EP2235355A1

EP2235355A1 - Fuel injector

Info

Publication number: EP2235355A1
Application number: EP08871441A
Authority: EP
Inventors: Nadja Eisenmenger
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2008-01-23
Filing date: 2008-12-30
Publication date: 2010-10-06
Anticipated expiration: 2028-12-30
Also published as: CN101925734A; RU2010134914A; WO2009092508A1; RU2485344C2; JP5193312B2; CN101925734B; EP2235355B1; DE102008005523A1; JP2011510222A

Abstract

The invention relates to an injector (1) for injecting fuel into a combustion chamber of an internal combustion engine, in particular a common rail injector, with an injection valve element (9) which can be adjusted between a closed position and an open position which allows fuel to flow into the combustion chamber depending on the fuel pressure in a control chamber (11) and a control valve (21) provided in the control chamber (11) having a control valve element (22) adjustable relative to a control valve seat (28) provided on an injector component (13) by means of an actuator (31) guided on the outer circumference thereof by means of a guide component (33). According to the invention, the guide component (33) contacts a second centering surface (39) of eh injector component (13) with a first centering surface (38).

Description

description

title

fuel injector

State of the art

The invention relates to an injector for injecting fuel into a combustion chamber of an internal combustion engine, in particular a common rail injector, according to the preamble of claim 1.

From EP 1 612 403 A1, a common rail injector with a pressure-balanced control valve in the axial direction is known. By means of the control valve, which has a sleeve-shaped control valve element, the fuel pressure can be influenced within a control chamber bounded on the end side by an injection valve element. Due to the variation of the fuel pressure within the control chamber, the injection valve element is adjusted between an open position and a closed position, the injection valve element releasing the fuel flow into the combustion chamber of an internal combustion engine in its open position. In the known injector, the sleeve-shaped control valve is guided with its inner circumference on an axial extension of an injector component which passes centrally through the control valve element and on which the control valve seat is also arranged.

It is also known from DE 10 2006 056 840 Al an injector, wherein the sleeve-shaped control valve element of a pressure-balanced in the axial direction of the control valve is guided by means of a guide member on its outer periphery. In this case, the guide component is designed as a separate component from the control valve seat having injector component. An advantage of this embodiment is that the control valve seat can be processed independently of the guide for the control valve element. If the described control valve is designed with a control valve seat embodied as a flat seat, the radial positioning of the guide component relative to the injector component plays a subordinate role. However, if the control valve seat is to be designed as a conical seat, then this is problematic, since the guide component during assembly must be centered consuming relative to the Injektor component to produce a coaxiality between the conical seat and outer guide for the control valve element.

DISCLOSURE OF THE INVENTION Technical Problem

The invention has for its object to provide an injector with a guided on the outer circumference control valve element, in which automatically adjusts a good coaxiality between the outer guide and the control valve seat during assembly.

Technical solution

This object is achieved with an injector having the features of claim 1. Advantageous developments of the invention are specified in the subclaims. All combinations of at least two features specified in the description, the claims and / or the figures fall within the scope of the invention. The invention is based on the idea of arranging the guide component directly adjacent to the injector component, the contact surfaces between the guide component and the injector component being designed as centering surfaces which are such that the guide component automatically aligns coaxially with the injector component during assembly. As a result, an embodiment of the injector with a conical seat formed as a control valve seat can be realized in a simple manner, the invention is not limited to such an embodiment. A trained according to the concept of the invention injector can be realized, for example, with a flat seat. The injector according to the invention, on the one hand, ensures good accessibility of the control valve seat during production and on an optional coating process and, on the other hand, optimum coaxiality between the outer guide (guide component) and the control valve seat is ensured. In other words, an injector designed according to the concept of the invention combines the advantages of an injector in which a separate guide component is provided in addition to the injector component and an injector in which the control valve element is guided on an axial extension of the injector component. In order to further optimize the precision in the production, it is advantageous if the second centering surface of the injector component and the control valve seat cooperating with the first centering surface of the guide component are manufactured in one clamping. In addition, it is advantageous to manufacture the guide and the centering surface also in one setting in the guide component. As a result, the respective flange impact tolerances of both components are minimized. In order to simultaneously ensure both a high precision with regard to the coaxiality and the squareness of the control valve seat to the outer guide, an embodiment is advantageous in which the two centering surfaces form a combination of inner cone and outer cone, so either the first centering as Innenkonusflache and the second centering as outer cone surface or the first centering surface is formed as an outer cone surface and the second centering surface as Innenkonusflache. Preferably, the inner cone angle and the outer cone angle are selected from an angle range between about 80 ° and about 160 °, wherein other cone angles can be realized.

