WO2012130452A1

WO2012130452A1 - Injection valve

Info

Publication number: WO2012130452A1
Application number: PCT/EP2012/001379
Authority: WO
Inventors: Raphael FÜCHSLIN
Original assignee: Fuechslin Raphael
Priority date: 2011-03-31
Filing date: 2012-03-29
Publication date: 2012-10-04
Also published as: DE102011015753A1

Abstract

The invention relates to an injection valve for fuel injection in a combustion chamber of an internal combustion engine, comprising a valve housing (18) and a valve member (E1) arranged therein so as to be displaceable in a longitudinal direction for opening and closing at least one injection opening (14). The valve member has a plurality of valve member elements (8, 11, 1b, 11c, 12a, 12b) arranged one behind the other in the longitudinal direction and also at least one coupling element (9a, 9b, 9c, 9d). The coupling element (9a, 9b, 9c, 9d) encloses an end region of a first valve member element in such a manner that between an outer face (24a, 24b) of the end region of the first valve member element and a first inner face of the coupling element (9a, 9b, 9c, 9d) an annular gap (26) remains to equalise an angle error (W1) between a longitudinal axis of the first valve member element and a longitudinal axis of the coupling element (9a, 9b, 9c, 9d). The valve member (E1), in particular the coupling element (9a, 9b, 9c, 9d), is surrounded at least partially by a pressurised fluid, and the annular gap (26) is dimensioned such that when a tensile force is applied to the valve member (E1) a negative pressure develops in an inner space (20) of the coupling element (9a, 9b, 9c, 9d) for kinematic coupling of the first and a second valve member element.

Description

Injector

The present invention relates to an injection valve for fuel injection in a combustion chamber of an internal combustion engine, for example a diesel engine.

Such injection valves are used in particular for the intermittent injection of a fuel present in liquid form, for example gasoline or diesel fuel, into a combustion chamber of an internal combustion engine. For this purpose, the fuel is provided by a high-pressure pump at a high pressure and injected into the combustion chamber through the injection valve arranged on the combustion chamber, for example a cylinder of a diesel or gasoline engine. The injection process is usually controlled by an electronic engine control.

Such an injection valve comprises a housing, which is usually elongated for reasons of the available installation space and in which an elongated valve member is displaceably arranged. By displacing the valve member, an injection port disposed in a valve seat member can be closed or opened. On the housing, a high-pressure fuel port is provided, which communicates via a bore in communication with the injection port. Furthermore, the injection valve comprises an actuator, via a control device, in particular

CONFIRMATION COPY the electronic engine control, can be controlled, and a typically hydraulic control device, with which the activity of the actuator can be converted into a movement of the valve member. Such actuators and control devices are known per se and described, for example, in EP 0 976 924 A2 or EP 0 228 578 A1. An injection valve of the type mentioned is disclosed for example in WO 02/086309 AI.

The length of the valve member of such an injector is usually much larger than the diameter of the valve member. The large ratio of length to diameter can lead to many disadvantages. Thus, long, thin components are more difficult to produce than short, thick components, which leads to higher production costs. In addition, an injection valve member is usually subjected to a heat treatment or curing during its processing, which can lead to a disadvantageous for the use delay of the valve member.

It has therefore been proposed to implement an injection valve member in several parts, wherein the individual elements are in operative connection with each other during operation. This also makes it possible to produce the highly stressed seat from a high-quality, expensive material, while the rest of the injection valve member can be made of a cost-effective material. In addition, a multi-part design of the valve member allows a modular execution, in which at least individual elements of the valve member for a plurality of engine types can be used, even if different lengths of the valve members are necessary for this. This makes it possible to produce in larger, more cost-effective batch sizes.

Since even with the elements of a multi-part valve member due to a heat treatment can occur and also manufacturing inaccuracies can lead to non-parallelism and / or misalignment of the axes of the individual elements of the valve member, it would be desirable if such errors tolerated without adverse consequences could become. In DE 198 15 892 AI a fuel injector with a nozzle body, a slidably mounted in a lower part of an inner bore of the nozzle body needle for opening and closing an injection port and a slidably mounted in an upper part of the inner bore of the nozzle body piston rod to Driving the needle revealed. The needle and the piston rod are rigidly connected by a substantially triangular shaped connecting member in the axial direction, while relative sliding in the radial direction within a slot of the connecting member is possible to absorb misalignment of both axes. An angular error between the needle and the piston rod is not compensated.

