DE102007044355A1 - Control valve for a fuel injector and fuel injector - Google Patents

Abstract

The invention relates to a control valve (25) for a fuel injector with a control sleeve (24) defining a pressure chamber (23) and which is movably mounted in the longitudinal direction, wherein the control sleeve (24) on the front side has a sealing surface (36) it cooperates with a valve body (28) formed, outer truncated cone-shaped control valve seat (27). According to the invention, it is provided that the cone angle of the control valve seat (27) is selected from a value range between 120 ° and 170 °. Furthermore, the invention relates to a fuel injector.

Description

State of the art

The The invention relates to a control valve for a fuel injector according to the preamble of claim 1 and a Fuel injector according to claim 10.

From the EP 1 612 403 A1 is a fuel injector with a pressure-balanced in the axial direction control valve known. The control valve has an adjustable by means of an electromagnetic actuator in the axial direction between a closed position and an open position control sleeve which is guided on a, passing through the control sleeve guide pin. In this case, the guide pin is formed integrally with a valve body on which the control valve seat is arranged for the control sleeve. A disadvantage of the known control valve is that the control valve seat is expensive to manufacture due to its poor accessibility and that a comparatively large minimum diameter of the guide pin must not be exceeded for reasons of strength, since the supply of fuel from a control chamber via a provided in the valve body drain passage which is cut perpendicularly inside the guide pin by transverse bores.

When the applicant's in-house state of the art is an optimized one Control valve known. This, in the axial direction Rich also pressure balanced Valve has a control sleeve which has a pressure pin enclosing the inside of the control sleeve arranged, connected to the control chamber pressure chamber in the axial Seals direction. The pressure pin is not in one piece formed with the valve body, on which also the control valve seat is arranged, but as separate from the valve body Component extending in the axial direction at one of the control valve seat spaced injector component, in particular spring assisted, is supported. This allows an improved Accessibility of the control valve seat and thus a simplified Manufacturability. In addition, strength problems are avoided. In experiments with the in-house control valve it was found that both in a conical seat formed as a control valve seat with a Cone angle of 90 ° as well as a flat seat (cone angle = 180 °) trained control valve seat when striking the control sleeve on the control valve seat to a relative movement the valve sleeve transverse to its longitudinal extent comes relative to the control valve seat. It was observed that in a trained as a conical seat control valve seat a cone angle of 90 ° of the sealing surface the control sleeve having portion of the control sleeve elastically adjusted radially outwards, d. H. expanded whereas, in the case of a flat seat, it becomes a radial adjustment comes inside. This slip between the control sleeve and control valve seat leads to increased wear the control sleeve and the control valve seat and thus to Formation of a pressure step on the control sleeve, which is an undesirable force acting in the opening direction of the control sleeve effected on the control sleeve.

Disclosure of the invention

Technical task

Of the Invention is based on the object, a control valve (servo valve) to propose minimizing signs of wear are. Furthermore, the object is a correspondingly optimized Propose fuel injector.

Technical solution

These Task is with respect to the control valve with the characteristics of Claim 1 and with regard to the fuel injector with the features of Claim 10 solved. Advantageous developments of the invention are given in the subclaims. In the context of Invention also fall all combinations of at least two of in the description, the claims and / or the Figures revealed features.

