seat 18, the part of the housing 12 in question not having to be weakened and its wall having the same wall thickness all around.

In Figure 6 On the intermediate part 66, the guide passage 74, the two bores of the high-pressure admission 86 running radially to this, the recess 94 with the further throttle passage 96, and the two positioning bores 106 'are shown. It can also be seen that the intermediate part 66, on the side diametrically opposite the circular sector-shaped recess 132, has a groove-shaped inflow recess 134 which is continuous in the axial direction and is open to the outside in the radial direction and into which the associated bore of the high-pressure inlet 86 opens. This inflow recess 134 enables fuel to flow through this bore into the guide passage 74 and thus into the annular space 120.

In Figure 7 In addition to the low pressure outlet 42, the positioning bore 106 and the circular recess 132 are also visible.

Starting from the closed position of the intermediate valve 83 shown in the figures, the plunger 40 is lifted from the intermediate element 98 for injection by means of the electromagnet of the actuator arrangement 38, as a result of which the low-pressure outlet 42 is opened. The result of this is that a larger quantity of fuel flows out of the valve chamber 44 into the low-pressure fuel return 46 per unit time than can flow into the valve chamber 44 through the throttle passage 90 and any further throttle passage 96 that is present. As a result, the pressure in the valve chamber 44 drops, with the result that, on the one hand, the intermediate valve member 78 is pressed onto the intermediate part 66 with great force in order to keep the intermediate valve 83 securely closed and, on the other hand, the pressure in the control chamber 70 drops. This in turn has the consequence that the injection valve member 56 is lifted off the injection valve seat 18 by the action of the double-acting control piston 68 against the force of the compression spring 62, whereby an injection of fuel into the combustion chamber of the internal combustion engine is started.

If this injection is to be ended, the plunger 40 is brought into contact with the intermediate element 98, as a result of which the low-pressure outlet 42 is closed. The pressure in the valve chamber 44 rises through the fuel flowing in through the throttle passage 90 and any additional throttle passage 96 that is present, which causes the intermediate valve member 78 to move away from the intermediate valve seat 82 causes. This movement is further supported by the double-piston effect of the intermediate valve member 78 designed according to the present invention, the adhesion counteracting this opening movement of the intermediate valve member 78 being minimized.

By lifting the head 80 of the intermediate valve member 78 from the intermediate element 98, a large flow cross-section is quickly released from the annular space 120 into the control space 70, which leads to a rapid termination of the injection process by the injection valve member 56 being quickly moved toward the injection valve seat 18 and towards it Plant arrives.

In all the embodiments shown, the intermediate part 66 and the intermediate element 98 are each formed as a one-piece body. It is also possible to realize the intermediate part 66 and the intermediate element 98 from a single workpiece.

Claims (16)