According to DE 44 27 378 A1, a slight offset of the guides provided in different housing parts of the nozzle needle and the piston of an injector for fuel injection can be compensated for by the fact that the mutually facing end regions of nozzle needle and piston rod each have a recess into which one in the longitudinal direction Split sleeve engages positively. DE 100 20 867 A1 proposes a common rail injector in which, despite an axial offset between a valve piece and a nozzle needle, a centric introduction of the closing force into the nozzle needle is achieved by an elongated valve piston being moved into a short valve piston and a pressure rod is split, which is tapered at its end facing the valve piston. In US 2010/0065020 AI a fuel injector is described in which a connecting piece is firmly connected both with a valve piston and with a nozzle needle.

In EP 0 685 645 Bl an injection valve for a fuel injection system of an internal combustion engine is described, wherein in a valve housing, a multi-part valve body with a nozzle needle and a coaxially arranged on this lying overlying valve body part is slidably disposed. The fuel passes from an inlet line via a laterally arranged in the valve housing bore in a nozzle needle adjacent pressure chamber. In order to avoid an overload of the nozzle tip of the valve at an increased closing speed. a fuel-filled damping chamber is provided between the nozzle needle and the overlying valve body part. An operative connection between the nozzle needle and the overlying valve body part can be imparted by a ring element into which the nozzle needle protrudes approximately free of play. An articulated function is exercised by a ring element made of plastic, which is inserted over the two ends of the nozzle needle and the valve body part and together with these forms a tight fit. The damping chamber can be connected via a throttle bore with the pressure chamber. However, a plastic ring member is not satisfactory in durability due to the chemical, thermal and mechanical conditions prevailing in the injector. Further, for the exercise of the articulated function, a deformation of the ring element is necessary, whereby lateral forces are exerted on the nozzle needle and the overlying valve body part or the respective guides, which lead to friction and wear, which ultimately affects the function of the injection valve.

It is therefore an object of the present invention to provide an injection valve of the type mentioned, wherein said disadvantages are avoided, which is particularly insensitive to angular errors.

This object is achieved by an injection valve according to claim 1.

Advantageous developments of the invention will become apparent from the subclaims.

An injection valve according to the invention for fuel injection into a combustion chamber of an internal combustion engine, for example an Otto or a diesel engine, comprises a valve housing and a valve member, which is arranged displaceably in the valve housing for opening and closing at least one injection opening in a longitudinal direction. The injection opening can be arranged for injecting the fuel into the combustion chamber and is accompanied by For example, formed by a valve housing associated valve seat member. The valve member is elongated in particular in the longitudinal direction and comprises a plurality of valve member elements arranged one after the other in the longitudinal direction, in particular likewise elongate. Of these, at least one valve member element can be designed to open and close the injection opening; Furthermore, at least one valve member element may be provided on which a drive of the valve member engages.

The valve member according to the invention further comprises a coupling element for coupling a first valve member element with a second valve member element. In this case, the first valve member element can be arranged on the nozzle side of the second or vice versa. The coupling element may be sleeve-shaped and surrounds an end region of the first valve member element such that an annular gap is formed between an outer surface of the end region of the first valve element element and a first inner surface of the coupling element. The coupling element may comprise further elements for connection to the first and the second valve member element. The end region of the first valve member element and a region of the coupling element enclosing the latter can be approximately configured as full or hollow cylinders with a circular cross section, so that the outer surface of the end region of the first valve element element and the first inner surface of the coupling element are approximately circular cylindrical. The annular gap can have a uniform or an uneven width along the circumference of the first valve member element. The injection valve is designed such that the valve member, in particular the coupling element, can be at least partially surrounded by a pressurized fluid. In particular, the valve member is surrounded during operation of the injection valve in the region of the opening of the annular gap of the pressurized fluid. Upon application of a tensile force to the valve member, whereby the protruding into the coupling element first valve member element and the second valve member element, which may be connected to the coupling element in other ways than the first, are pulled apart, arises in an interior of the coupling element, in which the first VEN extends tilgliedelement and which, apart from the annular gap, closed or sealed, a negative pressure. Due to the negative pressure pressure fluid can flow through the annular gap in the interior. The annular gap is dimensioned such that at least for a period of time during which the tensile force acts to carry out an injection, a sufficiently small amount of liquid flows into the interior space in order to maintain the negative pressure substantially. The annular gap is thus dimensioned such that the kinematic coupling of the first and a second valve member element adjacent in the longitudinal direction is maintained at least for this period of time. The annular gap can for this purpose have a width in the micrometer range, for example of a maximum of about 5 μπι. The first and the second valve member element are at least as far surrounded by the pressure fluid, so that by the negative pressure in relation to the surrounding pressure of the pressure fluid and possibly taking into account other forces, such as a spring, a corresponding movement of the first and the second valve member member is triggered. As a result, an operative connection for transmitting the tensile force or the longitudinal movement of the valve member is created, which allows the compensation of the angular error without exerting substantial lateral forces. Due to the hydraulic coupling created in this way, a further connection between the first and the second valve member element is not necessary, in particular, no positive or frictional connection is necessary.