The invention is based on the idea of selecting the cone angle of the external truncated-cone-shaped control valve seat so that the stop slip of the sealing surface region of the control sleeve is minimized relative to the control valve seat or, in the optimum case, completely avoided. It has surprisingly been found that when the cone angle of the control valve seat is selected from a value range between about 120 ° and about 170 °, a positive effect with regard to minimizing the stop slip across the length of the control sleeve results. This effect can be attributed to the fact that by a cone angle from a range of values between about 120 ° and about 170 °, depending on the dimensions and geometric design of the sealing surface having sealing region of the control sleeve must be selected, a radially outwardly acting force component in the Sealing region of the control sleeve is induced, which counteracts the Nachinnengleiten the sealing area, as this is observed in a flat seat. The fact that a cone angle of 120 ° is not exceeded, it is achieved that the induced, radially outwardly acting force component is lower than in a conical control valve seat with a cone angle of 90 °, whereby, a (too large) radially outwardly acting, elastic deformation or movement of the control sleeve in its sealing area relative to the control valve seat surprisingly avoided becomes. For the purposes of the invention, the term "cone angle" is understood to mean the angle that two lateral surface sections (oblique sections) of the control valve seat enclose in a plane receiving the longitudinal central axis of the control valve seat. In other words, the cone angle is the doubled angle between the lateral surface of the outer frusto-conical control valve seat and the longitudinal center axis of the control valve seat.

It is within the scope of the invention that the control sleeve guided on its inner circumference and / or on its outer circumference is. It can be used to guide the control sleeve its inner circumference with the control valve seat having Component integral guide pin provided be, who passes through the control sleeve. Alternatively it is it is conceivable that arranged in the control sleeve, a pressure pin is as the valve body having the control valve seat Separate component is formed and positioned so firmly in position is that he will take over the leadership of the control sleeve can. Preferred is an embodiment in which in the Control sleeve only one at one of which the STEU erventilsitz having valve body, spaced component abstützender Pressure pin is provided and the control sleeve on her Outside circumference is guided. Furthermore, it is in the frame the invention, the control sleeve alternatively by means of a Piezoaktuators or an electromagnetic actuator between its closed position, in which it rests on the control valve seat and an open position spaced from the control valve seat, in the control chamber with a low pressure area of the injector hydraulically connected, is adjustable.

ever according to geometric design of the control sleeve, in particular in their sealing surface having sealing area must an optimum cone angle for the specific application the control valve seat from the range between about 120 ° and about 170 ° can be selected. It turned out that cone angle from a value range between 130 ° and 170 ° are preferable. Especially preferred are cone angles from a value range between 140 ° and 170 °. In tests, particularly good results were obtained in the combination a seat diameter (sealing diameter) of 2.5 mm and a Cone angle of 140 ° achieved. Particularly advantageous the choice of a cone angle from a value range between 150 ° and 170 °, preferably from a range of values exposed between 155 ° and 160 °. Especially for a seat diameter (sealing diameter) of 1.8 mm is a cone angle of the control valve seat of 160 ° optimal.

Prefers is an embodiment in which the sealing surface, the with the outer cone-shaped control valve seat cooperates, on an inner cone-shaped end portion the control sleeve is formed, the sealing surface So is itself innenkonusförmig. This allows Wear phenomena are further minimized.

to Realization of a sealing edge with a minimum radial extent is an embodiment of advantage, wherein the inner cone angle of the sealing surface having inner cone (something) larger is selected as the cone angle of the external truncated cone Control valve seat.

It has proved to be particularly advantageous when the angular difference between the inner cone angle and the sealing surface having Section of the control sleeve from a range between about 1 ° and about 10 ° is selected. Especially preferred is an about 2 ° to 9 ° larger inner cone angle as the cone angle of the control valve seat. Especially optimized Results in terms of wear and tightness of the control valve in the closed state were with an angular difference between inner cone angle and cone angle of the control valve seat obtained from a range of values between 3 ° and 6 °.

Especially preferred is an embodiment of the control valve as in the axial direction pressure compensated valve, so a valve, on the control sleeve in the closed state no in axial direction, resulting adjustment forces Act. This can be realized in particular by the fact that the Sealing surface frontally directly to the inner peripheral wall the control sleeve adjacent and from this in radial Direction outward and in the axial direction, ie in Direction of the control valve seat extends. In other words, borders the seat line (sealing line), with the control sleeve with the external truncated cone-shaped control valve seat cooperates on the inner circumference of the control sleeve. The inner diameter the sealing line corresponds to the inner diameter of the control sleeve.