Of particular advantage is an embodiment in which the inner cone angle and the outer cone angle are chosen such that the combination of the two centering surfaces is not self-locking to allow automatic alignment of the guide member to the injector during assembly.

In a further development of the invention is advantageously provided that the control valve seat is designed as a conical seat. The provision of a conical seat as a control valve seat in the described injector, in which the guide member and the Injektorbauteil each rest on a centering surface, no problem in terms of coaxiality between the control valve seat and outer guide.

The guide member is suitable with appropriate shape for guiding all possible types of control valve elements. However, especially preferred is one Embodiment of the injector, wherein the control valve element is designed such that the control valve is pressure-balanced in the axial direction. In a particularly elegant way this can be realized in that the control valve is designed as a valve sleeve, act on the closed control valve exclusively in the radial direction oriented forces. Forces acting in the axial direction are preferably intercepted by a bolt projecting into the control valve element and by the injector component. In this case, it is possible to carry out the bolt in one piece with the injector component, wherein, however, an embodiment is preferred in which the bolt is designed as a separate component from the Injektorbauteil for facilitated production of the control valve seat, preferably in the axial direction up to an electromagnet assembly of a electromagnetic actuator and / or supported on an injector closure lid.

In order to ensure sufficient positional stability of the guide component relative to the injector component during operation of the injector, an embodiment is preferred in which the guide component is pressed against the end, ie with its centering surface, against the injector component, ie against the centering surface of the injector component. In this case, an embodiment is particularly preferred in which the guide member is pressurized by means of an external thread part, in particular with the end face of a male threaded nut, which preferably cooperates with an internal thread on an injector body, in the axial direction of the injector component. In order to ensure that the two centering surfaces, at least approximately, completely abut each other, an embodiment is preferred in which the outer cone angle and the inner cone angle of the centering surfaces, preferably slightly, are different, so that during assembly, the centering surfaces first in come into contact with a radially outer region or in a radially inner region. By introducing an axial force, for example with the externally threaded nut described above, then the guide member is suppressed, preferably such that the two centering surfaces, at least approximately, abut each other over the entire surface. For this purpose, the guide member and / or the Injektorbauteil must be elastic within limits, to join in the desired deformation during assembly without cracking. In order to design the contact surfaces, ie the centering surfaces, in a more defined manner, at least one of the two centering surfaces, preferably both centering surfaces, can each be divided into at least two surface regions, for example by providing at least one annular groove located between the surface regions. However, it is also conceivable to form one or both centering surfaces as a contiguous surface.

In order to allow for open control valve seat, a flow of fuel from the control chamber to an injector return, is provided in a further development of the invention advantageously that at least one, at least approximately, extending in the radial direction bore is provided as a fuel channel in the guide member. Additionally or alternatively, on the outer circumference of the control valve element and / or on the inner circumference of a Guide bore in the guide member at least one Flächenanschliff be provided so that at least one axial passage for the outflow of fuel from the control chamber is formed.

Brief description of the drawings

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

1: a section of a common rail injector designed as an injector with control valve and

2 shows a perspective, sectional view of a guide component and an injector component.

Embodiments of the invention

In the figures, the same components and components with the same function with the same reference numerals.

In Fig. 1, designed as a common rail injector injector 1 is shown for injecting fuel into a combustion chamber of an internal combustion engine. The injector 1 is supplied via a high-pressure supply line 2 from a high-pressure fuel storage 3 (rail) with high pressure, in this embodiment about 2000 bar, standing fuel, especially diesel or gasoline. The fuel high-pressure accumulator 3 is of one, in particular designed as a radial piston pump, high-pressure pump 4 supplied with fuel from a low-pressure reservoir 5. A low pressure region 6 of the injector 1 is hydraulically connected via an injector return 7 to the reservoir 5. In the injector return 7, a later to be explained control amount of fuel is discharged and fed via the high-pressure pump 4 to the high-pressure circuit again.

The injector 1 has an injector body 8, in which a one-piece or multi-part injection valve element 9 in the axial direction between an open position and a closed position is adjustable. In its open position, the injection valve element 9 releases the fuel flow from a nozzle hole arrangement (not shown) into the combustion chamber of the internal combustion engine (not shown).