Characterized in that an annular gap is present between an outer surface of the end region of the first valve member element and a first inner surface of the coupling element, a compensation of an angular error between a longitudinal axis of the first valve member element and a longitudinal axis of the coupling element and thus in particular a longitudinal axis of the second valve member element is made possible. In particular, the clearance ensured by the annular gap makes it possible to tilt the first valve element element relative to the coupling element, without having to apply a force for deforming the coupling element from the guides of the valve element. Since no deflection of the coupling element or the first valve member element necessary to compensate for the angular error are, they can be made of resistant materials of high rigidity, such as steel, in particular hardened steel. As a result, an operative connection between the first and the second valve member element is provided, which allows actuation of the valve member for opening and closing the injection port, however, for example, deformations and guiding errors of the valve member elements can be tolerated.

Preferably, the length of the annular gap measured in the longitudinal direction and the width of the annular gap are dimensioned such that an angular error of at least approximately 2 '(2 arc minutes) can be compensated. This corresponds to a deviation of, for example, about 0.01 mm to a length of 15 mm. As a result, based on manufacturing tolerances achievable with conventional means tolerances the resulting angular error can be compensated usually, creating a cost-effective production is possible.

When a pressure force in the longitudinal direction acts on the valve member for closing the at least one injection opening or for triggering a corresponding acceleration of a valve member element, the pressure fluid can escape through the annular gap. In particular, when the pressure force acts for longer periods than the tensile force, it may be provided that the pressure fluid escapes so much from the interior of the coupling element, that the end portion of the first valve member element in contact with an end portion of the second valve member element or a correspondingly formed stop of the coupling element passes. As a result, a secure transmission of the pressure force is possible.

According to a particularly preferred embodiment of the invention, the valve member on all sides or practically on all sides of the pressurized fluid umber; at least during the injection process, the valve member is surrounded on all sides or practically on all sides by the pressurized fluid. In particular, when the valve member is surrounded on all sides or practically on all sides by the pressurized fluid, occurs in the execution of an injection process, the situation that within the valve member a Traction acts. The annular gap is dimensioned such that upon application of a tensile force to the valve member in the interior of the coupling element, a negative pressure is formed; the negative pressure is used to transmit the tensile force between the first and second valve member element. Thus, no further connection between the first and the second valve member element is necessary to transmit the resulting in the execution of the injection process tensile force. The fact that the valve member can be surrounded on all sides or practically on all sides by the pressure fluid, a particularly simple design is possible; In particular, no pressure-tight sealing of the valve member is required.

Preferably, the first and second valve member members are hydraulic only in the longitudinal direction when a tensile force is applied, i. by the resulting negative pressure, coupled together. By eliminating further connections between the first and the second valve member element a simple manufacture and assembly and an improved compensation of the angular errors are made possible.

In a particularly advantageous manner, the annular gap is dimensioned such that upon application of the tensile force to the valve member such a small amount of the pressurized fluid penetrates into the interior of the coupling element, that there is no significant damping of the movement of the valve member. In particular, the movement of a nozzle-remote of the first or the second valve member element is thus transferred to a nozzle closer of the two interconnected valve member elements, without substantial relative movement of the two valve member element takes place underneath each other. Such a relative movement would reduce the control of the injection process, in particular the control of the movement of a nozzle needle.