Around the maximum extent of which is due to wear in the course the time increasing sealing surface limit, an embodiment is preferred in which at the sealing surface having sealing area in the radial Direction a ring surface connects, the preferred in an imaginary, transverse to the longitudinal extent of the control sleeve arranged level lies. It is within the scope of further education, that this, limiting the maximum extent of the sealing surface Ring surface with the transverse to the longitudinal extent of the Control sleeve extending, imaginary plane an angle from a value range between about -20 ° and about + 20 °.

The invention also leads to a Kraftst Offinjektor for injecting fuel into a combustion chamber of an internal combustion engine. This has a designed according to the concept of the invention, preferably in the axial direction pressure compensated control valve with a control sleeve which cooperates with an outer truncated cone-shaped control valve seat having a cone angle from a value range between 120 ° and 170 °. By opening the control valve, ie by lifting the control sleeve of the control valve seat operatively connected to a one-piece or multi-part injection valve element control chamber is connected to an injector return, so that the fuel pressure in the control chamber drops rapidly and the injection valve element lifts from its valve seat and fuel through at least one Nozzle hole opening can flow into the combustion chamber of the internal combustion engine. In this case, an embodiment is preferred in which the control sleeve is operatively connected to an armature plate, that is formed integrally therewith or, in particular form-fitting, is connected thereto, wherein the armature plate cooperates for adjusting the control sleeve with an electromagnetic actuator.

Brief description of the drawings

Further Advantages, features and details of the invention will become apparent the following description of preferred embodiments as well as from the drawings. These show in:

1 : An incomplete illustration of a fuel injector with a control sleeve having a control valve and

2 : An enlarged view of a possible design of the control valve seat.

embodiments the invention

In The figures are the same components and components with the same Function marked with the same reference numerals.

In 1 is a common rail injector trained fuel injector with the fuel supply components shown schematically in longitudinal section. The fuel injector comprises a holding body 1 and a nozzle body 2 passing through a clamping nut 3 clamped together. Inside the holding body 1 and the nozzle body 2 is a two-part injection valve element 3 mounted longitudinally displaceable. The injection valve element 3 consists of a nozzle needle 4 in the nozzle body 2 is arranged longitudinally displaceable and a control rod 5 , which are longitudinally displaceable within the holding body 1 is arranged.

The nozzle needle 4 controlled by their longitudinal movement, the opening of at least one injection port 6 , The fuel becomes the injection ports 6 from the nozzle room 7 fed to the nozzle needle 4 surrounds and the via an inlet channel 8th can be filled with fuel under high pressure. Moves the nozzle needle 10 from the injection ports 6 away and thus moves into its open position, fuel, substantially under rail pressure, from the nozzle chamber 7 over the injection openings 6 injected into a combustion chamber, not shown in the drawing of an internal combustion engine. On the other hand, is the nozzle needle 10 in their closed position, ie in abutment with a valve seat, so are the openings 6 through the nozzle needle 4 locked.

The control rod 5 is in a longitudinal bore 9 within the holding body 1 added. The control rod 5 lies over a pressure piece 10 at the nozzle needle 4 within a low-pressure space 11 , which is connected via a channel, not shown, to the injector return, so that the control rod 5 synchronous with the nozzle needle 4 moved in the longitudinal direction. At the nozzle body 2 facing end is the control rod 5 from a closing spring 12 surrounded on the one hand in a paragraph on the holding body 1 supported and on the other hand on the pressure piece 10 , so by the force of the closing spring 12 the pressure piece 10 in the direction of the nozzle needle 4 and thus the nozzle needle 4 is subjected to force in its closed position.

To supply the fuel under high pressure is a high pressure pump 13 provided the fuel from a reservoir 14 compressed and a high-pressure accumulator 15 (Rail) supplies, in which the fuel is kept under high pressure. Via a high pressure line 16 and a high pressure connection 17 , which is formed on the fuel injector, the high-pressure fuel is supplied to the fuel injector and in the manner described via the injection openings 6 injected into the combustion chamber of the internal combustion engine.