With an upper end face 10, the injection valve element 9 delimits a control chamber 11, which is arranged in a blind bore 12 of an injector component 13. Alternatively, the control chamber 11 may for example be delimited by a sleeve component, which is spring-loaded in the axial direction by a spring, not shown, on the injector component 13.

In the control chamber 11 opens a introduced into the injector 13 radial inlet throttle 14, which supplies the control chamber 11 with fuel from a lower, the control chamber 11 receiving, portion of the Injektor- component 13 surrounding pressure chamber 15 (annulus). The pressure chamber 15 is in turn via the high pressure supply line 2 and a supply channel 16 in the injector body 8 with fuel from the fuel High-pressure accumulator 3 supplied. Via a branched off from the supply channel 16 bore 17 fuel flows directly to a nozzle chamber, not shown, from which then 9 fuel can flow into the combustion chamber when the injection valve element is open.

The control chamber 11 is connected to a flow channel 18 extending in the axial direction within the Injektorbauteils 13 with outlet throttle 19 with a valve chamber 20 of a control valve 21 (servo-valve). The valve chamber 20 is bounded in an upper portion radially outwardly by a control valve element 22 designed as a valve sleeve and in the axial direction in the plane of the drawing upwards by a multipart bolt 23 (pressure pin). The bolt 23 is pressurized during operation in the axial direction of the drawing plane upwards, whereby the bolt 23 is supported via a contact plate 24 to an injector 25, which is fixed via a clamping nut 26 on the injector body 8. The control valve 21 is a pressure-balanced valve in the axial direction, since the control valve element 22 formed integrally with an armature plate 27 does not have any hydraulic opening forces when the control valve 21 is closed.

To open the control valve 21, so for lifting the control valve element 22 formed by its injector 13, formed as a conical seat, control valve seat 28, an electromagnet 29 is energized in a holding body 30 of an electromagnetic actuator 31, so that arranged in the drawing plane below the electromagnet 29 Anchor plate 27 and thus the control valve element 22 in the plane of the drawing in axial Direction to be moved upwards. As a result, fuel can flow out of the valve chamber 20 radially below the control valve element 22 via transverse bores 32 in a guide component 33 in the direction of the injector return 7. On its way to injector return 7, the fuel must flow through a central channel 34 in the holding body 30, which is penetrated by the bolt 23. The flow cross sections of the outlet throttle 19 and the inlet throttle 14 are matched to one another such that a net outflow of fuel from the control chamber 11 results, with the result that the force acting on the end face 10 of the injection valve element 9 pressure force drops and the injection valve element 9 of its not shown Injector element seat lifts. The amount of fuel flowing to the injector return 7 is the control quantity of fuel mentioned in the introduction, which is then returned to the high-pressure circuit via the high-pressure pump 4. To end the injection process, the energization of the electromagnet 29 is interrupted, so that the control valve element 22 is moved by a arranged in the channel 34 compression spring 35 back on its trained on the injector component 13 control valve seat 28. By the fuel flowing through the inlet throttle 14 continues in the control chamber 11 fuel, the pressure in the control chamber 11 increases rapidly, whereby the injection valve element 9 is moved in the drawing plane down to its injector seat, not shown, whereby the flow of fuel is interrupted in the combustion chamber of the internal combustion engine ,

As can be seen from Fig. 1, the sleeve-shaped control valve element 22 is guided on its outer periphery. For this purpose, the guide member 33 has a sleeve portion 36 whose inner diameter corresponds to the outer diameter of the control valve element 22 plus a minimum guide clearance. The sleeve portion 36 merges into an abutment portion 37 in its end region, wherein the transverse bores 32 are arranged in the transition region between the sleeve portion 36 and the abutment portion 37. The abutment portion 37 has an inner cone-shaped first centering surface 38 on the side facing the injector component 13, in the plane of the drawing, with which the abutment portion 37 or the guide component 33 rests on an outer cone-shaped second centering surface 39 which abuts the guide component 33 facing, in the drawing plane upper end face of the Injektorbauteils 13 is arranged. The cone angle (inner cone angle and outer cone angle) of the two centering surfaces 38, 39 are identical in the assembled state, but slightly different before assembly, so that in the clamped state of the guide member 33 a full surface contact of the centering surfaces 38, 39 is guaranteed to each other.