The coupling element is preferably designed such that it is deformed under the effect of the negative pressure, so that the width of the annular gap to maintain the negative pressure is reduced. For this purpose, the coupling element can, at least in a partial region which surrounds the end region of the first valve element. limb member encloses, be formed thin-walled. Due to the prevailing in the interior of the coupling element negative pressure compared to the external pressure of the pressure fluid, the coupling element is compressed in the micrometer range, so that the width of the annular gap is reduced and the inflowing amount of the pressurized fluid is reduced. Due to the deformation, the coupling element can even enclose the end region of the first valve member element in a sealing manner under the effect of the negative pressure. As a result, the transmission of a lifting movement of the valve member is further improved. In particular, the pressurized fluid is pressurized liquid fuel or fuel that can be supplied via a high-pressure connection of the valve housing. Characterized in that the fuel to be injected is used as the pressurized fluid for mediating the coupling between the first and the second valve member element, a particularly simple and safe execution of the injection process is achieved.

Preferably, the injection valve according to the invention is designed as an injection valve of an injection system with a common high-pressure supply. Such an injection system is characterized by a high-pressure pump which provides the fuel to be injected at a high pressure, for example 100 bar to over 2500 bar, of a plurality of injection valves via a common high-pressure line system. Such injection systems are therefore also referred to as common rail systems. The high-pressure supply of the injection valves in such an injection system is known per se. The injectors effect an intermittent injection of the high pressure fuel into the combustion chamber of an internal combustion engine, the injections typically being controlled by an electronic engine controller. Furthermore, it is preferred that the valve member is guided in a central bore of the valve housing and the fuel from the high pressure port through the central bore can be fed to the Einspritzöffhung. Because of that, the fuel In the same space of the valve housing, in which the valve member is arranged, is guided to the injection port, can be ensured in a simple manner that the valve member, in particular the coupling element, is surrounded by pressurized fuel and thereby even when applying a tensile force an operative connection between consists of the first and the second valve member element due to the resulting in the interior of the coupling element due to the tensile force negative pressure. The fact that the valve member and the fuel are guided in a central bore, a simple and inexpensive production is possible.

According to a preferred embodiment of the invention, the first inner surface of the coupling element and / or the outer surface of the end region of the first valve member element seen in longitudinal section is formed crowned. Seen spatially, the first inner surface of the coupling element is thus spindle-shaped or the outer surface of the end region of the first valve member element is barrel-shaped. The deviations from a cylindrical, in particular circular cylindrical shape can be dimensioned such that a compensation of angular errors to the desired extent, however, the width of the annular gap, in particular in a central region is sufficiently low to the inflow of pressurized fluid into the interior of the coupling element so far to limit that maintaining a sufficient negative pressure for a time sufficient for actuation of the valve member is ensured or that a sufficiently small amount of fluid penetrates into the interior, so that no significant damping occurs. As a result, a compensation of larger angle errors while maintaining the operative connection between the first and a second valve member element can be made possible.

According to a further preferred embodiment, the first inner surface of the coupling element and / or the outer surface of the end region of the first valve member member may be formed frusto-conical. In addition, a crown may be superimposed in the manner described. This can also equal larger angle error while maintaining the operative connection are made possible.

Furthermore, it can be advantageously provided that between the end region of the first valve member element and an end region of a second valve member element, i. in an interior of the coupling element, at least one spacer is arranged or can be arranged. The at least one spacer is formed in particular for transmitting a compressive force between the first and the second valve member element. As a result, length deviations of the valve member elements can be compensated. It can also be provided that according to the dimensions and the number of spacers different length coupling elements can be used.

According to one embodiment of the invention, the coupling element is fixedly connected to a second valve member element, for example shrunk or connected by soldering, or formed integrally with the second valve element element, i. integrated with this into a component. As a result, a particularly simple, firm and secure connection for the transmission of tensile and compressive forces within the valve member is achieved.

Alternatively, the coupling element may enclose an end region of a second valve element element such that an annular gap for compensating an angular error between a longitudinal axis of the second valve element element and a longitudinal axis of the coupling element is formed between an outer surface of the end region of the second valve element element and a second inner surface of the coupling element. The coupling element is connected according to this embodiment, in particular in a corresponding manner with the second valve member element as with the first valve member element. As a result, the first and the second valve member element are coupled to each other such that both in the connection of the first and in the connection of the second valve member element with the coupling element, a compensation of an angle error is made possible. This can be compensated for a total of a larger angle error, it can but also a radial offset of the axes of the first and second valve member element are compensated.

According to a further preferred embodiment of the invention, the valve member comprises more than two valve member elements, which are operatively connected by a plurality of coupling elements. As a result, a simpler and more cost-effective production than when using correspondingly longer undivided valve member elements is possible. Furthermore, a larger angle error and in particular a larger radial offset can be compensated thereby.