With his the nozzle needle 4 opposite end limits the control rod 5 a control chamber 18 that have an inlet hole 19 with inlet throttle 20 with the inlet channel 8th connected is. The control chamber 18 is via a drainage channel 21 with outlet throttle 22 with a pressure room 23 connected. The pressure room 23 is radially within an axially adjustable control sleeve 24 a control valve 25 (Servo valve) arranged. The control sleeve 24 acts with an external frusto-conical control valve seat 27 that is attached to a valve body 28 is trained. Inside the control sleeve 24 is a push pin 29 arranged as of the valve body 28 Separate component is formed and moving in the axial direction in the drawing plane supported at the top of a component, not shown. The pressure pin 29 serves in the embodiment shown to guide the control sleeve 24 in the axial direction. Additionally or alternatively, a guide for the control sleeve 24 be provided on its outer periphery.

In the embodiment shown, the control sleeve 24 integral with an anchor plate 30 formed with an electromagnetic actuator 31 interacts, the kind that the anchor plate 30 and thus the control sleeve 24 with energized electromagnetic actuator 31 be moved up in the drawing plane, allowing fuel from the pressure chamber 23 in a low pressure area 32 the fuel injector and from there to a return 33 can flow through the later to be explained control amount of fuel back to the reservoir 14 is supplied. To close the control valve 25 becomes the energization of the electromagnetic actuator 31 interrupted and a tax closing spring 34 pushes the control sleeve 24 in the axial direction in the plane of the drawing down on the control valve seat 27 ,

To initiate an injection process becomes the electromagnetic actuator 31 of the control valve 35 energized. This raises the control sleeve 24 from their external frustoconical control valve seat 27 starting, causing fuel from the control chamber 18 through the drainage channel 21 with outlet throttle 22 and the pressure room 23 radially between the lower end face of the control sleeve 24 and the control valve seat over into the low pressure area 32 and thus to the return 33 can flow. The flow cross sections of the outlet throttle are 22 and the inlet throttle 20 , about which continues to fuel in the control chamber 18 nachströmt, so coordinated that a net outflow (tax amount) of fuel in the low-pressure area 32 and from there into the return 33 results. As a result, the pressure within the control chamber decreases 18 rapidly, which causes the injection valve element 3 , supported by the high-pressure fuel in the nozzle chamber 7 moved in the axial direction in the plane of the drawing up and the fuel flow through the injection openings 6 releases into the combustion chamber of the internal combustion engine.

To stop the injection process, the energization of the electromagnetic actuator 31 interrupted, leaving the control sleeve 24 from the control closing spring 34 on her control valve seat 27 is moved. Through the through the inlet throttle 20 in the control chamber 18 As fuel flows, the pressure in the control chamber increases 18 rapidly, so that the injection valve element 3 moved down to its valve seat in the drawing plane and the fuel flow through the injection ports 6 thus interrupting.

In 6 is a possible embodiment of the seat portion of the control valve 25 shown enlarged. You can see the control sleeve 24 in which the pressure pin 29 is absorbed and thus by the control sleeve 24 radially outside limited pressure chamber 23 seals up in the axial direction in the plane of the drawing and absorbs the compressive forces. Evident is also the frontal sealing area 35 the control sleeve 24 with its annular sealing surface 36 , which with the external truncated cone-shaped control valve seat 27 interacts.

The drainage channel can also be seen 21 , from the fuel from the control chamber into the pressure chamber 23 can flow. The cone angle α of the control valve seat 27 is about 120 ° in the embodiment shown. Preference is given to an even greater design of the cone angle, in particular of about 160 °. The cone angle is formed by the lateral surface 37 of the control valve seat 27 More specifically, two lying in a longitudinal center axis L of the control valve seat receiving plane lying portions of the lateral surface 37 , By selecting the cone angle α is a slip when hitting the control sleeve 24 in the radial direction relative to the control valve seat 27 at least largely avoided.