In order to ensure a full-surface contact of the guide member 33 on the Injektorbauteil 13, a male screw 40 is provided, which is with its external thread 41 in engagement with an internal thread 42 of the injector body 8 in a region axially between the anchor plate 27 and the Injektorbauteil 13. By rotating the externally threaded nut 40 relative to the injector body 8, the guide member 33 is pressed with its first centering surface 38 against the second centering surface 39 of the Injektorbauteils 13. It can be seen that between the inner circumference of the externally threaded nut 40 and the Sleeve portion 36 of the guide member 33, an annular space 43 is arranged, via the fuel with open control valve 21 from the valve chamber 20 in an overlying armature space 44 and from there into the channel 34 and the Injektorrücklauf 7 can flow.

1, is also formed between an axial extension 45 of the Injektorbauteils 13, at the free end of the control valve seat 28 is formed and the radially outwardly bounded in a lower portion of the valve chamber 20 and the inner circumference of the guide member 33, more precisely of the contact section 37, another annular space 46 is arranged, which is hydraulically connected via the transverse bores 32 with the annular space 43.

In FIG. 2, both the guide component 33 and the injector component 13 are shown in perspective in a cutaway exploded view. Evident is the previously described axial extension 45 of the injector component 13, on the end face of the conical-seat-shaped control valve seat 28 is formed. On a side facing away from the axial extension 45, in the drawing plane lower side, the injector component 13 has an annular shoulder 47, with which it is supported in the axial direction on the injector body 8 (see Fig .. 1).

Radially outside and at axial distance from the axial extension 45 is formed as an annular surface, outer conical second centering surface 39 of the Injektorbauteils 13, which cooperates in the assembled state with the first centering surface 38 of the guide member 33. As can be seen from FIG. 2, the second centering surface 39 is formed from two partial surfaces 48, 49, which are connected via an intermediate surface 48, 49. lying annular groove 50 are spaced from each other. It is also conceivable to form the first centering surface 38 as a continuous surface or consisting of more than two partial surfaces.

Furthermore, it can be seen from FIG. 2 that the inner diameter D ₁ I of the guide component 33 over the greatest longitudinal extent of the sleeve portion 36 is greater than the inner diameter D _{12 of} the guide component 33 in the lowermost portion of the sleeve portion 36 and in the abutment portion 37, so that the guide the control valve element 22 takes place exclusively in the sleeve section 36 and not in the radially wider support section 37.

Claims

claims

1. injector for injecting fuel into a combustion chamber of an internal combustion engine, in particular a common rail Inj ector, with a function of the fuel pressure in a control chamber (11) between a closed position and a fuel flow in the combustion chamber releasing opening position adjustable injection valve element (9 ), and with a control valve (21) associated with a control chamber (11) with a control valve element (22) which can be adjusted by means of an actuator (31) relative to a control valve seat (28) arranged on an injector component (13) and which is guided by a guide component (33). guided on its outer circumference,

characterized,

the guide component (33) rests with a first centering surface (38) on a second centering surface (39) of the injector component (13).

2. An injector according to claim 1, characterized in that the first centering surface (38) is an inner cone surface and the second centering surface (39) is an outer cone surface, or that the first centering surface (38) is an outer cone surface and the second centering surface (39) is an inner cone surface ,

3. Injector according to one of the preceding claims, characterized in that the combination of first centering surface (38) and second centering surface (39) is not self-locking.

4. Injector according to one of the preceding claims, characterized in that the control valve seat (28) is designed as a conical seat.

5. Injector according to one of the preceding claims, characterized in that the control valve (21) is designed as a pressure balanced in the axial direction valve.

6. Injector according to one of the preceding claims, characterized in that the control valve element (22) is designed as a valve sleeve.

7. Injector according to one of the preceding claims, characterized in that the guide member (33), preferably by means of an externally threaded nut (40), the end face against the injector component (13) is pressed.

8. Injector according to one of claims 2 to 7, characterized in that the outer cone angle and the inner cone angle before assembly, preferably slightly, are different.

9. Injector according to one of the preceding claims, characterized in that the guide member (33) and / or the Injektorbauteil (13) are elastic, such that the first and the second centering surface (38, 39), at least approximately, rest against each other over the entire surface ,

10. Injector according to one of the preceding claims, characterized in that the first centering surface (38) and / or the second

Centering surface (39) of at least two partial surfaces

(48, 49) are formed, which are preferably separated from each other via at least one annular groove (50).

11. Injector according to one of the preceding claims, characterized in that in the guide member (33) at least one transverse bore (32) and / or at least one axial channel radially between the guide member (33) and the

Control valve element (22) are / is provided by the / the fuel with the control valve element open

(22) in the direction of an injector return (7) can flow.