In particular, the valve member may comprise a valve member formed as a nozzle needle, which is designed to open and close the injection opening. At the end opposite the nozzle needle, the valve member has a control part, which can be driven via a control device which can be actuated by means of an actuator. The control part is thus displaced due to the action of the actuator and drives the valve member to its movement in the longitudinal direction. For this purpose, suitable actuators or control devices are known per se. In particular, the actuator may have a control unit, such as an electronic engine control, electromagnetically operable valve that controls the flow of pressurized fluid from a control room. When the pressurized fluid flows out of the control chamber, the control part follows, so that the valve member releases the injection opening; On the other hand, when the pressurized fluid fills the control space, the valve member is moved in the reverse direction by a spring for closing the injection port.

The valve member may comprise only two valve member elements, namely the valve member element designed as a nozzle needle and the control part, wherein these two valve member elements are in operative connection via a coupling element described above; However, the valve member may also have more than two Ventilgliedele- elements, more than one coupling element of the type described may be present. The coupling element or the coupling elements can or can NEN also integrated into a valve member element, ie be integrally formed with this.

Further embodiments of the invention are evident from the priority-based patent application DE 10 201 1015 753.0, which is incorporated by reference in the present application.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Further aspects of the invention will become apparent from the following description of a preferred embodiment and the accompanying drawings. It shows in a schematic representation:

1 shows a longitudinal section of an embodiment of an injection valve according to the invention. Fig. 2 is an enlarged detail of Fig. 1;

3 shows an enlarged view in longitudinal section of the geometric relationships on a coupling element according to the embodiment shown in Figures 1 and 2 in a misalignment ..;

Fig. 4 is a cross-sectional view taken along the plane D-D shown in Fig. 3;

5 shows a coupling element according to a further embodiment of the invention in longitudinal section;

6 shows a coupling element according to a further embodiment of the invention, also in longitudinal section; 7 shows a coupling element according to a further embodiment of the invention in longitudinal section; Fig. 8 is a coupling element according to a further embodiment of the invention in longitudinal section.

In the embodiment of the invention shown in Fig. 1, an injection valve comprises a valve housing 18, a valve housing 18 associated with this and a holding member 16 fixedly connected valve seat member 13 and an actuator 1. The valve seat member 13 has an injection port 14; There may also be several injection openings. The injection opening 14 can be closed by a seat part 12a of a valve member El arranged inside the valve housing 18. The valve member El is formed thin and elongated and at least partially disposed in a central bore 17 of the valve housing 18, wherein it is slidably guided in its longitudinal direction; For this purpose, suitable guides may be present (not shown). The valve member El comprises, in addition to the seat part 12a, a spacer part 11a and a control part 8, which are coupled to one another via coupling elements 9a, 9b. The seat part 12a, the spacer I Ia and the control part 8, for example, each have a diameter of about 4 mm and strung together give a total length of the valve member El of about 130 mm. The valve housing 18 has a high-pressure fuel connection 10 through which liquid fuel under high pressure is supplied. The high-pressure fuel connection 10 is connected to the central bore 17, through which the fuel reaches the injection opening 14. The valve member El is thus largely surrounded by the fuel under high pressure.

At that end of the valve housing 18, which is opposite to the valve seat member 13, a not shown in Fig. 1 in detail actuator 1 is arranged, which may for example comprise an electromagnet. The actuator 1, together with a sealing seat 2, an outlet throttle 3, a control chamber 4, an inlet throttle 5, a spring 6 and an associated spring plate 7, a control device Sl. The end face 21 of the control part 8 limits the effective area of the control chamber 4. The actuator 1 can be caused via an unillustrated control unit to release the sealing seat 2. It can now escape under pressure fuel through the outlet throttle 3 from the control chamber 4, which can flow virtually pressure-free via a symbolically illustrated return line back into a tank 22. Since the control chamber 4 is connected to the fuel high-pressure connection 10 only via an inlet throttle 5, the pressure in the control chamber 4 drops until the injection valve member E 1, comprising the control part 8, spacer part 11a, seat part 12a and the two coupling elements 9a, 9b, moved out of his seat 15. This fuel is injected into a combustion chamber, not shown in Fig. 1. If the injection is to be terminated, the actuator 1 is caused by the control unit to close the sealing seat 2. Thus, no fuel can escape through the outlet throttle 3 more and the pressure in the control chamber 4 increases. With the help of the spring 6, which is supported with its spring plate 7 on the injection valve member El, this is pressed into its seat 15 and the injection is stopped.