As is also apparent 2 results, the sealing surface lies 36 that with the lateral surface 37 cooperates on an inner cone-shaped section 26 with an inner cone angle β of about 125 ° in this embodiment. It is essential that the inner cone angle β of the annular sealing surface 36 comprising section 26 which is attached to the axial process 38 is (slightly) greater than the cone angle α of the outer frustoconical control valve seat 27 ,

It can also be seen that the sealing surface 36 on an annular axial extension 38 on the front side of the control sleeve 24 is arranged, wherein the sealing surface 36 directly from the inner circumference of the control sleeve 24 extending in both the radial and in the axial direction. The axial process 38 with the the sealing surface 36 having inner cone-shaped section 26 goes radially outwardly slightly concave curved in an end face ring surface 39 the control sleeve over, with the annular surface 39 lies in a direction perpendicular to the longitudinal central axis L extending plane. As a result, the maximum extent, which increases by wear increasing sealing surface 36 limited.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1612403 A1 [0002]

Claims (10)

Control valve for a fuel injector with a control sleeve ( 24 ), which has a pressure chamber ( 23 ) and which is movably mounted in the longitudinal direction, wherein the control sleeve ( 24 ) at its front side a sealing surface ( 36 ) with which it is connected to a valve body ( 28 ) formed, outer truncated cone-shaped control valve seat ( 27 ) cooperates, characterized in that the cone angle of the control valve seat ( 27 ) is selected from a value range between 120 ° and 170 °. Control valve according to claim 1, characterized in that the cone angle of the control valve seat ( 27 ) is selected from a value range between 130 ° and 170 °, in particular from a value range between 140 ° and 170 °, preferably from a value range between 150 ° and 170 °, particularly preferably between 155 ° and 165 °. Control valve according to one of claims 1 or 2, characterized in that the cone angle is about 160 °. Control valve according to one of claims 1 to 3, characterized in that the sealing surface ( 36 ) on an inner cone-shaped section ( 26 ) of the control sleeve ( 24 ) is trained. Control valve according to claim 4, characterized in that the inner cone angle of the sealing surface ( 36 ) ( 26 ) is greater than the cone angle of the control valve seat ( 27 ). Control valve according to claim 5, characterized in that the inner cone angle by an angle from a value range between 1 ° and 10 °, in particular between 2 ° and 9 °, preferably between 3 ° and 6 °, is greater than the cone angle of the control valve seat ( 27 ). Control valve according to one of claims 4 to 6, characterized in that the sealing surface ( 36 ) to the inner peripheral wall of the control sleeve ( 24 ) adjoins and extends from this radially outward and in the axial direction. Control valve according to one of claims 4 to 7, characterized in that the sealing surface ( 36 ) on a frontal, annular axial extension ( 38 ) of the control sleeve ( 24 ) is arranged at the radially outwardly an annular surface ( 39 ), which are transverse to the longitudinal extent of the control sleeve ( 24 ) or with an imaginary transverse to the longitudinal extent of the control sleeve ( 24 ) includes an angle from a range between -20 ° and + 20 °. Control valve according to one of the preceding claims, characterized in that the control sleeve ( 24 ), if these at the control valve seat ( 27 ) is applied, is pressure balanced in the axial direction. Fuel injector for injecting fuel into a combustion chamber of an internal combustion engine, in particular a common rail injector, with a control valve ( 25 ) according to one of claims 1 to 10, with which the fuel pressure in one with an injection valve element ( 3 ) Actively connected control chamber ( 18 ) is influenced, wherein the injection valve element ( 3 ) in dependence on the fuel pressure in the control chamber ( 18 ) is adjustable between a closed position and an opening position releasing the fuel flow into the combustion chamber.