1. A fuel injection valve for intermittent injection of fuel into the combustion chamber of an internal combustion engine, having
   a housing (12), which has a housing body (14) and a nozzle body (16) with an injection valve seat (18),
   a high-pressure space (26), which is arranged in the housing (12) and extends from a high-pressure fuel inlet (24) to the injection valve seat (18),
   an injection valve member (56), which is arranged movably in the housing (12) and interacts with the injection valve seat (18),
   a compression spring (62), which is supported, on the one hand, on the injection valve member (56) and subjects the latter to a closing force directed toward the injection valve seat (18) and, on the other hand, is supported in a fixed manner relative to the housing (12),
   a guiding part (64), in which a control plunger (68) of the injection valve member (56) is guided with a sliding fit,
   an intermediate part (66), which, together with the guiding part (64) and the control plunger (68), delimits a control space (70),
   a control device (72) for controlling the axial movement of the injection valve member (56) by varying the pressure in the control space (70), having an intermediate valve (83), the mushroom-shaped intermediate valve member (78) of which has a stem (76), which is guided with a sliding fit in a guide passage (74) of the intermediate part (66), and a head (80), which rests with its sealing surface (116) which extends at a radial distance around the stem (76), in the closed position of the intermediate valve member (78), against an annular intermediate valve seat (82) formed on the intermediate part (66), thereby forming an annular sealing surface (122),
   an annular space (120), which is delimited by the intermediate part (66), the stem (76) and the head (80) and has an at least approximately hollow-cylinder-shaped inner annular space (108) extending around the stem (76), wherein the annular space (120) has an annular gap space (118), which adjoins the inner annular space (108) and which is formed by a gap between the intermediate part (66) and the head (80) in the closed position of the intermediate valve member (78), and wherein a high-pressure fuel feed (86) connected to the high-pressure fuel inlet (24) opens into the annular space (120),
   wherein the intermediate valve (83) cuts off the high-pressure fuel feed (86) and the annular space (120) from the control space (70) in the closed position of the intermediate valve member (78) and otherwise opens the connection from the annular space (120) and the high-pressure fuel feed (86) to the control space (70), and the intermediate valve member (78) continuously cuts off the control space (70) from a valve space (44) - apart from a restrictor passage (90), and
   an electrically actuated actuator arrangement (38) for connecting the valve space (44) to and cutting the valve space (44) off from a low-pressure fuel return (46),
   characterized in that the high-pressure fuel feed (86) opens into the inner annular space (108).
2. The fuel injection valve as claimed in claim 1, characterized in that the annular gap space (118) has an at least approximately constant gap width in the closed position of the intermediate valve member (78), and the gap width is preferably at least five times smaller than the inner annular space (108), in each case measured in the longitudinal direction of the stem (76).
3. The fuel injection valve as claimed in claim 1 or 2, characterized in that the opening of the high-pressure fuel feed (86) is arranged fully in the region of the inner annular space (108).
4. The fuel injection valve as claimed in one of claims 1 to 3, characterized in that the width of the annular sealing surface (122) is 0.1 mm to 1 mm, preferably 0.2 mm to 0.5 mm, measured in the radial direction.
5. The fuel injection valve as claimed in one of claims 1 to 4, characterized in that the annular gap space (118) has a thickness of 0.04 mm to 0.4 mm, measured in the longitudinal direction, in the closed position of the intermediate valve member (78), in order to ensure that the surface of the head (80) between the stem (76) and the sealing surface (116) is provided with an optimum supply of fuel during transient processes.
6. The fuel injection valve as claimed in one of claims 1 to 5, characterized in that the annular gap space (118) has a width of at least 0.2 mm, measured in the radial direction.
7. The fuel injection valve as claimed in one of claims 1 to 6, characterized in that a projecting annular sealing bead (112), the free end face (114) of which forms the sealing surface (116), is formed on the head (80) on the side thereof facing the intermediate part (66).
8. The fuel injection valve as claimed in claim 7, characterized in that the sealing bead (112) has an at least approximately square or rectangular cross section.
9. The fuel injection valve as claimed in claim 8, characterized in that the sealing bead (112) has a cross section corresponding at least approximately to a right trapezoid, wherein the at least approximately right angles are situated radially on the inside, and the head (80), when viewed in cross section, preferably forms a rectilinear extension of the radially outer oblique side of the trapezoid as far as to its radial outer edge (124).
10. The fuel injection valve as claimed in one of claims 1 to 9, characterized in that that the end face of the intermediate part (66) which faces the control space (70) and forms the intermediate valve seat (82) is of flat design.
11. The fuel injection valve as claimed in one of claims 1 to 6, characterized in that a radially inner undercut (128) is formed on the side of the head (80) facing the intermediate part (66), and a radially outer undercut (130) is formed on the intermediate part (66), and the undercuts (128; 130) delimit the annular sealing surface (122).
12. The fuel injection valve as claimed in one of claims 1 to 6, characterized in that an annular sealing projection (112), the free end face (114) of which forms the valve seat (82), is formed on the intermediate part (66), on the side thereof facing the head (80), the sealing projection preferably being at least approximately square or rectangular in cross section.
13. The fuel injection valve as claimed in one of claims 1 to 12, characterized in that the valve space (44) is continuously connected to the high-pressure space (26) via a further restrictor passage (96).
14. The fuel injection valve as claimed in one of claims 1 to 13, characterized in that a plate-shaped intermediate element (98) rests on the intermediate part (66), on the side facing away from the guiding part (64), and the intermediate element (98) has, eccentrically with respect to the stem (76) and the guide passage (74), an outlet passage (102) which, together with the intermediate part (66) and the intermediate valve member (78), delimits the valve space (44) and which, on the side facing away from the intermediate part (66), can be closed and opened by means of a tappet (40) of the actuator arrangement (38).
15. The fuel injection valve as claimed in one of claims 1 to 14, characterized in that the guiding part (64) is formed by a guiding sleeve (64'), on which the compression spring (62) is supported, wherein the compression spring (62) presses the guiding sleeve (64') sealingly against the intermediate part (66) of plate-shaped design.
16. A fuel injection valve as claimed in one of claims 1 to 15, characterized in that the stem (76) is guided with a close sliding fit in the guide passage (74) .

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