The operation of the actuator 1 or the control device Sl is described here only by way of example. There are also known other embodiments of the actuator 1 and the control device Sl for controlling the movement of the valve member El, which can also be used in the context of the present invention.

Fig. 2 shows a coupling element 9b, whereby the spacer 1 la and the seat part 12a are operatively connected. The coupling element 9b is at least as firmly connected to the spacer 1 la, that the function of mediating the movement of the spacer I Ia is guaranteed to the seat part 12a. The coupling element 9b could, for example, be shrunk, pressed or soldered onto the spacer part 11a, although other types of connection are also conceivable. On the side of the Seat part 12a, the coupling element 9b has an inner surface which is formed as a substantially circular cylindrical annular surface 19a and which encloses with a clearance fit the seat part 12a at its end portion having a substantially circular cylindrical outer surface 24a. Between the outer surface 24a and the annular surface 19a thus an annular gap 26 is present. The clearance fit is sufficiently tight or the annular gap 26 sufficiently narrow that at a stroke in the opposite direction to the seat 15 (see Fig. 1) in the interior 20 of the coupling element 9a at least one such negative pressure sets that with the resulting force and if necessary, with a frictional force acting between annular surface 19a and outer surface 24a, the seat part 12a is pulled out of its seat 15.

The annular gap 26 may initially be slightly wider than is necessary for a sufficiently long maintenance of the negative pressure. The pressure drop occurring at the beginning of the stroke movement in the interior 20 may be sufficient to deform the coupling element 9b such that the clearance is reduced or the annular gap 26 becomes narrower. As a result, the clearance can be sufficiently sealed, so that a sufficient negative pressure is maintained long enough to pull the seat part 12a out of the seat 15 (see Fig. 1). For this purpose, the coupling element 9b is preferably made thin-walled at least in the region of its annular surface 19a. However, the clearance must be at least so tight that at the start of the stroke movement sufficient for the deformation pressure drop comes about. In Fig. 2, the ideal case is shown, in which the longitudinal axes of the seat part 12a and spacer I Ia match and form a common longitudinal axis 23; The coupling element 9b may also be rotationally symmetrical, so that a longitudinal axis of the coupling element 9b also coincides with the longitudinal axis 23. However, for example due to inaccuracies in the manufacture of the valve member elements 8, 11a, 12a or of the valve housing 18, deviations may arise between the individual axes, which are compensated according to the invention. This will be explained below with reference to FIGS. 3 and 4. In Fig. 3, the lower part of the coupling element 9b and the end portion of the seat part 12a, which has the outer surface 24a shown. The spacer 1 la is not shown in Fig. 3. As shown in FIG. 3, the longitudinal axis of the seat part 12a can be tilted by an angle W1 relative to the longitudinal axis of the coupling element 9b, which here coincides with that of the spacer part 1a. As shown not to scale in FIG. 3, the diameter D1 of the annular surface 19a, ie the inner diameter of the coupling element 9b, and the diameter DO of the outer surface 24a of the end region of the seat part 12a are dimensioned such that an annular gap 26 is formed between the annular surface 19a and the outer surface 24a consists. The width of the annular gap is in a symmetrical arrangement 'Λ (Dl -DO).

The angular error Wl, which can be compensated by the connection between coupling element 9a and seat part 12a, is greater, the greater the width of the annular gap 26 and the shorter the length LI of the clearance between the substantially circular cylindrical annular surface 19a and the outer surface 24a , If the length LI of the annular surface 19a is increased in FIG. 3 for a given diameter DO and given angular error Wl, then the diameter D1 of the annular surface 19a and thus the width of the annular gap 26 must increase in order to obtain the angular error W1 without deformation of the coupling element 9b or 9b of the seat part 12a compensate.

In Fig. 4, the situation shown in Fig. 3 is shown as a cross section in the plane D-D. In the plane D-D, the annular gap 26 is unevenly wide over the circumference of the end region of the seat part 12a. For the gap widths S2, S3 measured at two opposing positions (see also Fig. 3):

S2 + S3 = D1 - DO The wider the annular gap 26, ie, the larger S2 and S3 become, the lower the sealing effect of the clearance fit between the annular surface 19a and the outer surface 24a of the end portion of the seat portion 12a. The sealing effect may but do not fall below a certain level to ensure that the pressure in the interior 20 of the coupling element 9b may drop so far during a lifting movement that the seat part 12a can be pulled along with the spacer 1 la. Furthermore, the sealing effect should be sufficiently large, so that during the lifting movement only a small amount of the pressurized fluid flows into the interior 20 of the coupling element 9b and passes between the end region of the seat part 12a and the adjacent end region of the spacer I Ia. The quantity should in particular be so small that no appreciable damping takes place by means of a liquid cushion formed between the end region of the seat part 12a and the spacer part 11a. This should also apply in particular to the reverse movement following the stroke movement, ie when a pressure force is exerted in the valve member El for closing the injection nozzle 14. As a result, an improved control of the movement of the seat part 12a is made possible and a reduction in the Nutzhubs of the seat part 12a and thus a reduction in the flow through the valve seat member 13 and the Einspritzöffhung 14 avoided, which is advantageous especially for multiple injections and correspondingly short driving time of the valve member El , The relative movement of the seat part 12a relative to the spacer part 11a or to the control part 8 should advantageously be so low that the relative quantity reduces the injection quantity at the full load point of the engine by less than 3% for the same control duration of the valve.

The amount of pressure fluid flowing through the annular gap into the inner space 20 of the coupling element 9b per unit of time is approximately proportional to the cube of the width of the annular gap and inversely proportional to the length LI of the clearance fit for a given pressure difference in the simplest case. The combination of the diameter DO, Dl and the length LI is therefore to be chosen so that on the one hand the clearance is tight enough, on the other hand, a compensation of the angular error Wl via an inclined position of the end portion of the seat portion 12a in the annular gap 26 and not or not to a substantial Part of a deformation of the coupling element 9b and the end portion of the seat part 12a, since such a deformation would lead to high side forces on the injection valve member El, which would be problematic for its function. Preferably, the width of the annular gap 26 and the length LI of the annular surface 19a are selected such that an angular error Wl of at least approximately 2 'is permissible. With a width of the annular gap 26 of a maximum of about 2 μπι and a length LI of about 6 mm, such an angle error can be compensated without deformation of the coupling element 9b or the seat part 12a. Such a clearance fit is economical to produce, whereby in this way a sufficiently resilient and sufficiently articulated connection between the spacer 1 la and the seat part 12 a can be achieved in this way. The coupling element 9b can also be designed such that the coupling element 9b is deformed by the negative pressure arising in the interior 20 during a lifting movement and the width of the annular gap 26 is reduced; With an inner diameter D1 of approximately 4 mm, a wall thickness in the relevant region of the coupling element 9b of approximately 0.4 mm may be suitable for this purpose when using non-hardened steel.

In principle, the same considerations apply if the coupling element 9b is firmly connected to the seat part 12a and the spacer part 1a is enclosed by the coupling element 9b to form an annular gap. The spacer 1 la may be operatively connected in the same way by a coupling element 9 a with the control part 8, as shown in Figures 3 and 4 for the connection between the seat part 12 a and spacer 1 la. If the injection valve member El comprises more than one coupling element, as a whole, a radial offset of the axes of the interconnected elements can be compensated. In the further embodiment shown in FIG. 5, the coupling element is designed in one piece with a spacer part Ib. The annular surface 19b is therefore formed by the spacer part Ib. A separate component, which takes over the coupling function, is eliminated. Another embodiment is shown in FIG. Here, a coupling element 9c has two inner surfaces which are each designed as annular surfaces 19c, 19d. As a result, the seat part 12a and the spacer 1 lc are articulated with the head pelelement 9c and connected to each other. As a result, a larger angle error or a radial offset can be compensated.

According to FIG. 7, a spacer 25 can be provided between the spacer part 11a and the seat part 12a, which is enclosed by the coupling element 9b. The spacer may for example consist of hardened steel.

FIG. 8 shows a simplified embodiment. The annular surface 19e simultaneously forms the receptacle for the spacer part ld, so that the coupling element 9d has only a single inner diameter. The outer surface 24 b of the end portion of the seat portion 12 b is adapted to the corresponding diameter to form an annular gap 26.

For the sake of clarity, not all figures are shown in all figures. Reference numerals not explained to a figure have the same meaning as in the other figures.

LIST OF REFERENCE NUMBERS

El valve member

Sl control device

1 actuator

2 sealing seat

3 outlet throttle

4 control room

5 inlet throttle

6 spring

7 spring plate

8 control part

9a, 9b, 9c, 9d coupling element

10 high-pressure fuel connection 1 la, l Ib, l lc spacer

12a, 12b seat part

13 valve seat element

14 injection opening

15 seat

16 holding part

17 Central hole

18 valve housing

19a, 19b, 19c, 19d, 19e annular surface 20 interior

21 face

22 tank

23 longitudinal axis

24a, 24b outer surface

25 spacer

26 annular gap

Claims

claims

1. injection valve for fuel injection into a combustion chamber of an internal combustion engine with a valve housing (18) and in this opening and closing at least one injection port (14) in one

Longitudinally displaceably arranged valve member (El), which comprises a plurality of longitudinally successively arranged valve member elements (8, I Ia, I Ib, 1 1c, 12a, 12b) and at least one coupling element (9a, 9b, 9c, 9d), characterized characterized in that the coupling element (9a, 9b, 9c, 9d) encloses an end portion of a first valve member member such that between an outer surface (24a, 24b) of the end portion of the first valve member member and a first inner surface of the coupling member (9a, 9b, 9c, 9d ) an annular gap (26) remains to compensate for an angular error (Wl) between a longitudinal axis of the first valve member element and a longitudinal axis of the coupling element (9a, 9b, 9c, 9d), and that the valve member (El), in particular the coupling element (9a, 9b , 9c, 9d), at least partially surrounded by a pressure fluid and the annular gap (26) is dimensioned such that upon application of a tensile force to the valve member (El) in an interior (20) of the coupling element ( 9a, 9b, 9c, 9d) a negative pressure for the kinematic coupling of the first and a second valve member element is formed.

2. Injection valve according to claim 1, characterized in that the length measured in the longitudinal direction and the width of the annular gap (26) are dimensioned such that an angular error (Wl) of at least 2 'can be compensated.

3. Injection valve according to claim 1 or 2, characterized in that the valve member (El) is at least temporarily surrounded on all sides by the pressure fluid.

4. Injection valve according to one of claims 1 to 3, characterized in that the first and the second valve member element are coupled in the longitudinal direction only hydraulically with each other.

5. Injection valve according to one of claims 1 to 4, characterized in that the annular gap (26) is dimensioned such that upon application of the tensile force to the valve member (El) in the interior (20) of the coupling element (9a, 9b, 9c, 9d) penetrates such a small amount of the pressurized fluid that there is no significant damping of the movement of the valve member.

6. Injection valve according to one of claims 1 to 5, characterized in that the coupling element (9a, 9b, 9c, 9d) is designed such that it deforms under the action of the negative pressure and the width of the annular gap (26) for maintaining the negative pressure is reduced.

7. Injection valve according to one of claims 1 to 6, characterized in that the pressurized fluid is pressurized fuel which can be supplied via a high pressure port (10) of the valve housing (18).

8. An injector according to claim 7, characterized in that the valve member (El) in a central bore (17) of the valve housing (18) is guided and the fuel from the high pressure port (10) through the central bore (17) to the injection port (14) can be fed.

9. Injection valve according to one of the preceding claims, characterized in that the first inner surface of the coupling element (9a, 9b, 9c, 9d) and / or the outer surface (24a, 24b) of the end portion of the first valve member element is formed crowned.

10. Injection valve according to one of the preceding claims, characterized in that between the end region of the first valve member element and an end region of a second valve member element at least one spacer (25) is arranged.

1 1. Injection valve according to one of the preceding claims, characterized in that the coupling element (9a, 9b, 9c, 9d) is fixedly connected to a second valve member element or formed integrally therewith.

12. Injection valve according to one of claims 1 to 10, characterized in that the coupling element (9c) an end portion of a second Ventilgliedele- element encloses such that between an outer surface (24a) of the end portion of the second valve member element and a second inner surface of the coupling element, an annular gap (26) remains to compensate for an angular error between a longitudinal axis of the second valve member element and a longitudinal axis of the coupling element (9c).

13. Injection valve according to one of the preceding claims, characterized in that the valve member (El) a plurality of coupling elements (19a, 19b, 19c, 19d, 19e) and more than two valve member elements (8, I Ia, I Ib, 11c, 12a , 12b).

14. Injection valve according to one of the preceding claims, characterized in that the valve member (El) by a at one of the injection port (14) opposite end and by means of an actuator (1) operable control device (Sl) is displaceable.